NUCLEAR RESPONSES TO PROTEIN-KINASE-C SIGNAL TRANSDUCTION ARE SENSITIVE TO GRAVITY CHANGES

A number of studies have suggested that gravity changes may influence mammalian cell growth and differentiation. To obtain insight in the molecular mechanisms underlying these effects, we have studied immediate early gene expression in response to activation of cytoplasmic signal transduction under microgravity conditions. In this paper we show that epidermal growth factor (EGF)- and 12-O-tetradecanoyl-phorbol-13-acetate (TPA)-induced expression of thec-fos and c-jun protooncogenes is decreased in microgravity, while no effect of gravity changes was observed on A23187- and forskolin-induced expression of these genes. These decrease inc-fos expression was not due to delayed kinetics under microgravity. These results demonstrate that gravity differentially modulates distinctive signal transduction pathways. © 1991 Academic Press, Inc. All rights of reproduction in any form reserved.