Studies on Cytoskeletal Function in the Generation and Maintenance of Cell Shape

细胞骨架在细胞形状生成和维持中的功能研究

• 批准号: 9808368
• 负责人: William Cohen
• 金额: $ 18.47万
• 依托单位: CUNY Hunter College
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-09-15 至 2003-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9808368&HistoricalAwards=false
• 关键词: Studies; Cytoskeletal; Function; Generation; Maintenance

In the case of mature mammalian erythrocytes (red blood cells), the cells have lost their nuclei during differentiation, and their candy-like discoid shape is maintained by a complex cytoskeletal network on the cytoplasmic face of the plasma membrane. In other animals, including vertebrates such as birds, fish and amphibians, and also certain mollusks that possess hemoglobin-bearing blood cells (Vesicomyid clams, or "blood clams"), the mature erythrocytes maintain their nuclei, and the shapes of these cells (usually flattened ellipsoids) are maintained by a submembranous band of microtubules termed the marginal band. This work examines how cells maintain or change their shape, using nucleated erythrocytes of Xenopus, axolotls, and "blood clams" as a model system because of their constancy of shape and relative simplicity of cytoskeletal organization. Major questions addressed are: (1) how is the characteristic flattened ellipsoidal shape of these cells generated? and (2) how is this morphology maintained? With respect to the first, Dr. Cohen's laboratory has previously found that immature singly- and doubly-pointed erythroid cells containing correspondingly pointed, incomplete marginal bands of microtubules occur in many species. Experiments are designed to test the hypothesis that these represent true cytoskeletal intermediates and to establish the morphogenetic sequence, using bromodeoxyuridine labeling of differentiating erythroblasts (immature red cells) in the larval amphibian spleen (axolotl), in circulating blood of anemic adults (Xenopus), and in erythroid cell cultures from both sources. With respect to the second question, in recent work, Dr. Cohen's laboratory has discovered that the hemoglobin-bearing erythrocytes of "blood clams" undergo a drastic transformation of cell shape from flattened ellipsoids to wrinkled spheroids that is induced by a natural factor in the "blood" (hemolymph) and is remarkably reversible. These cells are particularly interesting because they not only contain marginal bands, but also have marginal band-associated centrosomes (microtubule organizing centers; centrioles). A variety of experiments will examine cytoskeletal function and its control in this natural reversible change of cell shape, and additional data on cytoskeletal organization will be obtained by fluorescence localization of selected cytoskeletal proteins, both in this system and in the two amphibian systems. Of particular interest are proteins characteristic of microtubule organizing centers, centrin and gamma tubulin, the localization of which will shed light on centrosome function in cell shape maintenance. The work is expected to provide basic new information on the function of ubiquitous cytoskeletal elements. This information will be of importance not only in understanding how nucleated red blood cells maintain their shape and volume, but also for its potential to contribute important new insights to the knowledge base of how microtubules influence cell shape in eukaryotic cells in general. Dr. Cohen routinely involves both undergraduate and graduate students in his research, both in his laboratory at Hunter College and during the summer months at the Marine Biological Laboratory in Woods Hole, Massachusetts. Thus, this project is expected to contribute significantly to the integration of research and education.

在成熟的哺乳动物红细胞（红细胞）的情况下，细胞在分化过程中失去了它们的细胞核，并且它们的糖果样盘状形状由质膜的细胞质面上的复杂的细胞骨架网络维持。 在其他动物中，包括脊椎动物，如鸟类、鱼类和两栖动物，以及某些拥有血红蛋白的血细胞的软体动物（Vesicomyid clams，或“血蛤”），成熟的红细胞保持其细胞核，这些细胞的形状（通常是扁平的椭圆形）由称为边缘带的微管的膜下带维持。 这项工作研究细胞如何保持或改变其形状，使用有核红细胞的爪蟾，蝾螈，和“血蛤”作为模型系统，因为它们的形状和相对简单的细胞骨架组织的恒定性。 主要问题是：（1）这些细胞的特征性扁平椭圆形是如何产生的？以及（2）这种形态是如何维持的？ 关于第一个，科恩博士的实验室以前发现，在许多物种中，不成熟的单尖和双尖红细胞含有相应的尖的，不完整的微管边缘带。 实验的目的是测试的假设，这些代表真正的细胞骨架中间体，并建立形态发生序列，使用溴脱氧尿苷标记的分化成红细胞（未成熟的红细胞）在幼虫两栖类动物脾脏（蝾螈），在贫血的成年人（非洲爪蟾）的循环血液，并在红系细胞培养从这两个来源。 关于第二个问题，科恩博士的实验室在最近的工作中发现，“血蛤”中含有血红蛋白的红细胞的细胞形状发生了剧烈的转变，从扁平的椭圆体变成了皱纹的球体，这是由“血液”中的自然因素引起的（血淋巴）并且是显着可逆的。 这些细胞特别有趣，因为它们不仅含有边缘带，而且还具有边缘带相关的中心体（微管组织中心;中心粒）。 各种各样的实验将检查细胞骨架的功能及其控制在这种自然的可逆变化的细胞形状，和细胞骨架组织的额外数据将获得通过荧光定位选定的细胞骨架蛋白质，在这个系统和两个两栖类系统。 特别令人感兴趣的是微管组织中心，中心蛋白和γ微管蛋白，其定位将揭示中心体功能在细胞形状维持的特征蛋白。 这项工作有望为普遍存在的细胞骨架元件的功能提供新的基础信息。 这些信息不仅在了解有核红细胞如何保持其形状和体积方面具有重要意义，而且还可能为微管如何影响真核细胞中细胞形状的知识基础提供重要的新见解。科恩博士经常让本科生和研究生参与他的研究，无论是在亨特学院的实验室，还是在马萨诸塞州伍兹霍尔的海洋生物实验室的夏季。 因此，预计该项目将大大有助于研究和教育的一体化。