Protein kinase C and T cell activation

Abstract

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 focussed 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.