SRSF2 Protein
Overview
SRSF2 (Serine/Arginine-Rich Splicing Factor 2), also known as SC35, is a highly conserved RNA-binding protein belonging to the SR protein family. This nuclear protein plays a central role in pre-mRNA splicing, a fundamental process that generates protein diversity in cells. SRSF2 is encoded by the SRSF2 gene and contains characteristic domains including two RNA recognition motifs (RRMs) and a carboxy-terminal arginine/serine-rich (RS) domain. The protein is expressed ubiquitously across human tissues, with particularly high levels in metabolically active cells including neurons. SRSF2 functions as both a splicing regulator and a component of the spliceosome, the ribonucleoprotein complex responsible for removing introns from precursor mRNA molecules.
Function/Biology
SRSF2 operates primarily as a splicing enhancer, promoting the recognition and utilization of weak splice sites during RNA processing. The protein recognizes specific RNA sequences through its two RRM domains, which bind to purine-rich elements (typically SSNG motifs where S represents serine/arginine-rich positions). Once bound, SRSF2 recruits additional spliceosomal components and facilitates the assembly of the U1 and U2 snRNPs (small nuclear ribonucleoproteins) at 5' and 3' splice sites, respectively.
...SRSF2 Protein
Overview
SRSF2 (Serine/Arginine-Rich Splicing Factor 2), also known as SC35, is a highly conserved RNA-binding protein belonging to the SR protein family. This nuclear protein plays a central role in pre-mRNA splicing, a fundamental process that generates protein diversity in cells. SRSF2 is encoded by the SRSF2 gene and contains characteristic domains including two RNA recognition motifs (RRMs) and a carboxy-terminal arginine/serine-rich (RS) domain. The protein is expressed ubiquitously across human tissues, with particularly high levels in metabolically active cells including neurons. SRSF2 functions as both a splicing regulator and a component of the spliceosome, the ribonucleoprotein complex responsible for removing introns from precursor mRNA molecules.
Function/Biology
SRSF2 operates primarily as a splicing enhancer, promoting the recognition and utilization of weak splice sites during RNA processing. The protein recognizes specific RNA sequences through its two RRM domains, which bind to purine-rich elements (typically SSNG motifs where S represents serine/arginine-rich positions). Once bound, SRSF2 recruits additional spliceosomal components and facilitates the assembly of the U1 and U2 snRNPs (small nuclear ribonucleoproteins) at 5' and 3' splice sites, respectively.
Beyond its canonical splicing role, SRSF2 participates in multiple cellular processes including mRNA export, nonsense-mediated decay surveillance, and translation regulation. The protein shuttles between the nucleus and cytoplasm, allowing it to influence post-transcriptional gene expression at multiple levels. Through its RS domain, SRSF2 interacts with numerous splicing factors and kinases that phosphorylate its SR residues, modulating its activity and localization. This phosphorylation-dependent regulation enables cells to dynamically adjust splicing patterns in response to developmental cues and stress conditions.
Role in Neurodegeneration
SRSF2 dysfunction has emerged as a significant contributor to neurodegeneration through multiple pathways. In ALS (amyotrophic lateral sclerosis) and frontotemporal dementia (FTD), splicing dysregulation represents a hallmark feature, and SRSF2 alterations compromise the production of disease-relevant proteins. The protein's impaired function leads to aberrant splicing of transcripts encoding synaptic proteins, cytoskeletal components, and proteins involved in stress granule formation and clearance.
Accumulating evidence suggests SRSF2 contributes to neurodegeneration through effects on TDP-43 and FUS protein homeostasis. These RNA-binding proteins undergo liquid-liquid phase separation under stress conditions, forming pathological aggregates characteristic of neurodegeneration. SRSF2 dysfunction disrupts the normal balance of these proteins, promoting toxic accumulation. Additionally, impaired SRSF2 function affects splicing of the MAPT gene (encoding tau protein), potentially contributing to tau pathology observed in Alzheimer's disease and other tauopathies.
Molecular Mechanisms
SRSF2 mediates neurodegeneration through several interconnected mechanisms. First, reduced SRSF2 activity or expression compromises splicing fidelity of neuron-specific transcripts, particularly those encoding proteins with multiple isoforms that must be precisely coordinated. This leads to production of non-functional or toxic protein variants. Second, SRSF2 dysfunction impairs the splicing of genes involved in RNA quality control pathways, including components of the ubiquitin-proteasome system and autophagy machinery.
Third, SRSF2 interacts with stress granule assembly factors; dysregulated SRSF2 promotes aberrant granule assembly that transitions from reversible storage structures into stable, pathological aggregates. Fourth, SRSF2 phosphorylation states are dysregulated in neurodegenerative conditions, as kinases including Clk/Sty and SRPK1 function abnormally under oxidative stress and proteotoxic conditions common to neurodegeneration.
Clinical/Research Significance
SRSF2 represents a potential therapeutic target for multiple neurodegenerative diseases. Restoring SRSF2 levels or activity could normalize splicing patterns and maintain proteostasis in affected neurons. Current research explores small-molecule modulators of SR protein phosphorylation and protein replacement therapies. Understanding SRSF2 function also provides insights into common pathogenic mechanisms underlying seemingly distinct neurodegenerative conditions.
Related SR proteins include SRSF1, SRSF3, and SRSF6. SRSF2 functionally interacts with U1 and U2 snRNPs, TDP-43, FUS, and kinases including SRPK1. Disease associations include ALS, FTD, Alzheimer's disease, and Parkinson's disease.