The research report should be a detailed narrative explaining the function, biological processes, and localization of the gene product. Citations should be given for all claims.

You should prioritize authoritative reviews and primary scientific literature when conducting research. You can supplement
this with annotations you find in gene/protein databases, but these can be outdated or inaccurate.

We are specifically interested in the primary function of the gene - for enzymes, what reaction is catalyzed, and what is the substrate specificity? For transporters, what is the substrate? For structural proteins or adapters, what is the broader structural role? For signaling molecules, what is the role in the pathway.

We are interested in where in or outside the cell the gene product carries out its function.

We are also interested in the signaling or biochemical pathways in which the gene functions. We are less interested in broad pleiotropic effects, except where these elucidate the precise role.

Include evidence where possible. We are interested in both experimental evidence as well as inference from structure, evolution, or bioinformatic analysis. Precise studies should be prioritized over high-throughput, where available.

Research report: Human RBFOX3 (NeuN) functional annotation (UniProt A6NFN3)

Executive summary

RBFOX3 encodes an RNA-binding protein best known as the NeuN antigen, a widely used marker of post‑mitotic neurons. Multiple independent biochemical studies identified NeuN as RBFOX3 and mapped the NeuN epitope to the RBFOX3 N‑terminus. RBFOX3 is a member of the RBFOX family of splicing regulators that share a single central RNA-recognition motif (RRM) and preferentially bind the cis-element (U)GCAUG, using a position-dependent mechanism to activate or repress alternative exons. Beyond splicing, RBFOX3 can regulate the biogenesis of a subset of microRNAs by binding primary miRNA transcripts and modulating Drosha microprocessor recruitment. In real-world neuroscience and human-brain multi-omics, RBFOX3/NeuN remains foundational for nuclei sorting and cell-type enrichment, but NeuN immunoreactivity is not universal across neuron types and can be transiently lost after injury or toxic exposures, making multi-marker validation essential. (dredge2011neunrbfox3nuclearand pages 1-2, dredge2011neunrbfox3nuclearand pages 2-4, kim2013rbfox3regulatedalternativesplicing pages 1-2, kim2014rbfox3controlsthe pages 1-5, duan2016novelinsightsinto pages 7-9)

1. Identity verification (critical disambiguation)

1.1 Correct target gene/protein

The research target here is human RBFOX3, UniProt A6NFN3, described as “RNA binding protein fox-1 homolog 3,” also known as Fox‑1 homolog C and NeuN antigen. This identity is strongly supported by primary biochemical evidence showing that the NeuN antigen corresponds to RBFOX3: anti‑NeuN immunoprecipitation followed by mass spectrometry produced peptides mapping to RBFOX3, including unique RBFOX3 peptides that allow unambiguous assignment. (dredge2011neunrbfox3nuclearand pages 2-4)

1.2 Relationship to paralogs RBFOX1/2

RBFOX3 belongs to the RBFOX family (RBFOX1/2/3), all characterized by a single RRM and similar motif preferences, but with distinct tissue distributions: RBFOX3 is largely neuron-restricted, whereas RBFOX1 is expressed in neurons as well as muscle/heart and RBFOX2 has broader expression across tissues/cell types. (dredge2011neunrbfox3nuclearand pages 1-2, kim2013rbfox3regulatedalternativesplicing pages 1-2, mukherjee2024torna‐bindingand pages 3-3)

2. Key concepts and definitions (current understanding)

2.1 RBFOX3 is an RNA-binding splicing regulator with a single RRM

RBFOX3/NeuN is an RNA-binding protein that contains a single central RRM/RBD typical of RBFOX proteins, supporting its primary role as a sequence-specific regulator of RNA processing. (duan2016novelinsightsinto pages 3-5)

Visual evidence (domain/isoform schematic): Kim et al. (2013) depict RBFOX3 isoforms and highlight the RRM region and conserved RNP elements. (kim2013rbfox3regulatedalternativesplicing media bb037b32)

2.2 Sequence motif recognition: (U)GCAUG

RBFOX family proteins (including RBFOX3) preferentially bind the canonical RNA element (U)GCAUG. This element is repeatedly implicated as the key cis determinant for RBFOX-dependent splicing regulation and appears in validated targets. (duan2016novelinsightsinto pages 3-5, kim2013rbfox3regulatedalternativesplicing pages 1-2, conboy2017developmentalregulationof pages 1-3)

2.3 Position-dependent splicing regulation

A central mechanistic concept for RBFOX proteins is position-dependent splicing control: binding downstream of an alternative exon tends to enhance exon inclusion, whereas binding upstream tends to repress inclusion. This rule is supported for RBFOX3 in direct target analyses. (kim2013rbfox3regulatedalternativesplicing pages 1-2)

3. Molecular functions of RBFOX3

3.1 Primary function: regulation of alternative splicing in neurons

RBFOX3 regulates alternative splicing programs characteristic of neuronal differentiation and mature neuronal identity. The best-characterized mechanism is binding to intronic (U)GCAUG elements to modulate splice-site choice. (duan2016novelinsightsinto pages 3-5, kim2013rbfox3regulatedalternativesplicing pages 1-2)

3.1.1 Validated target: Numb alternative splicing (developmental neuronal differentiation)

A mechanistically detailed example is Numb pre-mRNA: RBFOX3 binds a conserved upstream intronic UGCAUG element near an alternative exon and represses its inclusion. In vivo and in-development loss-of-function experiments support that RBFOX3-dependent Numb splicing promotes neuronal differentiation. (kim2013rbfox3regulatedalternativesplicing pages 1-2)

Visual evidence (cis-elements and splicing assay panels): Kim et al. (2013) show the UGCAUG motif placement and mutation effects in the Numb upstream intronic silencer region and corresponding isoform shifts. (kim2013rbfox3regulatedalternativesplicing media 12bb47c3)

3.1.2 Cross-regulation of RBFOX2 via splicing-coupled expression control (AS-NMD)

RBFOX3 can cross-regulate RBFOX2 expression by driving RBFOX2 transcript isoforms that are unproductive.

• Exon 6 regulation / dominant-negative output: RBFOX3 promotes skipping of a RBFOX2 exon encoding RRM sequence, producing a dominant-negative RBFOX2 isoform. (dredge2011neunrbfox3nuclearand pages 1-2)
• Cryptic exons and NMD: nuclear RBFOX3 isoforms promote inclusion of cryptic RBFOX2 exons that introduce premature termination codons and target RBFOX2 transcripts for nonsense-mediated decay (NMD). (dredge2011neunrbfox3nuclearand pages 8-10)

Quantitative splicing effect: In 293T assays, RBFOX3 isoforms reduced exon-6-containing RBFOX2 mRNA from 92% to 47%, 48%, and 39% for RBFOX3 v1, v2, and v3, respectively. (dredge2011neunrbfox3nuclearand pages 5-6)

3.2 Non-splicing function: regulation of miRNA biogenesis via Drosha microprocessor

A major expansion beyond the “NeuN marker” concept is RBFOX3’s role in microRNA maturation.

• Transcriptome-wide binding data (PAR-CLIP) identified RBFOX3 binding to pri-miRNAs (including binding clusters overlapping pri-miRNA stem-loop regions). (kim2014rbfox3controlsthe pages 1-5)
• Functional assays showed RBFOX3 can act as a positive or negative regulator at the pri‑miRNA to pre‑miRNA processing step by modulating microprocessor recruitment, i.e., RBFOX3 can control the biogenesis of a subset of miRNAs. (conboy2017developmentalregulationof pages 6-8)

4. Subcellular localization and isoforms

4.1 Nuclear/cytoplasmic isoforms and localization determinants

RBFOX3 exists as multiple isoforms produced by alternative splicing, and isoforms differ in steady-state localization.

• Alternative splicing can generate isoforms with nuclear versus cytoplasmic distribution; one mechanism is inclusion/exclusion of a C-terminal extension contributing to a bipartite hPY-NLS affecting nuclear localization. (dredge2011neunrbfox3nuclearand pages 1-2)
• In cell-based assays, RBFOX3v2 is mainly nuclear and RBFOX3v3 is mainly cytoplasmic; the cytoplasmic isoform may still access the nucleus (potential shuttling), allowing it to regulate splicing. (dredge2011neunrbfox3nuclearand pages 6-8)
• RBFOX3 nuclear export was reported as not dependent on Crm1/exportin1. (dredge2011neunrbfox3nuclearand pages 8-10)

5. Biological processes and pathways

5.1 Neurogenesis and neuronal differentiation

RBFOX3 is implicated in neurogenesis and post-mitotic neuronal differentiation by controlling splicing choices in key developmental regulators, exemplified by its direct control of Numb isoform output and differentiation phenotypes upon RBFOX3 perturbation. (kim2013rbfox3regulatedalternativesplicing pages 1-2)

5.2 Splicing-regulatory networks and RBP cross-regulation

RBFOX3 participates in splicing-regulatory networks that include autoregulation and cross-regulation among RBFOX paralogs, including AS-NMD-based control of RBFOX2, helping tune splicing factor dosage in neurons. (dredge2011neunrbfox3nuclearand pages 1-2, dredge2011neunrbfox3nuclearand pages 8-10)

6. Recent developments (prioritizing 2023–2024)

6.1 2024 synthesis: RBFOX proteins and neuron-restricted RBFOX3

A 2024 neuronal-development review reiterates that RBFOX3 (NeuN) is predominantly expressed in post‑mitotic neurons and summarizes the position-dependent mechanism and network-level operation of RBFOX proteins (including LASR association and noncanonical recruitment). (nazim2024posttranscriptionalregulationof pages 4-5)

6.2 2024–2025: RBFOX3/NeuN as an enabling technology for single-nucleus and epigenomics

Although many mechanistic RBFOX3 discoveries are earlier, 2023–2024 work highlights RBFOX3’s practical centrality in state-of-the-art neuronal genomics.

• A 2024 mouse neuron epigenomics study purified NeuN+ neuronal nuclei using FANS with >97% purity, enabling neuron-resolved chromatin profiling across aging. (signal2024ageingrelatedchangesto pages 2-4)
• A 2024 Nature study describes NeuN antibody use in methanol-fixed nuclei sorting workflows and provides standardized protocol parameters for neuronal nuclei gating and pooling. (chung2024celltyperesolvedmosaicismreveals pages 4-4)

7. Current applications and real-world implementations

7.1 Histology and neuropathology (NeuN immunostaining)

NeuN immunostaining is widely used to label neuronal nuclei in tissue sections and quantify neuronal populations. However, NeuN is not universally expressed across all mature neuron types and can be altered by physiological state or injury. (duan2016novelinsightsinto pages 5-6)

7.2 Nuclei sorting (FANS/FACS) for transcriptomics/epigenomics

NeuN labeling is widely used for neuronal-nuclei enrichment from frozen tissue.

• Purity metric: NeuN+ nuclei were validated at >97% purity in one 2024 FANS pipeline for mouse neurons. (signal2024ageingrelatedchangesto pages 2-4)
• Human cortex yields (protocol-level): In a human cortical FANS workflow, neurons represented 34.5% ± 13.5 of sorted events, with routine recovery per cell type of ~50,000 nuclei for DNA methylation, ~300,000 for nuclear RNA, and ~100,000 each for ATAC-seq and histone profiling from ~300 mg tissue input. (chioza2025optimisedfluorescenceactivatednuclei pages 9-12)

These implementations illustrate why NeuN remains a standard “neuronal gate” for modern multi-omic profiling.

8. Expert opinions and authoritative analysis (limitations and interpretation)

8.1 NeuN negativity does not necessarily imply neuron loss

Because NeuN is an epitope on RBFOX3 that can show loss of immunoreactivity without corresponding neuron death, caution is required in interpreting NeuN loss in disease/injury.

