Vitamin A contained in the lipid droplets of rat liver stellate cells is substrate for acid retinyl ester hydrolase.
Vitamin A is stored in the lipid droplets of liver stellate cells (LSCs), as retinyl esters whose hydrolysis is necessary for the secretion of retinol into the blood. Here, we isolated these retinyl esters under their physiological form, i.e., in LSC lipid droplets, which had retained their morphological and biochemical characteristics. These retinyl esters are substrate for an hydrolytic enzyme, whose optimum pH is 4.1, and which is kinetically similar to the acidic retinyl ester hydrolase (aREH) we had previously described (Mercier et al., Biochim. Biophys. Acta (1994) 1212, 176-182). The cellular and subcellular localizations of aREH activity in rat liver suggest that this enzyme could be involved in the hydrolysis of the esterified vitamin A stores.
Azaïs-Braesco
V
V
I.N.R.A. Metabolic Diseases and Micronutrients Research Unit, CRNH, Clermont-Ferrand, France.
Dodeman
I
I
Delpal
S
S
Alexandre-Gouabau
M C
MC
Partier
A
A
Borel
P
P
Grolier
P
P
D000135:Acid Phosphatase / Q000378:metabolism; D017667:Adipocytes / Q000378:metabolism* / Q000648:ultrastructure; D000818:Animals; D002265:Carboxylic Ester Hydrolases / Q000378:metabolism*; D002458:Cell Fractionation; D002478:Cells, Cultured; D004224:Diterpenes; D004591:Electrophoresis, Polyacrylamide Gel; D006863:Hydrogen-Ion Concentration; D008051:Lipid Bilayers; D008055:Lipids / Q000737:chemistry*; D008081:Liposomes / Q000378:metabolism; D008099:Liver / Q000166:cytology* / Q000378:metabolism; D008297:Male; D008854:Microscopy, Electron; D051381:Rats; D017208:Rats, Wistar; D000084562:Retinyl Esters; D014801:Vitamin A / Q000031:analogs & derivatives* / Q000378:metabolism*
D004224:Diterpenes; D008051:Lipid Bilayers; D008055:Lipids; D008081:Liposomes; D000084562:Retinyl Esters; D014801:Vitamin A; C014794:retinol palmitate; D002265:Carboxylic Ester Hydrolases; C022523:retinyl esterase; D000135:Acid Phosphatase