Clathrin sheets on the protoplasmic surface of ventral membranes of osteoclasts in culture
Clathrin sheets on the protoplasmic surface of ventral membranes of osteoclasts in culture
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DOI：
10.1093/jmicro/52.6.535
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发表时间：
2003-01-01
期刊：
影响因子：
--
通讯作者：
Takama, KE
中科院分区：
文献类型：
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作者：
Akisaka, T;Yoshida, H;Takama, KE
物理细胞剪切导致基底外侧（上）膜、细胞骨架或细胞器的不同程度的破坏，并暴露出附着于下层基质（如盖玻片、云母或合成磷灰石板）的破骨细胞的粘附（粘附）膜的原生质表面。细胞剪切后留在基底上的腹膜的冷冻干燥复制品提供了培养的破骨细胞的原生质膜表面的超微结构的三维信息。可见原生质表面的广泛区域和附着于质膜的粘附腹面的不同数量的细胞骨架结构。特别地，本研究最具特征的发现是在腹侧膜上显示出许多显示各种大小、形状和曲率的网格蛋白片。网格蛋白晶格的多边形亚结构似乎由六边形和散布的几个五边形组成。在外周膜上观察到它们，它们位于与下层基质密切接触的部位。此外，在基底外侧（上）膜上从未观察到网格蛋白晶格。在有利的立体视图中，大多数细胞骨架不与网格蛋白片直接接触。然而，一些观察结果表明，可能残留的细胞骨架连接到网格蛋白晶格。Podosomes没有直接的结构关系，网格蛋白晶格。虽然人们普遍认为，在运动细胞，如破骨细胞，细胞骨架的podosomes在细胞粘附中发挥了重要作用，本研究表明，膜相关网格蛋白也可能在附着到基板上的功能。在这方面，网格蛋白被认为是受体介导的内吞作用所需的，但它是否也可能在细胞附着中起作用仍然是一个争论的问题。这种类型的网格蛋白相关的粘附似乎是一个以前未被认识的破骨细胞细胞/基质粘附的网站。为了评估这种可能的功能，我们集中在网格蛋白和相关的细胞骨架元素的腹侧膜培养的破骨细胞。
Physical cell-shearing resulted in various degrees of disruption of the basolateral (upper) membranes, cytoskeletons or cell organelles and exposed the protoplasmic surface of Ventral (adhesion) membranes of osteoclasts that were attached to the underlying substratum, such as coverslips, mica or synthetic apatite plates. Freeze-dried replicas of the ventral membranes left behind on the substratum after cell-shearing provided three-dimensional information on the ultrastructure of the protoplasmic membrane surface of cultured osteoclasts. An extensive area of the protoplasmic surface and various amounts of cytoskeletal structures attached to the adherent ventral surface of the plasma membrane were visible. in particular the most characteristic finding of the present study is that numerous clathrin sheets displaying various sizes, shapes and curvature were revealed on the ventral membrane. The polygon substructures of the clathrin lattices appeared to be composed of hexagons with a few pentagons interspersed. They were seen at the peripheral membranes where they were situated at the sites of close contact with the underlying substratum. in addition, clathrin lattices were never observed on the basolateral (upper) membranes. In favourable stereo views, most cytoskeletons were not in direct contact with the clathrin sheets. However, a few observations indicated possible remnants of cytoskeletons attached to clathrin lattices. Podosomes did not have a direct structural relationship to clathrin lattices. Although it is generally accepted that cytoskeletal podosomes in motile cells, such as osteoclasts, play a major role in cell adhesion, the present study indicates that membrane-associated clathrin might also function during attachment to the substrate. In this regard, clathrin is thought to be required for receptor-mediated endocytosis, but whether it might also function in cell attachment is still a matter for debate. This type of clathrin-related adhesion appears to be a previously unrecognized site of cell/substrate adhesion in osteoclasts. To assess this possible function, we focused on clathrin and related cytoskeletal elements on the ventral membranes of cultured osteoclasts.