Far upstream element-binding protein 1 and RNA secondary structure both mediate second-step splicing repression.

Area of Science:

• Molecular Biology
• RNA Processing
• Gene Regulation

Background:

• mRNA splicing is a crucial two-step process for generating mature mRNA.
• A previously identified splicing substrate exhibited a unique block after the first splicing step.
• Understanding the mechanisms behind splicing regulation is vital for comprehending gene expression.

Purpose of the Study:

• To investigate the molecular basis for the second-step splicing inhibition.
• To identify novel factors involved in regulating splicing fidelity.
• To elucidate the role of specific RNA structures and binding proteins in splicing control.

Main Methods:

• In vitro splicing assays using a blocked splicing substrate.
• Analysis of RNA stem-loop structures and exonic splicing silencers (ESS).
• Identification and characterization of RNA-binding proteins associated with ESS elements, including far upstream element-binding protein 1 (FUBP1).
• In vivo studies using siRNA-mediated knockdown and overexpression of FUBP1.

Main Results:

• Two independent mechanisms were identified: a downstream stem-loop structure and an ESS.
• Both elements were shown to inhibit the second step of splicing in vitro and cause exon skipping in vivo.
• Far upstream element-binding protein 1 (FUBP1) was identified as a novel ESS-binding protein and a functional splicing repressor.
• FUBP1 depletion and overexpression modulated exon inclusion in vivo, confirming its regulatory role.

Conclusions:

• The study reveals novel mechanisms of splicing regulation involving RNA structures and protein factors.
• Far upstream element-binding protein 1 (FUBP1) is identified as a significant splicing regulator, acting as a second-step repressor.
• These findings contribute to a deeper understanding of the intricate control of mRNA splicing and its impact on gene expression.