title: Retinyl ester hydrolysis and retinol efflux from BFC-1beta adipocytes.
abstract: Adipose tissue is an important storage depot for retinol, but there are no data regarding retinol mobilization from adipose stores. To address this, dibutyryl cAMP was provided to murine BFC-1beta adipocytes and its effects on retinol efflux assessed. High performance liquid chromatography analysis of retinol and retinyl esters in adipocytes and media indicated that cAMP stimulated, in a time- and dose-dependent manner, retinol accumulation in the culture media and decreased cellular retinyl ester concentrations. Study of adipocyte retinol-binding protein synthesis and secretion indicated that cAMP-stimulated retinol efflux into the media did not result from increased retinol-retinol-binding protein secretion but was dependent on the presence of fetal bovine serum in the culture media. Since our data suggested that retinyl esters can be hydrolyzed by a cAMP-dependent enzyme like hormone-sensitive lipase (HSL), in separate studies, we purified a HSL-containing fraction from BFC-1beta adipocytes and demonstrated that it catalyzed retinyl palmitate hydrolysis. Homogenates of Chinese hamster ovary cells overexpressing HSL catalyzed retinyl palmitate hydrolysis in a time-, protein-, and substrate-dependent manner, with an apparent Km for retinyl palmitate of 161 microM, whereas homogenates from control Chinese hamster ovary cells did not.
authors.affiliation: Institute of Human Nutrition, Columbia University, New York, New York 10032, USA.
authors.forename: S
authors.initials: S
authors.lastname: Wei
authors.forename: K
authors.initials: K
authors.lastname: Lai
authors.forename: S
authors.initials: S
authors.lastname: Patel
authors.forename: R
authors.initials: R
authors.lastname: Piantedosi
authors.forename: H
authors.initials: H
authors.lastname: Shen
authors.forename: V
authors.initials: V
authors.lastname: Colantuoni
authors.forename: F B
authors.initials: FB
authors.lastname: Kraemer
authors.forename: W S
authors.initials: WS
authors.lastname: Blaner
mesh_terms: D017667:Adipocytes / Q000378:metabolism*; D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D016466:CHO Cells; D002417:Cattle; D002460:Cell Line; D006224:Cricetinae; D000242:Cyclic AMP / Q000494:pharmacology; D006868:Hydrolysis; D051379:Mice; D012177:Retinol-Binding Proteins / Q000378:metabolism*; D014801:Vitamin A / Q000378:metabolism*
chemical_list: D012177:Retinol-Binding Proteins; D014801:Vitamin A; D000242:Cyclic AMP