The Loss of Cbl-Phosphatidylinositol 3-Kinase Interaction Perturbs RANKL-mediated Signaling, Inhibiting Bone Resorption and Promoting Osteoclast Survival
The Loss of Cbl-Phosphatidylinositol 3-Kinase Interaction Perturbs RANKL-mediated Signaling, Inhibiting Bone Resorption and Promoting Osteoclast Survival
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DOI：
10.1074/jbc.m110.124628
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发表时间：
2010-11-19
影响因子：
4.8
通讯作者：
Sanjay, Archana
中科院分区：
文献类型：
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作者：
Adapala, Naga Suresh;Barbe, Mary F.;Sanjay, Archana
Cbl是一种衔接蛋白和E3连接酶，在影响各种细胞功能的几种信号通路中起着积极和消极的作用。酪氨酸737是Cbl特有的，并且被Syk和Src家族激酶磷酸化。磷酸化Cbl Tyr（737）为PI 3 K的p85调节亚基产生结合位点，其在破骨细胞的骨吸收调节中也起重要作用。为了研究Cbl-PI 3 K相互作用在骨稳态中的作用，我们检查了基因敲入小鼠（Cbl（YF/YF）），其中Cbl中的PI 3 K结合位点由于调节酪氨酸的突变而被消融。我们报告说，在CblYF/YF小鼠，尽管破骨细胞的数量增加，骨体积增加，由于破骨细胞功能缺陷。此外，在离体培养物中，成熟的CblYF/YF破骨细胞由于细胞凋亡的延迟发生而显示出在RANKL存在下存活的能力增加。RANKL介导的信号传导在CblYF/YF破骨细胞中受到干扰，并且最有趣的是，AKT磷酸化被上调，表明Cbl缺乏PI 3 K螯合导致存活率增加和骨吸收减少。累积地，这些体内和体外结果表明，一方面，Cbl与PI 3 K的结合负调节破骨细胞分化、存活和信号传导事件（例如AKT磷酸化），而另一方面，它正影响破骨细胞功能。
Cbl is an adaptor protein and an E3 ligase that plays both positive and negative roles in several signaling pathways that affect various cellular functions. Tyrosine 737 is unique to Cbl and is phosphorylated by Syk and Src family kinases. Phosphorylated Cbl Tyr(737) creates a binding site for the p85 regulatory subunit of PI3K, which also plays an important role in the regulation of bone resorption by osteoclasts. To investigate the role of Cbl-PI3K interaction in bone homeostasis, we examined the knock-in mice (Cbl(YF/YF)) in which the PI3K binding site in Cbl is ablated due to the mutation in the regulatory tyrosine. We report that in CblYF/YF mice, despite increased numbers of osteoclasts, bone volume is increased due to defective osteoclast function. Additionally, in ex vivo cultures, mature CblYF/YF osteoclasts showed an increased ability to survive in the presence of RANKL due to delayed onset of apoptosis. RANKL-mediated signaling is perturbed in CblYF/YF osteoclasts, and most interestingly, AKT phosphorylation is up-regulated, suggesting that the lack of PI3K sequestration by Cbl results in increased survival and decreased bone resorption. Cumulatively, these in vivo and in vitro results show that, on one hand, binding of Cbl to PI3K negatively regulates osteoclast differentiation, survival, and signaling events (e.g. AKT phosphorylation), whereas on the other hand it positively influences osteoclast function.