STEROID-RECEPTOR HETERODIMERIZATION DEMONSTRATED IN-VITRO AND IN-VIVO

The mineralocorticoid and glucocorticoid receptors (MR and GR, respect ively) are members of the intracellular receptor superfamily that bind as homodimers to the same hormone response elements (HREs). Physiolog ical evidence suggests that MR and GR interact with each other in cell s that express both receptors, implying that they might directly inter act in the regulation of transcription initiation, Indeed, we have fou nd that coexpressed MR and GR interact functionally at the transcripti onal level and furthermore that they interact physically through heter odimer formation at a shared HRE in vitro and in vivo. We suggest from these findings that heterodimerization may play an important role in steroid receptor transcriptional regulation.