Role of transient receptor potential(TRP) of Ca^<2+>-permeable cation channels in osteoclast apoptosis

破骨细胞表达TRPM 7，一种Ca^2+和Mg^2+可渗透的阳离子通道。然而，TRPM 7在破骨细胞中的功能作用尚不清楚。我们检测了成熟破骨细胞中通过TRPM 7的阳离子转运特性，并进一步研究了TRPM 7对破骨细胞凋亡的贡献。尽管在生理浓度的Mg^2+存在下，通过TRPM 7的阳离子转运是不活跃的，但细胞外酸化消除了Mg^2+依赖性阻断。破骨细胞排出H+和Cl-，形成酸性室以溶解骨基质的无机成分。在酸性细胞外环境中，Mg^2+依赖性的阳离子转运阻滞被消除，有利于骨吸收过程中从骨中洗脱的Ca^2+和Mg^2+的吸收。我们的证据还表明TRPM 7不太可能参与破骨细胞凋亡。

Osteoclasts express TRPM7, a Ca^<2+-> and Mg^<2+-> permeable cation channel. However, the functional role of TRPM7 in osteoclasts is unknown. We examined the properties of cation transport through TRPM7 in mature osteoclasts and further investigated the contribution of TRPM7 to osteoclast apoptosis. Although cation transport via TRPM7 was inactive in the presence of physiological concentration of Mg^<2+>, extracellular acidification abrogated the Mg^<2+-> dependent blockade. Osteoclasts extrude H+and Cl-and form an acidic compartment to dissolve inorganic component of bone matrix. Abrogation of Mg^<2+-> dependent block of cation transport at acidic extracellular milieu is convenient for uptake of Ca^<2+> and Mg^<2+> eluted from bone during bone resorption. Our evidence also showed that TRPM7 was less likely to participate in osteoclast apoptosis.