TROPOMYOSINS IN NORMAL AND TRANSFORMED CELLS

这项研究的目的是分析细胞的功能作用。 原肌球蛋白在微丝束的结构和组织中的作用 正常和转化的动物培养细胞。我们发现：(1)五个中的 在“正常”大鼠细胞系中发现的原肌球蛋白形式，主要有三种 原肌球蛋白和两个相对较小的原肌球蛋白；(2) 转化时，一种或两种主要原肌球蛋白的水平为 降低，微量原肌球蛋白水平显著升高； (3)原肌球蛋白图谱的这些变化程度有很好的相关性 与形态变化的程度有关；(4) 在温度漂移实验中也观察到原肌球蛋白的模式 用甲状腺肉瘤病毒突变体转化的大鼠-1细胞； 原肌球蛋白表达模式的变化是在 MRNA水平，而不是翻译后修饰；以及 (6)原肌球蛋白模式的变化一致地表现为 各种转化剂，包括病毒、化学致癌物、 紫外线照射，DNA转染法。这些结果意味着这一点 原肌球蛋白在“正常”和转化后的差异表达 细胞可能参与了肌动蛋白电缆线的变化 形态变换。为了探索这种可能性，我们有 从大鼠培养细胞中纯化原肌球蛋白的每一种异构体 不同浓度的微丝体外生理特性的检测 通过各种生化和生物物理方法制备原肌球蛋白。在……里面 原肌球蛋白的体内功能作用将通过微量注射来确定 不同形式的原肌球蛋白或单抗进入活体 细胞。这些研究的长期目标是了解如何 原肌球蛋白差异表达对细胞形态变化的影响 在致癌转化和肌动蛋白连接线如何在 进程。(L)

This research is aimed at an analysis of the functional roles of tropomyosin in the structure and organization of microfilament bundles in normal and transformed animal cultured cells. We found that: (1)\of five forms of tropomyosin found in "normal" rat cell lines, three are major tropomyosins and two are relatively minor tropomyosins; (2)\upon transformation, the level of one or both of the major tropomyosins is decreased and the levels of minor tropomyosins are greatly increased; (3)\the degree of these changes in tropomyosin patterns correlates well with the extent of morphological transformation; (4)\the changes in tropomyosin patterns were also observed in temperature shift experiments with rat-1 cells transformed with a ts Rous sarcoma virus mutant; (5)\the changes in the pattern of tropomyosin expression are regulated at the level of mRNA ratherthan by post-translational modification; and (6)\changes in tropomyosin patterns are consistently expressed with a variety of transformation agents including virus, chemical carcinogen, UV-irradiation, and DNA transfection. These results imply that this differential expression of tropomyosin between "normal" and transformed cells may be involved in the changes in actin cables associated with morphological transformation. To explore this possibility, we have purified each isoform of tropomyosins from rat cultured cells and will examine in vitro physiological properties of microfilaments with different sets of tropomyosin by various biochemical and biophysical methods. In vivo functional roles of tropomyosin will be determined by microinjection of different forms of tropomyosin or monoclonal antibodies into living cells. The long-term goal of these studies is to understand how differential expression of tropomyosin effects cell morphology changes upon oncogenic transformation and how actin cables rearrange in this process. (L)