Cleavage and polyadenylation specificity factor 1 (CPSF1) regulates alternative splicing of interleukin 7 receptor (IL7R) exon 6.

Journal Article

Interleukin 7 receptor, IL7R, is expressed exclusively on cells of the lymphoid lineage, and its expression is crucial for the development and maintenance of T cells. Alternative splicing of IL7R exon 6 results in membrane-bound (exon 6 included) and soluble (exon 6 skipped) IL7R isoforms. Interestingly, the inclusion of exon 6 is affected by a single-nucleotide polymorphism associated with the risk of developing multiple sclerosis. Given the potential association of exon 6 inclusion with multiple sclerosis, we investigated the cis-acting elements and trans-acting factors that regulate exon 6 splicing. We identified multiple exonic and intronic cis-acting elements that impact inclusion of exon 6. Moreover, we utilized RNA affinity chromatography followed by mass spectrometry to identify trans-acting protein factors that bind exon 6 and regulate its splicing. These experiments identified cleavage and polyadenylation specificity factor 1 (CPSF1) among protein-binding candidates. A consensus polyadenylation signal AAUAAA is present in intron 6 of IL7R directly downstream from the 5' splice site. Mutations to this site and CPSF1 knockdown both resulted in an increase in exon 6 inclusion. We found no evidence that this site is used to produce cleaved and polyadenylated mRNAs, suggesting that CPSF1 interaction with intronic IL7R pre-mRNA interferes with spliceosome binding to the exon 6 5' splice site. Our results suggest that competing mRNA splicing and polyadenylation regulate exon 6 inclusion and consequently determine the ratios of soluble to membrane-bound IL7R. This may be relevant for both T cell ontogeny and function and development of multiple sclerosis.

Full Text

Duke Authors

Cited Authors

  • Evsyukova, I; Bradrick, SS; Gregory, SG; Garcia-Blanco, MA

Published Date

  • January 2013

Published In

Volume / Issue

  • 19 / 1

Start / End Page

  • 103 - 115

PubMed ID

  • 23151878

Electronic International Standard Serial Number (EISSN)

  • 1469-9001

Digital Object Identifier (DOI)

  • 10.1261/rna.035410.112

Language

  • eng

Conference Location

  • United States