| Aspect | Key points | Evidence type (primary/review/protocol) | Representative sources (with year) | Notes/limitations |
|---|---|---|---|---|
| Identity / synonyms | Human RBFOX3 (UniProt A6NFN3) corresponds to the NeuN antigen; common aliases include Fox-3, HRNBP3, NeuN, and RNA binding protein fox-1 homolog 3. Anti-NeuN epitope maps to the N-terminus of RBFOX3. Neuron-restricted expression distinguishes it from RBFOX1/2. (pqac-00000001, pqac-00000002, pqac-00000003, pqac-00000004, pqac-00000005) | Primary + review | Dredge et al., 2011; Kim et al., 2013; Duan et al., 2016; Mukherjee & Nongthomba, 2024 | Direct NeuN identification was established experimentally mainly in mouse brain and extrapolated to human ortholog/family annotation. |
| Domains / family architecture | RBFOX3 is a member of the RBFOX family and contains a single central RNA recognition motif (RRM/RBD). RBFOX3 RRM is highly similar, but not identical, to RBFOX1/2; exon skipping can delete part of the RRM. (pqac-00000002, pqac-00000004, pqac-00000008, pqac-00000011, pqac-00000031) | Primary + review | Dredge et al., 2011; Duan et al., 2016; Kim et al., 2013 | Domain-level evidence is strong, but most mechanistic structural details are family-level rather than human RBFOX3-only. |
| RNA motif specificity | RBFOX3 binds the canonical (U)GCAUG motif with high affinity, consistent with RBFOX family specificity. UGCAUG sites are central to target recognition in introns and some noncoding RNAs. (pqac-00000008, pqac-00000012, pqac-00000015) | Primary + review | Kim et al., 2013; Duan et al., 2016; Conboy, 2017 | Motif specificity is best established across the RBFOX family; direct RBFOX3 examples exist but transcriptome-wide motif maps are limited versus RBFOX1/2. |
| Position-dependent splicing mechanism | As for other RBFOX proteins, RBFOX3 generally promotes exon inclusion when bound downstream of an alternative exon and promotes exon skipping/repression when bound upstream. This rule explains target-specific effects on neuronal exons. (pqac-00000008, pqac-00000012, pqac-00000015) | Primary + review | Kim et al., 2013; Duan et al., 2016; Conboy, 2017 | Position-dependence is well supported, but quantitative predictive rules for individual human RBFOX3 targets remain incomplete. |
| Validated target: Numb exon 12 | RBFOX3 directly regulates Numb alternative splicing by binding a conserved upstream UGCAUG-containing intronic silencer near exon 12, repressing exon inclusion. Loss- and gain-of-function assays linked this event to neuronal differentiation during development. (pqac-00000008, pqac-00000012, pqac-00000031) | Primary + review | Kim et al., 2013; Duan et al., 2016 | Strong mechanistic target; much of the functional differentiation evidence is from chick/mouse developmental systems rather than human neurons. |
| Validated target: RBFOX2 exon 6 / cryptic exons / NMD | RBFOX3 cross-regulates RBFOX2 by promoting skipping of RBFOX2 exon 6 and enhancing inclusion of cryptic exons (e.g., 5*/6*) that introduce premature stop codons and trigger nonsense-mediated decay, reducing productive RBFOX2 output. In 293T assays, RBFOX3 isoforms reduced exon-6-containing RBFOX2 mRNA from 92% to 47%, 48%, and 39% for v1, v2, and v3, respectively. (pqac-00000001, pqac-00000011, pqac-00000014) | Primary | Dredge et al., 2011 | Robust cross-regulation evidence, but largely from heterologous cell assays plus mouse-derived constructs; human in vivo extent remains less defined. |
| miRNA biogenesis / Drosha microprocessor | Beyond pre-mRNA splicing, RBFOX3 binds pri-miRNAs and modulates their processing by the Drosha microprocessor. PAR-CLIP identified RBFOX3 binding clusters on pri-miRNAs; functional assays showed positive or negative effects on specific pri-miRNA-to-pre-miRNA processing. Drosha-knockdown qRT-PCR analyses used n=3 biological replicates with significant changes reported at P<0.001 for tested cases. (pqac-00000016, pqac-00000018, pqac-00000019, pqac-00000020) | Primary + review | Kim et al., 2014; Conboy, 2017 | This is a bona fide non-splicing function, but many affected miRNAs and physiological consequences remain incompletely mapped. |
| Subcellular localization / isoforms | RBFOX3 exists as alternatively spliced isoforms with distinct localization. Nuclear isoforms retain a complete C-terminal hPY-NLS, whereas at least one isoform (v3) is predominantly cytoplasmic because of altered C-terminus/NLS composition. Nuclear export was reported as not Crm1/exportin1-dependent. (pqac-00000000, pqac-00000007, pqac-00000011, pqac-00000014, pqac-00000031) | Primary + review | Dredge et al., 2011; Kim et al., 2013 | Cytoplasmic isoforms may still shuttle and affect nuclear splicing; exact localization dynamics in human neurons remain incompletely resolved. |
| Neuronal specificity / localization in tissue | RBFOX3 is observed predominantly or exclusively in post-mitotic neurons and is widely used as a mature neuronal nuclear marker. Compared with RBFOX1 (neurons, heart, skeletal muscle) and RBFOX2 (broader expression), RBFOX3 is the neuron-restricted paralog. (pqac-00000001, pqac-00000002, pqac-00000003, pqac-00000005, pqac-00000035) | Primary + review | Dredge et al., 2011; Kim et al., 2013; Duan et al., 2016; Mukherjee & Nongthomba, 2024; Nazim, 2024 | “Neuron-specific” is broadly true in tissue, but marker behavior can vary with developmental stage, injury, fixation, and disease context. |
| Disease / phenotype links | Reviews and recent summaries connect RBFOX3 dysregulation with neurological phenotypes; an epilepsy association/knockout-related link is mentioned in recent summaries, and older reviews cite RBFOX1/RBFOX3 variants in rolandic epilepsy. NeuN immunoreactivity can decrease or relocalize after injury/disease, so loss of staining does not necessarily equal neuron loss. (pqac-00000028, pqac-00000029, pqac-00000030, pqac-00000036, pqac-00000037) | Review / secondary synthesis | Weissbach, 2025 summary; Duan et al., 2016 | Disease evidence specific to human RBFOX3 is comparatively limited and often indirect, family-level, or cited through reviews rather than direct 2023–2024 human genetics papers. |
| Practical applications: NeuN marker in FANS / snRNA-seq / histology | RBFOX3/NeuN is widely used to identify neuronal nuclei in histology and nuclei sorting workflows. Recent protocols report >97% purity for NeuN+ sorted neuronal nuclei in mouse FANS, ~34.5% ± 13.5 of sorted events as neurons in one human cortical FANS workflow, routine recovery of ~300,000 neuronal nuclei for nuclear RNA from ~300 mg human cortex, and use of 31,669 NEUN+ nuclei in a human midbrain snRNA-seq study. (pqac-00000021, pqac-00000022, pqac-00000024, pqac-00000025, pqac-00000026) | Protocol + primary application studies | Signal et al., 2024; Chioza et al., 2025; Alsema et al., 2025; Chung et al., 2024 | Excellent real-world utility, but NeuN-negative neurons exist in some regions/states; protocols differ by tissue, fixation, antibody, and gating strategy. |


*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.*