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Arachidonic acid-induced down-regulation of protein kinase C δ in beta-cells

✍ Scribed by Keith L. Knutson; Margarethe Hoenig

Publisher
John Wiley and Sons
Year
1996
Tongue
English
Weight
954 KB
Volume
62
Category
Article
ISSN
0730-2312

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✦ Synopsis

We have previously identified expression of multiple protein kinase C (PKC) isoforms in insulinomaderived beta-cells and whole islets. Both PKC 6 and PKC a appear to be the more abundantly expressed isoforms. in this report we studied the effects of arachidonic acid (AA) on the subcellular distribution of PKC a and PKC 6. AA has been reported to activate both PKC a and PKC 6 and it is thought to be an important second messenger in beta-cells. Here we report that AA interacted with and altered beta-cell pools of PKC 6 preferentially over PKC a. AA (100 pM) over the course of 45 min reduced cytosolic levels of PKC 6 (to 40 * 15%, compared to time zero control) leaving membraneand cytoskeleton-associated levels near control levels. Analysis of whole cell homogenates showed a slight downregulation of PKC 6 indicating proteolysis. The down-regulation of cytosolic PKC 6 appeared to be isoform specific since cytosolic PKC a remained at control levels over the time course. The response was dose-dependent and negligible at concentrations below 30 pM and occurred, at least partially, in the cytosolic compartment of the cell. lndomethacin also down-regulated cytosolic PKC 6 preferentially over PKC a possibly through accumulation of AA. These findings suggest that cytosolic PKC 6 may be a downstream target of this beta-cell second messenger.

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