Cleavage and polyadenylation specificity factor 1 (CPSF1) regulates alternative splicing of interleukin 7 receptor (IL7R) exon 6.
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.
Mesh Terms:
Alternative Splicing, Animals, Cell Line, Chromatography, Affinity, Cleavage And Polyadenylation Specificity Factor, Exons, Gene Silencing, Humans, Introns, Mass Spectrometry, Multiple Sclerosis, Mutation, Polymorphism, Single Nucleotide, Protein Isoforms, RNA Splice Sites, RNA, Messenger, Rats, Receptors, Interleukin-7, Spliceosomes, Trans-Activators
Alternative Splicing, Animals, Cell Line, Chromatography, Affinity, Cleavage And Polyadenylation Specificity Factor, Exons, Gene Silencing, Humans, Introns, Mass Spectrometry, Multiple Sclerosis, Mutation, Polymorphism, Single Nucleotide, Protein Isoforms, RNA Splice Sites, RNA, Messenger, Rats, Receptors, Interleukin-7, Spliceosomes, Trans-Activators
RNA
Date: Jan. 01, 2013
PubMed ID: 23151878
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