A retinol-binding protein receptor-mediated mechanism for uptake of vitamin A to postimplantation rat embryos.
The major form of dietary vitamin A in blood is retinol bound to retinol-binding protein (RBP), but it is not clear how maternal retinol reaches the embryo. We demonstrate here that uptake of radiolabeled retinol from holo-RBP to the visceral yolk sac of cultured rat embryos exhibits receptor-mediated characteristics (Km = 4.1 x 10(-7) M, Vmax = 3.0 x 10(-12) mol/sec per gram yolk sac protein) and also demonstrate the presence in the yolk sac endoderm of a protein previously described as an RBP receptor. Furthermore, transport of radiolabeled retinol from the yolk sac to the embryo proper can be markedly decreased by inhibition of visceral yolk sac RBP synthesis. Thus embryonic accumulation of retinol depends on a relay of retinol from maternal RBP to RBP synthesized in the yolk sac, via interaction with a visceral yolk sac RBP receptor.
Ward
S J
SJ
Institut de Génétique et de Biologie Moléculaire et Cellulaire, Centre National de la Recherche Scientifique, Institut National de la Santé et de la Recherche Médicale, Université Louis Pasteur, Collège de France, C.U. de Strasbourg, France.
Chambon
P
P
Ong
D E
DE
Båvik
C
C
D000818:Animals; D004622:Embryo, Mammalian / Q000378:metabolism*; D047108:Embryonic Development / Q000502:physiology*; D005260:Female; D007150:Immunohistochemistry; D007700:Kinetics; D009838:Oligodeoxyribonucleotides / Q000494:pharmacology; D011247:Pregnancy; D051381:Rats; D011956:Receptors, Cell Surface / Q000378:metabolism*; D012177:Retinol-Binding Proteins / Q000378:metabolism*; D014801:Vitamin A / Q000378:metabolism*; D015017:Yolk Sac / Q000187:drug effects
D009838:Oligodeoxyribonucleotides; D011956:Receptors, Cell Surface; D012177:Retinol-Binding Proteins; C027928:retinol binding protein receptor; D014801:Vitamin A