SRSF3 Gene

SRSF3 Gene

<table class="infobox infobox-gene">
<tr>
<th class="infobox-header" colspan="2">SRSF3 Gene</th>
</tr>
<tr>
<td class="label">Gene Symbol</td>
<td>SRSF3</td>
</tr>
<tr>
<td class="label">Full Name</td>
<td>Serine/Arginine-Rich Splicing Factor 3</td>
</tr>
<tr>
<td class="label">Alternative Names</td>
<td>SRp20, ASF/SF3</td>
</tr>
<tr>
<td class="label">Chromosomal Location</td>
<td>6p21.33</td>
</tr>
<tr>
<td class="label">NCBI Gene ID</td>
<td>6734</td>
</tr>
<tr>
<td class="label">Ensembl ID</td>
<td>ENSG00000161547</td>
</tr>
<tr>
<td class="label">UniProt ID</td>
<td>P84104</td>
</tr>
<tr>
<td class="label">Protein Class</td>
<td>RNA-binding protein; Splicing factor</td>
</tr>
<tr>
<td class="label">Associated Diseases</td>
<td>ALS, Alzheimer's disease, Parkinson's disease, cancer</td>
</tr>
<tr>
<td class="label">Approach</td>
<td>Mechanism</td>
</tr>
<tr>
<td class="label">ASO therapy</td>
<td>Restore proper SRSF3 splicing patterns</td>
</tr>
<tr>
<td class="label">SRPK inhibitors</td>
<td>Modulate SRSF3 phosphorylation</td>
</tr>
<tr>
<td class="label">Small molecule modulators</td>
<td>Direct SRSF3 targeting</td>
</tr>
</table>

SRSF3 Gene

<table class="infobox infobox-gene">
<tr>
<th class="infobox-header" colspan="2">SRSF3 Gene</th>
</tr>
<tr>
<td class="label">Gene Symbol</td>
<td>SRSF3</td>
</tr>
<tr>
<td class="label">Full Name</td>
<td>Serine/Arginine-Rich Splicing Factor 3</td>
</tr>
<tr>
<td class="label">Alternative Names</td>
<td>SRp20, ASF/SF3</td>
</tr>
<tr>
<td class="label">Chromosomal Location</td>
<td>6p21.33</td>
</tr>
<tr>
<td class="label">NCBI Gene ID</td>
<td>6734</td>
</tr>
<tr>
<td class="label">Ensembl ID</td>
<td>ENSG00000161547</td>
</tr>
<tr>
<td class="label">UniProt ID</td>
<td>P84104</td>
</tr>
<tr>
<td class="label">Protein Class</td>
<td>RNA-binding protein; Splicing factor</td>
</tr>
<tr>
<td class="label">Associated Diseases</td>
<td>ALS, Alzheimer's disease, Parkinson's disease, cancer</td>
</tr>
<tr>
<td class="label">Approach</td>
<td>Mechanism</td>
</tr>
<tr>
<td class="label">ASO therapy</td>
<td>Restore proper SRSF3 splicing patterns</td>
</tr>
<tr>
<td class="label">SRPK inhibitors</td>
<td>Modulate SRSF3 phosphorylation</td>
</tr>
<tr>
<td class="label">Small molecule modulators</td>
<td>Direct SRSF3 targeting</td>
</tr>
</table>

SRSF3 (Serine/Arginine-Rich Splicing Factor 3), also known as SRp20, is an essential RNA-binding protein that plays critical roles in pre-mRNA splicing, alternative splicing regulation, mRNA export, and translation. Located on chromosome 6p21.33, SRSF3 is the smallest member of the serine/arginine (SR) family of splicing factors. Dysregulation of SRSF3 has been implicated in [amyotrophic lateral sclerosis](/diseases/amyotrophic-lateral-sclerosis) (ALS), [Alzheimer's disease](/diseases/alzheimers-disease), [Parkinson's disease](/diseases/parkinsons-disease), and various cancers. The protein's ability to regulate tissue-specific alternative splicing makes it a key player in neuronal function and neurodegeneration.

Pathway / Interaction Diagram

Overview

Gene Structure

The SRSF3 gene consists of 4 exons encoding a 248-amino acid protein. The protein contains a single RNA recognition motif (RRM) at its N-terminus, followed by an RS domain (arginine-serine-rich domain) at the C-terminus. The RRM mediates RNA binding specificity, while the RS domain participates in protein-protein interactions with other splicing factors and the spliceosome machinery.

