Costameres are sites of force transmission to the substratum in adult rat cardiomyocytes.
Costameres are sites of force transmission to the substratum in adult rat cardiomyocytes.
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DOI：
10.1083/jcb.118.6.1411
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发表时间：
1992-09
期刊：
影响因子：
--
通讯作者：
Sanger JW
中科院分区：
文献类型：
--
作者：
Danowski BA;Imanaka-Yoshida K;Sanger JM;Sanger JW
许多骨骼和心肌细胞(Pardo，J.V.，J.D.Siniliano，和S.W.Craig)中发现的富含纽蛋白的亚膜质横向肋骨。1983年。程序娜塔莉。阿卡德。SCI。美国。80：363-367。)被认为是将肌原纤维的Z线锚定在肌膜上。此外，人们还推测，胞囊在细胞的内部收缩机制和细胞外基质之间提供了机械连接，但缺乏直接的证据来支持这一假设。通过结合柔性硅橡胶衬底技术(Harris，A.K.，P.Wild和D.Stopak.1980年。科学(华盛顿州DC)。208：177-179。)通过显微注射荧光标记的纽蛋白和α-肌动蛋白，我们已经能够将成年大鼠心肌细胞的胞浆分布与这些细胞施加在柔性底物上的力模式联系起来。此外，我们使用干涉反射显微镜来识别与底物密切接触的细胞区域。我们的结果表明，在较老的细胞培养中，胞囊可以将力量传递到细胞外环境。我们的这一结论基于以下观察：(A)成年大鼠心肌细胞在硅橡胶基质上培养8天或更长时间，在收缩过程中产生褶皱，松弛时皱纹减少或消失；(B)在相邻的α-肌动蛋白阳性Z线之间形成褶皱；(C)褶皱的存在总是与褶皱形成区域的肌球蛋白周期性的“中胚层”分布有关；以及(D)在培养了8天或更长时间的许多细胞中，观察到深灰色或紧密接触的条带或周期性图案(由干涉反射显微镜确定)，这些紧密接触含有纽蛋白。一个令人惊讶的发现是，在正在收缩的细胞中，可以在胞核中发现纽蛋白，但不会在底物中产生褶皱状的皱纹。这表明，为了在肌原纤维和细胞外基质之间形成连续的联系，额外的蛋白质或已知的胞间蛋白的翻译后修饰是必要的。这些结果证实了这样的假设，即胞囊机械地将肌原纤维连接到细胞外基质。我们提出的假说是，胞囊是由许多蛋白质组分组成的复合结构；其中一些组分的功能主要是将肌原纤维固定在肌膜上，而另一些组分则形成与细胞外基质的跨膜连接。
Costameres, the vinculin-rich, sub-membranous transverse ribs found in many skeletal and cardiac muscle cells (Pardo, J. V., J. D. Siciliano, and S. W. Craig. 1983. Proc. Natl. Acad. Sci. USA. 80:363-367.) are thought to anchor the Z-lines of the myofibrils to the sarcolemma. In addition, it has been postulated that costameres provide mechanical linkage between the cells' internal contractile machinery and the extracellular matrix, but direct evidence for this supposition has been lacking. By combining the flexible silicone rubber substratum technique (Harris, A. K., P. Wild, and D. Stopak. 1980. Science (Wash. DC). 208:177-179.) with the microinjection of fluorescently labeled vinculin and alpha-actinin, we have been able to correlate the distribution of costameres in adult rat cardiac myocytes with the pattern of forces these cells exert on the flexible substratum. In addition, we used interference reflection microscopy to identify areas of the cells which are in close contact to the underlying substratum. Our results indicate that, in older cell cultures, costameres can transmit forces to the extracellular environment. We base this conclusion on the following observations: (a) adult rat heart cells, cultured on the silicone rubber substratum for 8 or more days, produce pleat-like wrinkles during contraction, which diminish or disappear during relaxation; (b) the pleat-like wrinkles form between adjacent alpha-actinin-positive Z- lines; (c) the presence of pleat-like wrinkles is always associated with a periodic, "costameric" distribution of vinculin in the areas where the pleats form; and (d) a banded or periodic pattern of dark gray or close contacts (as determined by interference reflection microscopy) has been observed in many cells which have been in culture for eight or more days, and these close contacts contain vinculin. A surprising finding is that vinculin can be found in a costameric pattern in cells which are contracting, but not producing pleat-like wrinkles in the substratum. This suggests that additional proteins or posttranslational modifications of known costamere proteins are necessary to form a continuous linkage between the myofibrils and the extracellular matrix. These results confirm the hypothesis that costameres mechanically link the myofibrils to the extracellular matrix. We put forth the hypothesis that costameres are composite structures, made up of many protein components; some of these components function primarily to anchor myofibrils to the sarcolemma, while others form transmembrane linkages to the extracellular matrix.