• After peripheral axotomy, NeuN immunoreactivity in certain neurons was reported as completely lost at 3 days, began returning within 7 days, and returned by 28 days, consistent with reversible changes in antigenicity/localization rather than cell death. (duan2016novelinsightsinto pages 7-9)
• In soman exposure models, approximately 49% of rat hippocampal neurons were damaged, yet NeuN loss was described as reflecting loss of immunogenicity rather than a direct readout of protein abundance, highlighting potential false negatives if NeuN alone is used for survival counts. (duan2016novelinsightsinto pages 7-9)

8.2 NeuN is not universal across neuron subtypes

Certain neuron classes can be NeuN-negative even when mature/viable (e.g., Purkinje and mitral cells noted in reviews), which can bias both histological quantification and nuclei sorting if NeuN is used as a sole neuronal identifier. (duan2016novelinsightsinto pages 5-6)

9. Evidence-backed statistics and quantitative findings (selected)

• RBFOX3 isoforms modulate RBFOX2 exon-6-containing mRNA from 92% to 47%/48%/39% (v1/v2/v3) in splicing assays. (dredge2011neunrbfox3nuclearand pages 5-6)
• NeuN+ neuronal nuclei sorting purity reported as >97% in a 2024 study. (signal2024ageingrelatedchangesto pages 2-4)
• Human cortical FANS: neurons were 34.5% ± 13.5 of sorted events; typical recoveries include ~300,000 neuronal nuclei for nuclear RNA from ~300 mg tissue. (chioza2025optimisedfluorescenceactivatednuclei pages 9-12)
• Injury-related NeuN dynamics: complete loss at 3 days, recovery by 28 days after peripheral nerve injury in cited studies. (duan2016novelinsightsinto pages 7-9)

10. Practical takeaways for functional annotation of human RBFOX3 (A6NFN3)

1. Primary molecular function: sequence-specific RNA-binding regulator of alternative splicing in neurons via a single RRM and (U)GCAUG recognition, using position-dependent logic. (duan2016novelinsightsinto pages 3-5, kim2013rbfox3regulatedalternativesplicing pages 1-2)
2. Validated targets/pathways: neuronal differentiation via Numb isoform control; network regulation via RBFOX2 AS-NMD cross-regulation. (kim2013rbfox3regulatedalternativesplicing pages 1-2, dredge2011neunrbfox3nuclearand pages 8-10)
3. Noncanonical function: direct regulation of pri-miRNA processing via Drosha microprocessor recruitment/antagonism for selected miRNAs. (kim2014rbfox3controlsthe pages 1-5, conboy2017developmentalregulationof pages 6-8)
4. Localization: primarily nuclear in neurons but with functionally relevant isoform-dependent nuclear/cytoplasmic partitioning. (dredge2011neunrbfox3nuclearand pages 6-8)
5. Applications: foundational neuronal marker for histology and nuclei sorting, enabling single-nucleus multi-omics; must be paired with additional markers to address NeuN-negative neuron classes and context-dependent loss of immunoreactivity. (signal2024ageingrelatedchangesto pages 2-4, duan2016novelinsightsinto pages 7-9, chioza2025optimisedfluorescenceactivatednuclei pages 9-12)

Included URLs and publication dates (selected key sources)

• Dredge et al. 2011-06 (PLoS ONE): https://doi.org/10.1371/journal.pone.0021585 (dredge2011neunrbfox3nuclearand pages 1-2, dredge2011neunrbfox3nuclearand pages 2-4)
• Kim et al. 2013-02 (J Cell Biol): https://doi.org/10.1083/jcb.201206146 (kim2013rbfox3regulatedalternativesplicing pages 1-2)
• Kim et al. 2014-09 (Nat Struct Mol Biol): https://doi.org/10.1038/nsmb.2892 (kim2014rbfox3controlsthe pages 1-5)
• Duan et al. 2016-04 (Mol Neurobiol): https://doi.org/10.1007/s12035-015-9122-5 (duan2016novelinsightsinto pages 3-5)
• Conboy 2017-03 (WIREs RNA): https://doi.org/10.1002/wrna.1398 (conboy2017developmentalregulationof pages 1-3)
• Nazim 2024-12 (Frontiers Mol Neurosci): https://doi.org/10.3389/fnmol.2024.1483901 (nazim2024posttranscriptionalregulationof pages 4-5)
• Signal et al. 2024-08 (Cells): https://doi.org/10.3390/cells13161393 (signal2024ageingrelatedchangesto pages 2-4)
• Chung et al. 2024-04 (Nature): https://doi.org/10.1038/s41586-024-07292-5 (chung2024celltyperesolvedmosaicismreveals pages 4-4)

Evidence visualization (figures)

• RBFOX3 isoform/domain (RRM) schematic: (kim2013rbfox3regulatedalternativesplicing media bb037b32)
• Numb UGCAUG cis-element and splicing regulation panels: (kim2013rbfox3regulatedalternativesplicing media 12bb47c3)

Table: This table summarizes the evidence-backed functional annotation of human RBFOX3/NeuN, including identity, molecular mechanism, validated targets, localization, disease relevance, and practical applications. It is useful as a compact reference for distinguishing core RBFOX3 biology from broader RBFOX family findings and marker-based applications.

References

1. (dredge2011neunrbfox3nuclearand pages 1-2): B. Dredge, K. Jensen, Juan Valcarcel, Centre De, Regulació Genò, and Spain. Neun/rbfox3 nuclear and cytoplasmic isoforms differentially regulate alternative splicing and nonsense-mediated decay of rbfox2. PLoS ONE, 6:e21585, Jun 2011. URL: https://doi.org/10.1371/journal.pone.0021585, doi:10.1371/journal.pone.0021585. This article has 126 citations and is from a peer-reviewed journal.

2. (dredge2011neunrbfox3nuclearand pages 2-4): B. Dredge, K. Jensen, Juan Valcarcel, Centre De, Regulació Genò, and Spain. Neun/rbfox3 nuclear and cytoplasmic isoforms differentially regulate alternative splicing and nonsense-mediated decay of rbfox2. PLoS ONE, 6:e21585, Jun 2011. URL: https://doi.org/10.1371/journal.pone.0021585, doi:10.1371/journal.pone.0021585. This article has 126 citations and is from a peer-reviewed journal.

3. (kim2013rbfox3regulatedalternativesplicing pages 1-2): Kee K. Kim, Joseph Nam, Yoh-suke Mukouyama, and Sachiyo Kawamoto. Rbfox3-regulated alternative splicing of numb promotes neuronal differentiation during development. The Journal of Cell Biology, 200:443-458, Feb 2013. URL: https://doi.org/10.1083/jcb.201206146, doi:10.1083/jcb.201206146. This article has 163 citations.

4. (kim2014rbfox3controlsthe pages 1-5): Kee K Kim, Yanqin Yang, Jun Zhu, Robert S Adelstein, and Sachiyo Kawamoto. Rbfox3 controls the biogenesis of a subset of micrornas. Nature Structural & Molecular Biology, 21:901-910, Sep 2014. URL: https://doi.org/10.1038/nsmb.2892, doi:10.1038/nsmb.2892. This article has 62 citations and is from a highest quality peer-reviewed journal.

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8. (kim2013rbfox3regulatedalternativesplicing media bb037b32): Kee K. Kim, Joseph Nam, Yoh-suke Mukouyama, and Sachiyo Kawamoto. Rbfox3-regulated alternative splicing of numb promotes neuronal differentiation during development. The Journal of Cell Biology, 200:443-458, Feb 2013. URL: https://doi.org/10.1083/jcb.201206146, doi:10.1083/jcb.201206146. This article has 163 citations.

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10. (kim2013rbfox3regulatedalternativesplicing media 12bb47c3): Kee K. Kim, Joseph Nam, Yoh-suke Mukouyama, and Sachiyo Kawamoto. Rbfox3-regulated alternative splicing of numb promotes neuronal differentiation during development. The Journal of Cell Biology, 200:443-458, Feb 2013. URL: https://doi.org/10.1083/jcb.201206146, doi:10.1083/jcb.201206146. This article has 163 citations.

11. (dredge2011neunrbfox3nuclearand pages 8-10): B. Dredge, K. Jensen, Juan Valcarcel, Centre De, Regulació Genò, and Spain. Neun/rbfox3 nuclear and cytoplasmic isoforms differentially regulate alternative splicing and nonsense-mediated decay of rbfox2. PLoS ONE, 6:e21585, Jun 2011. URL: https://doi.org/10.1371/journal.pone.0021585, doi:10.1371/journal.pone.0021585. This article has 126 citations and is from a peer-reviewed journal.

12. (dredge2011neunrbfox3nuclearand pages 5-6): B. Dredge, K. Jensen, Juan Valcarcel, Centre De, Regulació Genò, and Spain. Neun/rbfox3 nuclear and cytoplasmic isoforms differentially regulate alternative splicing and nonsense-mediated decay of rbfox2. PLoS ONE, 6:e21585, Jun 2011. URL: https://doi.org/10.1371/journal.pone.0021585, doi:10.1371/journal.pone.0021585. This article has 126 citations and is from a peer-reviewed journal.

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Artifacts

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Citations

1. duan2016novelinsightsinto pages 3-5
2. conboy2017developmentalregulationof pages 6-8
3. nazim2024posttranscriptionalregulationof pages 4-5
4. signal2024ageingrelatedchangesto pages 2-4
5. chung2024celltyperesolvedmosaicismreveals pages 4-4
6. duan2016novelinsightsinto pages 5-6
7. chioza2025optimisedfluorescenceactivatednuclei pages 9-12
8. duan2016novelinsightsinto pages 7-9
9. conboy2017developmentalregulationof pages 1-3
10. weissbach2025exploringtranscriptomicregulationa pages 30-35
11. weissbach2025exploringtranscriptomicregulationb pages 30-35
12. weissbach2025exploringtranscriptomicregulationa pages 26-30
13. weissbach2025exploringtranscriptomicregulation pages 26-30
14. weissbach2025exploringtranscriptomicregulationb pages 26-30
15. duan2016novelinsightsinto pages 11-12
16. duan2016novelinsightsinto pages 9-10
17. alsema2025schizophreniaassociatedchangesin pages 1-2
18. chioza2025optimisedfluorescenceactivatednuclei pages 4-7
19. https://doi.org/10.1371/journal.pone.0021585
20. https://doi.org/10.1083/jcb.201206146
21. https://doi.org/10.1038/nsmb.2892
22. https://doi.org/10.1007/s12035-015-9122-5
23. https://doi.org/10.1002/wrna.1398
24. https://doi.org/10.3389/fnmol.2024.1483901
25. https://doi.org/10.3390/cells13161393
26. https://doi.org/10.1038/s41586-024-07292-5
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RBFOX3 (NeuN) – An RNA-Binding Splicing Regulator in Neurons

Gene Identity and Family

RBFOX3 (RNA Binding Fox-1 Homolog 3, UniProt A6NFN3) is a human gene encoding a neuron-specific RNA-binding protein. It belongs to the RBFOX (Fox-1) family of alternative splicing factors, which also includes RBFOX1 and RBFOX2 (www.nature.com). RBFOX3 is also known as Fox-1 homolog C, NeuN antigen, or FOX3 (historically HRNBP3) (www.ncbi.nlm.nih.gov). The protein contains an N-terminal proline-rich region, a central RNA Recognition Motif (RRM domain), and a C-terminal alanine-rich domain (www.ncbi.nlm.nih.gov). This domain architecture is characteristic of RBFOX family proteins and is critical for its RNA-binding and regulatory functions. RBFOX3 is highly conserved across vertebrates and was identified in 2009 as the antigen recognized by the NeuN (Neuronal Nuclei) monoclonal antibody (www.nature.com). NeuN immunoreactivity is specific to post-mitotic neurons, making RBFOX3 a widely used marker for mature neurons in the brain and spinal cord (pubmed.ncbi.nlm.nih.gov) (pubmed.ncbi.nlm.nih.gov). Notably, RBFOX3 is predominantly expressed in the central nervous system and plays a prominent role in neural development and adult brain function (www.ncbi.nlm.nih.gov). Its expression is largely restricted to neurons – for example, it is abundant in brain tissue (RPKM ~11 in RNA-seq data) with much lower levels in most non-neural tissues (www.ncbi.nlm.nih.gov). This brain-specific expression underlies its use as a neuronal marker and hints at specialized functions in the nervous system.

