An emerging role for co-receptors in inhibin signal transduction

While many transforming growth factor-beta (TGF beta) superfamily ligands s uch as TGF beta, activin, and the bone morphogenic proteins (BMPs) are crit ical to the control of growth. differentiation. and cell fate. inhibin has a more limited role and is primarily responsible for the regulation of one hormone from one cell-type in the anterior pituitary. Inhibin is an endocri ne hormone, produced by the gonads. that inhibits follicle stimulating horm one (FSH) release from the pituitary gonadotrope. The other hormones in the superfamily do not appear to act in an endocrine fashion. but rather contr ol cell function in a paracrine or autocrine manner. Many components of the TGF beta /activin/BMP signal transduction pathway have been elegantly defi ned, however, the mechanism of inhibin action has not been completely disse cted. Several cell surface proteins that associate with inhibin have been i dentified recently, and these molecules may provide the clues necessary to understand how inhibin regulates reproductive function. (C) 2001 Elsevier S cience Ireland Ltd. All rights reserved.