KMID : 0620920020340060444
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Experimental & Molecular Medicine 2002 Volume.34 No. 6 p.444 ~ p.450
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Phosphorylation of glycogen synthase kinase-3¥â at serine-9 by phospholipase C¥ã1 through protein kinase C in rat 3Y1 fibroblasts
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Young Han Lee/Soon Young Shin
Se Chang Yoon/Young Ho Kim/Yong Sik Kim/Young Han Lee
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Abstract
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Phospholipase C¥ã1 (PLC¥ã1) plays an important role in controlling cellular proliferation and differentiation. PLC¥ã1 is overexpressed in some tumors, and its overexpression induces solid tumors in nude mice. However, the regulatory mechanisms underlying PLC¥ã1-induced cell proliferation are not fully understood. Here we show that overexpression of PLC¥ã1 highly phosphorylated glycogen synthase kinase-3¥â (GSK-3¥â) at serine-9 in 3Y1 fibroblasts. Inhibition of protein kinase C (PKC)s with GF109203X abrogated GSK-3¥â phosphorylation by PLC¥ã1. We also found that steady-state level of cyclin D1 protein, but not cyclin D1 mRNA, was highly elevated in response to serum stimulation in PLC¥ã1-transfected cells as compared with vector-transfected cells. Since GSK-3¥â is involved in cyclin D1 proteolysis in response to mitogenic stimulation, PLC¥ã1-mediated GSK-3¥â phosphorylation may function as a regulation of cyclin D1 accumulation in PLC¥ã1-overexpressing cells.
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KEYWORD
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cyclin D1, fibroblasts, glycogen synthase kinase 3, phospholipase C, protein kinase C,
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