Expression and translocation of protein kinase C isoforms in rat microglial and astroglial cultures

Cellular distribution and activation by phorbol myristate acetate (PMA) of classical (alpha, beta II, beta II,gamma), novel (delta, epsilon, theta, et a), and atypical (zeta, iota) protein kinase C (PKC) isoforms were studied in cultured rat neonatal microglial and astroglial cells by Western blot an alysis. Among the classical, isoforms, only PII was expressed in microglia and astrocytes in the same abundance. The expression of PI in microglia was less abundant, while PKC alpha was not detectable in this cell type. PKC g amma was absent in both cell populations, A different pattern of expression was also found for novel and atypical isoenzymes: Both cell types expresse d delta, theta, eta, zeta, and iota isoforms, but PKC epsilon was absent in microglia and the expression of PKC zeta and PKC iota in these cells was l ow compared to astrocytes, The pattern of PKC distribution in cytosolic and particulate fractions as well as activation by short (10 min) and prolonge d (4 hr) PMA treatment in both cell types were similar. On the whole, in co mparison with astrocytes, PKC in microglial cells was less expressed, both in terms of number of isoforms and level of expression, The microglial prof ile of PKC isoforms differed from that of rat peritoneal macrophages, which did express PKC alpha, Preliminary evidence suggests that the ability of P MA to enhance cyclic AMP responses in astrocytes, but not in microglia, is related to the different pattern of expression of PKC alpha and PKC epsilon in the two cell types. (C) 1999 Wiley-Liss, Inc.