Immunophilins, Heat Shock Proteins, and Glucocorticoid Receptor Actions in Vivo

The glucocorticoid receptor is a member of the steroid/thyroid receptor family and, as such, acts as a ligand-inducible enhancer of specific gene transcription. Many studies have demonstrated the in vitro association of steroid receptors with members of both the heat shock and the immunophilin family of proteins. This has led to speculation of a functional convergence in the signal transduction pathways for immunophilins, heat shock proteins, and steroid receptors. In this work, we review the association of heat shock proteins and immunophilins with steroid receptors, with an emphasis on the in vivo effects of heat shock and immunosuppressive macrolides (FK506, rapamycin, and cyclosporin A) on glucocorticoid receptor transcription enhancement activity.