Regulation of Co-transcriptional Pre-mRNA Splicing by m⁶A through the Low-Complexity Protein hnRNPG

Area of Science:

• Molecular Biology
• RNA Biology
• Gene Regulation

Background:

• N⁶-methyladenosine (m⁶A) modification is crucial for RNA processing, but its role in co-transcriptional splicing regulation remains unclear.
• Heterogeneous nuclear ribonucleoprotein G (hnRNPG) is an m⁶A reader protein with RNA-binding domains (RRM and RGG motifs).

Purpose of the Study:

• To elucidate the mechanism of co-transcriptional m⁶A-dependent alternative splicing regulation.
• To investigate the interaction between hnRNPG, RNA polymerase II (RNAPII), and nascent RNA.

Main Methods:

• Co-immunoprecipitation assays to detect protein-RNA interactions.
• Analysis of RNAPII occupancy and nascent RNA modifications.
• Transcriptome-wide analysis of alternative splicing patterns.

Main Results:

• hnRNPG directly binds the phosphorylated carboxy-terminal domain (CTD) of RNAPII via its RGG motifs.
• hnRNPG associates co-transcriptionally with RNAPII and nascent RNA, regulating alternative splicing.
• m⁶A modification near splice sites influences hnRNPG binding, affecting RNAPII occupancy and promoting exon inclusion.

Conclusions:

• An integrated mechanism for co-transcriptional m⁶A-mediated splicing regulation is revealed.
• The m⁶A reader hnRNPG utilizes RGG motifs to interact with RNAPII and m⁶A-modified nascent RNA.
• This interaction modulates RNAPII occupancy and alternative splicing during transcription.