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Molecular Mechanism in Regulation of Neuronal Dendritic Morphology

神经元树突形态调控的分子机制

基本信息

批准号：
07458203
负责人：
SHIRAO Tomoaki
金额：
$ 4.8万
依托单位：
Gunma University School of Medicine
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1996
项目状态：
已结题

项目摘要

(1) In order to find out the relationships between drebrin and other actin associated proteins, drebrin, myosin, actin, toropomyosin, alpha-actinin, caldeson and gelsoin were purified, and various co-purification study with actin filament have been done. Drebrin binds to actin filaments at a stoichiometry of 1 : 5, with a dissociation constant (Kd) of 1.2x10^<-7>M.Drebrin does not exhibit any actin-nucleating, actin-severing or actin-capping activity, nor does it crosslink actin filaments. Drebrin did not affect the activity of gelsolin or actin binding activity of caldesmon and filamin, but strongly inhibited the actin binding activity of tropomyosin, and the actin binding and actin cross-linking activities of alpha-actinin and fascin. Drebrin has an inhibitory effect on actomyosin interation and might be an actin-linked regulatory protein of actomyosin interaction within neurons.(2) The morphological changes of dendritic spines of neurons have been postulated to participate in the expression of synaptic plasticity. We have examined the molecular mechanisms responsible for the changes in spine morphology, focusing on a protein that binds to actin filaments, drebrin, that is concentrated in neurons. We found that adult-type drebrin is localized in the dendritic spines in the forebrain of the rat, where it binds to the cytoskeleton of the spine. The drebrin-containing cytoskeleton consisted of drebrin, actin, myosin and gelsolin. In vitro, drebrin inhibited the movement of actin filaments on a glass surface that had been coated with myosin and reduced the actin-dependent ATPase activity of myosin. These results suggest that drebrin modulates the acto-myosin activity within spines and plays a role in the structure-based plasticity of synapses.

(1)为了找出drebrin与其他肌动蛋白相关蛋白之间的关系，对drebrin、myosin、actin、toropomyosin、α - actitin、caldeson和gelsoin进行了纯化，并与actin丝进行了各种共纯化研究。Drebrin与肌动蛋白丝结合的化学计量比为1:5，解离常数（Kd）为1.2x10^<-7>M。Drebrin不表现出任何肌动蛋白成核、肌动蛋白切断或肌动蛋白封盖活性，也不交联肌动蛋白丝。Drebrin对caldesmon和filamin的凝胶蛋白活性和肌动蛋白结合活性没有影响，但对原肌球蛋白的肌动蛋白结合活性以及α -肌动蛋白和fasin的肌动蛋白结合和肌动蛋白交联活性有较强的抑制作用。Drebrin对肌动球蛋白相互作用有抑制作用，可能是神经元内肌动球蛋白相互作用的肌动蛋白相关调节蛋白。(2)神经元树突棘的形态变化参与突触可塑性的表达。我们研究了导致脊柱形态变化的分子机制，重点研究了一种与肌动蛋白丝结合的蛋白质，这种蛋白质集中在神经元中。我们发现成体型drebrin位于大鼠前脑的树突棘中，在那里它与脊柱的细胞骨架结合。含drebrin的细胞骨架由drebrin、actin、myosin和gelsolin组成。在体外实验中，drebrin抑制了肌凝蛋白覆盖的玻璃表面上肌动蛋白丝的运动，并降低了肌凝蛋白依赖的atp酶活性。这些结果表明，drebrin调节脊髓内肌动蛋白活性，并在突触的结构可塑性中发挥作用。