| Research Abstract |
Phenotypic change of vascular smooth muscle cells (SMC) is an important aspect of atherogenesis. Activated cytokinegrowth factor network in the injured vessels subsequently induces a number of intracellular events resulting in the phenotypic modulation of SMC. Here, we investigated the role of beta2-chimaerin, a novel phorbol ester receptor with Rac GTPase-activating protein activity, in growth factor-stimulated SMC. Endogenous expression of beta2-chimaerin was detected in cultured human SMC by RT-PCR and immunohistochemistiy. Next, an overexpression of HA-tagged wild type human beta2-chimaerin was attempted in cultured rat SMC with a recombinant adenovirus (Adv-Ch). Confocal microscopy revealed 12-O-tetradecanoyl phorbol 13-acetate (TPA)-induced translocation of exogenous beta2-chimaerin from cytoplasm to plasma membrane in the presence of the PKC inhibitor (GF109203X). Proliferation of SMC stimulated by 10% FCS, bFGF (25ng/ml), and PDGF (10ng/ml) were inhibited by the infection with Adv-Ch (10-200MOI), but not with control viruses (Adv-LacZ), which was measured by cell counting and BrdU incorporation assays. PDGF-induced SMC migration was inhibited by the infection with Adv-Ch (200MOI) by about 25% in a modified Boyden chamber assay with the fibronectin-coated membrane. These data suggested that beta2-chimaerin might regulate proliferation and migration of SMC at the down-stream of the receptor tyrosine kinases. Beta2-chimaerin system may be involved in human atherogenesis, as is a potential therapeutic target.
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