A model system for activation-induced alternative splicing of CD45 pre-mRNA in T cells implicates protein kinase C and Ras.
Multiple isoforms of the protein tyrosine phosphatase CD45 are expressed on the surface of human T cells. Interestingly, the expression of these isoforms has been shown to vary significantly upon T-cell activation. In this report, we describe a novel cell line-based model system in which we can mimic the activation-induced alternative splicing of CD45 observed in primary T cells. Of the many proximal signaling events induced by T-cell stimulation, we show that activation of protein kinase C and activation of Ras are important for the switch toward the exclusion of CD45 variable exons, whereas events related to Ca(2+) flux are not. In addition, the ability of cycloheximide to block the activation-induced alternative splicing of CD45 suggests a requirement for de novo protein synthesis. We further demonstrate that sequences which have previously been implicated in the tissue-specific regulation of CD45 variable exons are likewise necessary and sufficient for activation-induced splicing. These results provide an initial understanding of the requirements for CD45 alternative splicing upon T-cell activation, and they confirm the importance of this novel cell line in facilitating a more detailed analysis of the activation-induced regulation of CD45 than has been previously possible.
Lynch
K W
KW
Departments of Medicine, Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, California 94143-0795, USA.
Weiss
A
A
D017398:Alternative Splicing; D006801:Humans; D017493:Leukocyte Common Antigens / Q000096:biosynthesis* / Q000235:genetics*; D008213:Lymphocyte Activation; D011493:Protein Kinase C / Q000235:genetics / Q000378:metabolism*; D012322:RNA Precursors / Q000096:biosynthesis* / Q000235:genetics*; D013601:T-Lymphocytes / Q000378:metabolism*; D018631:ras Proteins / Q000235:genetics / Q000378:metabolism*
D012322:RNA Precursors; D011493:Protein Kinase C; D017493:Leukocyte Common Antigens; D018631:ras Proteins