ELAVL4 encodes HuD, a predominantly neuronal RNA-binding protein and paraneoplastic Hu antigen with three RNA recognition motifs. HuD recognizes U-rich and AU-rich elements, especially in mRNA 3-prime UTRs, and commonly protects selected neuronal transcripts from deadenylation and decay while promoting their translation. It also binds pyrimidine-rich intronic RNA in the nucleus to regulate neuron-specific alternative pre-mRNA processing. Cytoplasmic HuD occurs in neuronal cell bodies, axons, dendrites, and growth cones, where association with SMN contributes to target-mRNA recruitment into neuronal RNA granules. Target context can reverse its translational effect: in pancreatic beta cells, binding a conserved insulin-mRNA 5-prime-UTR element represses translation. CARM1-dependent hinge methylation modulates HuD RNA binding, SMN interaction, cell-cycle exit, and neurite differentiation.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0035925 mRNA 3'-UTR AU-rich region binding | IBA GO_REF:0000033 | ACCEPT | Summary: PAINT infers conserved binding to AU-rich regions in mRNA 3-prime UTRs. Reason: This is a defining HuD activity. Direct structural, kinetic, and target-RNA assays demonstrate selective binding to extended U-rich and AU-rich 3-prime-UTR elements. Supporting Evidence: PMID:10710437 With this assay, I demonstrate that HuC and HuD bind to the VEGF 3'-UTR regulatory segment (VRS) and to the c- myc 3'-UTR in a specific and concentration-dependent pattern, with both proteins showing a greater affinity for the VRS. file:human/ELAVL4/ELAVL4-deep-research-manual.md The core annotation model contains three linked activities |
| GO:0140517 protein-RNA adaptor activity | IBA GO_REF:0000033 | ACCEPT | Summary: PAINT infers a conserved protein-RNA adaptor activity in the ELAV family. Reason: HuD binds target RNAs through its RRMs and binds SMN independently of RNA. The SMN-HuD interaction is required for recruitment of HuD and its target mRNAs into neuronal granules, providing direct mechanistic support for coupling RNA cargo to protein machinery. Supporting Evidence: PMID:21088113 the interaction between HuD and SMN is required for proper recruitment of HuD and its mRNA targets in neuronal RNA granules |
| GO:0070935 3'-UTR-mediated mRNA stabilization | IBA GO_REF:0000033 | ACCEPT | Summary: PAINT infers conserved stabilization of mRNAs through their 3-prime UTRs. Reason: GAP43 decay assays directly show that HuD binding delays degradation and deadenylation, and ACHE, NOVA1, APP, and BACE1 provide independent target examples. Supporting Evidence: PMID:12034726 Here we report that overexpression of HuD protein in PC12 cells stabilizes the GAP-43 mRNA by delaying the onset of mRNA degradation and that this process depends on the size of the poly(A) tail. |
| GO:0003676 nucleic acid binding | IEA GO_REF:0000002 | MODIFY | Summary: InterPro maps the RRM fold to generic nucleic acid binding. Reason: The parent term is true but too broad. Structural and biochemical studies identify RNA, rather than an unspecified nucleic acid, as the relevant ligand; RNA binding is the informative replacement. Proposed replacements: RNA binding Supporting Evidence: PMID:11175903 Hu proteins bind to adenosine-uridine (AU)-rich elements (AREs) in the 3' untranslated regions of many short-lived mRNAs, thereby stabilizing them. |
| GO:0003723 RNA binding | IEA GO_REF:0000002 | ACCEPT | Summary: InterPro assigns RNA binding from HuD's three-RRM architecture. Reason: RNA binding is the fundamental molecular activity of HuD and is supported by direct structures, quantitative binding assays, and multiple target-RNA studies. |
