TROPOMYOSINS IN NORMAL AND TRANSFORMED CELLS

本研究的目的是分析 原肌球蛋白的结构和组织的微丝束， 正常和转化的动物培养细胞。 我们发现：（1）五个 在“正常”大鼠细胞系中发现的原肌球蛋白的三种主要形式， 原肌球蛋白和两个是相对较小的原肌球蛋白;（2）在 在转化过程中，一种或两种主要原肌球蛋白的水平是 降低，次要原肌球蛋白的水平大大增加; (3)原肌球蛋白模式的这些变化程度与 （4）植物形态的变化 在温度变化实验中也观察到原肌球蛋白的模式 用用ts Rous肉瘤病毒突变体转化的大鼠-1细胞;（5） 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与 各种转化剂，包括病毒，化学致癌物， UV照射和DNA转染。 这些结果表明， 原肌球蛋白在“正常”和转化之间的差异表达 细胞可能参与肌动蛋白电缆的变化， 形态转换 为了探索这种可能性，我们 从大鼠培养的细胞中纯化原肌球蛋白的每种同种型， 检查具有不同的微丝的体外生理特性， 通过各种生物化学和生物物理学方法测定原肌球蛋白。 在 原肌球蛋白的体内功能作用将通过显微注射来确定 不同形式的原肌球蛋白或单克隆抗体 细胞 这些研究的长期目标是了解 原肌球蛋白的差异表达对细胞形态的影响 以及肌动蛋白电缆如何在这个过程中重新排列， 过程 （左）

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)