MYOSINS I AND II AND CELL MOTILITY

细胞运动性在多种正常和 病理过程。 神经系统中细胞运动的例子 包括生长锥的运动和成神经细胞的迁移， 在发育过程中出现的神经胶质细胞。 一个突出的例子， 运动导致疾病可以在恶性胶质瘤中看到。 细胞 这些肿瘤从原发部位迁移相当远的距离， 有时从一个大脑半球传到另一个大脑半球。 是 很可能运动性在使这些肿瘤具有侵袭性方面很重要， 很难治疗。 有越来越多的证据表明，两个细胞骨架 蛋白质--肌动蛋白和肌球蛋白--组成驱动运动的马达。 肌球蛋白可以分为两类，称为肌球蛋白I和II。 这些 在运动细胞的不同区域发现了两种形式的肌球蛋白， 它们显然有不同的作用。 这些不同的功能必须 反映在酶学、结构和机制上的差异， 调控 本申请中提供的数据将表明肌球蛋白I和 II亚型存在于几种原发性CNS恶性肿瘤中，包括 神经胶质瘤 我将在本申请中建议首先扩展此 通过筛选更广泛的胶质瘤细胞系以及 发育中的胚胎大脑，以了解两种肌球蛋白亚型是否 礼物 我还将检查这些细胞的细胞内分布， 同种型及其对运动刺激生长因子的反应。 其次，我将分离肌球蛋白I和II，并测量其速率， 描述它们与肌动蛋白相互作用的平衡常数， ATP 最后，我将研究肌球蛋白I的独特结构 详细地说，使用各种生物化学和生物物理技术。 后面的这些实验将使用得自西洋参的肌球蛋白I和II castellanii，一种单细胞运动生物，因为这个来源可以提供 大量的蛋白质足以进行测量， 求婚 阿米巴之间的高度序列同源性 肌球蛋白I和II及其脊椎动物对应物意味着这些 实验应该让我对CNS做出有效的结论， 胶质瘤肌球蛋白。 这些研究的结果将用于构建一个详细的 肌动蛋白-肌球蛋白相互作用如何产生运动的分子模型。 这些研究可能最终使药理学的发展 细胞运动的调节剂，可以改变生物 恶性神经胶质瘤的侵袭性。

Cell motility plays a central role in a wide variety of normal and pathological processes. Examples of cell motility in the nervous system include the movement of growth cones and the migration of neuroblasts and glial cells that occur in development. A striking example of how motility leads to disease can be seen in malignant gliomas. Cells from these tumors migrate considerable distances from the primary site, sometimes crossing from one cerebral hemisphere to the other. It is likely that motility is important in making these tumors so invasive and difficult to treat. There is a growing body of evidence that two cytoskeletal proteins--actin and myosin--compose the motor that drives motility. Myosins can be divided into two groups, called myosins I and II. These two forms of myosin are found in different regions of motile cells, and they clearly have different roles. These different functions must be reflected in differences in enzymology, structure, and mechanism of regulation. Data to be presented in this application will show that myosin I and II isoforms are present in several primary CNS malignancies, including gliomas. I will propose in this application to first expand on this observation by screening a wider variety of glioma cell lines as well as developing, embryonic brain in order to see if both myosin isoforms are present. I will also examine the intracellular distribution of these isoforms and their response to motility-stimulating growth factors. Second, I will isolate myosins I and II and measure the rate and equilibrium constants that describe their interactions with actin and ATP. Finally, I will examine the unique structural aspects of myosin I in detail, using a variety of biochemical and biophysical techniques. These latter experiments will use myosins I and II from Acanthameoba castellanii, a unicellular motile organism, as this source can provide quantities of protein large enough to perform the measurements that I propose. The high degree of sequence homology between Acanthamoeba myosins I and II and their vertebrate counterparts means that these experiments should allow me to make valid conclusions about CNS and glioma myosins. Results of these studies will be used to construct a detailed molecular model of how the actin-myosin interaction produces motility. These studies may ultimately allow the development of pharmacologic modulators of cell motility that could alter the biological aggressiveness of malignant glial tumors.