The F-actin modulator SWAP-70 controls podosome patterning in osteoclasts.
The F-actin modulator SWAP-70 controls podosome patterning in osteoclasts.
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DOI：
10.1016/j.bonr.2016.07.002
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发表时间：
2016-12
期刊：
影响因子：
2.5
通讯作者：
Garbe AI
中科院分区：
文献类型：
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作者：
Roscher A;Hasegawa T;Dohnke S;Ocaña-Morgner C;Amizuka N;Jessberger R;Garbe AI
破骨细胞是骨吸收细胞，是骨疾病的关键介质。在粘附到骨上时，破骨细胞伸展并重组它们的细胞骨架以产生富含F-肌动蛋白的环状结构，即密封区，其中形成破骨细胞的吸收细胞器，即皱褶边缘。富含肌动蛋白的粘附结构（足状体）从簇到带的动态自组织对于破骨细胞介导的骨降解至关重要。缺乏蛋白SWAP-70的小鼠表现出骨硬化表型，这是由于Swap-70−/−破骨细胞中肌动蛋白环形成受损引起的骨吸收缺陷所致。为了进一步阐明这种缺陷的机制，我们研究了SWAP-70在podosomes的组织和动力学中的特定功能。这些详细的研究表明，在Swap-70−/−破骨细胞中，从podosome簇到环的转变受到损害。动态F-肌动蛋白周转和SWAP-70定位在podosome图案化过程中的活细胞成像表明，SWAP-70是集群形成的关键，但在F-肌动蛋白环的生成中起着关键作用。我们的数据提供了深入了解SWAP-70的F-肌动蛋白结合结构域和pleckstrin同源性（PH）结构域的作用，在适当的本地化SWAP-70和形成一个外围的podosome带，分别。离体骨分析表明，SWAP-70缺陷破骨细胞表现出有缺陷的皱褶边缘形成和V-ATP酶表达。我们的研究结果表明，膜结合的SWAP-70的肌动蛋白动力学的调节，这是必不可少的足体图案，从而为破骨细胞的吸收活性的重要作用。SWAP-70控制动态podosome图案化，但不控制podosome的组装。PIP 3和F-肌动蛋白结合是SWAP-70正确亚细胞定位所必需的。SWAP-70缺陷型破骨细胞在皱褶边缘形成中受损。
Osteoclasts are bone resorbing cells acting as key mediators of bone disorders. Upon adhesion to bone, osteoclasts polarize and reorganize their cytoskeleton to generate a ring-like F-actin-rich structure, the sealing zone, wherein the osteoclast's resorptive organelle, the ruffled border, is formed. The dynamic self-organization of actin-rich adhesive structures, the podosomes, from clusters to belts is crucial for osteoclast-mediated bone degradation. Mice lacking the protein SWAP-70 display an osteopetrotic phenotype due to defective bone resorption caused by impaired actin ring formation in Swap-70−/− osteoclasts. To further elucidate the mechanisms underlying this defect, we investigated the specific function of SWAP-70 in the organization and dynamics of podosomes. These detailed studies show that the transition from podosome clusters to rings is impaired in Swap-70−/− osteoclasts. Live cell imaging of dynamic F-actin turnover and SWAP-70 localization during podosome patterning indicate that SWAP-70 is dispensable for cluster formation but plays a key role in F-actin ring generation. Our data provide insights in the role of SWAP-70's F-actin binding domain and pleckstrin homology (PH) domain in the proper localization of SWAP-70 and formation of a peripheral podosome belt, respectively. Ex vivo bone analyses revealed that SWAP-70-deficient osteoclasts exhibit defective ruffled border formation and V-ATPase expression. Our findings suggest an important role of membrane binding of SWAP-70 for the regulation of actin dynamics, which is essential for podosome patterning, and thus for the resorptive activity of osteoclasts. SWAP-70 controls dynamic podosome patterning but not assembly of podosomes. PIP3 and F-actin binding are required for proper subcellular localization of SWAP-70. SWAP-70-deficient osteoclasts are impaired in ruffled border formation.