Effect of high-density lipoproteins with varying ratios of apolipoprotein A-I to apolipoprotein A-II on steroidogenesis by cultured rat ovary granulosa cells》.pdf

Biochimica et Siophysica Acta 835 (1985) 169-175 169 Elsevier BBA 51939 Effect of high-densi~ li~prot~ins with varying ratios of a~~i~protein A-I to apolipoprotein A-II on steroidogenesis by cultured rat ovary granulosa cells James R. Schreiber a, Celina Edelstein b and Angelo M. Scanu b-c @Depurtment of Obstetrics and Gynecology, ’ Department of Medicine, and (’Departments of Biochemtstv and Moiecalar Bioiogv, The University of Chicago%Pritzker School oJIMedicine,Chicago, IL 60637 (U.S.A.] (Received September 6th, 1984) (Revised manuscript received January 2nd, 1985) Key words: Steroidogenesis; Apolipoprote~n A-I; Lipoprotein; HDL hybrid; (Rat ovary) Plasma high-density lipoproteins (HDL) can provide rat ovary steroidogenic tissue with cholesterol for steroid hormone production, but the mechanism of cholesterol transfer is unknown. To test the importance of a~i~~tein A-I (the major HDL a~li~~oteiu} in HDL-cell interactions, we examined the ability of canine-human HDL hybrids containing various proportions of canine apolipoprotein A-I and human a~li~otein A-II to stimulate ste~id~en~is by cultured rat ovary granulosa cells. We observed that as the apolipoprotein A-I to apolipoprotein A-II ratio decreased, the ability of the hybrid particles to stimulate granulosa cell progestin (progesterone and 20a-dihydroprogesterone) production diminished. However, a~i~protein A-I was not