Protein Structure and Domains

SRSF3 contains two functional domains:

• Protein-protein interactions with other SR proteins
• Localization to nuclear speckles
• Recruitment to splice sites
• Regulation of spliceosome assembly

Function

Pre-mRNA Splicing

SRSF3 is a fundamental component of the spliceosome and participates in both constitutive and alternative splicing:

• Spliceosome assembly — SRSF3 interacts with U1 and U2 snRNPs to facilitate spliceosome formation
• Exon recognition — The protein binds to exonic splicing enhancers (ESEs) to promote exon inclusion
• Splice site selection — SRSF3 helps define 5' and 3' splice sites
• Splicing catalysis — As part of the spliceosome, SRSF3 contributes to the two transesterification reactions

Alternative Splicing Regulation

SRSF3 regulates tissue-specific and developmentally regulated alternative splicing:

• Exon skipping — Promotes or inhibits exon inclusion in mRNA transcripts
• Alternative 5' splice sites — Controls usage of upstream 5' splice sites
• Alternative 3' splice sites — Modulates 3' splice site selection
• Intron retention — Influences retention of introns in mature mRNAs

mRNA Export and Stability

Beyond splicing, SRSF3 participates in:

• mRNA export — Facilitates nuclear export of spliced mRNAs through interactions with export factors
• mRNA stability — Influences mRNA half-life and degradation
• Translation regulation — Interacts with the cap-binding complex to regulate translation initiation

Interaction with Stress Granules

SRSF3 localizes to stress granules (SGs) under cellular stress conditions. Stress granules are membraneless organelles that contain translationally stalled mRNPs. SRSF3 participation in stress granule dynamics is relevant to neurodegeneration, as SG formation is linked to [ALS](/diseases/amyotrophic-lateral-sclerosis) and other neurodegenerative diseases.

Brain Expression

SRSF3 is widely expressed throughout the brain:

• Cerebral cortex — Pyramidal neurons and interneurons
• Hippocampus — CA1-CA3 regions, dentate gyrus (critical for [memory](/diseases/alzheimers-disease))
• Cerebellum — Purkinje cells
• Brainstem — Motor neurons
• Spinal cord — Motor neurons (relevant to [ALS](/diseases/amyotrophic-lateral-sclerosis))

Regulation

SRSF3 activity is tightly regulated:

• Phosphorylation — SR protein-specific kinases (SRPKs, CLK) phosphorylate the RS domain, modulating splicing activity
• Alternative splicing — SRSF3 itself undergoes alternative splicing to generate isoforms with different functions
• Transcriptional control — SRSF3 expression is regulated at the transcriptional level by neuronal activity
• Auto-regulation — SRSF3 can regulate its own splicing through feedback mechanisms

Disease Associations

Amyotrophic Lateral Sclerosis (ALS)

SRSF3 is dysregulated in [ALS](/diseases/amyotrophic-lateral-sclerosis), a fatal neurodegenerative disorder affecting motor neurons:

• Altered splicing patterns — SRSF3 dysregulation leads to aberrant splicing of transcripts critical for motor neuron survival
• Stress granule dynamics — SRSF3 participation in stress granule assembly is affected in ALS; TDP-43 pathology alters SG function
• Motor neuron vulnerability — Loss of proper SRSF3 function contributes to impaired RNA processing in motor neurons
• FUS/TLS interactions — SRSF3 interacts with other ALS-associated RNA-binding proteins (FUS, TDP-43)

Alzheimer's Disease

In [Alzheimer's disease](/diseases/alzheimers-disease), SRSF3 dysregulation contributes to disease pathogenesis:

• Tau splicing — SRSF3 regulates alternative splicing of tau (MAPT) transcripts; dysregulation affects tau isoform ratios
• Amyloid precursor protein (APP) — SRSF3 affects APP splicing patterns
• Synaptic function — Aberrant splicing of synaptic transcripts due to SRSF3 dysfunction
• Neuronal stress — Altered stress granule dynamics in AD brains

Parkinson's Disease

SRSF3 may be relevant to [Parkinson's disease](/diseases/parkinsons-disease) through:

• Alpha-synuclein splicing — Potential regulation of SNCA transcript splicing
• Dopaminergic neuron function — SRSF3 is expressed in substantia nigra neurons
• Mitochondrial transcripts — Regulation of splicing for mitochondrial function genes

Cancer

SRSF3 acts as an oncogene in various cancers:

• Cell proliferation — Promotes cell cycle progression through altered splicing
• Alternative splicing of oncogenes — Regulates splicing of transcripts like BIM, MST1R
• Tumor progression — SRSF3 overexpression correlates with poor prognosis
• Therapeutic target — SRSF3 is being explored as a cancer therapeutic target

Molecular Mechanisms

Spliceosome Recruitment

SRSF3 participates in early spliceosome assembly:

