Journal
RNA
Volume 14, Issue 10, Pages 2038-2049Publisher
COLD SPRING HARBOR LAB PRESS, PUBLICATIONS DEPT
DOI: 10.1261/rna.1212008
Keywords
CD45; alternative splicing; hnRNP LL; hnRNP L; screening
Categories
Funding
- NRSA [F32 GM083620]
- Welch Foundation [I-1634]
- [R01 GM067719]
Ask authors/readers for more resources
The human CD45 gene encodes a protein-tyrosine phosphatase that exhibits differential isoform expression in resting and activated T cells due to alternative splicing of three variable exons. Previously, we have used biochemical methods to identify two regulatory proteins, hnRNP L and PSF, which contribute to the activation-induced skipping of CD45 via the ESS1 regulatory element in variable exon 4. Here we report the identification of a third CD45 regulatory factor, hnRNP L-like (hnRNP LL), via a cell-based screen for clonal variants that exhibit an activation-like phenotype of CD45 splicing even under resting conditions. Microarray analysis of two splicing-altered clones revealed increased expression of hnRNP LL relative to wild-type cells. We further demonstrate that both the expression of hnRNP LL protein and its binding to ESS1 are up-regulated in wild-type cells upon activation. Forced overexpression of hnRNP LL in wild-type cells results in an increase in exon repression, while knockdown of hnRNP LL eliminates activation-induced exon skipping. Interestingly, analysis of the binding of hnRNP L and hnRNP LL to mutants of ESS1 reveals that these proteins have overlapping, but distinct binding requirements. Together, these data establish that hnRNP LL plays a critical and unique role in the signal-induced regulation of CD45 and demonstrate the utility of cell-based screens for the identification of novel splicing regulatory factors.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available