Expression and Subcellular Localization

Within neurons, RBFOX3 is primarily a nuclear protein, consistent with its role in pre-mRNA splicing (pmc.ncbi.nlm.nih.gov). NeuN/RBFOX3 immunostaining strongly labels neuronal nuclei (and to a lesser extent perikarya), indicating that the protein resides in the nucleus where splicing occurs (pubmed.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). However, RBFOX3 exists as multiple isoforms due to alternative splicing of its own transcript (pmc.ncbi.nlm.nih.gov). Importantly, one splicing event adds or removes part of a bipartite nuclear localization signal in the C-terminus, producing distinct isoforms with different steady-state localization (pmc.ncbi.nlm.nih.gov). Nuclear isoforms of RBFOX3 contain the full NLS and concentrate in the nucleus, whereas a cytoplasmic isoform lacks part of the NLS and distributes to the cytoplasm (pmc.ncbi.nlm.nih.gov). In healthy mature neurons, the majority of RBFOX3 is in the nucleus, but studies have noted that under certain conditions the localization can shift. For instance, in HIV-associated neurocognitive disorder (a neurodegenerative condition), RBFOX3 was observed to mislocalize from the nucleus to the cytoplasm (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). Since pre-mRNA splicing is nuclear, such mislocalization may effectively downregulate RBFOX3’s splicing activity, contributing to neuronal gene expression deficits in disease (pmc.ncbi.nlm.nih.gov). Apart from pathological cases, RBFOX3 is generally a reliable nuclear marker of neurons. (It is noteworthy that a few neuron types show little or no NeuN expression – e.g. cerebellar Purkinje cells – but this reflects cell-type specific gene regulation rather than a different protein identity (pubmed.ncbi.nlm.nih.gov).) Overall, RBFOX3’s presence in the neuronal nucleus is tightly linked to its function as an RNA-binding regulator of gene expression.

Molecular Function: RNA Binding and Alternative Splicing

RBFOX3 is an RNA-binding protein (RBP) that regulates alternative splicing of pre-mRNAs in neurons (www.ncbi.nlm.nih.gov) (www.nature.com). Like other RBFOX family members, RBFOX3 recognizes a short RNA sequence motif (the consensus (U)GCAUG element) in target transcripts (pmc.ncbi.nlm.nih.gov). This motif is typically located in intronic regions flanking alternative exons. By binding to these elements, RBFOX proteins influence spliceosome activity to either include or skip the exon. The effect is position-dependent: when RBFOX3 binds in an intron downstream of an alternative exon, it generally enhances that exon’s inclusion; binding in the upstream intron causes exon skipping (exclusion) (pmc.ncbi.nlm.nih.gov). This functional rule has been demonstrated in several neuronally expressed genes. For example, RBFOX3 directly targets the pre-mRNA of Numb, a cell fate determinant, by binding to two UGCAUG sites in the intron upstream of an alternative exon (exon 12 of Numb) (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). RBFOX3 binding there represses inclusion of that exon, promoting the production of a particular Numb isoform crucial for neuronal differentiation (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). In contrast, RBFOX3 can promote exon inclusion in other targets; a notable case is the Tau (MAPT) gene, where an intronic UGCAUG motif downstream of Tau’s exon 10 mediates RBFOX3-dependent inclusion of that exon (pubmed.ncbi.nlm.nih.gov). Tau exon 10 encodes a microtubule-binding repeat, and its inclusion generates the 4-repeat Tau isoform. A 2018 study confirmed that RBFOX3 (NeuN) binds Tau pre-mRNA and enhances exon 10 splicing, with deletion of RBFOX3’s RRM or its binding sites abolishing this effect (pubmed.ncbi.nlm.nih.gov). Thus, RBFOX3 can differentially regulate splicing outcomes, contributing to the cell-type-specific transcript diversity in neurons.

On a molecular level, RBFOX3 operates as part of larger splicing complexes. It often works in concert with other splicing regulators and can auto-regulate or cross-regulate splicing within its family. Indeed, RBFOX3 has been shown to modulate splicing of RBFOX2 pre-mRNA: nuclear RBFOX3 isoforms promote inclusion of a “poison” exon in RBFOX2 transcripts, triggering nonsense-mediated decay of RBFOX2 mRNA (pmc.ncbi.nlm.nih.gov). This creates a feedback loop whereby RBFOX3 limits the production of RBFOX2 protein in neurons. Such fine-tuning underscores that RBFOX3 is not just a passive marker protein but an active regulator of gene expression programs. Genome-wide studies have identified many RBFOX-binding elements in brain mRNAs, particularly in genes related to synaptic function and ion channels (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). In fact, de novo motif analyses in neurons often recover the UGCAUG sequence, highlighting RBFOX1/2/3 as central players in neuron-specific splicing networks (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). Through its RRM domain and binding specificity, RBFOX3 helps sculpt the mRNA output of neural genes, affecting the proteome of the brain.

Role in Neuronal Development and Function

RBFOX3 plays a critical role in neuron maturation, connectivity, and circuit function. It is expressed as neurons exit the cell cycle and differentiate, and accumulating evidence indicates it actively promotes neuronal differentiation. In an experimental model of spinal cord development (chick embryo), loss of RBFOX3 blocked proper neuronal maturation: silencing RBFOX3 led to aberrant inclusion of the Numb exon discussed above, and as a result, post-mitotic neurons failed to fully differentiate (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). Restoration of the correct Numb splicing isoform could rescue the differentiation defect, proving that RBFOX3’s splicing activity is required for normal neuron development (Kim et al., J. Cell Biol. 2013) (pmc.ncbi.nlm.nih.gov). Consistently, RBFOX3 expression is developmentally regulated in the brain – it rises as neurons mature (pmc.ncbi.nlm.nih.gov) – and is largely confined to mature neurons (it is not expressed in neural progenitor cells) (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). This timing suggests RBFOX3 helps coordinate the transition from a progenitor transcriptome to a mature neuronal transcriptome, by switching on the splicing of neuron-specific exons.

In the adult brain, RBFOX3 continues to be important for maintaining healthy neural circuits. Knockout mouse studies have been instrumental in revealing RBFOX3’s functions. Mice completely lacking Rbfox3 (Rbfox3^-/-) are viable but exhibit a range of neural deficits. Behaviourally, Rbfox3 knockout mice show impaired learning and memory, heightened seizure susceptibility, and sensory abnormalities. For example, a 2016 study reported that Rbfox3^-/- mice had significant cognitive impairments in spatial learning tasks and displayed cold hyperalgesia (abnormally increased pain sensation to cold) compared to wild-type (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). Another study (2015) noted that Rbfox3 knockouts had increased seizure susceptibility (lower threshold for seizures) along with reduced anxiety-like behavior (pubmed.ncbi.nlm.nih.gov), consistent with RBFOX3’s proposed link to human epilepsy (see next section). These behavioral phenotypes correlate with synaptic and circuit-level abnormalities: in the hippocampus – a region critical for learning and memory – Rbfox3^-/- mice have defects in synaptic plasticity and circuit balance (pubmed.ncbi.nlm.nih.gov). Electrophysiological recordings showed their hippocampal synapses cannot sustain normal long-term depression (LTD) and have abnormally enhanced basal transmission (pmc.ncbi.nlm.nih.gov). Notably, knockout mice exhibited an increased frequency of spontaneous excitatory synaptic events onto dentate gyrus neurons (with normal amplitude), indicating an excess of functional excitatory synapses or release probability (pubmed.ncbi.nlm.nih.gov). Dendritic spine counting confirmed that spine density on these neurons was significantly higher in knockouts than in controls (pubmed.ncbi.nlm.nih.gov). Paradoxically, while there were more synaptic contacts, the quality of synaptic plasticity was reduced – suggesting the synapses formed without RBFOX3 are perhaps aberrant or immature. Indeed, Rbfox3^-/- brains had an increased number of excitatory synapses but showed deficits in synaptic strength modulation (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). These findings illustrate that RBFOX3 is required for proper synaptic organization and function, likely by ensuring the correct splicing of synaptic protein mRNAs.

RBFOX3 also influences neurogenesis in the adult brain. In the adult hippocampus, new neurons are continuously generated in the dentate gyrus, a process tied to learning and mood regulation. Rbfox3 knockout mice have reduced adult neurogenesis in the dentate gyrus: they show significantly fewer proliferating neural progenitors (Ki67-positive) and immature neurons (DCX-positive) compared to wild-type mice (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). In one analysis, Ki67^+ cell counts in the dentate gyrus of Rbfox3^-/- mice were only about half of those in normal mice (p < 0.001) (pmc.ncbi.nlm.nih.gov), indicating a marked drop in the generation of new neurons. This reduction in neurogenesis is thought to contribute to the impaired learning observed in knockouts (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). Interestingly, RBFOX3 itself is not expressed in the progenitors but in the new neurons as they differentiate (pmc.ncbi.nlm.nih.gov), implying that the microenvironment or feedback from mature neurons (where RBFOX3 acts) is necessary to support neurogenesis. Together, these developmental and physiological studies demonstrate that RBFOX3 is essential for neuronal maturation, the formation of balanced neural circuits, and ongoing adult brain plasticity. Its absence causes specific synaptic and behavioral pathologies, underscoring its precise role in the nervous system.

It should be noted that RBFOX3’s importance can vary between neural circuits. For example, in the retina, RBFOX3 is expressed in certain neurons (ganglion, amacrine, and horizontal cells) but not others (pmc.ncbi.nlm.nih.gov). Deleting Rbfox3 leads to a thinner inner plexiform layer (the synaptic layer) in the retina, yet the overall visual function (both image-forming vision and reflexive light responses) remains largely normal (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). Knockout mice had a normal number of retinal ganglion cells and intact optic nerve projections, and they performed normally in visual assays (pmc.ncbi.nlm.nih.gov). This suggests that unlike in the hippocampus, RBFOX3 is dispensable for basic visual function – possibly because other RBFOX family members (or splicing factors) compensate in retinal neurons, or because the splicing events controlled by RBFOX3 are not critical to vision. Thus, the requirement for RBFOX3 can be context-specific, being crucial in some brain regions (hippocampus, cortex) but not in others (retina). Determining the tissue-specific targets of RBFOX3 may explain these differences.

Pathology and Clinical Implications

Given its key role in neuronal gene regulation, it is not surprising that RBFOX3 has been implicated in neurological diseases. Mutations or dysfunction of RBFOX3 are linked to several neurodevelopmental and neuropsychiatric disorders. Human genetic studies have found RBFOX3 variants associated with autism spectrum disorder, epilepsy, and intellectual disability (pmc.ncbi.nlm.nih.gov). In particular, RBFOX3 has been flagged in analyses of autism and cognitive impairment cases, though such mutations are relatively rare. A 2015 review noted that “dysfunctional RBFOX3” (e.g. due to mutation or altered expression) can lead to cognitive deficits and seizure phenotypes, echoing what is seen in knockout mice (pmc.ncbi.nlm.nih.gov). Indeed, Rbfox3^-/- mice show epilepsy-like hyperexcitability and memory deficits that mirror human epilepsy and intellectual disability symptoms (pubmed.ncbi.nlm.nih.gov). This suggests a causal relationship: RBFOX3-related splicing defects disrupt neural circuit balance, contributing to these disorders (pubmed.ncbi.nlm.nih.gov) (pubmed.ncbi.nlm.nih.gov). For example, imbalances in excitatory/inhibitory synapses and impaired synaptic plasticity in RBFOX3-null mice may model the network dysfunction underlying epilepsy (pubmed.ncbi.nlm.nih.gov). Some genome-wide association studies have also linked RBFOX3 polymorphisms to traits like sleep latency (difficulty falling asleep) (pmc.ncbi.nlm.nih.gov), highlighting that even common variants in RBFOX3 can have measurable effects on human neurophysiology (in this case, sleep regulation).

