Splicing of precursor mRNA (pre-mRNA) is an important regulatory step in gene expression. Recent evidence points to a regulatory role of chromatin-related proteins in alternative splicing regulation. Using an unbiased approach, we have identified the acetyltransferase p300 as a key chromatin-related regulator of alternative splicing. p300 promotes genome-wide exon inclusion in both a transcription-dependent and -independent manner. Using CD44 as a paradigm, we found that p300 regulates alternative splicing by modulating the binding of splicing factors to pre-mRNA. Using a tethering strategy, we found that binding of p300 to the CD44 promoter region promotes CD44v exon inclusion independently of RNAPII transcriptional elongation rate. Promoter-bound p300 regulates alternative splicing by acetylating splicing factors, leading to exclusion of hnRNPM from CD44 pre-mRNA and activation of Sam68. p300-mediated CD44 alternative splicing reduces cell motility and promotes epithelial features. Our findings reveal a chromatin-related mechanism of alternative splicing regulation and demonstrate its impact on cellular function.
Bibliographical noteFunding Information:
We thank Chonghui Cheng and Rotem Karni for valuable discussion. We thank Abed Nasereddin and Idit Shiff from the Genomic Applications Laboratory, The Core Research Facility, The Faculty of Medicine - Ein Kerem, The Hebrew University of Jerusalem, Israel, for their professional advice and RNA-seq service. We thank Amina Jbara for guidance on scratch assay technique. We thank Chonghui Cheng for the hnRNP M plasmid and Alberto Kornblihtt for slow RNAPII plasmids. This work was in part supported by the Israeli Cancer Association, Alon Award by the Israeli Planning and Budgeting Committee (PBC), and the Israel Science Foundation (ISF 1154/17). The RNA-seq reagents were funded by a Core Laboratory Grant Program launched by Danyel Biotech, the authorized Illumina Channel Partner in Israel.
© 2019 Siam et al.
- Alternative splicing
- Pre-mRNA splicing