Downregulation of calcitonin receptor mRNA expression by calcitonin during human osteoclast-like cell differentiation.
Downregulation of calcitonin receptor mRNA expression by calcitonin during human osteoclast-like cell differentiation.
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DOI：
10.1172/jci117634
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发表时间：
1995
期刊：
影响因子：
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通讯作者：
S. Takahashi;S. Goldring;M. S. Katz;S. Hilsenbeck;R. Williams;G. Roodman
中科院分区：
文献类型：
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作者：
S. Takahashi;S. Goldring;M. S. Katz;S. Hilsenbeck;R. Williams;G. Roodman
降钙素抑制破骨细胞形成和骨吸收，是高钙血症和骨转换增加患者的主要治疗方法。然而，降钙素的临床应用受到限制，因为患者在几天后对降钙素产生耐药性（降钙素“逃逸现象”）。降钙素“逃逸”的分子基础尚不清楚。为了确定控制破骨细胞及其前体中降钙素受体（CTR）表达的调节机制，我们用1,25-（OH）2D3处理体外形成的人破骨细胞样多核细胞（MNC）的未成熟单核前体，诱导其分化为定型单核前体和成熟的多核破骨细胞，并使用逆转录酶（RT）-PCR评估两种定型单核细胞中CTR mRNA的表达前体和跨国公司。对产生的 PCR 片段进行克隆和测序，以确认其源自 CTR mRNA。 1,25-(OH)2D3 处理 7 天后，在单核 MNC 前体中检测到 CTR mRNA 表达。它也存在于破骨细胞样 MNC 和来自破骨细胞瘤的高度纯化的巨细胞中，但不存在于体外形成的单核细胞或多核细胞中。 12小时后，降钙素显着降低巨细胞和MNC中的CTR但不降低肌动蛋白mRNA表达，去除降钙素可恢复CTR mRNA表达。类似地，降钙素降低降钙素诱导的腺苷酸环化酶活性。这些数据表明：(a)降钙素对CTR基因表达的下调可能部分解释了降钙素的“逃逸现象”； (b) 暴露于 1,25-(OH)2D3 后 7 天内，单核破骨细胞前体中出现 CTR mRNA 表达。
Calcitonin inhibits both osteoclast formation and bone resorption, and is a primary treatment for patients with hypercalcemia and increased bone turnover. However, the clinical utility of calcitonin is limited because patients become refractory to calcitonin after several days (the calcitonin "escape phenomenon"). The molecular basis for calcitonin "escape" is unclear. To determine the regulatory mechanisms controlling calcitonin receptor (CTR) expression in osteoclasts and their precursors, we treated immature mononuclear precursors for human osteoclast-like multinucleated cells (MNC) formed in vitro with 1,25-(OH)2D3, to induce their differentiation to committed mononuclear precursors, and mature multinucleated osteoclasts, and used reverse transcriptase (RT)-PCR to assess expression of CTR mRNA in both committed mononuclear precursors and MNC. The PCR fragment produced was cloned and sequenced to confirm that it was derived from CTR mRNA. CTR mRNA expression was detected in mononuclear MNC precursors after 7 d of 1,25-(OH)2D3 treatment. It was also present in osteoclast-like MNC and highly purified giant cells from osteoclastomas, but not in monocytes or macrophage polykaryons formed in vitro. Calcitonin markedly decreased CTR but not actin mRNA expression in giant cells and MNC after 12 h, and removal of calcitonin restored CTR mRNA expression. Similarly, calcitonin decreased calcitonin-induced adenylate cyclase activity. These data suggest: (a) downregulation of CTR gene expression by calcitonin may in part explain the calcitonin "escape phenomenon"; and (b) expression of CTR mRNA occurs in mononuclear osteoclast precursors within 7 d after exposure to 1,25-(OH)2D3.