IMMUNOLOCALIZATION OF MUSCLE AND NONMUSCLE ISOFORMS OF ACTIN IN MYOGENIC CELLS AND ADULT SKELETAL-MUSCLE
IMMUNOLOCALIZATION OF MUSCLE AND NONMUSCLE ISOFORMS OF ACTIN IN MYOGENIC CELLS AND ADULT SKELETAL-MUSCLE
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DOI：
10.1002/cm.970090406
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发表时间：
1988-01-01
影响因子：
--
通讯作者：
BULINSKI, JC
中科院分区：
文献类型：
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作者：
OTEY, CA;KALNOSKI, MH;BULINSKI, JC
在脊椎动物骨骼肌中，增殖的成肌细胞合成肌动蛋白的非肌肉亚型，并且细胞在其生肌分化期间开始表达肌肉特异性肌动蛋白亚型。为了研究肌动蛋白亚型在生肌细胞和完全分化的骨骼肌中的分布，我们制备了骨骼肌α特异性肽抗体。肌动蛋白的亚型，并使用该抗体以及与非肌肉γ特异性反应的抗体。肌动蛋白通过双重间接免疫荧光对培养的肌管和成人骨骼肌原纤维进行染色。在此分辨率水平下，未观察到同种型定位的差异：在肌管和成熟肌原纤维的条纹中检测到肌肉和非肌肉肌动蛋白。还使用免疫金电子显微镜对肌管进行双重染色，并通过计数与每种抗体标记相对应的两种尺寸的金颗粒来定量确定亚型分布。免疫反应性的定量分析表明，尽管两种形式都存在于所有含肌动蛋白的结构中，但非肌肉肌动蛋白沿肌管边缘（皮质微丝）相对更普遍，而肌肉亚型在内部区域（包含形成的肌原纤维）占主导地位。因此，我们发现了肌肉和非肌肉肌动蛋白亚型在分化生肌细胞中异质分布的证据，并且我们已经证明非肌肉肌动蛋白亚型是肌肉收缩装置的组成部分。
In vertebrate skeletal muscle, the proliferating myoblasts synthesize nonmuscle isoforms of actin, and the cells begin to express muscle-specific actin isoforms during their myogenic differentiation. To study the distributions of the actin isoforms in myogenic cells and fully differentiated skeletal muscle, we prepared a peptide antibody specific for the skeletal .alpha. isoform of actin and used this antibody along with an antibody specifically reactive with nonmuscle .gamma. actin to stain cultured myotubes and adult skeletal myofibrils by double-indirect immunofluorescence. At this level of resoltuion, no differences in isoform localization were seen: Both muscle and nonmuscle actins were detected in the myotubes and in the striations of mature myofibrils. Myotubes were also double-stained using immunogold electron microscopy, and the isoform distributions were determined quantitatively by counting the two sizes of gold particles that corresponded to labeling with each antibody. A quantitative analysis of immunoreactivity revealed that, although both forms were present in all actin-containing structures, nonmuscle actin was relatively more prevalent along the edges (cortical microfilaments) of the myotubes, whereas the muscle isoform predominated in the interior regions (containing forming myofibrils). Thus, we have found evidence of a heterogeneous distribution of muscle and nonmuscle actin isoforms in differentiating myogenic cells, and we have demonstrated that a nonmuscle actin isoform is a component of the muscle contractile apparatus.