Splicing activator RNPS1 suppresses errors in pre-mRNA splicing: A key factor for mRNA quality control

Area of Science:

• Molecular Biology
• Genetics
• Cell Biology

Background:

• Human RNPS1 protein is a known pre-mRNA splicing activator and regulator of alternative splicing.
• RNPS1 has been previously described as a peripheral component of the exon junction complex (EJC).

Purpose of the Study:

• To investigate the role of RNPS1 in maintaining pre-mRNA splicing fidelity.
• To determine the functional consequences of RNPS1 knockdown on gene expression and cellular phenotypes.

Main Methods:

• Cellular knockdown of RNPS1 using RNA interference.
• Analysis of aurora kinase B (AURKB) pre-mRNA splicing patterns and protein levels.
• Assessment of multinucleation phenotype and rescue experiments with AURKB re-expression.
• Investigation of RNPS1 binding to AURKB pre-mRNA and its effect on splicing.
• Analysis of splicing patterns in MDM2 pre-mRNA following RNPS1 knockdown.

Main Results:

• RNPS1 knockdown led to reduced wild-type AURKB protein levels due to aberrant splicing events.
• Aberrant splicing in AURKB involved pseudo 5' and 3' splice sites in intron 5, producing non-functional truncated protein.
• RNPS1 knockdown cells exhibited a multinucleation phenotype, characteristic of AURKB absence, which was rescued by AURKB re-expression.
• RNPS1 directly binds to a specific element in AURKB exon, crucial for normal splicing, and is not a component of the EJC.
• RNPS1 knockdown induced similar aberrant splicing in MDM2 pre-mRNA, indicating a global role in splicing fidelity.

Conclusions:

• RNPS1 acts as a crucial guardian of splicing fidelity, essential for accurate mRNA production.
• RNPS1's role extends beyond the EJC, involving direct binding to pre-mRNA to ensure correct splicing.
• Disruption of RNPS1 function leads to aberrant splicing, impacting essential genes and cellular processes like cell division.