| GO:0003730 mRNA 3'-UTR binding | IEA GO_REF:0000117 | ACCEPT | Summary: ARBA predicts binding to mRNA 3-prime UTRs. Reason: The broader term is correct alongside the more specific AU-rich-region term. HuD directly binds the 3-prime UTRs of VEGF, c-MYC, GAP43, ACHE, NOVA1, APP, and BACE1 transcripts. |
| GO:0005737 cytoplasm | IEA GO_REF:0000120 | ACCEPT | Summary: Combined automated annotation assigns cytoplasmic localization. Reason: Cytoplasmic HuD is directly observed and is the site of mRNA stabilization, translation control, and neuronal RNA-granule recruitment. Independent experimental and curator-reviewed transfer records corroborate this location. |
| GO:0030424 axon | IEA GO_REF:0000120 | ACCEPT | Summary: Combined automated annotation transfers axonal localization from mouse HuD. Reason: The orthology transfer is biologically sound and is independently supported by primary-motor-neuron imaging of HuD-positive axonal granules and by HuD-SMN cotransport. Supporting Evidence: PMID:21389246 Importantly, SMN knockdown in primary motor neurons resulted in a specific reduction of both HuD protein and poly(A) mRNA levels in the axonal compartment. |
| GO:0030425 dendrite | IEA GO_REF:0000120 | ACCEPT | Summary: Combined automated annotation transfers dendritic localization from mouse HuD. Reason: UniProt's reviewed orthology-based dendritic localization is consistent with HuD-dependent dendritic morphogenesis and neuronal mRNA transport in vertebrate systems. |
| GO:0030426 growth cone | IEA GO_REF:0000044 | ACCEPT | Summary: UniProt subcellular-location mapping assigns HuD to neuronal growth cones. Reason: The reviewed localization is consistent with primary-neuron imaging, axonal mRNP transport, and HuD-dependent neurite development. No contrary evidence was found. |
| GO:0043204 perikaryon | IEA GO_REF:0000044 | ACCEPT | Summary: UniProt subcellular-location mapping assigns HuD to the neuronal cell body. Reason: This is a well-supported neuronal distribution and complements axonal and dendritic localization; it is consistent with reviewed mouse evidence and HuD-positive granules in motor-neuron cell bodies. |
| GO:1990904 ribonucleoprotein complex | IEA GO_REF:0000002 | KEEP AS NON CORE | Summary: InterPro maps the HuD RRM family to generic ribonucleoprotein-complex membership. Reason: HuD clearly forms target-specific mRNPs and neuronal RNA granules, so the annotation is not wrong. It is non-core because it does not identify a specific stable complex and largely restates the consequence of RNA binding. |
| GO:0003729 mRNA binding | IEA GO_REF:0000107 | ACCEPT | Summary: Ensembl Compara transfers mRNA binding from mouse Elavl4. Reason: The transfer is correct and independently established by many direct human HuD target studies. The broad term remains useful alongside site-specific 3-prime-UTR annotations. |
| GO:0005737 cytoplasm | EXP PMID:21088113 HuD interacts with survival motor neuron protein and can res... | ACCEPT | Summary: HuD localization was experimentally examined in motor-neuron-derived cells. Reason: The experimental record is consistent with cytoplasmic HuD in neurites and RNA granules and with independent neuronal localization evidence. Although the local publication cache is abstract-only, there is no basis to overrule the curator's full-text assessment. Supporting Evidence: PMID:21088113 We report here that SMN interacts with RNA-binding protein HuD in neurites of motorneuron-derived MN-1 cells. |
| GO:0043204 perikaryon | ISS GO_REF:0000024 | ACCEPT | Summary: Curator-reviewed sequence-similarity transfer assigns perikaryon localization from mouse Elavl4. Reason: ELAVL4 is a one-to-one conserved neuronal Hu protein, and the transferred cell-body location is consistent with human HuD distribution and primary-neuron imaging. |
