Borrione A C, Zanellato A M, Giuriato L, Scannapieco G, Pauletto P, Sartore S
Institute of General Pathology, University of Padova, Italy.
Exp Cell Res. 1990 Sep;190(1):1-10. doi: 10.1016/0014-4827(90)90136-x.
A panel of monoclonal antibodies, specific for human platelet (NM-A9, NM-F6, and NM-G2) and for bovine smooth muscle (SM-E7) myosin heavy chains (MHC), were used to study the composition and the distribution of myosin isoforms in bovine endothelial cells (EC), in vivo and in vitro. Using indirect and double immunofluorescence techniques, we have found that in the intact aortic endothelium there is expression of nonmuscle MHC (NM-MHC), exclusively. By contrast, hepatic sinusoidal endothelium as well as cultured bovine aortic EC (BAEC) in the subconfluent phase of growth show coexistence of NM- and smooth muscle MHC (SM-MHC) isoforms. SM myosin immunoreactivity disappears when cultured BAEC become confluent. In this phase of cell growth, NM-MHC isoforms are localized differently within the cells, i.e., in the cytoplasm around the nucleus or in the cortical, submembranous region of EC cytoplasm. A third type of intracellular distribution of NM-MHC immunoreactivity was evident in the cell periphery of binucleated, confluent BAEC. These data indicate that (1) several myosin isoforms are differently distributed in bovine endothelia; and (2) SM myosin expression and the specific subcellular localization of NM myosin isoforms within EC might be regulated by cell-cell interactions.
一组针对人血小板（NM-A9、NM-F6和NM-G2）以及牛平滑肌（SM-E7）肌球蛋白重链（MHC）的单克隆抗体，被用于研究牛内皮细胞（EC）体内和体外肌球蛋白同工型的组成及分布。运用间接免疫荧光和双重免疫荧光技术，我们发现完整主动脉内皮中仅表达非肌肉MHC（NM-MHC）。相比之下，肝血窦内皮以及生长至亚汇合期的培养牛主动脉内皮细胞（BAEC）则显示NM-和平滑肌MHC（SM-MHC）同工型共存。当培养的BAEC汇合时，平滑肌肌球蛋白免疫反应性消失。在细胞生长的这个阶段，NM-MHC同工型在细胞内的定位不同，即在细胞核周围的细胞质中或在EC细胞质的皮质、膜下区域。在双核、汇合的BAEC的细胞周边，NM-MHC免疫反应性的第三种细胞内分布很明显。这些数据表明：（1）几种肌球蛋白同工型在牛内皮细胞中分布不同；（2）平滑肌肌球蛋白的表达以及NM肌球蛋白同工型在EC内的特定亚细胞定位可能受细胞间相互作用调控。
