Role of connexin 43 in the mechanism of action of alendronate: dissociation of anti-apoptotic and proliferative signaling pathways.
Role of connexin 43 in the mechanism of action of alendronate: dissociation of anti-apoptotic and proliferative signaling pathways.
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DOI：
10.1016/j.abb.2011.12.022
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发表时间：
2012-02-15
影响因子：
3.9
通讯作者：
Morelli S
中科院分区：
文献类型：
--
作者：
Lezcano V;Bellido T;Plotkin LI;Boland R;Morelli S
双磷酸盐（BPs）通过开放连接蛋白（Cx）43半通道和激活细胞外信号调节激酶ERKs抑制骨细胞和成骨细胞凋亡。以前，我们假设细胞内生存信号是由BPs与Cx43的相互作用启动的。然而，使用[3 H]-阿仑膦酸盐的全细胞结合试验，在此我们证明了在表达Cx43的ROS 17/2.8成骨细胞、真正的成骨细胞和表达或不表达Cx43的MLO-Y 4细胞中，以及在缺乏Cx43表达的HeLa细胞和用分解Cx通道的试剂预处理的ROS 17/2.8细胞中存在可饱和的、特异性的和高亲和力的结合位点。此外，BPs和PTP抑制剂Na 3VO 4均增加表达Cx43或不表达Cx43的细胞的增殖。此外，尽管BP被内化并抑制破骨细胞中的细胞内酶，但药物是否穿透非吸收性骨细胞尚不清楚。为了阐明这一点，我们评估了成骨细胞对AF-ALN（一种荧光标记的阿仑膦酸钠类似物）的摄取。AF-ALN在表达Cx43或不表达Cx43的细胞中迅速内化，表明该过程不是通过Cx43半通道介导的。总之，这些发现表明，虽然需要触发细胞内生存信号的BP，Cx43是细胞BP结合，其摄取，以及这些代理商的增殖作用。
Bisphosphonates (BPs) inhibit osteocyte and osteoblast apoptosis via opening of connexin (Cx) 43 hemichannels and activating the extracellular signal regulated kinases ERKs. Previously, we hypothesized that intracellular survival signaling is initiated by interaction of BPs with Cx43. However, using whole cell binding assays with [3H]-alendronate, herein we demonstrated the presence of saturable, specific and high affinity binding sites in the Cx43-expressing ROS 17/2.8 osteoblastic cells, authentic osteoblasts and MLO-Y4 cells expressing Cx43 or not, as well as in HeLa cells lacking Cx43 expression and ROS 17/2.8 cells pretreated with agents that disassemble Cx channels. In addition, both BPs and the PTP inhibitor Na3VO4 increased proliferation of cells expressing Cx43 or not. Furthermore, although BPs are internalized and inhibit intracellular enzymes in osteoclasts, whether the drugs penetrate non-resorptive bone cells is not known. To clarify this, we evaluated the osteoblastic uptake of AF-ALN, a fluorescently labeled analog of alendronate. AF-ALN was rapidly internalized in cells expressing Cx43 or not indicating that this process is not mediated via Cx43 hemichannels. Altogether, these findings suggest that although required for triggering intracellular survival signaling by BPs, Cx43 is dispensable for cellular BP binding, its uptake, as well as the proliferative effects of these agents.
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