Enrich C, Vergés M, Evans W H
Departamento de Biología Celular, Facultad de Medicina, Universidad de Barcelona, Spain.
Exp Cell Res. 1992 Aug;201(2):399-407. doi: 10.1016/0014-4827(92)90289-k.
Antibodies raised to two membrane proteins present in rat liver endosomal fractions were used to study changes occurring in the endocytic compartment of hepatocytes during liver regeneration. Antibodies to the 42-kDa subunit (RHL-1) of the asialoglycoprotein receptor showed, by Western blotting of liver microsomes and endosomes, that there was a reduced expression of the receptor in liver 24 h following a partial hepatectomy. Immunocytochemical staining of thin sections of regenerating livers using these antibodies indicated that there was an intracellular relocation of endocytic structures in hepatocytes. The two main endocytic regions immunocytochemically stained in normal liver--one located beneath the sinusoidal plasma membrane and the other abutting the bile canaliculus--were replaced, in regenerating liver, by staining more closely associated with a region underlying the baso-lateral plasma membrane. A 140-kDa pI 4.3 calmodulin-binding protein located in endocytic and plasma membranes was also demonstrated, using a radio-iodinated calmodulin-binding assay, to be present at reduced levels in endosomes isolated from regenerating livers. Antibodies to this calmodulin-binding protein stained the hepatocyte's cytoplasm in a punctate manner. However, in regenerating liver, the staining was located in regions underlying the baso-lateral and apical plasma membrane of hepatocytes. Together, the results demonstrate that a reorganization of the endocytic compartment has occurred in hepatocytes 24 h following hepatectomy, with two endosomal proteins becoming relocated to a region below the baso-lateral-apical surface regions of hepatocytes.
用针对大鼠肝脏内体部分存在的两种膜蛋白产生的抗体，研究肝脏再生过程中肝细胞内吞区室发生的变化。通过对肝脏微粒体和内体进行蛋白质免疫印迹分析，抗去唾液酸糖蛋白受体42 kDa亚基（RHL-1）的抗体显示，部分肝切除术后24小时肝脏中该受体的表达降低。使用这些抗体对再生肝脏薄片进行免疫细胞化学染色表明，肝细胞内吞结构发生了细胞内重新定位。在正常肝脏中免疫细胞化学染色的两个主要内吞区域——一个位于窦状质膜下方，另一个邻接胆小管——在再生肝脏中，被与基底外侧质膜下方区域更紧密相关的染色所取代。使用放射性碘化钙调蛋白结合测定法还证明，位于内吞膜和质膜中的一种140 kDa、pI 4.3的钙调蛋白结合蛋白，在从再生肝脏分离的内体中的水平降低。针对这种钙调蛋白结合蛋白的抗体以点状方式对肝细胞细胞质进行染色。然而，在再生肝脏中，染色位于肝细胞基底外侧和顶端质膜下方的区域。总之，结果表明肝切除术后24小时肝细胞内吞区室发生了重组，两种内体蛋白重新定位到肝细胞基底外侧-顶端表面区域下方的一个区域。
