Implication of the calcium sensing receptor and the Phosphoinositide 3-kinase/Akt pathway in the extracellular calcium-mediated migration of RAW 264.7 osteoclast precursor cells
Implication of the calcium sensing receptor and the Phosphoinositide 3-kinase/Akt pathway in the extracellular calcium-mediated migration of RAW 264.7 osteoclast precursor cells
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DOI：
10.1016/j.bone.2010.01.383
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发表时间：
2010-05-01
期刊：
影响因子：
4.1
通讯作者：
Kamel, Said
中科院分区：
文献类型：
--
作者：
Boudot, Cedric;Saidak, Zuzana;Kamel, Said
虽然以往的研究对破骨细胞的形成、成熟和凋亡过程进行了广泛的研究，但对破骨细胞前体细胞定位和归巢到骨环境中以启动骨重塑过程的机制知之甚少。最近的研究表明，骨环境附近存在的细胞外Ca2+ (Ca-o(2+))浓度梯度可能是参与因子之一，对破骨细胞前体产生趋化作用。使用单核-巨噬细胞系的小鼠破骨前体细胞，RAW 264.7细胞系，我们已经证明Ca-o（2+）可以定向地增加这些细胞的迁移。钙敏感受体（CaR）参与了这种作用，通过RNA干扰来降低其表达，从而导致迁移反应的取消。通过特异性通路抑制剂和western blot分析，发现PI3K /Akt和磷脂酶C β通路参与了迁移作用。Akt通路在Ca-o（2+）诱导的RAW 264.7细胞的化学吸引中也得到了证实，通过将融合蛋白TAT-dominant -Akt转导细胞，降低了迁移效应。相反，MAPK通路（ERK1/2、p38和JNK）不参与迁移效应的产生。我们得出结论，通过激活CaR和随后通过PI3K/Akt通路的信号传导，Ca-o（2+）对破骨细胞前体RAW 264.7细胞产生化学引诱作用。这些结果表明，骨附近存在的Ca-o（2+）梯度可能是破骨细胞前体归巢到骨的启动因素之一，因此可能在骨重塑的启动中起作用。(C) 2010爱思唯尔公司版权所有。
While the processes involved in the formation, maturation and apoptosis of osteoclasts have been investigated extensively in previous studies, little is known about the mechanisms responsible for the localization and homing of osteoclast precursor cells to the bone environment in order to initiate the bone remodeling process. Recent studies have suggested that the extracellular Ca2+ (Ca-o(2+)) concentration gradient present near the bone environment may be one of the participating factors, producing a chemoattractant effect on osteoclast precursors. Using the murine osteoclast precursor cells of the monocyte-macrophage lineage, the RAW 264.7 cell line, we have shown that Ca-o(2+) increases the migration of these cells in a directional manner. The participation of the calcium sensing receptor (CaR) in this effect was tested by knocking down its expression through RNA interference, which resulted in an abolition of the migratory response. By the use of specific pathway inhibitors and western blot analysis, the phosphoinositide 3-kinase (PI3K)/Akt and phospholipase C beta pathways were shown to be implicated in the migratory effect. The implication of the Akt pathway in the Ca-o(2+)-induced chemoattraction of RAW 264.7 cells was also confirmed by transducing the cells with the fusion protein TAT-dominant negative-Akt, which decreased the migratory effect. In contrast, the MAPK pathways (ERK1/2, p38 and JNK) were not involved in the production of the migratory effect. We conclude that through the activation of the CaR and subsequent signaling via the PI3K/Akt pathway, Ca-o(2+) produces a chemoattractant effect on the osteoclast precursor RAW 264.7 cells. These results suggest that the Ca-o(2+) gradient present near the bone may be one of the initiating factors for the homing of osteoclast precursors to bone, thus possibly playing a role in the initiation of bone remodeling. (C) 2010 Elsevier Inc. All rights reserved.