RBFOX3 expression or localization can change in brain injuries and neurodegenerative conditions. Neuropathological studies show that NeuN immunoreactivity is sometimes lost or reduced in diseased neurons, which can complicate its use as a neuron marker. For instance, prolonged seizures, ischemia, or other neuronal stressors can cause a temporary loss of NeuN (RBFOX3) staining in affected neurons (pubmed.ncbi.nlm.nih.gov). This likely reflects either downregulation of RBFOX3 or epitope masking, and has led experts to caution that “NeuN immunoreactivity should not be the sole criterion for neuronal counts in pathologic conditions” (pubmed.ncbi.nlm.nih.gov). In HIV-associated neurocognitive disorder, as mentioned above, many neurons showed RBFOX3 relocated to the cytoplasm rather than nucleus (pmc.ncbi.nlm.nih.gov). Such mislocalization in diseased brains could mean that neurons are not performing normal splicing of key transcripts, potentially contributing to neurocognitive decline. Additionally, RBFOX3 has been proposed as a marker to assess neuronal loss: for example, reduced NeuN staining is used to quantify neuron loss in models of stroke or neurodegeneration (pubmed.ncbi.nlm.nih.gov). However, because NeuN can be dynamically regulated, scientists carefully interpret what “NeuN-negative” means in diseased tissue (it may indicate a non-neuronal cell, a lost neuron, or a neuron that has downregulated RBFOX3 due to stress).

Beyond the nervous system, emerging research has found RBFOX3 involvement in cancers, although RBFOX3 is normally not expressed in most healthy non-neural tissues. Interestingly, RBFOX3 has been detected in some tumor types and may play a functional role in cancer cell biology. For example, hepatocellular carcinoma (HCC) cells aberrantly express RBFOX3 at high levels, and this appears to promote tumor growth: one study found RBFOX3 was upregulated in HCC tumors and cell lines, and knocking it down inhibited cancer cell proliferation (pubmed.ncbi.nlm.nih.gov). RBFOX3 knockdown also made the HCC cells more sensitive to the chemotherapy drug 5-fluorouracil, increasing drug-induced apoptosis via the PI3K/Akt and caspase pathways (suggesting RBFOX3 helps confer chemo-resistance) (pubmed.ncbi.nlm.nih.gov). These findings imply RBFOX3 might act as a pro-survival or oncogenic factor in certain cancers, possibly by splicing tumor-related transcripts. Similarly, in lung cancer models, RBFOX3 was shown to impact cell migration and invasion: TGF-β signaling can suppress RBFOX3 expression, which in turn promotes an epithelial–mesenchymal transition (EMT) phenotype (www.sciencedirect.com). In that context, RBFOX3 normally may maintain expression of epithelial junction proteins (like Claudin-1) by regulating their mRNA – loss of RBFOX3 led to reduced Claudin-1 and increased EMT/invasion in lung cancer cells (pmc.ncbi.nlm.nih.gov). These are active areas of research, but they point to RBFOX3’s splicing activity as potentially relevant outside the brain, especially in diseases like cancer. It is unusual for a “neural-specific” splicing factor to be co-opted in tumors, and it underscores the pleiotropic impact that alternative splicing regulators can have when dysregulated.

Applications in Research and Diagnosis

RBFOX3/NeuN as a Neuronal Marker: In neuroscience research and neuropathology, RBFOX3’s most widespread use is as the NeuN antigen – a diagnostic marker of neurons. Antibodies against NeuN (RBFOX3 protein) reliably label neuronal nuclei in tissue sections, allowing researchers and clinicians to identify neurons and quantify neuronal density. For over two decades, NeuN immunostaining has been a gold-standard method to distinguish neurons from glial cells in histological samples (pubmed.ncbi.nlm.nih.gov). This is especially useful in studies of neurodegeneration (e.g. counting surviving neurons after an experimental stroke or in an Alzheimer’s brain) and development (e.g. verifying neuronal differentiation in stem cell cultures). NeuN staining is also used in pathology labs to help diagnose neuronal tumors or lesions. For example, Merkel cell carcinoma (MCC), an aggressive neuroendocrine skin carcinoma, can express neuronal markers. A 2021 analysis of 15 MCC cases showed robust NeuN (RBFOX3) positivity in the majority of these tumors, whereas normal Merkel cells in skin do not express NeuN (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). This suggests that aberrant RBFOX3 expression can indicate neuronal or neuroendocrine differentiation in a tumor and can aid in tumor identification. Likewise, NeuN immunohistochemistry is sometimes included in panels to identify metastatic neuroblastomas or other small round cell tumors as neuronal in origin. Researchers have to be cautious interpreting such staining, but it has practical value in diagnosing cancers with neuronal features.

RBFOX3 in Therapeutic Research: Understanding RBFOX3’s role has potential therapeutic implications. In neurological disorders where RBFOX3 or its targets are affected (such as epilepsy or autism), strategies to modulate alternative splicing could be beneficial. For instance, if a particular mis-spliced isoform due to RBFOX3 deficiency is pathogenic, one could imagine antisense oligonucleotides to correct that splicing. While this is still speculative, the principle has precedent in other splicing-related diseases (e.g. Spinraza for SMN2 splicing in spinal muscular atrophy). Additionally, the discovery of RBFOX3’s impact on cancer cell survival opens the question of whether RBFOX3 could be a drug target in oncology. Inhibiting RBFOX3 function (or mimicking its loss) might sensitize tumors to chemotherapy, as shown in HCC cells (pubmed.ncbi.nlm.nih.gov). Conversely, protecting or enhancing RBFOX3 activity in neurons might be neuroprotective in conditions like neuroAIDS (HIV-related cognitive disorder) or after brain injury, where RBFOX3 mislocalization correlates with neuronal dysfunction (pmc.ncbi.nlm.nih.gov). These ideas are in early stages, but they show how current research is translating the biology of RBFOX3 into real-world applications.

Expert Perspectives: Recent authoritative reviews emphasize that RBFOX3 is no longer viewed as just a static neuron marker, but as a dynamic regulator influencing neural phenotype (pubmed.ncbi.nlm.nih.gov). Wei Duan and colleagues (2015) dubbed it “from Neuronal Marker to Splicing Regulator,” highlighting that the protein’s identity as an RBP provides new perspective on why NeuN staining can change in certain states (pubmed.ncbi.nlm.nih.gov). They urge careful interpretation of NeuN in pathological samples, noting that changes in RBFOX3 expression or localization might themselves contribute to disease processes, rather than simply reflecting neuron presence (pubmed.ncbi.nlm.nih.gov). In 2024, a comprehensive review of alternative splicing in health and disease reiterated RBFOX3’s key role in neural development, using it as an example of how splicing factors drive cell fate. That review recaps how RBFOX3-mediated exon skipping in Numb is required for neuronal differentiation in the developing cortex (www.nature.com), underscoring the conserved mechanism initially discovered in earlier animal studies. Experts agree that RBFOX3 and its family unify two important aspects of neurobiology: the molecular control of gene expression (through AS regulation) and the cellular identity of neurons. In summary, RBFOX3 is a pivotal neuron-specific RBP that binds target mRNAs to regulate their splicing, thereby shaping neuronal gene expression, guiding neuron maturation, and maintaining synaptic function. Its discovery as NeuN’s antigen has bridged classic neuroanatomy with modern genomics, and ongoing research (2023–2024) continues to uncover its broader roles in both the nervous system and disease contexts. Each new finding – from adult neurogenesis deficits to cancer cell dependencies – highlights the importance of RBFOX3’s precise activity for normal cellular function, making it a fascinating subject of study in functional genomics and biomedicine.

References: (Key references are provided inline with citations, including publication year and source. For example, Lin et al., 2016, PLoS One (pmc.ncbi.nlm.nih.gov) and Lin et al., 2016, PLoS One (pmc.ncbi.nlm.nih.gov) document RBFOX3’s role in adult neurogenesis and synaptic regulation; Kim et al., 2013, J. Cell Biol. (pmc.ncbi.nlm.nih.gov) demonstrates RBFOX3’s regulation of Numb splicing in neuron differentiation; Dredge et al., 2011, PLoS One (pmc.ncbi.nlm.nih.gov) describes RBFOX3 isoforms and cross-regulation of RBFOX2; and Duan et al., 2015, Mol Neurobiol* (pubmed.ncbi.nlm.nih.gov) provides a review of RBFOX3/NeuN’s identity and significance. Additional contemporary sources (2016–2024) have been cited to illustrate recent developments and applications.)

