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Conserved role for spliceosomal component PRPF40A in microexon splicing
Bikash Choudhary1, Adam Norris2
1University of California, Riverside. Department of Biochemistry.
Abstract:
Microexons (exons ≤30 nts) are important features of neuronal transcriptomes, but pose mechanistic challenges to the splicing machinery. We previously showed that PRP-40, a component of the U1 spliceosome, is globally required for microexon splicing in C. elegans. Here we show that the homologous PRPF40A is also globally required for microexon splicing in mouse neuroblastoma cells. We find that PRPF40A co-regulates microexons along with SRRM4, a neuron-specific regulator of microexon splicing. The relationship between exon size and dependence on PRPF40A/SRRM4 is distinct, with SRRM4-dependence exhibiting a size threshold (~30 nts) and PRPF40A-dependence exhibiting a graded decrease as exon size increases. Finally, we show that PRPF40A knockdown causes an increase in productive splicing of its spliceosomal binding partner Luc7l by skipping of a small "poison exon." Similar homeostatic cross-regulation is often observed across paralogous RNA binding proteins. Here we find this concept likewise applies across evolutionarily unrelated but functionally and physically coupled spliceosomal components.
Insights
The spliceosome component PRPF40A is crucial for splicing microexons in mouse neurons, working with SRRM4. This protein also regulates its own splicing, demonstrating cross-regulation within the spliceosome.
Area of Science:
- Molecular Biology
- Genetics
- Neuroscience
Background:
- Microexons are critical for neuronal transcriptome complexity but present splicing challenges.
- PRP-40, a U1 spliceosome component, was previously found essential for microexon splicing in C. elegans.
Purpose of the Study:
- To investigate the role of the homologous PRPF40A in microexon splicing in mouse neuroblastoma cells.
- To understand the relationship between PRPF40A, SRRM4, and microexon splicing.
- To explore the impact of PRPF40A knockdown on its binding partners' splicing.
Main Methods:
- Utilized mouse neuroblastoma cells for experimental analysis.
- Investigated the co-regulation of microexons by PRPF40A and SRRM4.
- Analyzed the impact of PRPF40A knockdown on splicing patterns, including poison exon skipping.
Main Results:
- PRPF40A is globally required for microexon splicing in mouse neuroblastoma cells.
- PRPF40A co-regulates microexons with SRRM4, showing distinct size-dependent relationships.
- PRPF40A knockdown leads to increased productive splicing of Luc7l via poison exon skipping.
Conclusions:
- PRPF40A plays a vital role in neuronal microexon splicing, similar to its C. elegans homolog.
- Functional and physical coupling exists between spliceosomal components, extending the concept of cross-regulation.
- This study highlights conserved mechanisms in spliceosome function across evolution.
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