Cell-type specific regulator RBPMS switches alternative splicing via higher-order oligomerization and heterotypic...

Area of Science:

• Molecular Biology
• RNA Biology
• Gene Regulation

Background:

• Alternative pre-mRNA splicing is controlled by RNA-binding proteins (RBPs) that bind RNA multivalently.
• Widely expressed RBPs regulate splicing but require cell-specific factors to elicit cell-specific effects.
• Intrinsically disordered regions (IDRs) and multiple RNA-binding domains contribute to RBP multivalency.

Purpose of the Study:

• To investigate how cell-specific regulators collaborate with constitutive RBPs in alternative splicing.
• To elucidate the mechanism by which RBPMS confers smooth muscle cell-specific alternative splicing.

Main Methods:

• Used recombinant RBPMS in cell-free assays to study alternative splicing of Tpm1 exon 3.
• Investigated the role of RBPMS's C-terminal intrinsically disordered region (IDR).
• Examined interactions between RBPMS, MBNL1, and RBFOX2.

Main Results:

• Recombinant RBPMS alone induced smooth muscle cell-specific alternative splicing of Tpm1 exon 3 in vitro.
• RBPMS activity was dependent on its C-terminal IDR, which mediates self-assembly and RNA binding.
• RBPMS cooperatively assembled stable regulatory complexes with MBNL1 and RBFOX2.

Conclusions:

• RBPMS acts as a smooth muscle-specific regulator by preventing ATP-dependent splicing complex assembly.
• The IDR of RBPMS is crucial for its function, enabling dynamic self-assembly and cooperative interactions.
• RBPMS collaborates with widely expressed splicing factors to achieve cell-specific alternative splicing regulation.