Activation of type I protein kinase A during receptor-mediated human T lymphocyte activation.
The experiments reported herein have characterized the signaling pathway leading to stimulation of type I protein kinase A isozyme (PKA-I) activity during the early events of Ag receptor-mediated T cell activation. Inhibitor studies demonstrated that receptor-initiated activation of nonreceptor protein tyrosine kinases, phosphorylation and activation of phospholipase C-gamma 1, and activation of protein kinase C occur temporally and precede PKA-I activation. Bypass of both the TCR/CD3 complex and IL-1R and direct activation of protein kinase C by a phorbol ester can also activate PKA-I. To confirm that PKA-I activation via the TCR/CD3 complex and IL-1R requires antecedent protein tyrosine kinase-catalyzed phosphorylation of phospholipase C-gamma 1, we used wild-type and CD45-deficient (mutant J45.01) Jurkat T cell lines. Unlike wild-type Jurkat T cells, the absence of CD45 tyrosine phosphatase resulted in the failure of receptor-mediated activation of PKA-I activity and of IL-2 mRNA transcription in the mutant J45.01 Jurkat cell line. In conclusion, our data support the concept that a signal derived from ligand binding to both the TCR/CD3 complex and IL-1R receptor mediates rapid activation of the PKA-I isozyme in primary T lymphocytes by sequential activation of an intracellular pathway comprised of CD45 phosphatase/protein tyrosine kinase/polyphosphoinositide/Ca2+/protein kinase C pathway rather than via the conventional surface receptor/stimulatory G protein system.
Department of Internal Medicine, Bowman Gray School of Medicine, Wake Forest University, Winston-Salem, NC 27157, USA.
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D016227:Benzoquinones; D004791:Enzyme Inhibitors; D007375:Interleukin-1; D007376:Interleukin-2; D007527:Isoenzymes; D047029:Lactams, Macrocyclic; D008565:Membrane Proteins; D016853:Muromonab-CD3; D010742:Phospholipid Ethers; D011809:Quinones; D012333:RNA, Messenger; D017260:Receptor-CD3 Complex, Antigen, T-Cell; D016693:Receptors, Antigen, T-Cell, alpha-beta; D017472:Receptors, Interleukin-1; D011994:Recombinant Proteins; D013873:Thionucleotides; D017828:Rifabutin; C026659:edelfosine; C016957:adenosine-3',5'-cyclic phosphorothioate; C020754:herbimycin; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D011493:Protein Kinase C; D017493:Leukocyte Common Antigens; D010738:Type C Phospholipases; D051966:Phospholipase C gamma; D019204:GTP-Binding Proteins; D013755:Tetradecanoylphorbol Acetate; D002118:Calcium