Soprano D R, Wyatt M L, Dixon J L, Soprano K J, Goodman D S
Department of Medicine, College of Physicians and Surgeons, Columbia University, New York, New York 10032.
J Biol Chem. 1988 Feb 25;263(6):2934-8.
Studies were conducted to explore in rats the role of retinol in the regulation of the synthesis and secretion of retinol-binding protein (RBP) by the visceral yolk sac compared to the liver. Previous studies have shown that in retinol deficiency, hepatic RBP secretion is specifically inhibited, whereas hepatic RBP synthesis rate is unchanged. Retinol-depleted, retinoic acid-supplemented female rats were mated, and maternal liver, fetal liver, and visceral yolk sac were obtained at 14 days of gestation (retinol-depleted group). A group of identically treated, retinol-depleted rats were repleted with retinol on the 14th day of gestation, and the same tissues were collected 6 h later (retinol-repleted group). Normal female rats were used as controls. RBP was assayed by radioimmunoassay and RBP mRNA levels by RNase protection assay using a rat RBP cDNA clone. RBP levels in the visceral yolk sac were elevated 10-fold in the retinol-depleted as compared to the control rats and had declined to near normal values in the retinol-repleted animals. The relative levels of RBP mRNA in the visceral yolk sac were very similar in all three groups of rats. Thus, as in the liver, in the visceral yolk sac retinol deficiency inhibits RBP secretion without altering RBP mRNA levels. In the visceral yolk sac, as in the liver, retinol status appears to regulate RBP secretion specifically, without affecting the rate of RBP biosynthesis.
开展了多项研究，以探究在大鼠体内，相较于肝脏，视黄醇在内脏卵黄囊中对视黄醇结合蛋白（RBP）合成与分泌的调节作用。先前的研究表明，在视黄醇缺乏的情况下，肝脏RBP分泌受到特异性抑制，而肝脏RBP合成速率不变。将视黄醇耗竭、补充视黄酸的雌性大鼠进行交配，并在妊娠第14天获取母体肝脏、胎儿肝脏和内脏卵黄囊（视黄醇耗竭组）。一组经过相同处理的视黄醇耗竭大鼠在妊娠第14天补充视黄醇，6小时后收集相同组织（视黄醇补充组）。正常雌性大鼠用作对照。采用放射免疫分析法测定RBP，使用大鼠RBP cDNA克隆通过核糖核酸酶保护分析法测定RBP mRNA水平。与对照大鼠相比，视黄醇耗竭组大鼠内脏卵黄囊中RBP水平升高了10倍，而在视黄醇补充的动物中已降至接近正常水平。三组大鼠内脏卵黄囊中RBP mRNA的相对水平非常相似。因此，与肝脏一样，在内脏卵黄囊中，视黄醇缺乏会抑制RBP分泌，而不会改变RBP mRNA水平。在内脏卵黄囊中，与肝脏一样，视黄醇状态似乎特异性调节RBP分泌，而不影响RBP生物合成速率。
