Effect of high-density lipoproteins with varying ratios of apolipoprotein A-I to apolipoprotein A-II on steroidogenesis by cultured rat ovary granulosa cells.
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 apolipoprotein A-I (the major HDL apolipoprotein) in HDL-cell interactions, we examined the ability of canine-human HDL hybrids containing various proportions of canine apolipoprotein A-I and human apolipoprotein A-II to stimulate steroidogenesis by cultured rat ovary granulosa cells. We observed that as the apolipoprotein A-II to apolipoprotein A-II ratio decreased, the ability of the hybrid particles to stimulate granulosa cell progestin (progesterone and 20 alpha-dihydroprogesterone) production diminished. However, granulosa cell progestin (progesterone and 20 alpha-dihydroprogesterone) production diminished. However, apolipoprotein A-I was not necessary for cholesterol transfer, since hybrids with less than 5% of their total apolipoprotein mass as apolipoprotein A-I stimulated progestin production 30% as effectively as canine HDL, which contained essentially only apolipoprotein A-I. These data indicate that the delivery of cholesterol from HDL into the rat ovary cell for steroidogenesis is not strictly dependent on the presence of a specific HDL apolipoprotein.
D000818:Animals; D016633:Apolipoprotein A-II; D001054:Apolipoproteins A / Q000494:pharmacology*; D002478:Cells, Cultured; D004285:Dogs; D005260:Female; D006107:Granulosa Cells / Q000187:drug effects / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D008075:Lipoproteins, HDL / Q000097:blood / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D013256:Steroids / Q000096:biosynthesis*
D016633:Apolipoprotein A-II; D001054:Apolipoproteins A; D008075:Lipoproteins, HDL; D013256:Steroids