Characterization and hormonal modulation of immunoreactive thiamin carrierprotein in immature rat Sertoli cells in culture

Immature rat Sertoli cells synthesize and secrete a protein species which h as immunological similarity with chicken egg thiamin carrier protein (TCP) as assessed by immunocytochemical localization, liquid phase radioimmunoass ay (RIA), immunoprecipitation of [S-35]-methionine incorporated newly synth esized proteins by polyclonal antibodies (pAbs) to chicken TCP and tryptic peptide mapping of iodinated immunoprecipitated proteins. FSH and testoster one together bring about 4-fold induction of Sertoli cell TCP over the cont rol levels which is inhibitable upto 75% by an aromatase inhibitor. Additio n of optimal concentrations of exogenous estradiol-17 beta to the cultures causes 2-fold enhancement of secretion of TCP which can significantly be in hibited by tamoxifen: when added along with estradiol-17 beta. These result s show that Sertoli cells produce estrogen-inducible TCP, presumably to tra nsport the vitamin to the developing germ cells. (C) 1999 Elsevier Science Ltd. All rights reserved.