ISSN:
1440-1681
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Medicine
Notes:
1. Phosphatidylinositol 3-kinase (PI3K) appears to have a crucial role in cellular proliferation induced by platelet-derived growth factor (PDGF). However, the mode of activation of the enzyme has been unclear so far. In the present study, we investigated the effects of a cholesterol lowering drug on [3H]-thymidine ([3H]-TdR) incorporation and PI3K activity in cultured vascular smooth muscle cells (VSMC) stimulated with PDGF.2. PDGF stimulated both [3H]-TdR incorporation and PI3K activity immunoprecipitated with antiphosphotyrosine antibody in a dose dependent manner (EDSO was 4 ng/mL for [3H]-TdR uptake and 3 ng/mL for PI3K activity). Lovastatin inhibited serum-stimulated [3H]-TdR incorporation dose dependently. PI3K activity induced by PDGF was also inhibited in a dose dependent manner; however, its activity was 61% at 10-6 mol/L, 72% at 10-5 mol/L and 8% at 10-4 mol/L of the control value.3. These inhibitory effects of lovastatin were completely abolished by adding 1 mmol/L mevalonic acid (MVA), suggesting that MVA metabolites had some important role on the PI3K activation and cellular proliferation.4. Fluoromevalonate (Fmev), a competitive inhibitor of mevalonate diphosphate (MVA-PP) decarboxylase, inhibited [3H]-TdR incorporation at concentrations more than 10-6 mol/L. Moreover, marked inhibitory effect was observed at concentrations of 10-7 and 10-8 mol/L (76% of control). PI3K activity was also reduced by 10-3 mol/L Fmev (0.2% of control). However, in contrast to [3H]-TdR uptake, there was no inhibitory effect detected at concentrations up to 10-4 mol/L.5. These results suggest that PDGF-stimulated PI3K activity as well as cellular proliferation was modified by protein isoprenylation.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1440-1681.1995.tb02935.x
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