Podosomes display actin turnover and dynamic self-organization in osteoclasts expressing actin-green fluorescent protein
Podosomes display actin turnover and dynamic self-organization in osteoclasts expressing actin-green fluorescent protein
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DOI：
10.1091/mbc.e02-07-0389
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发表时间：
2003-02-01
影响因子：
3.3
通讯作者：
Bard, F
中科院分区：
文献类型：
--
作者：
Destaing, O;Saltel, F;Bard, F
足体是基于肌动蛋白的小粘连结构，在两个方面与局灶性粘连不同：它们的核心结构和在破骨细胞中组织成大图案的能力。为了解决这些特征背后的机制，我们对在分化过程中表达绿色荧光蛋白-肌动蛋白的活的破骨前细胞进行了成像。我们观察到，足体总是形成在被肌动蛋白云包围的足体群内部或靠近足体群群。光漂白后的荧光恢复显示，肌动蛋白在单个足体中翻转，而不是Cortactin，这表明肌动蛋白在足体核心持续聚合。对破骨细胞分化过程中的足体组装的观察表明，它们从简单的簇演化成环，通过在其外脊不断形成新的足体而在环内抑制足体的形成而扩张。这种将足体自组织成动态环的机制是驱动细胞外围的足体形成大的环形图案的机制。我们还表明，额外的分化步骤，需要微管的完整性，稳定了细胞外围的足体环，形成了成熟破骨细胞特有的足体带模式。因此，这些结果为破骨细胞中的足体构型提供了一种机制，并揭示了足体内肌动蛋白的周转。
Podosomes, small actin-based adhesion structures, differ from focal adhesions in two aspects: their core structure and their ability to organize into large patterns in osteoclasts. To address the mechanisms underlying these features, we imaged live preosteoclasts expressing green fluorescent protein-actin during their differentiation. We observe that podosomes always form inside or close to podosome groups, which are surrounded by an actin cloud. Fluorescence recovery after photobleaching shows that actin turns over in individual podosomes in contrast to cortactin, suggesting a continuous actin polymerization in the podosome core. The observation of podosome assemblies during osteoclast differentiation reveals that they evolve from simple clusters into rings that expand by the continuous formation of new podosomes at their outer ridge and inhibition of podosome formation inside the rings. This self-organization of podosomes into dynamic rings is the mechanism that drives podosomes at the periphery of the cell in large circular patterns. We also show that an additional step of differentiation, requiring microtubule integrity, stabilizes the podosome circles at the cell periphery to form the characteristic podosome belt pattern of mature osteoclasts. These results therefore provide a mechanism for the patterning of podosomes in osteoclasts and reveal a turnover of actin inside the podosome.