Phosphorylation of PITSLRE p110 isoforms accompanies their processing by caspases during Fas-mediated cell death.
A number of cellular proteins have been identified as caspase targets during cell death, including the PITSLRE protein kinases. These targets generally fall into one of three possible categories: 1) other caspases, 2) proteins that are inactivated during apoptosis, and 3) proteins that are required for execution of the cell death program. However, not all proteins are cleaved by caspases during apoptosis. Why only specific proteins are destined to be processed by caspases during cell death is currently not clear. Here we show that multiple caspase-like activities are involved in the processing of the PITSLRE p110 isoforms during Fas-induced apoptosis in Jurkat T-cells. Three p110 caspase cleavage sites have been mapped to the amino-terminal domain of p110 and verified by site-directed mutagenesis. Curiously, the mutagenesis studies revealed that cleavage of two juxtaposed caspase sites is necessary for the complete processing of this protein during cell death in vivo. Finally, we demonstrate that the PITSLRE p110 protein is rapidly phosphorylated during Fas-induced apoptosis in Jurkat cells and that phosphorylation of an amino-terminal portion of the protein may enhance caspase cleavage in this region.
Tang
D
D
Department of Tumor Cell Biology, St. Jude Children's Research Hospital, Memphis, Tennessee 38101, USA.
Gururajan
R
R
Kidd
V J
VJ
D017209:Apoptosis; D053148:Caspase 3; D020169:Caspases; D018844:Cyclin-Dependent Kinases; D003546:Cysteine Endopeptidases / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000378:metabolism; D004789:Enzyme Activation; D006801:Humans; D020672:I-kappa B Proteins; D007527:Isoenzymes / Q000378:metabolism; D019169:Jurkat Cells; D048369:MAP Kinase Kinase 1; D020929:Mitogen-Activated Protein Kinase Kinases; D000072000:NF-KappaB Inhibitor alpha; D010449:Peptide Mapping; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D019014:fas Receptor / Q000378:metabolism*
D004268:DNA-Binding Proteins; D020672:I-kappa B Proteins; D007527:Isoenzymes; C000606204:NFKBIA protein, human; D019014:fas Receptor; D000072000:NF-KappaB Inhibitor alpha; D011494:Protein Kinases; D011505:Protein-Tyrosine Kinases; D017346:Protein Serine-Threonine Kinases; C447612:CDK11a protein, human; D018844:Cyclin-Dependent Kinases; D048369:MAP Kinase Kinase 1; C482125:MAP2K1 protein, human; D020929:Mitogen-Activated Protein Kinase Kinases; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases; D003546:Cysteine Endopeptidases