Ultrastructural analysis of apatite-degrading capability of extended invasive podosomes in resorbing osteoclasts
Ultrastructural analysis of apatite-degrading capability of extended invasive podosomes in resorbing osteoclasts
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DOI：
10.1016/j.micron.2016.05.006
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发表时间：
2016-09-01
期刊：
影响因子：
2.4
通讯作者：
Yoshida, Astushi
中科院分区：
文献类型：
--
作者：
Akisaka, Toshitaka;Yoshida, Astushi
培养中的破骨细胞是非转化的细胞类型，其自发地形成特定的细胞粘附装置，如足状体。单个的足体是丝状肌动蛋白（F-肌动蛋白）单元结构的复杂网络，其与其他蛋白质一起自组织为密封区。磷灰石上的主要基质降解似乎是在皱褶边界域下进行的，皱褶边界域是一个封闭的细胞外室，由该密封区紧密密封。目前，我们发现，通常指状突起的皱褶边缘的顶部达到对磷灰石表面的平面，在那里发生了磷灰石的浅降解。同时，我们获得了几个结构证据，表明一个特定的突起，称为侵入性的podosome（invadopodium），这是连续的podosomes来自密封带，侵入深入磷灰石基质和降解它。F-肌动蛋白结构的侵入podosome-an活性细胞外基质降解，肌动蛋白丰富的细胞突起-可以区别于其他点状的F-肌动蛋白结构，包括个别的podosome，密封区，和皱褶的边缘突起。侵入性的足体含有2种不同的F-肌动蛋白群体，即，一个相互连接的网络和一个平行的束阵列。这些突起的形态变异性是明显的，具有单一的圆柱形至片状细胞骨架组织。我们目前的观察结果强烈表明，磷灰石基质吸收破骨细胞的降解似乎已经由皱褶边界和侵入性podosomes的组合外观之前，也同时发生与细胞迁移在一个交替的周期中的吸收和迁移。(C)2016爱思唯尔有限公司版权所有
Osteoclasts in culture are non-transformed cell types that spontaneously develop specific cell-adhesion devices such as podosomes. An individual podosome is a complex network of filamentous actin (F-actin) unit structure that collectively, with other proteins, self-organizes as the sealing zone. Major matrix degradation on apatite seems to proceed under the ruffled-border domain, which is an enclosed extra cellular compartment tightly sealed off by this sealing zone. Presently we found that usually the top of finger-like projections of the ruffled border reached toward the plane of the apatite surface, where a shallow degradation of apatite took place. Simultaneously, we obtained several pieces of structural evidence indicating that a specific protrusion referred to as an invasive podosome (invadopodium), which was continuous with podosomes derived from the sealing zone, invaded deeply into apatite matrix and degraded it. The F-actin architecture of the invasive podosome-an active extracellular matrix-degrading, actin-rich cell protrusion- could be distinguished from that of other punctate F-actin structures including the individual podosome, sealing zone, and ruffled border projection. Invasive podosomes contained 2 different F-actin populations, i.e., an interconnected meshwork and a parallel array of bundles. The morphological variability of these protrusions was apparent, having a single cylindrical to lamella-shaped cytoskeletal organization. Our present observations strongly suggest that the degradation of apatite substrate-resorbing osteoclasts appears to have been preceded by the combined appearance of ruffled border and invasive podosomes, and also occurred simultaneously with cell migration during an alternating cycle of resorption and migration. (C) 2016 Elsevier Ltd. All rights reserved.