Molecular and cellular mechanisms of estrogen action on the skeleton

The many recent and exciting advances that have taken place in the field of estrogen action on the skeleton are the subjects of this review. Leading t hese new developments is the discovery of alternative estrogen receptors th at exhibit differential mechanisms of transcriptional control of estrogen-r esponsive promoters, thereby broadening both the ranges of possible target cells and their responses. More potentially important genes under estrogeni c control have been identified in vitro, and the skeletal phenotypes caused by disruption of estrogen signaling due to mutations in humans and mice ha ve been described. Lastly, clinical studies in humans have revealed a great er appreciation for the importance of estrogen in bone mass maintenance in both sexes. (C) 1999 Wiley-Liss, Inc.