Splicing Regulation via RRM-ESE Interactions

The RRM of SRSF3 recognizes specific sequence motifs:

• Purine-rich ESEs — SRSF3 binds to GAA and RGA repeat sequences
• Position-dependent effects — SRSF3 binding upstream or downstream of splice sites has different effects
• Cooperative binding — SRSF3 often works synergistically with other SR proteins

Post-Translational Modifications

SRSF3 function is modulated by:

• Phosphorylation by SRPK1/2 — Phosphorylation at serine residues in the RS domain controls nuclear speckle localization and splicing activity
• CLK1-4 phosphorylation — Additional kinases that modify SRSF3 activity
• Dephosphorylation by PP1/PP2A — Reverses phosphorylation, allowing dynamic regulation

Therapeutic Implications

SRSF3 represents a potential therapeutic target for:

• Neurodegenerative diseases — Modulating SRSF3 activity could correct aberrant splicing in ALS, AD, PD
• Cancer — SRSF3 inhibitors may have anti-tumor effects
• Splicing modulators — Small molecules that target SR protein kinases can indirectly modulate SRSF3

Therapeutic Approaches

• Antisense oligonucleotides — ASOs to restore proper SRSF3 splicing patterns
• SRPK inhibitors — Block SR protein phosphorylation including SRSF3
• Small molecule modulators — Develop compounds that directly modulate SRSF3

See Also

• [SRSF1](/genes/srsf1)
• [SRSF2](/genes/srsf2)
• [ALS](/diseases/amyotrophic-lateral-sclerosis)
• [Alzheimer's Disease](/diseases/alzheimers-disease)
• [Parkinson's Disease](/diseases/parkinsons-disease)
• [Alternative Splicing](/mechanisms/alternative-splicing)
• [Stress Granules](/mechanisms/stress-granules)
• [TDP-43](/proteins/tardbp-protein)
• [FUS](/proteins/fus-protein)

External Links

• [NCBI Gene: SRSF3](https://www.ncbi.nlm.nih.gov/gene/6734)
• [UniProt: P84104](https://www.uniprot.org/uniprotkb/P84104)
• [OMIM: 603364](https://www.omim.org/entry/603364)
• [GTEx Portal: SRSF3](https://gtexportal.org/home/gene/SRSF3)
• [GeneCards: SRSF3](https://www.genecards.org/cgi-bin/carddisp.pl?gene=SRSF3)

SRSF3 in Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is a devastating neurodegenerative disease characterized by progressive loss of motor neurons. SRSF3 dysregulation has been implicated in ALS pathogenesis through several mechanisms[@srsf3_als].

RNA Processing Defects

In ALS, SRSF3 function is compromised due to:

• Altered splicing patterns: Loss of proper SRSF3 function leads to aberrant inclusion or exclusion of exons in transcripts essential for motor neuron survival. Studies have identified specific splicing events that are dysregulated in ALS, including transcripts involved in cytoskeletal function, mitochondrial metabolism, and RNA granule dynamics[@srsf3_als].
• TDP-43 pathology: The majority of ALS cases feature TDP-43 protein aggregates in affected neurons. TDP-43 and SRSF3 interact in RNA metabolism, and TDP-43 pathology disrupts SRSF3 function[@srsf3_tdp43]. This interaction is particularly relevant because TDP-43 inclusions are a hallmark of ALS.
• Stress granule dysfunction: SRSF3 participates in stress granule assembly and dynamics. In ALS, stress granule formation is altered, and this affects RNA stability and translation regulation. The interaction between TDP-43, FUS, and SRSF3 in stress granules is an active area of research[@srsf3_stress_granules].

Motor Neuron Vulnerability

Motor neurons are particularly vulnerable to SRSF3 dysfunction:

• Large neurons have high RNA metabolism demands
• Motor neurons rely on long-range axonal transport of RNA granules
• The complexity of alternative splicing in motor neurons makes them susceptible to splicing factor dysregulation

FUS and SRSF3 Interaction

FUS (Fused in Sarcoma) is another RNA-binding protein mutated in familial ALS. SRSF3 interacts with FUS in RNA processing, and mutations in FUS can alter SRSF3 function. This suggests a shared pathway in ALS pathogenesis where multiple RNA-binding proteins converge on common targets[@srsf3_fus].

SRSF3 in Alzheimer's Disease

Alzheimer's disease (AD) involves complex changes in RNA processing, and SRSF3 plays a significant role[@srsf3_ad].

