TRPV-5 Mediates a Receptor Activator of NF-κB (RANK) Ligand-induced Increase in Cytosolic Ca2+ in Human Osteoclasts and Down-regulates Bone Resorption
TRPV-5 Mediates a Receptor Activator of NF-κB (RANK) Ligand-induced Increase in Cytosolic Ca2+ in Human Osteoclasts and Down-regulates Bone Resorption
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DOI：
10.1074/jbc.m109.075234
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发表时间：
2010-08-13
影响因子：
4.8
通讯作者：
Roux, Sophie
中科院分区：
文献类型：
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作者：
Chamoux, Estelle;Bisson, Martine;Roux, Sophie
位于NF-κ B（RANK）激活受体激活剂下游的大多数信号传导效应物对钙敏感。然而，导致人破骨细胞内钙动员的早期信号事件仍然知之甚少。使用钙敏感的荧光探针Fura 2检测人破骨细胞模型中细胞内钙浓度（[Ca 2 +]（i））的变化。用NF-κ B配体受体激活剂（RANKL）刺激这些细胞可诱导[Ca 2 +]（i）快速显著增加。加入细胞外Ca 2+螯合剂，消耗细胞内存储，和使用磷脂酶C抑制剂都表明，Ca 2+是细胞外的起源，这表明参与的Ca 2+通道。我们表明，经典的Ca 2+通道（L-、T-或R-型）均不参与RANKL诱导的Ca 2+峰。然而，高剂量Gd 3+的作用确实表明TRP家族通道存在于人类破骨细胞中。TRPV-5通道在破骨细胞中表达，主要位于与骨表面接触的细胞区域。此外，TRPV-5通道的RNA失活完全抑制了RANKL诱导的[Ca 2 +]（i）增加，这长期伴随着骨吸收的显著激活。总体而言，我们的结果表明，RANKL诱导细胞外来源的[Ca 2 +]（i）显著增加，可能是由于人破骨细胞表面TRPV-5钙通道开放所致。我们的研究结果表明，TRPV-5通过RANKL诱导的骨吸收中的负反馈回路有助于维持人体骨骼的稳态。
Most of the signaling effectors located downstream of receptor activator of NF-kappa B (RANK) activation are calcium-sensitive. However, the early signaling events that lead to the mobilization of intracellular calcium in human osteoclasts are still poorly understood. The Ca2+-sensitive fluorescent probe Fura2 was used to detect changes in the intracellular concentration of Ca2+ ([Ca2+](i)) in a model of human osteoclasts. Stimulating these cells with receptor activator of NF-kappa B ligand (RANKL) induced a rapid and significant increase in [Ca2+](i). Adding extracellular Ca2+ chelators, depleting intracellular stores, and the use of a phospholipase C inhibitor all indicated that the Ca2+ was of extracellular origin, suggesting the involvement of a Ca2+ channel. We showed that none of the classical Ca2+ channels (L-, T-, or R-type) were involved in the RANKL-induced Ca2+ spike. However, the effect of high doses of Gd3+ did suggest that TRP family channels were present in human osteoclasts. The TRPV-5 channel was expressed in osteoclasts and was mainly located in the cellular area in contact with the bone surface. Furthermore, the RNA inactivation of TRPV-5 channel completely inhibited the RANKL-induced increase in [Ca2+](i), which was accompanied in the long term by marked activation of bone resorption. Overall, our results show that RANKL induced a significant increase in [Ca2+](i) of extracellular origin, probably as a result of the opening of TRPV-5 calcium channels on the surface of human osteoclasts. Our findings suggest that TRPV-5 contributes to maintaining the homeostasis of the human skeleton via a negative feedback loop in RANKL-induced bone resorption.