Citations

1. AnnotationURLCitation(end_index=465, start_index=329, title='RBFOX3/NeuN is Required for Hippocampal Circuit Balance and Function | Scientific Reports', type='url_citation', url='https://www.nature.com/articles/srep17383#:~:text=Neuronal%20nuclei%20,Current%20evidence%20suggests%20that%20RBFOX3')
2. AnnotationURLCitation(end_index=735, start_index=568, title='RBFOX3 RNA binding fox-1 homolog 3 [Homo sapiens (human)] - Gene - NCBI', type='url_citation', url='https://www.ncbi.nlm.nih.gov/gene?Cmd=DetailsSearch&Db=gene&Term=146713#:~:text=FOX3%3B%20NEUN%3B%20FOX,and%20regulation%20of%20adult%20brain')
3. AnnotationURLCitation(end_index=1064, start_index=880, title='RBFOX3 RNA binding fox-1 homolog 3 [Homo sapiens (human)] - Gene - NCBI', type='url_citation', url='https://www.ncbi.nlm.nih.gov/gene?Cmd=DetailsSearch&Db=gene&Term=146713#:~:text=This%20gene%20encodes%20a%20member,gene%20results%20in%20multiple%20transcript')
4. AnnotationURLCitation(end_index=1485, start_index=1349, title='RBFOX3/NeuN is Required for Hippocampal Circuit Balance and Function | Scientific Reports', type='url_citation', url='https://www.nature.com/articles/srep17383#:~:text=Neuronal%20nuclei%20,Current%20evidence%20suggests%20that%20RBFOX3')
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16. AnnotationURLCitation(end_index=5030, start_index=4841, title='Altered Subcellular Localization of the NeuN/Rbfox3 RNA Splicing Factor in HIV-Associated Neurocognitive Disorders (HAND) - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC3880598/#:~:text=nuclear%20localization%2C%20we%20found%20significantly,downregulation%20of%20neuronal%20gene%20expression')
17. AnnotationURLCitation(end_index=5387, start_index=5211, title='Altered Subcellular Localization of the NeuN/Rbfox3 RNA Splicing Factor in HIV-Associated Neurocognitive Disorders (HAND) - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC3880598/#:~:text=Rbfox3%2C%20but%20its%20significance%20in,downregulation%20of%20neuronal%20gene%20expression')
18. AnnotationURLCitation(end_index=5808, start_index=5683, title='Novel Insights into NeuN: from Neuronal Marker to Splicing Regulator - PubMed', type='url_citation', url='https://pubmed.ncbi.nlm.nih.gov/25680637/#:~:text=for%20the%20past%20two%20decades,This%20review')
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21. AnnotationURLCitation(end_index=6712, start_index=6540, title='Rbfox3-regulated alternative splicing of Numb promotes neuronal differentiation during development - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC3575530/#:~:text=repressor%20of%20alternative%20splicing%20depending,same%20element%20upstream%20of%20the')
22. AnnotationURLCitation(end_index=7295, start_index=7123, title='Rbfox3-regulated alternative splicing of Numb promotes neuronal differentiation during development - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC3575530/#:~:text=repressor%20of%20alternative%20splicing%20depending,same%20element%20upstream%20of%20the')
23. AnnotationURLCitation(end_index=7726, start_index=7562, title='Rbfox3-regulated alternative splicing of Numb promotes neuronal differentiation during development - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC3575530/#:~:text=Repression%20of%20exon%2012%20splicing,UGCAUG%20element%20in%20chicken%20embryos')
24. AnnotationURLCitation(end_index=7850, start_index=7727, title='Rbfox3-regulated alternative splicing of Numb promotes neuronal differentiation during development - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC3575530/#:~:text=Rbfox3%20represses%20exon%2012%20of,see')
25. AnnotationURLCitation(end_index=8155, start_index=8002, title='Rbfox3-regulated alternative splicing of Numb promotes neuronal differentiation during development - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC3575530/#:~:text=found%20to%20be%20a%20target,the%20relevant%20Numb%20splice%20isoform')
26. AnnotationURLCitation(end_index=8320, start_index=8156, title='Rbfox3-regulated alternative splicing of Numb promotes neuronal differentiation during development - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC3575530/#:~:text=Repression%20of%20exon%2012%20splicing,UGCAUG%20element%20in%20chicken%20embryos')
27. AnnotationURLCitation(end_index=8684, start_index=8542, title='Rbfox3/NeuN Regulates Alternative Splicing of Tau Exon 10 - PubMed', type='url_citation', url='https://pubmed.ncbi.nlm.nih.gov/30475774/#:~:text=splicing%20is%20unknown,in%20the%20excitotoxic%20mouse%20brains')
28. AnnotationURLCitation(end_index=9098, start_index=8956, title='Rbfox3/NeuN Regulates Alternative Splicing of Tau Exon 10 - PubMed', type='url_citation', url='https://pubmed.ncbi.nlm.nih.gov/30475774/#:~:text=splicing%20is%20unknown,in%20the%20excitotoxic%20mouse%20brains')
29. AnnotationURLCitation(end_index=9804, start_index=9648, title='NeuN/Rbfox3 Nuclear and Cytoplasmic Isoforms Differentially Regulate Alternative Splicing and Nonsense-Mediated Decay of Rbfox2 - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC3126832/#:~:text=nuclear%20localization%20signal,Rbfox3%20through%20a%20novel%20mechanism')
30. AnnotationURLCitation(end_index=10313, start_index=10181, title='Neuronal Splicing Regulator RBFOX3 (NeuN) Regulates Adult Hippocampal Neurogenesis and Synaptogenesis - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5049801/#:~:text=impairments,decreased%20and%20the%20density%20of')
31. AnnotationURLCitation(end_index=10481, start_index=10314, title='Neuronal Splicing Regulator RBFOX3 (NeuN) Regulates Adult Hippocampal Neurogenesis and Synaptogenesis - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5049801/#:~:text=cognitive%20behaviors%2C%20were%20altered%20in,decreased%20and%20the%20density%20of')
32. AnnotationURLCitation(end_index=10794, start_index=10643, title='Neuronal Splicing Regulator RBFOX3 (NeuN) Regulates Adult Hippocampal Neurogenesis and Synaptogenesis - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5049801/#:~:text=the%20hippocampal%20DG,brain%20diseases%20with%20disrupted%20RBFOX3')
33. AnnotationURLCitation(end_index=10972, start_index=10795, title='Neuronal Splicing Regulator RBFOX3 (NeuN) Regulates Adult Hippocampal Neurogenesis and Synaptogenesis - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5049801/#:~:text=Rbfox3%20deletion%20causes%20abnormal%20exon,and%20increases%20excitatory%20synaptic%20number')
34. AnnotationURLCitation(end_index=11823, start_index=11668, title='Rbfox3-regulated alternative splicing of Numb promotes neuronal differentiation during development - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC3575530/#:~:text=development%20remain%20elusive,the%20relevant%20Numb%20splice%20isoform')
35. AnnotationURLCitation(end_index=11977, start_index=11824, title='Rbfox3-regulated alternative splicing of Numb promotes neuronal differentiation during development - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC3575530/#:~:text=found%20to%20be%20a%20target,the%20relevant%20Numb%20splice%20isoform')
36. AnnotationURLCitation(end_index=12359, start_index=12186, title='Rbfox3-regulated alternative splicing of Numb promotes neuronal differentiation during development - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC3575530/#:~:text=of%20postmitotic%20neurons,neuronal%20differentiation%20during%20vertebrate%20development')
37. AnnotationURLCitation(end_index=12652, start_index=12464, title='Neuronal Splicing Regulator RBFOX3 (NeuN) Regulates Adult Hippocampal Neurogenesis and Synaptogenesis - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5049801/#:~:text=neurodevelopment%2C%20the%20function%20of%20RBFOX3,hyperalgesia%20and%20impaired%20cognitive%20abilities')
38. AnnotationURLCitation(end_index=12939, start_index=12752, title='Neuronal Splicing Regulator RBFOX3 (NeuN) Regulates Adult Hippocampal Neurogenesis and Synaptogenesis - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5049801/#:~:text=match%20at%20L650%20hippocampal%20neurogenesis,environment%20for%20hippocampal%20neurogenesis%20through')
39. AnnotationURLCitation(end_index=13110, start_index=12940, title='Neuronal Splicing Regulator RBFOX3 (NeuN) Regulates Adult Hippocampal Neurogenesis and Synaptogenesis - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5049801/#:~:text=hippocampal%20neurogenesis%20,environment%20for%20hippocampal%20neurogenesis%20through')
40. AnnotationURLCitation(end_index=14107, start_index=13929, title='Neuronal Splicing Regulator RBFOX3 (NeuN) Regulates Adult Hippocampal Neurogenesis and Synaptogenesis - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5049801/#:~:text=plasticity%2C%20and%20synaptogenesis%20in%20Rbfox3,hippocampal%20dentate%20gyrus%20of%20Rbfox3')
41. AnnotationURLCitation(end_index=14249, start_index=14108, title='Neuronal Splicing Regulator RBFOX3 (NeuN) Regulates Adult Hippocampal Neurogenesis and Synaptogenesis - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5049801/#:~:text=synaptogenesis,synaptic%20plasticity%20and%20density%20in')
42. AnnotationURLCitation(end_index=14594, start_index=14413, title='RBFOX3/NeuN is Required for Hippocampal Circuit Balance and Function - PubMed', type='url_citation', url='https://pubmed.ncbi.nlm.nih.gov/26619789/#:~:text=Rbfox3%20knockout%20mice%20displayed%20increased,results%20demonstrate%20anatomical%20and%20functional')
43. AnnotationURLCitation(end_index=15081, start_index=14899, title='RBFOX3/NeuN is Required for Hippocampal Circuit Balance and Function - PubMed', type='url_citation', url='https://pubmed.ncbi.nlm.nih.gov/26619789/#:~:text=knockout%20mice%20showed%20increased%20expression,results%20demonstrate%20anatomical%20and%20functional')
44. AnnotationURLCitation(end_index=15408, start_index=15246, title='Neuronal Splicing Regulator RBFOX3 (NeuN) Regulates Adult Hippocampal Neurogenesis and Synaptogenesis - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5049801/#:~:text=match%20at%20L515%20increased%20synaptic,mice%20%28Fig%205d%29%2C%20consistent')
45. AnnotationURLCitation(end_index=15824, start_index=15642, title='RBFOX3/NeuN is Required for Hippocampal Circuit Balance and Function - PubMed', type='url_citation', url='https://pubmed.ncbi.nlm.nih.gov/26619789/#:~:text=knockout%20mice%20showed%20increased%20expression,results%20demonstrate%20anatomical%20and%20functional')
46. AnnotationURLCitation(end_index=16096, start_index=15956, title='RBFOX3/NeuN is Required for Hippocampal Circuit Balance and Function - PubMed', type='url_citation', url='https://pubmed.ncbi.nlm.nih.gov/26619789/#:~:text=pathway,results%20demonstrate%20anatomical%20and%20functional')
47. AnnotationURLCitation(end_index=16585, start_index=16414, title='Neuronal Splicing Regulator RBFOX3 (NeuN) Regulates Adult Hippocampal Neurogenesis and Synaptogenesis - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5049801/#:~:text=deletion%20of%20Rbfox3%20resulted%20in,increased%20numbers%20of%20excitatory%20synapses')
48. AnnotationURLCitation(end_index=16760, start_index=16586, title='Neuronal Splicing Regulator RBFOX3 (NeuN) Regulates Adult Hippocampal Neurogenesis and Synaptogenesis - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5049801/#:~:text=an%20environment%20for%20normal%20neurogenesis,and%20excitatory%20synapses%20increase%20in')
49. AnnotationURLCitation(end_index=17516, start_index=17339, title='Neuronal Splicing Regulator RBFOX3 (NeuN) Regulates Adult Hippocampal Neurogenesis and Synaptogenesis - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5049801/#:~:text=dysfunctional%20neurogenesis%20in%20the%20hippocampal,both%20markers%20in%20the%20hippocampal')
50. AnnotationURLCitation(end_index=17685, start_index=17517, title='Neuronal Splicing Regulator RBFOX3 (NeuN) Regulates Adult Hippocampal Neurogenesis and Synaptogenesis - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5049801/#:~:text=cells%20were%20quantified%20in%20the,sections%2C%206%20sections%2Fmice%2C%207%20mice')
51. AnnotationURLCitation(end_index=17997, start_index=17820, title='Neuronal Splicing Regulator RBFOX3 (NeuN) Regulates Adult Hippocampal Neurogenesis and Synaptogenesis - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5049801/#:~:text=showing%20different%20stages%20of%20postnatal,sections%2C%206%20sections%2Fmice%2C%207%20mice')
52. AnnotationURLCitation(end_index=18332, start_index=18161, title='Neuronal Splicing Regulator RBFOX3 (NeuN) Regulates Adult Hippocampal Neurogenesis and Synaptogenesis - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5049801/#:~:text=Since%20learning%20deficits%20were%20consistently,we%20further%20investigated%20whether')
53. AnnotationURLCitation(end_index=18504, start_index=18333, title='Neuronal Splicing Regulator RBFOX3 (NeuN) Regulates Adult Hippocampal Neurogenesis and Synaptogenesis - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5049801/#:~:text=deletion%20of%20Rbfox3%20resulted%20in,increased%20numbers%20of%20excitatory%20synapses')
54. AnnotationURLCitation(end_index=18803, start_index=18616, title='Neuronal Splicing Regulator RBFOX3 (NeuN) Regulates Adult Hippocampal Neurogenesis and Synaptogenesis - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5049801/#:~:text=match%20at%20L650%20hippocampal%20neurogenesis,environment%20for%20hippocampal%20neurogenesis%20through')
55. AnnotationURLCitation(end_index=19630, start_index=19459, title='RBFOX3/NeuN is dispensable for visual function - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5798780/#:~:text=balance%2C%20as%20well%20as%20neurogenesis,ganglion%20cells%2C%20amacrine%20cells%20and')
56. AnnotationURLCitation(end_index=20010, start_index=19838, title='RBFOX3/NeuN is dispensable for visual function - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5798780/#:~:text=the%20retina%20and%20specifically%20expressed,is%20dispensable%20for%20visual%20function')
57. AnnotationURLCitation(end_index=20175, start_index=20011, title='RBFOX3/NeuN is dispensable for visual function - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5798780/#:~:text=reduction%20in%20the%20thickness%20of,is%20dispensable%20for%20visual%20function')
58. AnnotationURLCitation(end_index=20482, start_index=20318, title='RBFOX3/NeuN is dispensable for visual function - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5798780/#:~:text=reduction%20in%20the%20thickness%20of,is%20dispensable%20for%20visual%20function')
59. AnnotationURLCitation(end_index=21565, start_index=21400, title='Neuronal Splicing Regulator RBFOX3 (NeuN) Regulates Adult Hippocampal Neurogenesis and Synaptogenesis - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5049801/#:~:text=Dysfunction%20of%20RBFOX3%20has%20been,homozygous%20knockout%20mice%20and%20their')
60. AnnotationURLCitation(end_index=22056, start_index=21891, title='Neuronal Splicing Regulator RBFOX3 (NeuN) Regulates Adult Hippocampal Neurogenesis and Synaptogenesis - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5049801/#:~:text=Dysfunction%20of%20RBFOX3%20has%20been,homozygous%20knockout%20mice%20and%20their')
61. AnnotationURLCitation(end_index=22383, start_index=22207, title='RBFOX3/NeuN is Required for Hippocampal Circuit Balance and Function - PubMed', type='url_citation', url='https://pubmed.ncbi.nlm.nih.gov/26619789/#:~:text=RBFOX3%20mutations%20are%20linked%20to,neurotransmitter%20release%20probability%20and%20dendritic')
62. AnnotationURLCitation(end_index=22618, start_index=22522, title='RBFOX3/NeuN is Required for Hippocampal Circuit Balance and Function - PubMed', type='url_citation', url='https://pubmed.ncbi.nlm.nih.gov/26619789/#:~:text=Display%20options')
63. AnnotationURLCitation(end_index=22792, start_index=22619, title='RBFOX3/NeuN is Required for Hippocampal Circuit Balance and Function - PubMed', type='url_citation', url='https://pubmed.ncbi.nlm.nih.gov/26619789/#:~:text=knockout%20mice%20showed%20increased%20expression,may%20provide%20mechanistic%20insights%20for')
64. AnnotationURLCitation(end_index=23140, start_index=22959, title='RBFOX3/NeuN is Required for Hippocampal Circuit Balance and Function - PubMed', type='url_citation', url='https://pubmed.ncbi.nlm.nih.gov/26619789/#:~:text=Rbfox3%20knockout%20mice%20displayed%20increased,results%20demonstrate%20anatomical%20and%20functional')
65. AnnotationURLCitation(end_index=23414, start_index=23278, title='Genetic variants in RBFOX3 are associated with sleep latency - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5027680/#:~:text=PMC%20pmc,PMCID%3A%20PMC5027680%20PMID%3A%2027142678')
66. AnnotationURLCitation(end_index=24081, start_index=23956, title='Novel Insights into NeuN: from Neuronal Marker to Splicing Regulator - PubMed', type='url_citation', url='https://pubmed.ncbi.nlm.nih.gov/25680637/#:~:text=for%20the%20past%20two%20decades,This%20review')
67. AnnotationURLCitation(end_index=24465, start_index=24296, title='Novel Insights into NeuN: from Neuronal Marker to Splicing Regulator - PubMed', type='url_citation', url='https://pubmed.ncbi.nlm.nih.gov/25680637/#:~:text=protein%20remained%20elusive%20for%2017,diseases%20and%20specific%20physiological%20states')
68. AnnotationURLCitation(end_index=24797, start_index=24608, title='Altered Subcellular Localization of the NeuN/Rbfox3 RNA Splicing Factor in HIV-Associated Neurocognitive Disorders (HAND) - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC3880598/#:~:text=nuclear%20localization%2C%20we%20found%20significantly,downregulation%20of%20neuronal%20gene%20expression')
69. AnnotationURLCitation(end_index=25317, start_index=25154, title='Novel Insights into NeuN: from Neuronal Marker to Splicing Regulator - PubMed', type='url_citation', url='https://pubmed.ncbi.nlm.nih.gov/25680637/#:~:text=for%20the%20past%20two%20decades,caution%20when%20applying%20NeuN%20immunoreactivity')
70. AnnotationURLCitation(end_index=26271, start_index=26111, title='RBFOX3 Regulates the Chemosensitivity of Cancer Cells to 5-Fluorouracil via the PI3K/AKT, EMT and Cytochrome-C/Caspase Pathways - PubMed', type='url_citation', url='https://pubmed.ncbi.nlm.nih.gov/29689552/#:~:text=Results%3A%20RBFOX3%20was%20found%20to,and%20enhanced%20the%20apoptosis%20induced')
71. AnnotationURLCitation(end_index=26652, start_index=26492, title='RBFOX3 Regulates the Chemosensitivity of Cancer Cells to 5-Fluorouracil via the PI3K/AKT, EMT and Cytochrome-C/Caspase Pathways - PubMed', type='url_citation', url='https://pubmed.ncbi.nlm.nih.gov/29689552/#:~:text=Results%3A%20RBFOX3%20was%20found%20to,and%20enhanced%20the%20apoptosis%20induced')
72. AnnotationURLCitation(end_index=27191, start_index=27016, title='Transforming Growth Factor-β-Induced RBFOX3 Inhibition Promotes Epithelial-Mesenchymal Transition of Lung Cancer Cells - ScienceDirect', type='url_citation', url='https://www.sciencedirect.com/science/article/pii/S1016847823050744#:~:text=...main%20contentSkip%20to%20article%20,0150Get%20rights%20and%20content')
73. AnnotationURLCitation(end_index=27541, start_index=27414, title='RBFOX3 regulates Claudin-1 expression in human lung tissue via attenuation of proteasomal degradation - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5322747/#:~:text=of%20proteasomal%20degradation%20,%E2%9C%89')
74. AnnotationURLCitation(end_index=28565, start_index=28425, title='Novel Insights into NeuN: from Neuronal Marker to Splicing Regulator - PubMed', type='url_citation', url='https://pubmed.ncbi.nlm.nih.gov/25680637/#:~:text=exclusively%20in%20post,More%20importantly%2C%20despite%20the')
75. AnnotationURLCitation(end_index=29313, start_index=29173, title='NeuN, a DNA-binding neuron-specific protein expressed by Merkel cell carcinoma: analysis of 15 cases - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC8720396/#:~:text=malignancies,tumors%2C%20in%20Merkel%20cell%20carcinomas')
76. AnnotationURLCitation(end_index=29438, start_index=29314, title='NeuN, a DNA-binding neuron-specific protein expressed by Merkel cell carcinoma: analysis of 15 cases - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC8720396/#:~:text=Fifteen%20cases%20of%20Merkel%20cell,The')
77. AnnotationURLCitation(end_index=30900, start_index=30740, title='RBFOX3 Regulates the Chemosensitivity of Cancer Cells to 5-Fluorouracil via the PI3K/AKT, EMT and Cytochrome-C/Caspase Pathways - PubMed', type='url_citation', url='https://pubmed.ncbi.nlm.nih.gov/29689552/#:~:text=Results%3A%20RBFOX3%20was%20found%20to,and%20enhanced%20the%20apoptosis%20induced')
78. AnnotationURLCitation(end_index=31330, start_index=31141, title='Altered Subcellular Localization of the NeuN/Rbfox3 RNA Splicing Factor in HIV-Associated Neurocognitive Disorders (HAND) - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC3880598/#:~:text=nuclear%20localization%2C%20we%20found%20significantly,downregulation%20of%20neuronal%20gene%20expression')
79. AnnotationURLCitation(end_index=31829, start_index=31660, title='Novel Insights into NeuN: from Neuronal Marker to Splicing Regulator - PubMed', type='url_citation', url='https://pubmed.ncbi.nlm.nih.gov/25680637/#:~:text=protein%20remained%20elusive%20for%2017,diseases%20and%20specific%20physiological%20states')
80. AnnotationURLCitation(end_index=32225, start_index=32044, title='Novel Insights into NeuN: from Neuronal Marker to Splicing Regulator - PubMed', type='url_citation', url='https://pubmed.ncbi.nlm.nih.gov/25680637/#:~:text=diseases%20and%20specific%20physiological%20states,caution%20when%20applying%20NeuN%20immunoreactivity')
81. AnnotationURLCitation(end_index=32617, start_index=32448, title='Novel Insights into NeuN: from Neuronal Marker to Splicing Regulator - PubMed', type='url_citation', url='https://pubmed.ncbi.nlm.nih.gov/25680637/#:~:text=protein%20remained%20elusive%20for%2017,diseases%20and%20specific%20physiological%20states')
82. AnnotationURLCitation(end_index=33098, start_index=32944, title='Alternative splicing and related RNA binding proteins in human health and disease | Signal Transduction and Targeted Therapy', type='url_citation', url='https://www.nature.com/articles/s41392-024-01734-2#:~:text=mammalian%20cerebral%20cortex%20development,93%20%2C%20106%2C95%20%2C%20108')
83. AnnotationURLCitation(end_index=34360, start_index=34195, title='Neuronal Splicing Regulator RBFOX3 (NeuN) Regulates Adult Hippocampal Neurogenesis and Synaptogenesis - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5049801/#:~:text=Dysfunction%20of%20RBFOX3%20has%20been,homozygous%20knockout%20mice%20and%20their')
84. AnnotationURLCitation(end_index=34578, start_index=34397, title='Neuronal Splicing Regulator RBFOX3 (NeuN) Regulates Adult Hippocampal Neurogenesis and Synaptogenesis - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5049801/#:~:text=differs%20developmentally%20for%20distinct%20brain,results%20demonstrate%20the%20important%20role')
85. AnnotationURLCitation(end_index=34858, start_index=34685, title='Rbfox3-regulated alternative splicing of Numb promotes neuronal differentiation during development - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC3575530/#:~:text=of%20postmitotic%20neurons,neuronal%20differentiation%20during%20vertebrate%20development')
86. AnnotationURLCitation(end_index=35126, start_index=34970, title='NeuN/Rbfox3 Nuclear and Cytoplasmic Isoforms Differentially Regulate Alternative Splicing and Nonsense-Mediated Decay of Rbfox2 - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC3126832/#:~:text=nuclear%20localization%20signal,Rbfox3%20through%20a%20novel%20mechanism')
87. AnnotationURLCitation(end_index=35407, start_index=35226, title='Novel Insights into NeuN: from Neuronal Marker to Splicing Regulator - PubMed', type='url_citation', url='https://pubmed.ncbi.nlm.nih.gov/25680637/#:~:text=diseases%20and%20specific%20physiological%20states,caution%20when%20applying%20NeuN%20immunoreactivity')

