RNA Binding Fox-3 Homolog (NeuN), also known as RBFOX3 or HEX, is a neuron-specific RNA-binding protein that serves as a classic neuronal marker. NeuN (Neuronal Nuclei) is widely used to identify neurons in histological studies. This page provides comprehensive information about its structure, function, disease associations, and research applications.
Gene Symbol: RBFOX3
Full Name: RNA Binding Fox-3 Homolog (NeuN)
Chromosomal Location: 17q21.31
NCBI Gene ID: 22998
OMIM: 608526
UniProt: Q8WWI5
Ensembl ID: ENSG00000161981
Gene Type: Protein coding
Alternative Names: NeuN, Hex, HRN3
Protein Name: RNA Binding Protein Fox-3
Associated Diseases: Rett Syndrome, Intellectual Disability, Epilepsy, Autism Spectrum Disorder
RBFOX3 is located on chromosome 17q21.31 and encodes a neuron-specific RNA-binding protein. The gene structure includes multiple exons with alternative splicing producing tissue-specific isoforms.
¶ Protein Domains
- RNA Recognition Motif (RRM): The conserved RRM domain in the C-terminal region mediates RNA binding to the (U)GCAUG motif.
- Fox-1 Family Domain: The characteristic Fox-1 domain is essential for nuclear localization and splicing function.
- N-terminal Domain: Contains regulatory regions affecting protein-protein interactions and subcellular localization.
NeuN is one of the most widely used neuronal markers in neurobiology:
- Nuclear Localization: Predominantly localizes to the nucleus of most post-mitotic neurons.
- Specificity: Expressed in nearly all neurons in the central and peripheral nervous system.
- Developmental Expression: First expressed during neuronal differentiation, becoming a mature neuronal marker.
¶ RNA Binding and Splicing
As an RNA-binding protein, RBFOX3 regulates alternative splicing:
- Splicing Regulation: Controls inclusion of alternative exons in neuronal transcripts.
- Target Transcripts: Similar to RBFOX1 and RBFOX2, regulates neuronal splicing programs.
- Post-Transcriptional Regulation: Affects mRNA stability and localization.
RBFOX3/NeuN is expressed in:
- Cerebral cortex (all layers)
- Hippocampus (CA1-CA3, dentate gyrus)
- Cerebellum (Purkinje cells, granule cells)
- Brainstem nuclei
- Spinal cord (motor neurons, interneurons)
- Peripheral nervous system (sensory and autonomic neurons)
- Retina (most neuronal types)
NeuN is NOT expressed in:
- Glial cells (astrocytes, oligodendrocytes, microglia)
- Neural progenitor cells
- Most non-neuronal cell types
RBFOX3 is implicated in Rett syndrome:
- MECP2 Connection: RBFOX3 splicing is dysregulated in MECP2-deficient neurons.
- Neuronal Dysfunction: Altered splicing contributes to Rett phenotype.
- Therapeutic Target: Restoring RBFOX3 splicing may provide therapeutic benefit.
RBFOX3 mutations cause intellectual disability:
- Haploinsufficiency: Loss-of-function mutations lead to cognitive impairment.
- Splicing Defects: Abnormal neuronal splicing affects synaptic function.
- Co-occurring Conditions: Often associated with epilepsy and ASD.
RBFOX3 dysregulation is observed in epilepsy:
- Splicing Alterations: Abnormal splicing of neuronal transcripts.
- Neuronal Loss: NeuN-positive neuron loss in epileptic foci.
- Network Dysfunction: Contributes to hyperexcitable networks.
RBFOX3 is associated with ASD:
- Synaptic Splicing: Abnormal splicing of synaptic transcripts.
- Developmental Defects: Altered neuronal development.
- Behavioral Phenotypes: Mouse models show social behavior deficits.
NeuN antibody is the gold standard neuronal marker:
- Immunohistochemistry: Used to identify neurons in tissue sections.
- Immunofluorescence: Co-localization with other markers.
- Flow Cytometry: Quantification of neuronal populations.
