Andersen K B, Nilsson A, Blomhoff H K, Oyen T B, Gabrielsen O S, Norum K R, Blomhoff R
Institute for Nutrition Research, School of Medicine, University of Oslo, Norway.
J Biol Chem. 1992 Jan 15;267(2):1340-4.
We have studied the mechanism for mobilization of retinol from stellate cells. Our data show that perisinusoidal stellate cells isolated from liver contained retinol-binding protein (RBP) mRNA. By Western blot analysis we found that cultivated liver stellate cells secreted RBP into the medium. Cultivated stellate cells loaded in vitro with [3H]retinyl ester mobilized radioactive retinol as a complex with RBP. Furthermore, exogenous RBP added to the medium of cultured stellate cells increased the secretion of retinol to the medium. These data suggest that liver stellate cells in vivo mobilize retinol directly to the blood and that a transfer to parenchymal cells for secretion as holo-RBP is not required. The direct mobilization of retinol from liver stellate cells as retinol-RBP to blood is indirectly supported by the demonstration of RBP mRNA production and RBP secretion by lung stellate cells. The data suggest that the same mechanism for retinol mobilization may exist in hepatic and extrahepatic stellate cells. This is, vitamin A-storing stellate cells in liver, lungs, and probably also in other organs may synthesize their own RBP (or alternatively use exogenous RBP) and mobilize holo-RBP directly to the blood.
我们研究了从星状细胞中动员视黄醇的机制。我们的数据表明，从肝脏分离的肝血窦周星状细胞含有视黄醇结合蛋白（RBP）mRNA。通过蛋白质印迹分析，我们发现培养的肝星状细胞将RBP分泌到培养基中。体外加载[3H]视黄酯的培养星状细胞将放射性视黄醇作为与RBP的复合物进行动员。此外，添加到培养星状细胞培养基中的外源性RBP增加了视黄醇向培养基中的分泌。这些数据表明，体内肝星状细胞直接将视黄醇动员到血液中，不需要转移到实质细胞以作为全RBP分泌。肺星状细胞产生RBP mRNA和分泌RBP间接支持了肝星状细胞将视黄醇-RBP直接动员到血液中的过程。数据表明，肝和肝外星状细胞中可能存在相同的视黄醇动员机制。也就是说，肝脏、肺以及可能其他器官中储存维生素A的星状细胞可能合成自身的RBP（或者使用外源性RBP）并将全RBP直接动员到血液中。
