Interaction of Alcohols and Anesthetics with Protein Kinase Cα

Abstract

Nature 364, 82-84). In this study, we show that interaction of n-alkanols and general anesthetics with PKC␣ results in dramatically different effects on membraneassociated compared with lipid-independent enzyme activity. Furthermore, the effects on membrane-associated PKC␣ differ markedly depending on whether activity is induced by diacylglycerol or phorbol ester and also on n-alkanol chain length. PKC␣ contains two distinct phorbol ester binding regions of low and high affinity for the activator, respectively (Slater, S. J., Ho, C., Kelly, M. B., Larkin, J. D., Taddeo, F. J., Yeager, M. D., and Stubbs, C. D. (1996) J. Biol. Chem. 271, 4627-4631). Short chain n-alkanols competed for low affinity phorbol ester binding to the enzyme, resulting in reduced enzyme activity, whereas high affinity phorbol ester binding was unaffected. Long chain n-alkanols not only competed for low affinity phorbol ester binding but also enhanced high affinity phorbol ester binding. Furthermore, long chain n-alkanols enhanced phorbol ester induced PKC␣ activity. This effect of long chain n-alkanols was similar to that of diacylglycerol, although the nalkanols alone were weak activators of the enzyme. The cellular effects of n-alkanols and general anesthetics on PKC-mediated processes will therefore depend in a complex manner on the locality of the enzyme (e.g. cytoskeletal or membrane-associated) and activator type, apart from any isoform-specific differences. Furthermore, effects mediated by interaction with the region on the enzyme possessing low affinity for phorbol esters represent a novel mechanism for the regulation of PKC activity.

1,25 dihydroxyvitamin D3 stimulates phospholipase C-gamma in rat colonocytes: role of c-Src in PLC-gamma activation.

“…While we have not mapped the specific phosphorylation site(s), as short term viability of primary colonocytes precludes high specific labeling of c-Src with [ 32 P]orthophosphoric acid, a dephosphorylation of Src at tyrosine 527 is likely involved in its activation (25,31). The additional finding that immunoprecipitated Src was stimulated by 1␣,25(OH) 2 D 3 incorporated into liposomes, suggests that this secosteroid may also directly activate the kinase, perhaps by an allosteric mechanism similar to that observed for PKC (27), and proposed as a mechanism for Src activation by the EGF receptor, independent of Src dephosphorylation (26). While the present studies in rat colonocytes indicate that Src activation induced by 1,25(OH) 2 D 3 involves, at least in part, tyrosine dephosphorylation, the specific role of allosteric alterations in this activation will require further study.…”

“…In this regard, 1,25(OH) 2 D 3 , when incorporated into liposomes, has also been shown to directly activate PKC, a serine/threonine kinase (27). We therefore studied the ability of 1,25(OH) 2 D 3 to directly activate c-Src which had been isolated by immunoprecipitation from unstimulated colonocytes.…”

Isoflurane Induces a Protein Kinase C α-Dependent Increase in Cell-Surface Protein Level and Activity of Glutamate Transporter Type 3

“…However, halothane, another volatile anesthetic, has been shown to stimulate the activity of purified brain PKC in the presence of physiologically relevant lipid bilayer vesicles (Hemmings et al, 1995). In addition, Slater et al (1993) suggested that PKC contains a hydrophobic binding site for alcohols and anesthetics in the regulatory region of PKC, and they observed that the activity of purified PKC␣ was increased by long-chain n-alkanols (Slater et al, 1997). However, a more recent study suggests that alcohols may activate PKC␣ not by direct binding to PKC but by altering lipid structure and by enhancing PKC-lipid bilayer binding (Shen et al, 1999).…”

Abnormal fatty alcohol metabolism in cultured keratinocytes from patients with Sjögren-Larsson syndrome

“…Previous studies have shown that rat brain PKC activity is inhibited by 1-O-alkylglycerol (51,52) and stimulated by 1-O-alkyl-2-acylglycerol (53), two potential metabolites of 1-O-alkyl-2,3-diacylglycerol. Interestingly, medium-chain fatty alcohols (C8-C10) either inhibit or enhance PKCa activity in a complex manner, but the effects of longer chain alcohols, which accumulate in SLS cells, have not been studied (54). Therefore, it is intriguing to speculate that two of the lipids (or their metabolites) that accumulate in SLS keratinocytes might influence PKC activity and interfere with certain steps in cell differentiation.…”