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Arachidonic acid‐induced down‐regulation of protein kinase C δ in beta‐cells
Author(s) -
Knutson Keith L.,
Hoenig Margarethe
Publication year - 1996
Publication title -
journal of cellular biochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.028
H-Index - 165
eISSN - 1097-4644
pISSN - 0730-2312
DOI - 10.1002/(sici)1097-4644(19960915)62:4<543::aid-jcb11>3.0.co;2-g
Subject(s) - protein kinase c , cytosol , second messenger system , gene isoform , microbiology and biotechnology , arachidonic acid , biology , cytoplasm , intracellular , chemistry , kinase , biochemistry , enzyme , gene
We have previously identified expression of multiple protein kinase C (PKC) isoforms in insulinoma‐derived beta‐cells and whole islets. Both PKC γ and PKC α 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 α and PKC γ. AA has been reported to activate both PKC α and PKC γ 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 γ preferentially over PKC α. AA (100 μM) over the course of 45 min reduced cytosolic levels of PKC γ (to 40 ± 15%, compared to time zero control) leaving membrane‐and cytoskeleton‐associated levels near control levels. Analysis of whole cell homogenates showed a slight down‐regulation of PKC γ indicating proteolysis. The down‐regulation of cytosolic PKC γ appeared to be isoform specific since cytosolic PKC α remained at control levels over the time course. The response was dose‐dependent and negligible at concentrations below 30 μM and occurred, at least partially, in the cytosolic compartment of the cell. Indomethacin also down‐regulated cytosolic PKC γ preferentially over PKC α possibly through accumulation of AA. These findings suggest that cytosolic PKC γ may be a downstream target of this beta‐cell second messenger. © 1996 Wiley‐Liss, Inc.