Expression of the insulin receptor-related receptor is induced by the preovulatory surge of luteinizing hormone in thecal-interstitial cells of the rat ovary

Abstract

The insulin receptor-related receptor (IRR) is a member of the insulin receptor family that, on its own, recognizes neither insulin nor any of the identified insulin-related peptides. In both the nervous system and peripheral tissues, IRR mRNA is detected in cells that also express trkA, the nerve growth factor tyrosine kinase receptor. In the ovary, the trkA gene is transiently activated in thecal-interstitial cells of large antral follicles at the time of the preovulatory surge of gonadotropins. The present study shows that the IRR gene is expressed in the same ovarian compartment, that IRR mRNA content increases strikingly in these cells in the afternoon of the first proestrus, and that - as in the case of trkA mRNA - the increase is caused by gonadotropins. The IRR mRNA species primarily affected is that encoding the full-length receptor; its increased abundance was accompanied by a corresponding change in IRR protein content. An extensive molecular search using several approaches,