EVIDENCE FOR A FUNCTIONAL INTERACTION BETWEEN CALMODULIN AND THE GLUCOCORTICOID RECEPTOR

In the signaling cascade of membrane-bound receptors, calmodulin (CaM) plays an important role. However, little is known about the role of C aM in the activation of intracellular steroid receptors, which are kno wn to act as ligand-regulated transcription factors. We report here th at CaM can interact in a calcium-dependent manner with the untransform ed glucocorticoid receptor (GR) complex containing hsp90. In addition, we demonstrate that four unrelated CaM antagonists (trifluoperazine, compound 48/80, W7, and phenoxybenzamine) can inhibit GR-mediated gene expression in mouse L929 cells stably-transfected with the MMTV-CAT r eporter gene. These results provide evidence that CaM may play an impo rtant role in the signal transduction pathways of steroid hormone rece ptors. (C) 1995 Academic Press, Inc.