Liu B Y, Guo J, Lanske B, Divieti P, Kronenberg H M, Bringhurst F R
Endocrine Unit, Massachusetts General Hospital, and Harvard Medical School, Boston 02114, USA.
Endocrinology. 1998 Apr;139(4):1952-64. doi: 10.1210/endo.139.4.5895.
PTH recruits and activates osteoclasts to cause bone resorption. These actions of PTH are thought to be mediated indirectly via type 1 PTH/PTH-related peptide receptors (PTH1Rs) expressed by adjacent marrow stromal or osteoblastic cells, although some evidence suggests that PTH may act directly on early hematopoietic osteoclast progenitors. We have established clonal, conditionally immortalized, PTH-responsive, bone marrow stromal cell lines from mice that harbor both a transgene encoding a temperature-sensitive mutant of the simian virus 40 large T antigen and deletion of a single allele of the PTH1R gene. Of 60 stromal cell lines isolated, 45 expressed functional PTH1Rs. During coculture with normal murine spleen cells, 5 of 42 such cell lines could support formation of tartrate-resistant acid phosphatase-positive, multinucleated cells (TRAP+ MNCs) in response to 1,25-dihydroxyvitamin D3, but only 2 of these did so in response to PTH. One of these, MS1 cells, expressed numerous cytokines and proteins characteristic of the osteogenic lineage and showed increased production of interleukin-6 in response to PTH. MS1 cells supported dose-dependent induction by rat (r) PTH-(1-34) (0.1-100 nM) of TRAP+ MNCs that expressed calcitonin receptors and formed resorption lacunae on dentine slices. This effect of PTH, which required cell to cell contact between MS1 and spleen cells, was mimicked by coadministration of cAMP analog and phorbol ester but only partially by either agent alone. The carboxyl-terminal fragment rPTH-(53-84) also induced osteoclast-like cell formation, but the maximal effect was only 30% as great as that of rPTH-(1-34). Importantly, rPTH-(1-34) induced TRAP+ MNC formation even when PTH1R-/- osteoclast progenitors (from fetal liver of mice homozygous for ablation of the PTH1R gene) were cocultured with MS1 cells. We conclude that activation of PTH1Rs on cells of the osteoclast lineage is not required for PTH-(1-34)-induced osteoclast formation in the presence of appropriate PTH-responsive marrow stromal cells. MS1 cells provide a useful model for further study of PTH regulation of osteoclastogenesis.
甲状旁腺激素（PTH）募集并激活破骨细胞，导致骨吸收。PTH的这些作用被认为是通过相邻骨髓基质细胞或成骨细胞表达的1型PTH/甲状旁腺激素相关肽受体（PTH1Rs）间接介导的，尽管一些证据表明PTH可能直接作用于早期造血破骨细胞祖细胞。我们从小鼠建立了克隆的、条件永生化的、PTH反应性骨髓基质细胞系，这些小鼠同时携带编码猿猴病毒40大T抗原温度敏感突变体的转基因和PTH1R基因单等位基因的缺失。在分离的60个基质细胞系中，45个表达功能性PTH1Rs。在与正常小鼠脾细胞共培养期间，42个这样的细胞系中有5个能够在1,25 - 二羟维生素D3刺激下支持抗酒石酸酸性磷酸酶阳性多核细胞（TRAP + MNCs）的形成，但其中只有2个对PTH有反应。其中之一，MS1细胞，表达了许多成骨谱系特征性的细胞因子和蛋白质，并在PTH刺激下显示白细胞介素 - 6产生增加。MS1细胞支持大鼠（r）PTH -（1 - 34）（0.1 - 100 nM）对表达降钙素受体并在牙本质切片上形成吸收陷窝的TRAP + MNCs的剂量依赖性诱导。PTH的这种作用需要MS1细胞和脾细胞之间的细胞间接触，cAMP类似物和佛波酯共同给药可模拟这种作用，但单独使用任何一种试剂只能部分模拟。羧基末端片段rPTH -（53 - 84）也诱导破骨细胞样细胞形成，但最大作用仅为rPTH -（1 - 34）的30%。重要的是，即使将PTH1R - / -破骨细胞祖细胞（来自PTH1R基因纯合敲除小鼠的胎肝）与MS1细胞共培养，rPTH -（1 - 34）也能诱导TRAP + MNC形成。我们得出结论，在存在适当的PTH反应性骨髓基质细胞的情况下，PTH -（1 - 34）诱导破骨细胞形成不需要破骨细胞谱系细胞上的PTH1Rs激活。MS1细胞为进一步研究PTH对破骨细胞生成的调节提供了一个有用的模型。
