Imanaka-Yoshida K, Danowski B A, Sanger J M, Sanger J W
Department of Cell and Developmental Biology, University of Pennsylvania School of Medicine, Philadelphia.
Cell Motil Cytoskeleton. 1996;33(4):263-75. doi: 10.1002/(SICI)1097-0169(1996)33:4<263::AID-CM3>3.0.CO;2-A.
Adult rat cardiomyocytes were placed in tissue culture to determine the relationships of their vinculin positive costameres, their attachments associated with the costameres, the fate of their myofibrils. The costameric structures were detected using interference contrast microscopy and the visualization of the fluorescently labeled vinculin and alpha-actinin molecules. The cardiomyocytes isolated from the heart retained their myofibrils upon attachment to the cell surfaces. One group of cells then rounded up, only to respread after 6 days in culture. These cells initially demonstrated costameric distributions of attachments and vinculin. These relationships were lost during the rounding-up process only to be regained as the cells respread. The second group of freshly isolated cardiomyocytes did not round up but began to spread on the substratum by sending out lamellipodia from their rectangularly shaped body. These newly cultured cardiomyocytes initially exhibited costameric distributions of close attachments detected by interference microscopy. Over the next 3 days although the cells remain attached to the substratum, the costameric attachments were gradually lost. Nevertheless, when similar cells were injected with fluorescently labeled vinculin, costameric distributions of vinculin could be detected in the absence of costameric attachments. Cardiomyocytes, injected with fluorescent alpha-actinin, revealed that during the first few days in culture the existing myofibrils disassembled from the edges of the cell towards the middle. The center group of myofibrils was retained as the cells began to spread. Our observations of living cells support the hypothesis that proteins in addition to vinculin are needed for cardiomyocytes to generate costameric attachments to the cell surfaces. We speculate that the ability of the vinculin-attached Z-lines of adult cardiomyocytes to dissociate from the extracellular matrix may aid in the remodeling of the adult heart in the repair process after myocardial infarction and also in stress induced hypertrophic growth.
将成年大鼠心肌细胞置于组织培养中，以确定其纽蛋白阳性肌动蛋白丝连接蛋白复合体、与肌动蛋白丝连接蛋白复合体相关的附着结构以及肌原纤维的命运之间的关系。使用干涉相差显微镜以及荧光标记的纽蛋白和α - 辅肌动蛋白分子的可视化来检测肌动蛋白丝连接蛋白复合体结构。从心脏分离出的心肌细胞在附着到细胞表面时保留了它们的肌原纤维。一组细胞随后变圆，仅在培养6天后重新铺展。这些细胞最初表现出附着结构和纽蛋白的肌动蛋白丝连接蛋白复合体分布。这些关系在变圆过程中丧失，仅在细胞重新铺展时恢复。第二组新鲜分离的心肌细胞没有变圆，而是通过从其矩形体发出片状伪足开始在基质上铺展。这些新培养的心肌细胞最初表现出通过干涉显微镜检测到的紧密附着的肌动蛋白丝连接蛋白复合体分布。在接下来的3天里，尽管细胞仍附着在基质上，但肌动蛋白丝连接蛋白复合体附着逐渐丧失。然而，当用荧光标记的纽蛋白注射类似细胞时，在没有肌动蛋白丝连接蛋白复合体附着的情况下可以检测到纽蛋白的肌动蛋白丝连接蛋白复合体分布。注射了荧光α - 辅肌动蛋白的心肌细胞显示，在培养的最初几天里，现有的肌原纤维从细胞边缘向中间解体。随着细胞开始铺展，中心的肌原纤维组得以保留。我们对活细胞的观察支持这样一种假设，即除了纽蛋白之外，心肌细胞还需要其他蛋白质来在细胞表面产生肌动蛋白丝连接蛋白复合体附着。我们推测成年心肌细胞中与纽蛋白相连的Z线与细胞外基质解离的能力可能有助于心肌梗死后修复过程中成年心脏的重塑以及应激诱导的肥大生长。