Tau Splicing Regulation

SRSF3 directly regulates the alternative splicing of tau (MAPT) transcripts. In AD, tau pathology is a hallmark, and dysregulated tau splicing contributes to disease progression:

• SRSF3 controls exon 10 inclusion in tau mRNA
• Alternative splicing produces different tau isoforms (3R vs 4R)
• Imbalanced 3R/4R ratio is observed in AD brains
• SRSF3-mediated splicing changes affect tau filament formation[@srsf3_tau]

APP Processing

SRSF3 regulates alternative splicing of amyloid precursor protein (APP) transcripts. Different APP isoforms have varying amyloidogenic properties:

• SRSF3 influences the production of APP isoforms
• Altered APP splicing may affect amyloid-beta generation
• The relationship between SRSF3 and APP processing provides insight into amyloid pathology[@srsf3_app]

Synaptic Dysfunction

Synaptic dysfunction is an early event in AD. SRSF3 regulates splicing of numerous synaptic proteins:

• Postsynaptic density proteins
• Synaptic vesicle components
• Ion channels at synapses

Neuroinflammation

SRSF3 may also influence neuroinflammatory responses in AD through regulation of cytokine and immune-related gene splicing.

SRSF3 in Parkinson's Disease

Emerging evidence suggests SRSF3 is relevant to Parkinson's disease (PD)[@srsf3_pd]:

Alpha-Synuclein Regulation

While direct regulation by SRSF3 is still being characterized, the general importance of RNA processing in SNCA expression suggests potential interactions.

Dopaminergic Neuron Vulnerability

The substantia nigra dopaminergic neurons affected in PD have high metabolic demands and complex RNA processing needs. SRSF3 dysfunction may contribute to their vulnerability.

Mitochondrial RNA Processing

Mitochondrial dysfunction is central to PD pathogenesis. SRSF3 may regulate splicing of transcripts involved in mitochondrial function.

Molecular Mechanisms in Detail

Spliceosome Recruitment Pathway

SRSF3 participates in spliceosome assembly through a well-characterized pathway:

RNA Recognition Motif Function

The RRM of SRSF3 (amino acids 1-90) has distinct properties:

• Recognizes specific ESE sequences
• Shows position-dependent effects on splicing
• Can work cooperatively with other SR proteins
• Structure reveals a canonical RNP fold with two consensus motifs (RNP1 and RNP2)[@srsf3_rrm]

RS Domain Function

The RS domain (amino acids 180-248) mediates:

• Protein-protein interactions with other splicing factors
• Nuclear speckle localization[@srsf3_nuclear_speckles]
• Recruitment to active splice sites
• Regulation by phosphorylation

• Nuclear speckle localization
• Splicing activity
• Interactions with other proteins
• Turnover and recycling[@srsf3_srpk]

Therapeutic Strategies

Targeting SRSF3 in Neurodegeneration

Several therapeutic approaches are being explored:

Antisense Oligonucleotides

Antisense oligonucleotides (ASOs) can:

• Target aberrant splicing events
• Restore proper exon inclusion
• Reduce toxic isoform production

Kinase Inhibitors

SRPK1/2 inhibitors indirectly modulate SRSF3 function by altering phosphorylation:

• Reduce hyperphosphorylation
• Alter splicing patterns
• Potential for CNS delivery needed

Research Techniques for SRSF3 Study

Molecular Methods

• CLIP-seq: Cross-linking immunoprecipitation to map SRSF3 binding sites
• RNA-seq: Genome-wide analysis of SRSF3-dependent splicing
• Minigene assays: Functional analysis of specific splicing events
• RT-PCR: Validation of splicing changes

Cellular Models

• Neuronal cultures: Primary neurons for functional studies
• iPSC-derived neurons: Disease modeling
• Cell lines: HEK293, SH-SY5Y for mechanistic work

Animal Models

• Transgenic mice: Overexpression and knockout models
• Zebrafish: Accessible developmental model
• C. elegans: Genetic screening platform

Clinical Relevance

Biomarkers

SRSF3 expression and splicing patterns may serve as:

• Disease progression markers
• Therapeutic response indicators

Diagnostic Potential

SRSF3 splicing signatures in:

• Cerebrospinal fluid
• Blood cells
• Tissue samples

Summary

SRSF3 (SRp20) is an essential RNA-binding protein with critical roles in pre-mRNA splicing, alternative splicing regulation, and RNA metabolism. Its dysregulation contributes to multiple neurodegenerative diseases including ALS, AD, and PD. The protein's functions in stress granule dynamics, tau splicing, and synaptic protein expression make it a compelling therapeutic target. Understanding SRSF3 function and developing modulators holds promise for treating neurodegenerative conditions.

References

Pathway Diagram

The following diagram shows the key molecular relationships involving SRSF3 Gene discovered through SciDEX knowledge graph analysis: