Vasopressin stimulates the induction of heat shock protein 27 and alpha B-Crystallin via protein kinase C activation in vascular smooth muscle cells

In the present study, we examined the effect of vasopressin on the inductio n of the low-molecular-weight heat shock proteins heat shock protein 27 (HS P27) and alpha B-crystallin in an aortic smooth muscle cell line, A10 cells . Vasopressin induced a time-dependent accumulation of HSP27 and alpha B-cr ystallin. The stimulatory effects of vasopressin were dose-dependent over t he range 0.1 nmol/L to 0.1 mu mol/L. The EC50 values for vasopressin were 2 (HSP27) and 4 nmol/L (alpha B-crystallin). Vasopressin induced increases i n the levels of the mRAs for HSP27 and alpha B-crystallin. 12-O-Tetradecano ylphorbol 13-acetate (TPA), a protein kinase C (PKC)-activating phorbol est er, induced an accumulation of HSP27 (EC50, 20 nmol/L) and alpha B-crystall in (EC50, 2 nmol/L). In contrast, 4 alpha-phorbol 12,13-didecanoate, a non- PKC-activating phorbol ester, had no such effect. Staurosporine and calphos tin C, inhibitors of PKC, significantly reduced the vasopressin-induced acc umulation of HSP27 and alpha B-crystallin as well as that induced by TPA. B APTA/AM and TMB-8, inhibitors of intracellular Ca2+ mobilization, significa ntly reduced the vasopressin-induced accumulation of HSP27 and alpha B-crys tallin. These results strongly suggest that vasopressin stimulates the indu ction of HSP27 and alpha B-crystallin via PKC activation in vascular smooth muscle cells and that this effect of vasopressin is dependent on intracell ular Ca2+ mobilization. (C) 1999 Academic Press.