| GO:0003730 mRNA 3'-UTR binding | IDA PMID:12468554 Post-transcriptional regulation of acetylcholinesterase mRNA... | ACCEPT | Summary: HuD directly binds AChE transcripts and regulates expression through the AChE 3-prime UTR. Reason: Immunoprecipitation, RNA binding, and 3-prime-UTR reporter experiments directly establish this molecular activity. Supporting Evidence: PMID:12468554 Immunoprecipitation experiments demonstrated that HuD can bind directly AChE transcripts. |
| GO:0003730 mRNA 3'-UTR binding | IDA PMID:18218628 Post-transcriptional regulation of neuro-oncological ventral... | ACCEPT | Summary: HuD/nELAV directly associates with the regulatory NOVA1 3-prime UTR. Reason: In-vivo and in-vitro RNP analysis plus deletion reporters define NOVA1 as a direct 3-prime-UTR target of neuronal ELAV proteins, with HuD perturbation altering stability and translation. Supporting Evidence: PMID:18218628 By analysis of ribonucleoprotein complexes in vivo and in vitro we demonstrated that the Nova1 mRNA is a novel target of the nELAV proteins. |
| GO:0005737 cytoplasm | ISS GO_REF:0000024 | ACCEPT | Summary: Curator-reviewed transfer assigns cytoplasmic localization from mouse Elavl4. Reason: The transfer is sound and independently corroborated by direct experimental human HuD localization and its cytoplasmic mRNA-regulatory activities. |
| GO:0006396 RNA processing | IDA PMID:17035636 A nuclear function of Hu proteins as neuron-specific alterna... | MODIFY | Summary: Neuronal Hu proteins regulate CALCA pre-mRNA processing in the nucleus. Reason: The broad parent is correct, but the direct experiments define the informative process as regulation of alternative mRNA splicing via the spliceosome. Proposed replacements: regulation of alternative mRNA splicing, via spliceosome Supporting Evidence: PMID:17035636 We show that in neuron-like cells, Hu proteins block the activity of TIA-1/TIAR, two previously identified, ubiquitously expressed proteins that promote the nonneuronal pathway of calcitonin/calcitonin gene-related peptide (CGRP) pre-mRNA processing. |
| GO:0008143 poly(A) binding | IDA PMID:12034726 Poly(A) tail length-dependent stabilization of GAP-43 mRNA b... | ACCEPT | Summary: GAP43 binding experiments show substantially greater HuD affinity when a long poly(A) tail is present. Reason: The curator-assigned IDA is consistent with the reported 10-fold tail-length effect. The abstract alone does not fully separate direct poly(A) contact from cooperative binding to the complete mRNA, so the curator's full-text assessment is retained rather than second-guessed. Supporting Evidence: PMID:12034726 In correlation with the effect of HuD on GAP-43 mRNA stability, we found that HuD binds GAP-43 mRNAs with long tails (A150) with 10-fold higher affinity than to those with short tails (A30). |
| GO:0030424 axon | ISS GO_REF:0000024 | ACCEPT | Summary: Curator-reviewed transfer assigns axonal localization from mouse Elavl4. Reason: The orthology transfer is independently corroborated by HuD-positive axonal granules and SMN-HuD cotransport in primary motor neurons. |
| GO:0030425 dendrite | ISS GO_REF:0000024 | ACCEPT | Summary: Curator-reviewed transfer assigns dendritic localization from mouse Elavl4. Reason: The one-to-one orthology transfer is sound and agrees with conserved HuD functions in dendritic RNA regulation and dendrite formation. |
| GO:0035925 mRNA 3'-UTR AU-rich region binding | IDA PMID:12034726 Poly(A) tail length-dependent stabilization of GAP-43 mRNA b... | ACCEPT | Summary: HuD binds the regulatory element in the GAP43 mRNA 3-prime UTR. Reason: Direct recombinant-protein, decay, and binding-element experiments establish AU-rich 3-prime-UTR recognition as the basis for GAP43 stabilization. Supporting Evidence: PMID:12034726 The neuronal ELAV-like RNA-binding protein HuD binds to a regulatory element in the 3'-untranslated region of the growth-associated protein-43 (GAP-43) mRNA. |
