Retinyl ester formation by lecithin: retinol acyltransferase is a key regulator of retinoid homeostasis in mouse embryogenesis.
The developing mammalian embryo is entirely dependent on the maternal circulation for its supply of retinoids (vitamin A and its metabolites). The mechanisms through which mammalian developing tissues maintain adequate retinoid levels in the face of suboptimal or excessive maternal dietary vitamin A intake have not been established. We investigated the role of retinyl ester formation catalyzed by lecithin:retinol acyltransferase (LRAT) in regulating retinoid homeostasis during embryogenesis. Dams lacking both LRAT and retinol-binding protein (RBP), the sole specific carrier for retinol in serum, were maintained on diets containing different amounts of vitamin A during pregnancy. We hypothesized that the lack of both proteins would make the embryo more vulnerable to changes in maternal dietary vitamin A intake. Our data demonstrate that maternal dietary vitamin A deprivation during pregnancy generates a severe retinoid-deficient phenotype of the embryo due to the severe retinoid-deficient status of the double mutant dams rather than to the lack of LRAT in the developing tissues. Moreover, in the case of excessive maternal dietary vitamin A intake, LRAT acts together with Cyp26A1, one of the enzymes that catalyze the degradation of retinoic acid, and possibly with STRA6, the recently identified cell surface receptor for retinol-RBP, in maintaining adequate levels of retinoids in embryonic and extraembryonic tissues. In contrast, the pathway of retinoic acid synthesis does not contribute significantly to regulating retinoid homeostasis during mammalian development except under conditions of severe maternal retinoid deficiency.
Kim
Youn-Kyung
YK
Department of Food Science and Rutgers Center for Lipid Research, Rutgers University, New Brunswick, New Jersey 08901, USA.
Wassef
Lesley
L
Hamberger
Leora
L
Piantedosi
Roseann
R
Palczewski
Krzysztof
K
Blaner
William S
WS
Quadro
Loredana
L
D000217:Acyltransferases / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics / Q000378:metabolism; D004622:Embryo, Mammalian / Q000166:cytology / Q000201:enzymology*; D047108:Embryonic Development / Q000187:drug effects / Q000502:physiology*; D005260:Female; D006706:Homeostasis / Q000502:physiology*; D008431:Maternal-Fetal Exchange / Q000502:physiology; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D011247:Pregnancy / Q000235:genetics / Q000378:metabolism*; D000072516:Retinoic Acid 4-Hydroxylase; D054840:Retinol-Binding Proteins, Cellular / Q000235:genetics / Q000378:metabolism; D014801:Vitamin A / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D014802:Vitamin A Deficiency / Q000201:enzymology / Q000235:genetics
D008565:Membrane Proteins; D054840:Retinol-Binding Proteins, Cellular; C108001:Stra6 protein, mouse; D014801:Vitamin A; D003577:Cytochrome P-450 Enzyme System; C000607080:Cyp26a1 protein, mouse; D000072516:Retinoic Acid 4-Hydroxylase; D000217:Acyltransferases; C056942:lecithin-retinol acyltransferase