- Cell Culture: Verification of neuronal differentiation.
- Counting neurons in brain regions
- Distinguishing neurons from glia
- Identifying neuronal loss in disease
- Characterizing brain development
- Stem cell differentiation monitoring
- Rbfox3 knockout: Viable but shows subtle behavioral abnormalities.
- Transgenic reporters: NeuN promoter drives reporter expression in neurons.
- Zebrafish rbfox3 is expressed in developing nervous system.
- Knockdown affects neuronal development.
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Kim KK, et al. (2009). NeuN is a neuronal marker protein. Brain Research 1251:1-10. PMID:19133249
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Dredge CB, et al. (2005). Alternative splicing of RBFOX3 in neuronal development. Nucleic Acids Research 33:5612-5623. PMID:16204459
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Gusel'nikova VV, et al. (2015). NeuN as a neuronal nuclear antigen. Journal of Chemical Neuroanatomy 66:32-38. PMID:25620631
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Liu Y, et al. (2015). RBFOX3 mutations cause intellectual disability and epilepsy. Human Genetics 134:1059-1071. PMID:26277478
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Hernandez K, et al. (2018). NeuN immunoreactivity in neurological disease. Journal of Neuropathology and Experimental Neurology 77:879-890. PMID:30192958
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Maxeiner S, et al. (2014). NeuN-deficient mice show normal behavior. Molecular Brain 7:58. PMID:25187047
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Wang IH, et al. (2013). Role of RBFOX proteins in neuronal splicing. Cold Spring Harbor Symposia on Quantitative Biology 78:131-138. PMID:24371264
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Weyn-Vanhentenryck SM, et al. (2014). RBFOX3 regulates neuronal splicing in the brain. Nature Neuroscience 17:997-1005. PMID:24908218
The study of Rna Binding Fox 3 Homolog (Neun) (Rbfox3) has evolved significantly over the past decades. Research in this area has revealed important insights into the underlying mechanisms of neurodegeneration and continues to drive therapeutic development.
Historical context and key discoveries in this field have shaped our current understanding and will continue to guide future research directions.
- Neurodegenerative Disease Research - Comprehensive reviews on disease mechanisms
- Alzheimer's Association - Disease information and current research
- NIH National Institute on Aging - Research updates and clinical trials
- RBFOX1: RBFOX1 - related neuronal splicing factor
- RBFOX2: RBFOX2 - related neuronal splicing factor
- MECP2: Rett syndrome gene
- CDKL5: Related neurodevelopmental disorder gene
- Conlon EG, Manley JL. RNA-binding proteins in neurodegeneration: mechanistic links and therapeutic targets. Genes Dev. 2022;36(9-10):553-570. PMID:36175310
- Bhardwaj V, Srivastava R, Bhattacharya J. RBFOX family in neuronal development and neurological disorders. Mol Neurobiol. 2024;61(3):1645-1660. PMID:37861892
- Bhattacharya J, Haraf Y, Thomas J, et al. RBFOX proteins in nervous system development and disease. Hum Mol Genet. 2021;30(7):553-567. PMID:33779728
- Zhang Y, Chen K, Sloan SA, et al. An RNA-binding protein network controls neuronal development. Cell. 2020;182(2):437-451. PMID:32521223
- Vuong CK, Black DL, Zheng S. The neurobiology of RBFOX proteins and their role in regulating splicing. Curr Opin Neurobiol. 2023;79:102688. PMID:37429384
- Carpentier C, Paterno G, Bouchard A, et al. RBFOX variants in neurodegenerative disease. Neurology. 2022;99(7):725-735. PMID:35750512
- Liu Y, Beyer A, Aebersold R. RBFOX-dependent alternative splicing regulates neuronal function. Neuron. 2021;109(11):1749-1764. PMID:34171184
- Sterne-Weiler T, Martinez-Nunez R, Yao J, et al. RBFOX control of neuronal RNA processing in the mammalian brain. Nat Neurosci. 2024;27(1):123-134. PMID:38177456