Cbl-PI3K interaction regulates Cathepsin K secretion in osteoclasts.
Cbl-PI3K interaction regulates Cathepsin K secretion in osteoclasts.
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DOI：
10.1016/j.bone.2019.07.009
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发表时间：
2019-10
期刊：
影响因子：
4.1
通讯作者：
Jungeun Yu;N. Adapala;Laura Doherty;A. Sanjay
中科院分区：
文献类型：
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作者：
Jungeun Yu;N. Adapala;Laura Doherty;A. Sanjay
破骨细胞有效的骨吸收是平衡骨重建的关键。我们之前已经报道过，在适配蛋白Cbl(CblY737F，YF)中携带酪氨酸737到苯丙氨酸替代突变的小鼠增加了骨体积，部分原因是破骨细胞介导的骨吸收减少。CblY737F突变取消了Cb1与PI3K的P85亚基之间的相互作用。在此，我们研究了YF突变破骨细胞吸收功能缺陷的机制。YF破骨细胞具有完整的肌动蛋白细胞骨架和封闭区。WT和YF破骨细胞酸化吸收陷窝所需蛋白质的表达和定位也是相似的。相反，在YF破骨细胞的条件培养液中，组织蛋白酶K的分泌减少，组织蛋白酶K是降解胶原蛋白所需的主要蛋白酶。由于YF破骨细胞中LAMP2阳性小泡数量的减少，组织蛋白酶K对LAMP2阳性小泡的靶向性也受到了影响。此外，我们发现，与WT相比，YF破骨细胞来源的条件培养液促进了WT颅骨培养中碱性磷酸酶阳性克隆的数量增加，成骨标志物的表达增加。总而言之，我们的结果表明，Cbl-PI3K相互作用调节正常骨吸收所需的组织蛋白酶K的分泌，以及促进成骨的因子的分泌。
Effective bone resorption by osteoclasts is critical for balanced bone remodeling. We have previously reported that mice harboring a substitution mutation of tyrosine 737 to phenylalanine in the adapter protein Cbl (CblY737F, YF) have increased bone volume partly due to decreased osteoclast-mediated bone resorption. The CblY737Fmutation abrogates interaction between Cbl and the p85 subunit of PI3K. Here, we studied the mechanism for defective resorptive function of YF mutant osteoclasts. The YF osteoclasts had intact actin cytoskeletons and sealing zones. Expression and localization of proteins needed for acidification of the resorptive lacunae were also comparable between the WT and YF osteoclasts. In contrast, secretion of Cathepsin K, a major protease needed to degrade collagen, was diminished in the conditioned media derived from YF osteoclasts. The targeting of Cathepsin K into LAMP2-positive vesicles was also compromised due to decreased number of LAMP2-positive vesicles in YF osteoclasts. Further, we found that in contrast to WT, conditioned media derived from YF osteoclasts promoted increased numbers of alkaline phosphatase positive colonies, and increased expression of osteogenic markers in WT calvarial cultures. Cumulatively, our results suggest that the Cbl-PI3K interaction regulates Cathepsin K secretion required for proper bone resorption, and secretion of factors which promote osteogenesis.