rottlerin and hispidin

The effect of protein kinase C (PKC) inhibitors on porcine oocyte activation by calcium ionophore A23187 was studied. Calcium ionophore applied in a 50 microM concentration for 10 min induced activation in 74% of oocytes matured in vitro. When the ionophore-treated oocytes were exposed to the effect of bisindolylmaleimide I, which inhibits calcium-dependent PKC isotypes (PKC-alpha, -beta(I), -beta(II), -gamma,) and calcium-independent PKC isotypes (PKC-delta, -epsilon), the portion of activated oocytes decreased (at a concentration of 100 nM, 2% of the oocytes were activated). Go6976, the inhibitor of calcium-dependent PKC isotypes PKC-alpha, -beta(I) did not prevent the action of the oocytes treated with calcium ionophore in concentrations from 1 to 100 microM. The inhibitor of PKC-beta(I) and beta(II) isotypes, hispidin, in a concentration of 2 microM-2 mM, was not effective either. The inhibitor of PKC-delta isotype, rottlerin, suppressed activation of the oocytes by calcium ionophore (no oocyte was activated at 10 microM concentration). The PKC-delta isotype in matured porcine oocytes, studied by Western blot analysis, appeared as non-truncated PKC-delta of 77.5 kDa molecular weight, on the one hand, and as truncated PKC-delta, which was present in the form of a doublet of approximately 62.5 and 68 kDa molecular weight, on the other hand. On the basis of these results, it can be supposed that PKC participates in the regulation of processes associated with oocyte activation. Calcium-dependent PKC-alpha, -beta isotypes do not seem to play any significant role in calcium activation. The activation seems to depend on the activity of the calcium-independent PKC-delta isoform.

Topics: Acetophenones; Animals; Benzopyrans; Blotting, Western; Calcimycin; Calcium; Carbazoles; Female; In Vitro Techniques; Indoles; Ionophores; Isoenzymes; Maleimides; Oocytes; Protein Kinase C; Protein Kinase Inhibitors; Pyrones; Swine

The effect of HIV-1 Tat protein on the production of IL-10, an immunosuppressive cytokine, was examined in human primary monocytes obtained from healthy HIV-1-negative blood donors. As expected and in agreement with our previous data, a dose-dependent induction of IL-10 was observed. In addition, we showed that this induction is mediated by the PKC pathway: in the presence of Ro 31-8220, an inhibitor of all PKC isozymes, or after 48 h of PMA treatment, Tat protein becomes unable to stimulate IL-10 production. Among the 11 PKC isozymes, eight (PKC alpha, beta(I), beta(II), delta, epsilon, eta, zeta, mu) are expressed in monocytes. In this study, by analyzing the translocation to the membrane after Tat stimulation, we showed that PKC alpha, beta(I), beta(II), delta and epsilon isozymes are activated by Tat. Moreover, by combining different approaches including selective PKC inhibitors (Gö6983, Gö6976, hispidin and rottlerin), we showed that PKC beta(II) and delta isozymes are essential for the activation of IL-10 production in human monocytes following stimulation by HIV-1 Tat protein.

Topics: Acetophenones; Benzopyrans; Carbazoles; Cells, Cultured; Enzyme Inhibitors; Gene Expression Regulation; Gene Products, tat; HIV-1; Humans; Indoles; Interleukin-10; Maleimides; Monocytes; Protein Kinase C; Protein Kinase C beta; Protein Kinase C-delta; Pyrones; tat Gene Products, Human Immunodeficiency Virus

Listeriolysin O (LLO) and a phosphatidylinositol-specific phospholipase C (PI-PLC) are known virulence factors of Listeria monocytogenes in both tissue cultures and the murine model of infection. LLO is a member of a family of pore-forming cholesterol-dependent cytotoxins and is known to play an essential role in escape from the primary phagocytic vacuole of macrophages. PI-PLC plays an accessory role, in that PI-PLC mutants are partially defective in escape. We have shown that both of these molecules are essential for initiating rapid increases in the calcium level in the J774 murine macrophage cell line (S. J. Wadsworth and H. Goldfine, Infect. Immun. 67:1770-1778, 1999). Here we show that both LLO and PI-PLC are required for translocation of protein kinase C delta (PKC delta) to the periphery of J774 cells and for translocation of PKC beta II to early endosomes beginning within the first minute after addition of bacteria to the culture medium. Treatment with the calcium channel blocker SK&F 96365 inhibited translocation of PKC beta II but not PKC delta. Our findings lead us to propose a host signaling pathway requiring LLO and the formation of diacylglycerol by PI-PLC in which calcium-independent PKC delta is responsible for the initial calcium signal and the subsequent PKC beta II translocation. LLO-dependent translocation of PKC beta I to early endosomes also occurs between 1 and 4 min after infection, but this occurs in the absence of PI-PLC. All of these signals were observed in cells that had not internalized bacteria. Blocking PKC beta translocation with hispidin resulted in more rapid uptake of wild-type bacteria and greatly reduced escape from the primary phagocytic vacuoles of J774 cells.

Topics: Acetophenones; Animals; Bacterial Proteins; Bacterial Toxins; Benzopyrans; Biological Transport; Calcium Channel Blockers; Cell Line; Endosomes; Enzyme Inhibitors; Heat-Shock Proteins; Hemolysin Proteins; Imidazoles; Isoenzymes; Listeria monocytogenes; Macrophages; Mice; Phagocytosis; Phagosomes; Phosphatidylinositol Diacylglycerol-Lyase; Phosphoinositide Phospholipase C; Protein Kinase C; Protein Kinase C beta; Protein Kinase C-delta; Pyrones; Type C Phospholipases; Vacuoles