| GO:0035925 mRNA 3'-UTR AU-rich region binding | IDA PMID:17234598 The RNA-binding protein HuD binds acetylcholinesterase mRNA ... | ACCEPT | Summary: HuD directly associates with the AU-rich element in the AChE 3-prime UTR in neurons. Reason: The paper combines direct HuD-AChE RNA interaction, an AU-rich-element binding region, and in-vivo human-HuD rescue after axotomy. Supporting Evidence: PMID:17234598 A combination of approaches performed using the region that directly encompasses an adenylate and uridylate (AU)-rich element within the AChE 3'-untranslated region demonstrated a decrease in RNA-protein complexes in response to axotomy of the SCG and, specifically, a decrease in HuD binding. |
| GO:0070935 3'-UTR-mediated mRNA stabilization | IDA PMID:12034726 Poly(A) tail length-dependent stabilization of GAP-43 mRNA b... | ACCEPT | Summary: HuD directly stabilizes GAP43 mRNA through its 3-prime-UTR binding element. Reason: Overexpression and recombinant-protein experiments show delayed decay, reduced deadenylation, and dependence on the HuD-binding element and poly(A)-tail length. Supporting Evidence: PMID:12034726 We conclude that HuD stabilizes the GAP-43 mRNA through a mechanism that is dependent on the length of the poly(A) tail and involves changes in its affinity for the mRNA. |
| GO:0097158 pre-mRNA intronic pyrimidine-rich binding | IDA PMID:17035636 A nuclear function of Hu proteins as neuron-specific alterna... | ACCEPT | Summary: HuD and related neuronal Hu proteins bind pyrimidine-rich CALCA intronic regulatory RNA. Reason: The full study directly maps Hu-protein competition with TIA1/TIAL1 at U-rich intronic processing elements. The cached abstract confirms the neuron-specific alternative-processing mechanism, so the curator's IDA is retained. Supporting Evidence: PMID:17035636 We show that in neuron-like cells, Hu proteins block the activity of TIA-1/TIAR, two previously identified, ubiquitously expressed proteins that promote the nonneuronal pathway of calcitonin/calcitonin gene-related peptide (CGRP) pre-mRNA processing. |
| GO:1905870 positive regulation of 3'-UTR-mediated mRNA stabilization | IDA PMID:18218628 Post-transcriptional regulation of neuro-oncological ventral... | ACCEPT | Summary: HuD positively controls NOVA1 mRNA stability through its regulatory 3-prime UTR. Reason: RNP mapping, HuD silencing, overexpression, and reporter experiments establish positive control of NOVA1 stability and translation. Supporting Evidence: PMID:18218628 Gene silencing and overexpression of the nELAV member HuD in motoneuronal NSC34 cells indicate that Nova1 mRNA stability and translation are positively and strongly controlled by the nELAV proteins. |
| GO:0035925 mRNA 3'-UTR AU-rich region binding | IDA PMID:10710437 RNA-binding analyses of HuC and HuD with the VEGF and c-myc ... | ACCEPT | Summary: Quantitative binding assays show specific HuD binding to AU-rich VEGF and c-MYC 3-prime UTRs. Reason: Direct recombinant-protein assays establish concentration-dependent, sequence-selective binding, with stronger affinity for the AU-motif-rich end of the VEGF regulatory segment. Supporting Evidence: PMID:10710437 With this assay, I demonstrate that HuC and HuD bind to the VEGF 3'-UTR regulatory segment (VRS) and to the c- myc 3'-UTR in a specific and concentration-dependent pattern, with both proteins showing a greater affinity for the VRS. |
| GO:0003730 mRNA 3'-UTR binding | TAS PMID:10848602 HuD RNA recognition motifs play distinct roles in the format... | ACCEPT | Summary: Quantitative kinetic experiments define stable HuD binding to prototype AU-rich 3-prime-UTR instability elements. Reason: The study directly establishes high-affinity binding and cooperation of all three RRMs. The broader 3-prime-UTR term is correct alongside the specific AU-rich-region term. Supporting Evidence: PMID:10848602 We show that a single molecule of HuD requires at least three AUUU repeats to bind tightly to the RNA. |
