Histone modifications involved in cassette exon inclusions: a quantitative and interpretable analysis

Area of Science:

• Molecular Biology
• Epigenetics
• Genomics

Background:

• Chromatin structure and epigenetic modifications are implicated in RNA precursor co-transcriptional splicing.
• Histone modifications (HMs) may act as exon marks influencing alternative splicing.
• Existing research often lacks quantitative analysis of HMs' impact on exon inclusion.

Purpose of the Study:

• To quantitatively analyze the influence of histone modifications (HMs) on cassette exon (CE) inclusion in mature RNAs.
• To determine the extent to which specific HMs contribute to CE inclusion.
• To understand the role of HMs in alternative splicing regulation.

Main Methods:

• Utilized high-throughput ChIP-seq and RNA-seq data from the ENCODE project.
• Employed logistic regression modeling to quantify the association between HMs and CE inclusions.
• Analyzed the impact of HMs in flanking regions and on CEs of specific lengths.

Main Results:

• Identified H3K36me3, H3K9me3, and H4K20me1 as major HMs influencing CE inclusion.
• Demonstrated that HM effects on CE inclusion are conserved across cell types and independent of gene expression levels.
• Found that HMs in bounded flanking regions moderately affect CE inclusion, while HMs on CEs near nucleosomal DNA length significantly impact inclusion.

Conclusions:

• A subset of HMs closely correlates with alternative splicing, potentially acting with the splicing machinery.
• Findings elucidate the role of HMs in exon definition and the mechanisms of co-transcriptional splicing.