Osteoprotegerin expression and secretion are regulated by calcium influx through the L-type voltage-sensitive calcium channel
Osteoprotegerin expression and secretion are regulated by calcium influx through the L-type voltage-sensitive calcium channel
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DOI：
10.1210/en.2003-0319
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发表时间：
2004-01-01
期刊：
影响因子：
4.8
通讯作者：
Farach-Carson, MC
中科院分区：
文献类型：
--
作者：
Bergh, JJ;Xu, YH;Farach-Carson, MC
我们之前的研究表明，1,25-二羟基维生素 D-3 [1,25(OH)(2)D-3] 通过两种时间上不同的机制调节 L 型电压敏感钙通道 (VSCC) 的 Ca-V1.2 α 亚基的活性。首先，1,25(OH)(2)D-3 快速调节增殖的成骨细胞质膜中的局部 Ca2+ 渗透性。其次，用 1,25(OH)(2)D-3 处理可减少 Ca-V1.2 的生物合成，使得 24 小时后转录物水平仅为原始水平的一半。骨保护素 (OPG) 和核因子 kappa B 配体受体激活剂 (RANKL) 为控制破骨细胞生成和 Ca2+ 稳态提供重要的调节机制。因为它们经常控制 Ca2+ 激活的分泌，我们研究了 L 型 VSCC 可能调节成骨细胞中基础 OPG 和 RANKL 分泌的可能性。我们还研究了 1,25(OH)(2)D-3 对 OPG 和 RANKL 表达的影响。为了解决这个问题，我们测量了用 1,25(OH)(2)D-3、VSCC 抑制剂和 Ca2+ 调节信号传导抑制剂处理后 MC3T3-E1 细胞和颅骨器官培养物中 OPG 和 RANKL 表达和分泌的变化。颅盖培养物中 RANKL 产量增加了 1,25(OH)(2)D-3，但在 MC3T3-E1 细胞培养基中基本上检测不到。相比之下，L型VSCC和钙调蛋白敏感蛋白激酶的抑制剂用1,25(OH)(2)D-3处理24小时后，两个系统中的OPG分泌均显着减少，但蛋白激酶A、MAPK或其他VSCC家族的抑制剂则没有显着减少。通过用诱饵 cAMP 反应元件结合位点转染来消除 OPG 分泌。我们的结果表明，OPG 分泌是通过钙调蛋白敏感蛋白激酶信号传导调节的，该信号传导取决于 L 型 VSCC 的活性，并通过 cAMP 反应元件结合蛋白介导。
Our previous studies showed that 1,25-dihydroxyvitamin D-3 [1,25(OH)(2)D-3] modulates the activity of the Ca-V1.2 alpha-subunit of the L-type voltage-sensitive calcium channel (VSCC) by two temporally distinct mechanisms. First, 1,25(OH)(2)D-3 rapidly modulates local Ca2+ permeability in the plasma membrane of the proliferating osteoblast. Second, treatment with 1,25(OH)(2)D-3 reduces biosynthesis of Ca-V1.2 such that transcript levels are half of original levels after 24 h. Osteoprotegerin (OPG) and receptor activator of nuclear factor kappa B ligand (RANKL) provide important regulatory mechanisms for controlling osteoclastogenesis and Ca2+ homeostasis. Because they often control Ca2+-activated secretion, we investigated the possibility that L-type VSCCs might regulate basal OPG and RANKL secretion in osteoblasts. We also studied 1,25(OH)(2)D-3 effects on OPG and RANKL expression. To address this, we measured changes in expression and secretion of OPG and RANKL in MC3T3-E1 cells and calvarial organ cultures after treatment with 1,25(OH)(2)D-3, VSCC inhibitors, and inhibitors of Ca2+-regulated signaling. RANKL production was increased in calvarial cultures by 1,25(OH)(2)D-3 but was essentially undetectable in the medium of MC3T3-E1 cells. In contrast, OPG secretion in both systems was significantly reduced after 24 h treatment with 1,25(OH)(2)D-3, by inhibitors of L-type VSCCs and calmodulin-sensitive protein kinases but not by inhibitors of protein kinase A, MAPKs, or other families of VSCCs. OPG secretion was abrogated by transfection with decoy cAMP response element binding sites. Our results suggest that OPG secretion is regulated through calmodulin-sensitive protein kinase signaling that depends on the activity of the L-type VSCC and is mediated through the cAMP response element-binding protein.