| GO:0006397 mRNA processing | TAS PMID:10348344 HuD, a neuronal-specific RNA-binding protein, is a putative ... | KEEP AS NON CORE | Summary: HuD binds exonic and intronic N-MYC RNA and was proposed to regulate nuclear pre-mRNA processing or stability. Reason: The abstract supports a real nuclear post-transcriptional association and coordinated HuD/N-MYC expression, so removal is not justified. The mechanism is explicitly proposed rather than resolved, and the full text is unavailable in the cache, so this broad tumor-cell context is retained as non-core. Supporting Evidence: PMID:10348344 Thus, we propose that HuD plays a role in the nuclear processing/stability of N-myc pre-mRNA in N-type neuroblastoma cells. |
| GO:0045727 positive regulation of translation | IMP PMID:24857657 HuD regulates coding and noncoding RNA to induce APPβAΞ² proc... | NEW | Summary: ELAVL4 depletion in human neuroblastoma cells reduces APP mRNA polysome loading and reporter output. Reason: Human-cell HuD knockdown, mRNA half-life, polysome fractionation, and 3-prime-UTR reporter experiments directly show that HuD enhances APP translation. This captures a missing, target-supported post-transcriptional activity without claiming that HuD activates every bound mRNA. Supporting Evidence: PMID:24857657 In sum, HuD enhanced both the stability and translation of APP mRNA. |
| GO:0048027 mRNA 5'-UTR binding | ISS PMID:22387028 RNA-binding protein HuD controls insulin translation. | NEW | Summary: Mouse HuD directly binds a conserved Ins2 mRNA 5-prime-UTR element. Reason: Endogenous RNP immunoprecipitation, biotin-RNA pulldown, recombinant HuD, mutations, and 5-prime-UTR reporters establish the activity in mouse beta cells. The element is conserved, but because the tested gene product is mouse Elavl4, the human recommendation uses ISS. Supporting Evidence: PMID:22387028 We found that HuD associated with a 22-nucleotide segment of the 5' untranslated region (UTR) of preproinsulin (Ins2) mRNA. |
| GO:0017148 negative regulation of translation | ISS PMID:22387028 RNA-binding protein HuD controls insulin translation. | NEW | Summary: Mouse HuD binding to the Ins2 5-prime UTR represses insulin-mRNA translation. Reason: Knockdown, overexpression, reporter, polysome, nascent-translation, knockout, and transgenic experiments establish a negative effect on translation in mouse beta cells. This conserved secondary function is transferred to human ELAVL4 with ISS rather than direct experimental evidence. Supporting Evidence: PMID:22387028 Modulating HuD abundance did not alter Ins2 mRNA levels, but HuD overexpression decreased Ins2 mRNA translation and insulin production, and conversely, HuD silencing enhanced Ins2 mRNA translation and insulin production. |
| GO:0005634 nucleus | IDA PMID:17035636 A nuclear function of Hu proteins as neuron-specific alterna... | NEW | Summary: HuD and related neuronal Hu proteins function in the nucleus during alternative pre-mRNA processing. Reason: The CALCA study directly establishes a nuclear Hu-protein pool that binds intronic RNA and regulates neuron-specific alternative processing. This missing location is required to represent the experimentally supported nuclear core function. Supporting Evidence: PMID:17035636 We report here a novel function of these proteins as RNA processing regulators in the nucleus. |
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Download this section (compressed HTML)Q: Which ELAVL4 isoforms predominate in human neuronal subtypes, and does the 264-277 hinge deletion alter CARM1 methylation, SMN binding, or RNA-granule transport?
