Uptake and metabolism of retinol in cultured Sertoli cells: evidence for a kinetic model.
When cultured Sertoli cells derived from 20-day-old weanling rats were supplied [3H]retinol bound to serum retinol binding protein-transthyretin complex, [3H]retinol was rapidly incorporated and [3H]retinyl esters were synthesized. Within 28 h after administration, 83% of the labeled retinoids were accounted for as retinyl esters (64% as retinyl palmitate). Sertoli cells derived from vitamin A deficient rats and supplied [3H]retinol in culture under identical conditions likewise incorporated [3H]retinol and synthesized retinyl esters. In contrast to normal Sertoli cells, vitamin A deficient Sertoli cells eventually metabolized virtually all of the cellular [3H]retinol to retinyl esters. The primary metabolic fate of retinol administered to Sertoli cell cultures was the synthesis of retinyl esters under all conditions tested. However, administration of [3H]retinol bound to serum retinol binding protein gave metabolic profiles having a higher proportion of retinyl esters and lower proportions of unresolved polar material than administration of [3H]retinol alone. The kinetics of retinol uptake and intracellular retinyl ester synthesis in cultured Sertoli cells was complex. An initial, rapid phase of [3H]retinol incorporation lasting 30 min was followed by a slower rate of incorporation and a concomitant decrease in the intracellular concentration of [3H]retinol. During the time course the specific activity of [3H]retinyl palmitate eventually exceeded that of intracellular [3H]retinol. These observations suggest that two intracellular pools of retinol may exist in Sertoli cells.
Bishop
P D
PD
Department of Biochemistry/Biophysics, Washington State University, Pullman 99164-4660.
Griswold
M D
MD
D000818:Animals; D001692:Biological Transport; D002478:Cells, Cultured; D002851:Chromatography, High Pressure Liquid; D007700:Kinetics; D008297:Male; D008954:Models, Biological; D051381:Rats; D012176:Retinoids / Q000096:biosynthesis / Q000302:isolation & purification; D012708:Sertoli Cells / Q000378:metabolism*; D014801:Vitamin A / Q000378:metabolism*
D012176:Retinoids; D014801:Vitamin A