Deep Research Report: RBFOX3 (human)

Generated using OpenAI Deep Research API

RBFOX3 (NeuN) – Comprehensive Gene Function and GO Annotation Report

Gene Function and Molecular Mechanisms

RBFOX3 (also known as NeuN or Fox-3) encodes an RNA-binding protein of the FOX family that is crucial for neuron-specific pre-mRNA splicing regulation (www.ncbi.nlm.nih.gov). Like its paralogs RBFOX1 and RBFOX2, RBFOX3 contains a central RNA-recognition motif (RRM) domain that binds the consensus RNA sequence UGCAUG in target transcripts (www.ncbi.nlm.nih.gov). Through this sequence-specific binding, RBFOX3 modulates alternative exon inclusion or skipping – a mechanism exemplified by the Numb gene, where RBFOX3 binding to an intronic UGCAUG element represses inclusion of an alternative exon (www.ncbi.nlm.nih.gov). This splicing switch in Numb pre-mRNA produces an isoform that promotes neuronal differentiation, highlighting RBFOX3’s role as a positive regulator of neuron-specific alternative splicing (www.ncbi.nlm.nih.gov). In general, RBFOX3 and its family members act as splicing factors that enhance or silence exons in numerous neuronal transcripts, thereby diversifying the proteome of the nervous system and influencing neuronal gene expression programs (www.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov).

Beyond splicing, RBFOX3 may participate in other post-transcriptional processes. Multiple isoforms of RBFOX3 exist, including nuclear and cytoplasmic variants, suggesting distinct functional roles (www.bio-techne.com). Indeed, studies have shown that nuclear RBFOX3 isoforms primarily regulate alternative splicing, whereas a cytoplasmic isoform can influence mRNA stability via nonsense-mediated decay (as seen for RBFOX2 mRNA targets) (pubmed.ncbi.nlm.nih.gov). RBFOX3 was initially identified by an immunological screen as the NeuN antigen; interestingly, early in vitro experiments indicated NeuN could bind DNA, though its physiological significance as a DNA-binding entity remains unclear (www.bio-techne.com). Overall, the key molecular function of RBFOX3 is as an RNA-binding splicing regulator, with the ability to shape neuronal gene expression by controlling the inclusion of specific exons in target mRNAs (www.ncbi.nlm.nih.gov). This activity is critical for the maturation and function of neurons, as it ensures the production of neuron-specific protein isoforms needed for proper cellular differentiation and synaptic function.