Q: What RNA sequence, position, structure, and protein-cofactor features make HuD activate one target's translation but repress another's?
Q: Does protein-RNA adaptor activity require simultaneous HuD contact with SMN and RNA, or does SMN primarily assemble or transport a preformed HuD mRNP?
Q: Which ELAVL4-dependent neuronal differentiation and projection phenotypes are conserved in human neurons?
Experiment: Endogenously deplete ELAVL4 in human iPSC-derived motor neurons and compare matched rescue with isoforms 1-6 using eCLIP, methyl-proteomics, SMN co-immunoprecipitation, and live single-molecule RNA transport imaging.
Hypothesis: Deletion of hinge residues 264-277 changes CARM1-sensitive SMN association and axonal mRNP transport without eliminating the core RRM-mediated AU-rich-RNA specificity.
Type: Isoform-resolved biochemical and neuronal rescue
Experiment: Build matched INS, GAP43, and APP reporters with systematically exchanged 5-prime-UTR and 3-prime-UTR elements, then measure HuD occupancy, decay, polysome loading, and local RNP proteomes after acute ELAVL4 degradation and rescue.
Hypothesis: HuD binding position and recruited cofactors determine whether a target is stabilized and translationally activated or translationally repressed.
Type: Cis-element swap and multi-omic mechanism mapping
Experiment: Use inducible ELAVL4 degradation after neuronal fate commitment in human iPSC-derived motor and cortical neurons, quantify projection morphology and electrophysiology, and rescue with wild-type or RNA-binding-defective HuD while monitoring GAP43 and other target RNAs.
Hypothesis: Human ELAVL4 is required cell-autonomously for late axon branching and dendrite maturation through stabilization and transport of a defined neuronal target-RNA module.
Type: Stage-specific human neuronal loss-of-function and rescue
What is not known β curated, literature-grounded statements of the open unknowns (the inverse of core functions).
Gap: The functional differences among the six human ELAVL4 isoforms are unresolved, especially the hinge deletion present in isoforms 2-5.
OPEN BIOLOGY MF_DARK
What is known: UniProt defines the sequence variants, but most RNA-binding, splicing, translation, and neuronal-granule studies do not resolve endogenous isoforms.
Significance: Isoform resolution is needed to determine whether hinge variation changes CARM1/SMN regulation, target selection, localization, or translational output.
What would resolve it: Combine long-read isoform quantification, isoform-resolved eCLIP, and matched rescue of RNA stabilization, splicing, and axonal-transport phenotypes after endogenous ELAVL4 depletion.
Provenance (the field's own admissions):
Gap: The sequence and protein-context rules that determine whether HuD activates or represses translation remain unresolved.
OPEN BIOLOGY BP_DARK
What is known: HuD usually stabilizes and promotes expression of 3-prime-UTR targets, but it represses INS/Ins2 and p27 translation through 5-prime-UTR binding.
Significance: A predictive mechanistic model is required before HuD binding can be interpreted as translational activation or repression for new targets.
What would resolve it: Perform matched endogenous 5-prime-UTR and 3-prime-UTR saturation mutagenesis, ribosome profiling, RNA-stability measurements, and RNP proteomics under wild-type and RRM/hinge-mutant rescue.
Provenance (the field's own admissions):
Gap: The extent to which conserved HuD-dependent neuronal-development phenotypes translate into direct human ELAVL4 requirements is unresolved.
OPEN BIOLOGY BP_DARK
What is known: Mouse and zebrafish genetics support neuronal differentiation, axon branching, dendrite formation, and motor function, while direct human evidence is mainly biochemical and cell-based.
Significance: Human-cell evidence would separate conserved developmental functions from lineage-, stage-, or model-specific phenotypes.
What would resolve it: Use isogenic human iPSC-derived neuronal lineages with acute ELAVL4 depletion, endogenous rescue, long-term morphology, electrophysiology, and target-resolved RNA stability and localization measurements.
Provenance (the field's own admissions):
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