Noda Y, Nakata T, Hirokawa N
Department of Anatomy and Cell Biology, University of Tokyo, School of Medicine, Japan.
Neuroscience. 1993 Jul;55(1):113-27. doi: 10.1016/0306-4522(93)90459-s.
Tissue distribution and intracellular localization of dynamin by immunoblotting and immunocytochemistry is investigated in this study. Dynamin was widely expressed in all the neurons we examined, and was especially abundant in the central nervous system after maturation, although its expression presented regional heterogeneity. Dynamin was present most abundantly in cerebellar Purkinje cells and hippocampal pyramidal cells, and to a lesser extent in motor neurons and peripheral nerves. However, dynamin was nearly absent in cells such as anterior pituitary cells and adrenal medullary cells which secrete mainly dense cored vesicles. Dynamin was localized not only in cell bodies, axons, and synapses but also in dendrites. Subcellular fractionation indicated that dynamin existed in the membrane fraction as well as in the soluble fraction. In ligated peripheral nerves, dynamin colocalized with tubulovesicular membranous organelles transported mainly anterogradely. By transfection of dynamin cDNA into mouse fibroblast L-cells, we showed it colocalized with some membranous organelles but not with microtubules. Our results show that dynamin is associated with membranous organelles in vivo, although a certain amount of dynamin also exists in the soluble fraction and is distributed diffusely throughout mature neurons. The data suggest that dynamin's fundamental role involves membrane trafficking in neurons in the central nervous system rather than in sliding microtubules as a motor protein.
本研究通过免疫印迹和免疫细胞化学方法研究了发动蛋白的组织分布和细胞内定位。发动蛋白在我们检测的所有神经元中广泛表达，成熟后在中枢神经系统中尤其丰富，尽管其表达呈现区域异质性。发动蛋白在小脑浦肯野细胞和海马锥体细胞中含量最为丰富，在运动神经元和外周神经中含量较少。然而，在主要分泌致密核心囊泡的细胞如垂体前叶细胞和肾上腺髓质细胞中，发动蛋白几乎不存在。发动蛋白不仅定位于细胞体、轴突和突触，还定位于树突。亚细胞分级分离表明，发动蛋白存在于膜组分以及可溶性组分中。在结扎的外周神经中，发动蛋白与主要沿顺行方向运输的微管泡状膜性细胞器共定位。通过将发动蛋白cDNA转染到小鼠成纤维细胞L-细胞中，我们发现它与一些膜性细胞器共定位，但与微管不共定位。我们的结果表明，发动蛋白在体内与膜性细胞器相关，尽管一定量的发动蛋白也存在于可溶性组分中，并在整个成熟神经元中广泛分布。数据表明，发动蛋白的基本作用涉及中枢神经系统中神经元的膜运输，而不是作为运动蛋白在微管滑动中起作用。
