The Biochemical Basis for the Mechanics of Cytokinesis

细胞分裂机制的生化基础

• 批准号: 7265203
• 负责人: DOUGLAS N ROBINSON
• 金额: $ 27.13万
• 依托单位: JOHNS HOPKINS UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-08-01 至 2009-06-14
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7265203
• 关键词: Biochemical; Basis; Mechanics; Cytokinesis

DESCRIPTION (provided by applicant): Cytokinesis is a dramatic example of a cell shape change during which the mechanical constriction of the contractile ring leads to cell separation at the end of mitosis. Cytokinesis is essential for normal cell proliferation and is of medical interest for its role in hyperproliferative diseases such as cancer. In Dictyostelium discoideum, genetic interactions have been identified between two actin cross-linking proteins that have complementary cellular distributions. Cortexillin-I is localized to the contractile ring while dynacortin is cortically enriched but excluded from the contractile ring. The implication is that cells have evolved distinct actin cross-linking proteins with complementary cellular distributions that orchestrate cell shape changes, and these different actin cross-linking proteins may control regional cortical viscoelasticity. In this proposal, to ascertain how dynacortin controls viscoelasticity, its actin cross-linking mechanism will be studied using purified proteins and a variety of equilibrium and kinetic techniques. The cellular role of dynacortin will be studied using a variety of in vivo assays including dominant effects in wild type cells, suppression of cortexillin-I and rescue of a dynacortin loss-of-function mutant. Because cytokinesis is a mechanical process and the actin cytoskeleton is the principal contributor to the cell's viscoelasticity, we hypothesize that dynacortin and cortexillin-I control regional viscoelasticity. We are using laser-tracking microrheology to measure the viscoelastic moduli of interphase and dividing wild type and genetically engineered strains where dynacortin, cortexillin-I and other activities have been altered. Indeed, in preliminary experiments, dynacortin and cortexillin-I are significant modulators of cortical viscoelasticity. New genes involved in cortical shape control will be identified using genetic suppression of cortexillin-I and genetic enhancement of myosin-II. Myosin-II is the major mechanical force generator located at the contractile ring. One novel protein, DdERM, which was identified as a cortexillin-I suppressor, is hypothesized to tether the cortical actin to the plasma membrane and contribute to cortical viscoelasticity. DdERM is a fusion of two classes of mammalian actin-associated proteins, ezrin-radixin-moesin (ERM) and fimbrin. Thus, this molecule is of considerable interest because of its role in cortical function and cell shape control and its unusual domain structure.

描述（由申请人提供）：细胞分裂是细胞形状变化的一个引人注目的例子，在此期间收缩环的机械收缩导致细胞在有丝分裂结束时分离。细胞分裂对于正常细胞增殖至关重要，并且因其在癌症等过度增殖性疾病中的作用而具有医学意义。 在盘基网柄菌中，已鉴定出两种具有互补细胞分布的肌动蛋白交联蛋白之间的遗传相互作用。 Cortexillin-I 位于收缩环，而 dynacortin 则在皮质层富集，但被排除在收缩环之外。这意味着细胞已经进化出不同的肌动蛋白交联蛋白，其具有互补的细胞分布，可以协调细胞形状的变化，并且这些不同的肌动蛋白交联蛋白可以控制区域皮质粘弹性。 在该提案中，为了确定动力皮质素如何控制粘弹性，将使用纯化的蛋白质和各种平衡和动力学技术来研究其肌动蛋白交联机制。将使用各种体内测定来研究动力皮质素的细胞作用，包括野生型细胞中的显性效应、皮质西林-I 的抑制以及动力皮质素功能丧失突变体的拯救。由于胞质分裂是一个机械过程，并且肌动蛋白细胞骨架是细胞粘弹性的主要贡献者，因此我们假设 dynacortin 和 cortexillin-I 控制区域粘弹性。我们正在使用激光跟踪微流变学来测量间期和分裂野生型和基因工程菌株的粘弹性模量，其中动力皮质素、皮质西林-I 和其他活性已被改变。事实上，在初步实验中，dynacortin 和 cortexillin-I 是皮质粘弹性的重要调节剂。 将通过皮质西林-I 的基因抑制和肌球蛋白-II 的基因增强来鉴定参与皮质形状控制的新基因。肌球蛋白-II 是位于收缩环的主要机械力发生器。一种新型蛋白质 DdERM 被鉴定为皮质西林 I 抑制剂，推测其将皮质肌动蛋白束缚在质膜上并有助于皮质粘弹性。 DdERM 是两类哺乳动物肌动蛋白相关蛋白、ezrin-radixin-moesin (ERM) 和 fimbrin 的融合体。因此，该分子因其在皮质功能和细胞形状控制中的作用及其不寻常的结构域而引起了相当大的兴趣。