Caspase-dependent cleavage of the hematopoietic specific adaptor protein Gads alters signalling from the T cell receptor.
Gads is a SH2 and SH3 domain-containing, hematopoietic-specific adaptor protein that functions in signalling from the T cell receptor. Gads acts by linking SLP-76, bound by the carboxy-terminal Gads SH3 domain, to tyrosine phosphorylated LAT which contains binding sites for the Gads SH2 domain. Gads is distinguished from Grb2 and the closely related Grap protein by the presence of a 120 amino acid unique region between the SH2 domain and the carboxy terminal SH3 domain. Here we demonstrate that the unique region of Gads contains a capase cleavage site. Induction of apoptosis in lymphocytes results in detectable Gads cleavage by 60 min. Gads cleavage is blocked in vivo by treating cells with a caspase 3 inhibitor. A putative caspase 3 cleavage site was identified within the unique region and mutation of this site prevented Gads cleavage in vitro, and in vivo. The Gads cleavage products retained the predicted binding specificity for SLP-76 and LAT. Expression of the Gads cleavage products in Jurkat T cells inhibited NFAT activation following TCR cross linking. These findings indicate that cleavage of Gads in vivo could function to alter signalling downstream of the T cell receptor by disrupting cross talk between SLP-76 and LAT.
Berry
D M
DM
The Arthur and Sonia Labatt Brain Tumour Research Centre, The Hospital for Sick Children, Toronto, Ontario, Canada.
Benn
S J
SJ
Cheng
A M
AM
McGlade
C J
CJ
D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins / Q000737:chemistry / Q000378:metabolism*; D053148:Caspase 3; D061945:Caspase Inhibitors; D020169:Caspases / Q000378:metabolism*; D002460:Cell Line; D004268:DNA-Binding Proteins / Q000378:metabolism; D004789:Enzyme Activation; D053222:Fas Ligand Protein; D006412:Hematopoietic Stem Cells / Q000502:physiology*; D006801:Humans; D019169:Jurkat Cells / Q000378:metabolism; D008213:Lymphocyte Activation / Q000187:drug effects; D008562:Membrane Glycoproteins / Q000494:pharmacology; D008565:Membrane Proteins; D016297:Mutagenesis, Site-Directed; D050778:NFATC Transcription Factors; D009687:Nuclear Proteins; D010750:Phosphoproteins / Q000737:chemistry / Q000378:metabolism; D010766:Phosphorylation; D011948:Receptors, Antigen, T-Cell / Q000378:metabolism; D015398:Signal Transduction; D013601:T-Lymphocytes / Q000187:drug effects / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism; D014162:Transfection; D014443:Tyrosine / Q000378:metabolism; D018909:src Homology Domains / Q000235:genetics
D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; D061945:Caspase Inhibitors; D004268:DNA-Binding Proteins; C505661:FASLG protein, human; D053222:Fas Ligand Protein; C409587:GRAP2 protein, human; C510602:Grap protein, human; C110810:LAT protein, human; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D050778:NFATC Transcription Factors; D009687:Nuclear Proteins; D010750:Phosphoproteins; D011948:Receptors, Antigen, T-Cell; C092947:SLP-76 signal Transducing adaptor proteins; D014157:Transcription Factors; D014443:Tyrosine; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases