Protein kinase C and T cell activation.
Understanding the intracellular mechanisms by which binding of ligands, such as hormones and growth factors, to their specific receptors elicits the appropriate cellular response has long been a topic of great interest. Considerable excitement was generated when it was recognised that several receptor-ligand interactions operate via the hydrolysis of inositol phospholipids. This yields, at least, two 'second messengers', namely, inositol 1,4,5-trisphosphate [Ins(1,4,5)P3], which causes the release of Ca2+ from intracellular stores, and 1,2-diacylglycerol (ac2Gro), which activates the serine/threonine-specific enzyme, protein kinase C(PKC), reviewed in [1] and [2]. The pertinent question that follows is, how do PKC activation and elevation of the intracellular Ca2+ concentration evoke cell responses? In this review, attention has been focused on PKC, and the consequences of its activation in resting human T cells. Evidence that PKC activity is, at least partially, responsible for activation of resting human T cells will be examined, and some of the more recent research investigating how PKC activation elicits this cell response will be described.
Department of Biochemistry, Kobe University School of Medicine, Japan.
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Berry
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Nishizuka
D000818:Animals; D015703:Antigens, CD / Q000276:immunology; D006801:Humans; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism; D008213:Lymphocyte Activation; D008954:Models, Biological; D011493:Protein Kinase C / Q000378:metabolism*; D015290:Second Messenger Systems; D015398:Signal Transduction; D013601:T-Lymphocytes / Q000201:enzymology / Q000276:immunology*
D015703:Antigens, CD; D015544:Inositol 1,4,5-Trisphosphate; D011493:Protein Kinase C