Cellular Localization and Subcellular Components

RBFOX3 is predominantly localized to the nucleus of neurons, consistent with its role in pre-mRNA splicing (pubmed.ncbi.nlm.nih.gov) (www.bio-techne.com). Immunostaining with the NeuN antibody (which recognizes an epitope at RBFOX3’s N-terminus) shows strong nuclear labeling in nearly all mature neurons throughout the central nervous system (pubmed.ncbi.nlm.nih.gov). In these cells, RBFOX3 concentrates in the neuronal nucleus (often excluding the nucleolus) and can also be detected in perikarya – reflecting its presence in the neuronal cell body (pubmed.ncbi.nlm.nih.gov). Notably, RBFOX3 is not expressed in glial cells or neural progenitors, but exclusively in post-mitotic neurons, which is why NeuN immunoreactivity is a definitive marker of neurons in tissue sections (pubmed.ncbi.nlm.nih.gov).

Although the bulk of RBFOX3 resides in the nucleus, alternative splicing of the RBFOX3 gene produces multiple protein isoforms with different subcellular distributions (www.bio-techne.com). Specifically, two major isoforms (~46 kDa and ~48 kDa) have been observed: the ~46 kDa form is largely nuclear, whereas the slightly larger ~48 kDa isoform is found predominantly in the cytoplasm (www.bio-techne.com). This suggests that RBFOX3 shuttling or retention may be modulated by the presence or absence of certain peptide segments. The N-terminus contains the NeuN epitope (amino acids 6–15) and likely a nuclear targeting signal, while the inclusion of an alternate exon in the larger isoform may affect nuclear import or export (www.bio-techne.com) (www.bio-techne.com). Consequently, a fraction of RBFOX3 protein can localize to the cytoplasm of neurons, where it might engage cytosolic RNA targets or interact with the translation machinery. Indeed, RBFOX3’s cytoplasmic isoform has been implicated in regulating mRNA turnover pathways (e.g. nonsense-mediated decay) in addition to its nuclear splicing role (pubmed.ncbi.nlm.nih.gov). Despite this, the dominant localization of RBFOX3 in most contexts is the neuronal nucleus, aligning with its function as a splicing regulator within the nuclear compartment (www.bio-techne.com).

Biological Processes Involvement

RBFOX3 plays a prominent role in several neuronal biological processes. During development, RBFOX3 is essential for proper neuronal differentiation: loss-of-function studies in cell culture and in vivo have demonstrated that RBFOX3 activity drives the maturation of post-mitotic neurons (www.ncbi.nlm.nih.gov) (www.ncbi.nlm.nih.gov). Knockdown of RBFOX3 impairs neuron differentiation (e.g., reduced neurite outgrowth and delayed expression of neuronal markers), whereas normal RBFOX3 promotes the transition of immature neurons into fully differentiated states (www.ncbi.nlm.nih.gov) (www.ncbi.nlm.nih.gov). Mechanistically, this pro-differentiation effect is mediated through alternative splicing of key developmental regulators like Numb, as described above, as well as other targets that influence cell fate decisions (www.ncbi.nlm.nih.gov) (www.ncbi.nlm.nih.gov). Thus, RBFOX3 is a positive regulator of neuronal differentiation, ensuring that newly generated neurons acquire the correct gene expression profile for maturation. Consistent with this, RBFOX3 expression is low or absent in neural progenitors but strongly upregulated as neurons exit the cell cycle and mature (pubmed.ncbi.nlm.nih.gov) (www.ncbi.nlm.nih.gov).

In the adult brain, RBFOX3 continues to be important for neuronal maintenance, plasticity, and circuit function. RBFOX3 (NeuN) has been implicated in adult neurogenesis, particularly in the hippocampus. Mice lacking RBFOX3 show deficits in adult hippocampal neurogenesis, evidenced by reduced proliferation or survival of newborn neurons in the dentate gyrus (pmc.ncbi.nlm.nih.gov). These mice also exhibit abnormalities in synaptogenesis and synaptic plasticity: for example, RBFOX3 knockout leads to altered expression of synapse-related gene isoforms, a decrease in long-term synaptic plasticity, and an increase in dendritic spine density (indicative of aberrant synapse formation) (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). Electrophysiological studies in RBFOX3-null mice reveal defective synaptic transmission and an increased frequency of spontaneous excitatory events, associated with an elevated neurotransmitter release probability (pmc.ncbi.nlm.nih.gov). This suggests that RBFOX3 normally helps maintain excitatory/inhibitory balance in neural circuits, likely through splicing control of ion channels, neurotransmitter receptors, or synaptic proteins that govern neurotransmission (pmc.ncbi.nlm.nih.gov) (pubmed.ncbi.nlm.nih.gov). In support of this idea, co-expression network analyses in humans have linked RBFOX3 to genes involved in neurotransmitter release (including GABAergic pathways) (pubmed.ncbi.nlm.nih.gov).

Through its widespread effects on neuronal mRNA processing, RBFOX3 influences higher-order brain functions. RBFOX3-null mice display cognitive impairments (for instance, poor performance in memory tests) and behavioral changes such as reduced anxiety-like behavior (pmc.ncbi.nlm.nih.gov). They are also prone to seizures, due to hyperexcitability in hippocampal circuits when RBFOX3 is absent (pmc.ncbi.nlm.nih.gov). These phenotypes underscore RBFOX3’s involvement in maintaining normal learning, memory, and network excitability. Additionally, RBFOX3 may contribute to neuronal stress responses or injury pathways, as NeuN immunoreactivity is known to diminish in certain pathological states (e.g. after axonal injury or ischemia) even if neurons are still present (pubmed.ncbi.nlm.nih.gov). This variability suggests that RBFOX3 expression or epitope availability can change in diseased neurons, a factor to consider when using NeuN as a neuronal marker (pubmed.ncbi.nlm.nih.gov). In summary, RBFOX3 is engaged in key biological processes including neuron differentiation, adult neurogenesis, synapse formation, and synaptic function/plasticity, all of which collectively support proper neural development and adult brain homeostasis.

Protein Domains and Structural Features

RBFOX3 is a relatively small, single-polypeptide protein characterized by a modular domain structure common to the Rbfox family. The human RBFOX3 protein is about 314 amino acids in length and consists of three main regions (www.ncbi.nlm.nih.gov) (www.bio-techne.com): an N-terminal region rich in proline residues, a central RNA-binding domain, and a C-terminal region enriched in alanine residues. The N-terminal proline-rich segment (approximately amino acids 1–100) may facilitate protein–protein interactions or contribute to subcellular targeting. Importantly, within the extreme N-terminus (aa 6–15) lies the NeuN antigenic epitope recognized by the classic anti-NeuN antibody (www.bio-techne.com). This epitope’s location in a low-complexity region might explain why certain NeuN antibodies fail to detect some isoforms or certain physiological states of the protein (pubmed.ncbi.nlm.nih.gov).

The central RNA Recognition Motif (RRM) is the defining feature of RBFOX3, spanning roughly 90 amino acids (the core RRM domain is ~77 aa) (www.bio-techne.com). This RRM domain folds into the conserved βαββαβ structure that binds RNA, and it is highly conserved among RBFOX family members. In fact, the RRM amino acid sequence of RBFOX3 is almost identical to that of RBFOX1 and RBFOX2 – differing by only 4 residues – indicating strong evolutionary pressure to maintain its RNA-binding function (www.bio-techne.com). The RRM directly recognizes the sequence UGCAUG in target RNAs, predominantly via its RNP1 and RNP2 submotifs that contact the guanosine and uridine bases (www.ncbi.nlm.nih.gov). Structural and biochemical studies of the RBFOX1 RRM bound to RNA have shown how this domain specifically latches onto the UGCAUG element (www.ncbi.nlm.nih.gov), and RBFOX3 is expected to bind identically given the near-identical RRM sequence. Flanking the RRM, RBFOX3 has short linker regions that may contribute to RNA binding affinity and specificity, or mediate interactions with other splicing factors.

The C-terminus of RBFOX3 contains an alanine-rich region (poly-Ala and Ala/Gly stretches) (www.ncbi.nlm.nih.gov). This C-terminal tail is intrinsically disordered and may enable RBFOX3 to engage in multivalent interactions or phase-separated nuclear bodies. In RBFOX1 and RBFOX2, the equivalent region contains a Tyrosine-rich motif that mediates self-aggregation and assembly into a larger splicing regulatory complex (the LASR complex) (pubmed.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). RBFOX3 likely shares this ability: its C-terminal low-complexity domain can facilitate incorporation into multi-protein complexes required for splicing regulation. Indeed, RBFOX proteins are known to function as part of a large spliceosomal assembly (the Large Assembly of Splicing Regulators) via their C-termini, interacting with other splicing co-factors to exert their effects on exon inclusion (pubmed.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). In summary, RBFOX3’s structure – comprising an RRM flanked by disordered regions – is well-suited for its role as a splicing factor, providing both sequence-specific RNA binding and flexible interaction interfaces to recruit or stabilize the splicing machinery at target pre-mRNAs.

Disease Associations and Phenotypes

Given its neuron-specific expression and critical role in regulating neuronal gene networks, it is not surprising that RBFOX3 has been linked to several neurological conditions. Mutations in RBFOX3 have been associated with a range of neurodevelopmental and neurological disorders (www.ncbi.nlm.nih.gov). Notably, rare loss-of-function variants in RBFOX3 have been identified in epilepsy patients. A study of Rolandic epilepsy (a common idiopathic focal epilepsy in children) found a de novo nonsense mutation in RBFOX3 (p.Tyr287*) and an exon 3 deletion, among other RBFOX-family mutations, in patients (pubmed.ncbi.nlm.nih.gov) (pubmed.ncbi.nlm.nih.gov). These RBFOX3 truncating variants were absent in large control cohorts, suggesting RBFOX3 dysfunction as a novel genetic risk factor for epilepsy (pubmed.ncbi.nlm.nih.gov). RBFOX3 haploinsufficiency or loss could lead to imbalanced splicing of neuronal excitability genes, predisposing individuals to seizures – consistent with the seizure phenotype observed in Rbfox3-knockout mice (pmc.ncbi.nlm.nih.gov). Indeed, RBFOX3-null mice show spontaneous epileptic activity and lowered seizure threshold, providing a mechanistic link between RBFOX3 disruption and epilepsy (pmc.ncbi.nlm.nih.gov). Beyond Rolandic epilepsy, truncating or copy number mutations in the related RBFOX1 gene have been implicated in generalized epilepsy and other neurodevelopmental syndromes, emphasizing that proper dosage of RBFOX-family proteins is crucial for neural circuit stability (pubmed.ncbi.nlm.nih.gov).

RBFOX3 has also emerged in genetic studies of sleep and cognition. A large human genome-wide association study identified common polymorphisms in the RBFOX3 locus that are significantly associated with sleep latency, i.e. the time it takes to fall asleep (pubmed.ncbi.nlm.nih.gov). Three highly correlated single-nucleotide polymorphisms in RBFOX3 showed genome-wide significance for longer sleep latency (P ~10^−8), and follow-up analysis across ~30,000 individuals confirmed this association (pubmed.ncbi.nlm.nih.gov). While the precise mechanism is unknown, co-expression data suggest RBFOX3 might influence neuronal circuits that regulate sleep onset, possibly through modulation of neurotransmitter release (including GABAergic signaling) (pubmed.ncbi.nlm.nih.gov). This finding points toward a role for RBFOX3 in sleep physiology and aligns with the protein’s involvement in synaptic function. Additionally, RBFOX3/NeuN levels or localization have been noted to change in certain neurodegenerative or neuropsychiatric conditions. For example, in HIV-associated neurocognitive disorder, RBFOX3 (NeuN) mislocalization from the nucleus to the cytoplasm has been observed in affected neurons (pubmed.ncbi.nlm.nih.gov) (pubmed.ncbi.nlm.nih.gov), which could disrupt normal splicing of neuron-specific transcripts. There is also interest in RBFOX3’s role in disorders like autism spectrum disorder and intellectual disability, given that RBFOX1/2 are known autism risk genes and all three RBFOX proteins regulate overlapping sets of neuronal transcripts (pubmed.ncbi.nlm.nih.gov). Some patients with neurodevelopmental delay have been reported with chromosomal anomalies affecting the RBFOX3 gene region (www.ncbi.nlm.nih.gov), though clear causal links for RBFOX3 in autism or intellectual disability remain to be fully established.

