Eppenberger-Eberhardt M, Flamme I, Kurer V, Eppenberger H M
Institute for Cell Biology, Swiss Federal Institute of Technology, Zurich.
Dev Biol. 1990 Jun;139(2):269-78. doi: 10.1016/0012-1606(90)90296-u.
Expression of alpha-smooth muscle (sm) actin in regenerating adult cardiomyocytes in culture was investigated. No alpha-sm-actin could be detected in adult ventricular tissue or in newly dissociated rod-shaped cells, whereas a fraction of the polymorphic flattened out adult cardiac cells in culture did express the protein. Immunofluorescence studies revealed a characteristic staining pattern, suggesting the preferential presence of alpha-sm-actin in stress fiber-like structures, while newly formed myofibrils contained only little alpha-sm-actin isoprotein. Cell-cell contacts were resumed, but formation of new gap junctions, as revealed by microinjecting Lucifer yellow, was not dependent on alpha-sm-actin expression. The behavior corresponds to fetal cardiomyocytes either in tissue or as single cells in culture where expression of alpha-sm-actin can be observed. Such immunofluorescence staining patterns with corresponding immunoblot data can be expected when a return to a less differentiated, more fetal state of the adult cardiomyocyte in culture is assumed. The possible role of the alpha-sm-actin and alpha-sarcomeric actin isoforms during reformation of myofibrillar sarcomeres is discussed.
研究了培养的成年再生心肌细胞中α-平滑肌（sm）肌动蛋白的表达。在成年心室组织或新解离的杆状细胞中未检测到α-sm-肌动蛋白，而培养的一部分多形扁平成年心脏细胞确实表达了该蛋白。免疫荧光研究揭示了一种特征性染色模式，表明α-sm-肌动蛋白优先存在于应力纤维样结构中，而新形成的肌原纤维仅含有少量的α-sm-肌动蛋白同工蛋白。细胞间接触得以恢复，但通过显微注射荧光素黄显示，新的间隙连接的形成并不依赖于α-sm-肌动蛋白的表达。这种行为与组织中的胎儿心肌细胞或培养中的单个细胞相对应，在这些细胞中可以观察到α-sm-肌动蛋白的表达。当假设培养的成年心肌细胞恢复到分化程度较低、更接近胎儿的状态时，可以预期会出现这种具有相应免疫印迹数据的免疫荧光染色模式。讨论了α-sm-肌动蛋白和α-肌节肌动蛋白同工型在肌原纤维肌节重塑过程中的可能作用。
