Role of kinase C in the insulin-like effects of human growth hormone in rat adipocytes.

Insulin and to a smaller extent, human growth hormone (hGH), both stimulate lipogenesis in isolated rat adipocytes preincubated 4 hours in the absence of hormone. The non-additivity of maximal doses suggested that hGH may share a subset of the metabolic pathways stimulated by insulin. We explored whether kinase C may be involved in the common lipogenic effect of both hormones. The stimulation of lipogenesis by phorbol ester 12-myristate 13-acetate (PMA) (an activator of kinase C) was not additive to the stimulation by either insulin or hGH. Downregulation of kinase C resulted in a marked decrease of the maximal insulin effect (44 +/- 9%) and even more of the hGH effect (64 +/- 14%). These data suggest that kinase C either mediates part of, or modulates, the effect of insulin and hGH on lipogenesis.