In summary, RBFOX3 dysfunction – whether through rare mutations or altered expression – is linked to neurological phenotypes including epilepsy, sleep disturbances, cognitive impairment, and possibly neurodevelopmental disorders (www.ncbi.nlm.nih.gov) (pubmed.ncbi.nlm.nih.gov). These associations underscore the gene’s importance for normal neuronal function. Clinically, RBFOX3 (NeuN) is also used as a neuronal injury marker: loss of NeuN staining in neurons can indicate degeneration or severe stress (as seen in stroke or trauma models), reflecting either protein downregulation or epitope masking (pubmed.ncbi.nlm.nih.gov). Thus, RBFOX3 serves as both a functional player in disease mechanisms and a practical marker in neuropathology.

Expression Patterns and Regulation

Tissue specificity: RBFOX3 is overwhelmingly specific to the nervous system. It is almost exclusively expressed in neurons of the central and peripheral nervous systems, with virtually no expression in non-neural tissues (www.bio-techne.com). High RBFOX3 mRNA and protein levels are detected in brain regions such as the cerebral cortex, hippocampus, thalamus, striatum (caudate/putamen), cerebellum, and spinal cord – essentially, RBFOX3 marks mature neurons across the brain and spinal cord gray matter (www.bio-techne.com). This neuron-specific expression is so consistent that NeuN immunostaining is routinely used to identify neurons in histological sections. In contrast, glial cells (astrocytes, oligodendrocytes, microglia) and neural progenitor/stem cells do not express RBFOX3/NeuN (pubmed.ncbi.nlm.nih.gov). Hence, RBFOX3 serves as a binary marker distinguishing neurons from other cell types in the CNS.

Developmental expression: RBFOX3 expression is tightly linked to neuronal differentiation. During embryonic development, Rbfox3 transcripts are low or absent in neural stem cells but are upregulated as neurons are born and undergo terminal differentiation (www.ncbi.nlm.nih.gov). For instance, in mouse embryos, Rbfox3 (NeuN) becomes detectable in post-mitotic neurons of the spinal cord and brain at the stage when they exit the cell cycle and start expressing pan-neuronal markers like β-III tubulin (www.ncbi.nlm.nih.gov) (www.ncbi.nlm.nih.gov). In vitro, when pluripotent cells or neural precursors are induced to differentiate into neurons (e.g., via retinoic acid treatment in P19 cell models), Rbfox3 is one of the genes strongly induced during the transition from progenitor to neuron (www.ncbi.nlm.nih.gov). This timing reinforces the concept that RBFOX3 is part of the gene expression program defining neuronal identity. Once expressed, RBFOX3 tends to remain stable in neurons throughout adulthood – it is considered a constitutive marker of mature neurons under normal conditions (pubmed.ncbi.nlm.nih.gov). The protein persists in aging neurons as well, indicating that its expression is maintained long-term in non-dividing neuronal cells.

Regulation of expression: The transcriptional regulation of RBFOX3 is less well characterized than that of some other neuron-specific genes, but it likely involves neuron-specific transcription factors and chromatin states. Given the restricted expression, the RBFOX3 gene promoter may have binding sites for neuronal fate determinants (such as NEUROD, RCORs, or SOX family members) and could be epigenetically repressed in non-neural tissues. Alternative splicing of RBFOX3 pre-mRNA gives rise to its multiple isoforms; interestingly, there is evidence of auto-regulation within the RBFOX family whereby RBFOX proteins can bind to their own or each other’s transcripts to influence splicing. For example, RBFOX3 and RBFOX2 have been reported to cross-regulate splicing of each other’s mRNAs, forming a feedback loop in neurons (pubmed.ncbi.nlm.nih.gov). Additionally, post-translational modifications might regulate RBFOX3’s stability or localization. Some observations suggest NeuN exists as two bands on SDS-PAGE (46–48 kDa) due not only to splicing isoforms but possibly phosphorylation differences (www.bio-techne.com). Phosphorylation state changes could alter RBFOX3’s interaction with RNA or other proteins, thereby modulating its splicing activity in response to signaling pathways.

Pathological changes: Although RBFOX3 is generally stably expressed, certain conditions can alter its levels. Neuronal injury or stress can lead to a reduction or loss of NeuN immunoreactivity, as noted in ischemic brain damage and axotomy studies (pubmed.ncbi.nlm.nih.gov). This loss might reflect proteolytic degradation of RBFOX3, transcriptional downregulation, or a conformational change that hides the NeuN epitope. For example, after severe axonal injury, affected neurons temporarily lose NeuN staining even if they survive, indicating a change in RBFOX3 expression or structure in response to trauma (pubmed.ncbi.nlm.nih.gov). Also, neurodegenerative diseases may impact RBFOX3: some reports in Alzheimer’s or Parkinson’s disease models note neurons with diminished NeuN despite being morphologically intact, possibly corresponding to functional silencing of those cells. In sum, RBFOX3 is a robust marker of neuronal identity under normal conditions, with tightly controlled expression from the point of neuron birth onward, though extreme stressors can downregulate this gene as part of a pathological response.

Evolutionary Conservation

RBFOX3 is highly conserved across vertebrate species, reflecting its fundamental role in neuron-specific RNA regulation. Orthologs of RBFOX3 are present in all mammals and show strong sequence similarity. Mouse Rbfox3, for instance, shares about 84% amino acid identity with human RBFOX3, and nearly 99% identity with rat Rbfox3 (www.bio-techne.com). This high degree of conservation is especially pronounced in functional domains: the RNA-recognition motif and flanking regions are almost identical between species, underscoring the importance of those sequences for RBFOX3’s splicing function. The RBFOX family as a whole is evolutionarily ancient – the “Fox-1” proteins were originally identified in C. elegans (the family name comes from a Caenorhabditis elegans gene, fox-1, which also binds the UGCAUG RNA motif) (www.bio-techne.com). In vertebrates, this family expanded into three paralogous genes (RBFOX1, RBFOX2, RBFOX3), likely via gene duplications that allowed tissue specialization. RBFOX3 appears to have diverged to specialize in neuronal functions, whereas RBFOX1 and RBFOX2 have broader expression (RBFOX1 is abundant in brain, heart, and muscle; RBFOX2 is ubiquitous). Despite this divergence in expression patterns, all three proteins retain the core RRM domain and recognize the same RNA sequence element (www.bio-techne.com). The few amino acid differences in RBFOX3’s RRM compared to RBFOX1/2 do not change its RNA-binding specificity, but they could fine-tune its protein interactions or regulation in neurons (www.bio-techne.com).

Outside of mammals, RBFOX3 counterparts can be found in other vertebrates such as birds, reptiles, amphibians, and fish, where they are expected to perform similar roles in neuronal gene splicing. For example, in chicken, an RBFOX3 homolog is expressed in differentiating neurons during development, analogous to the pattern seen in mammals (www.ncbi.nlm.nih.gov). In Drosophila and other invertebrates, there is generally a single Rbfox gene (often termed A2bp1 or Rbfox1) that combines functions equivalent to all three mammalian RBFOX proteins (www.sdbonline.org). The fruit fly Rbfox1 (A2bp1) is expressed in neurons and muscle and has been shown to regulate splicing of transcripts involved in neuromuscular function (www.sdbonline.org). Similarly, zebrafish possess fox1 and fox2 homologs that likely cover RBFOX3-like roles in neural tissues. The strong conservation of RBFOX3’s sequence and the phenotypes observed when it is disrupted (in mice or human patients) both indicate that this gene has been under purifying selection across evolution. Its neuron-specific expression and vital splicing regulatory function have been preserved from early vertebrates to humans. Evolution may have tuned RBFOX3’s non-core regions (like the proline- and alanine-rich ends) for specialized interactions in mammalian neurons, but the central RNA-binding function is a constant. Thus, RBFOX3 exemplifies a highly conserved neuronally expressed regulator, with homologous proteins performing analogous roles in managing RNA splicing in the nervous systems of diverse species (www.bio-techne.com) (www.bio-techne.com).

Relevant Gene Ontology (GO) Terms

Based on the functions, processes, and localizations discussed above, RBFOX3 can be annotated with several Gene Ontology terms, supported by experimental evidence:

• Molecular Function (MF):
• RNA binding (GO:0003723) – RBFOX3 binds to RNA via its RRM domain, recognizing the UGCAUG sequence in target pre-mRNAs (www.ncbi.nlm.nih.gov).
• RNA binding, sequence-specific (GO:0000980, broader context) – It selectively binds specific RNA motifs to regulate splicing (www.ncbi.nlm.nih.gov).

• mRNA splicing factor activity (GO:0003724) – Functions as a splicing regulator by binding pre-mRNA and influencing exon selection (www.ncbi.nlm.nih.gov).

• Biological Process (BP):

• Regulation of alternative mRNA splicing, via spliceosome (GO:0000381) – RBFOX3 modulates the inclusion/skipping of exons in target mRNAs in neurons (www.ncbi.nlm.nih.gov) (www.ncbi.nlm.nih.gov).
• Positive regulation of neuron differentiation (GO:0045666) – RBFOX3 activity promotes the maturation of post-mitotic neurons during development (www.ncbi.nlm.nih.gov) (www.ncbi.nlm.nih.gov).
• Adult neurogenesis (GO:0048170) – Involved in the generation and integration of new neurons in the adult hippocampus (knockout causes reduced adult neurogenesis) (pmc.ncbi.nlm.nih.gov).
• Synapse organization (GO:0050808) – Regulates synaptogenesis and synaptic structure (knockout alters spine density and synapse formation) (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov).
• Regulation of synaptic plasticity (GO:0048167) – Influences synaptic transmission and plasticity in hippocampal circuits (KO affects LTP/LTD and neurotransmitter release) (pmc.ncbi.nlm.nih.gov).

• Regulation of neurotransmitter levels (GO:0001505) – By controlling splicing of neurotransmission-related genes, RBFOX3 indirectly affects neurotransmitter release and neural excitability (pmc.ncbi.nlm.nih.gov) (pubmed.ncbi.nlm.nih.gov).

• Cellular Component (CC):

• Nucleus (GO:0005634) – RBFOX3 is predominantly located in the neuronal nucleus, where it carries out pre-mRNA splicing regulation (www.bio-techne.com).
• Neuronal cell body (GO:0043025) – As a neuronal protein, RBFOX3 is present in the soma of neurons (especially concentrated in the nucleus within the cell body) (pubmed.ncbi.nlm.nih.gov).
• Cytoplasm (GO:0005737) – A subset of RBFOX3 (the larger isoform) localizes to the cytoplasm, indicating some cytosolic presence (www.bio-techne.com).
• Spliceosomal complex (GO:0005681) – Functionally, RBFOX3 interacts with the spliceosome machinery; it can be considered a component of a splicing regulatory complex within the nucleus (pubmed.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov).

Each of these GO terms is supported by the literature evidence cited, reflecting RBFOX3’s role as an RNA-binding splicing factor (MF), its involvement in neuron-specific RNA processing and developmental processes (BP), and its localization to neuronal nuclei and related structures (CC). This comprehensive annotation of RBFOX3 captures its essential function in the gene expression program of neurons and its impact on neural development and function.