Saetersdal T, Greve G, Dalen H
Department of Anatomy, University of Bergen, Norway.
Histochemistry. 1990;95(1):1-10. doi: 10.1007/BF00737221.
We have investigated the associations between beta-tubulin and mitochondria in freshly isolated cardiac myocytes from the rat. Beta-tubulin was identified by using monoclonal antibodies for immunofluorescence and high resolution immunogold electron microscopy. In addition, conventional transmission and scanning electron microscopic studies were performed. After chemical stabilization in a formaldehyde solution, the myocytes were shock-frozen at -150 degrees C, cryosectioned at -70 degrees C and subsequently processed for immunohistochemical and immunocytochemical microscopy. A characteristic of the rod shaped myocytes is the presence of a dense network of microtubules in the cytoplasm displaying a pattern of strong anti-beta-tubulin reaction. The complexity of this network however varies considerably among the myocytes reflecting microtubule dynamic instability. Further, our findings demonstrate that the beta-tubulin label in rod cells is confined to the perinuclear and interfibrillar spaces and, therefore, is largely colocalized with the cytoplasmic organelles. In myocytes undergoing severe contracture the distribution of beta-tubulin is entirely restricted to the outer mitochondrial-containing domain. This implies that, in a cell model with marked segregation of the contractile filaments and organelles, mitochondria are codistributed with microtubules in the total absence of desmin intermediate filaments. Moreover, our immunogold preparations demonstrate anti-beta-tubulin labelling in the outer mitochondrial membrane as well as of fibres in close apposition to this membrane. These results indicate the presence of a specific beta-tubulin binding to the outer mitochondrial membrane that probably also involves microtubule based translocators and/or MAPs.
我们研究了大鼠新鲜分离心肌细胞中β-微管蛋白与线粒体之间的关联。通过使用单克隆抗体进行免疫荧光和高分辨率免疫金电子显微镜鉴定β-微管蛋白。此外，还进行了传统的透射和扫描电子显微镜研究。在甲醛溶液中进行化学固定后，将心肌细胞在-150℃下速冻，在-70℃下进行冰冻切片，随后进行免疫组织化学和免疫细胞化学显微镜检查。杆状心肌细胞的一个特征是细胞质中存在密集的微管网络，呈现出强烈的抗β-微管蛋白反应模式。然而，这种网络的复杂性在心肌细胞之间差异很大，反映了微管的动态不稳定性。此外，我们的研究结果表明，杆状细胞中的β-微管蛋白标记局限于核周和肌原纤维间空间，因此在很大程度上与细胞质细胞器共定位。在发生严重挛缩的心肌细胞中，β-微管蛋白的分布完全局限于含线粒体的外周区域。这意味着，在一个收缩细丝和细胞器明显分离的细胞模型中，线粒体在完全没有结蛋白中间丝的情况下与微管共分布。此外，我们的免疫金制剂显示在外线粒体膜以及与此膜紧密相邻的纤维上有抗β-微管蛋白标记。这些结果表明存在一种与外线粒体膜特异性结合的β-微管蛋白，这可能还涉及基于微管的转运体和/或微管相关蛋白。
