Parathyroid Hormone-responsive Smad3-related Factor, Tmem119, Promotes Osteoblast Differentiation and Interacts with the Bone Morphogenetic Protein-Runx2 Pathway
Parathyroid Hormone-responsive Smad3-related Factor, Tmem119, Promotes Osteoblast Differentiation and Interacts with the Bone Morphogenetic Protein-Runx2 Pathway
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DOI：
10.1074/jbc.m110.179127
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发表时间：
2011-03-18
影响因子：
4.8
通讯作者：
Kaji, Hiroshi
中科院分区：
文献类型：
--
作者：
Hisa, Itoko;Inoue, Yoshifumi;Kaji, Hiroshi
甲状旁腺激素（PTH）对骨发挥合成代谢作用的机制尚不完全清楚。我们以前发现，抑制ERK 1/2增强Smad 3诱导的骨合成作用，在成骨细胞。这些研究结果表明，与由ERK 1/2抑制剂引起的Smad 3诱导信号改变相关的基因表达变化将在成骨细胞中鉴定新的骨合成代谢因子。因此，我们在空载体转染的小鼠成骨细胞MC 3 T3-E1细胞和PD 98059处理的稳定的Smad 3过表达的MC 3 T3-E1细胞之间进行了比较DNA微阵列分析。在新的因子中，Tmem 119被选择的基础上，其快速诱导PTH独立于后来增加内源性TGF-β。在MC 3 T3-E1细胞和小鼠间充质ST-2细胞的培养物中，Tmem 119的水平随着时间的推移而增加，所述细胞通过BMP-2定向成骨细胞谱系。通过Western印迹分析和免疫细胞化学测定，PTH在1小时内刺激MC 3 T3-E1细胞中的Tmem 119水平。稳定过表达Tmem 119的MC 3 T3-E1细胞表现出Runx 2、骨钙素、碱性磷酸酶和β-连环蛋白水平升高，而Tmem 119增强了间充质细胞中BMP-2诱导的Runx 2水平。在C2 C12细胞中，Tmem 119与Runx 2、Smad 1和Smad 5相互作用。总之，我们确定了一个Smad 3相关因子，Tmem 119，这是由PTH诱导，促进小鼠成骨细胞的分化。Tmem 119是成骨细胞中PTH和Smad 3信号转导通路下游的重要分子。
The mechanisms whereby the parathyroid hormone (PTH) exerts its anabolic action on bone are incompletely understood. We previously showed that inhibition of ERK1/2 enhanced Smad3-induced bone anabolic action in osteoblasts. These findings suggested the hypothesis that changes in gene expression associated with the altered Smad3-induced signaling brought about by an ERK1/2 inhibitor would identify novel bone anabolic factors in osteoblasts. We therefore performed a comparative DNA microarray analysis between empty vector-transfected mouse osteoblastic MC3T3-E1 cells and PD98059-treated stable Smad3-overexpressing MC3T3-E1 cells. Among the novel factors, Tmem119 was selected on the basis of its rapid induction by PTH independent of later increases in endogenous TGF-beta. The levels of Tmem119 increased with time in cultures of MC3T3-E1 cells and mouse mesenchymal ST-2 cells committed to the osteoblast lineage by BMP-2. PTH stimulated Tmem119 levels within 1 h as determined by Western blot analysis and immunocytochemistry in MC3T3-E1 cells. MC3T3-E1 cells stably overexpressing Tmem119 exhibited elevated levels of Runx2, osteocalcin, alkaline phosphatase, and beta-catenin, whereas Tmem119 augmented BMP-2-induced Runx2 levels in mesenchymal cells. Tmem119 interacted with Runx2, Smad1, and Smad5 in C2C12 cells. In conclusion, we identified a Smad3-related factor, Tmem119, that is induced by PTH and promotes differentiation in mouse osteoblastic cells. Tmem119 is an important molecule in the pathway downstream of PTH and Smad3 signaling in osteoblasts.