ANA Deficiency Enhances Bone Morphogenetic Protein-induced Ectopic Bone Formation via Transcriptional Events
ANA Deficiency Enhances Bone Morphogenetic Protein-induced Ectopic Bone Formation via Transcriptional Events
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DOI：
10.1074/jbc.m807677200
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发表时间：
2009-04-17
影响因子：
4.8
通讯作者：
Nodaa, Masaki
中科院分区：
文献类型：
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作者：
Miyai, Kentaro;Yoneda, Mitsuhiro;Nodaa, Masaki
人类关节置换术或脑损伤后异位骨形成是一种严重的并发症，可导致关节不活动和剧烈疼痛。然而，这种异位骨形成的机制尚不完全清楚。骨形态发生蛋白（BMPs）被定义为异位骨形成的诱导剂，并受到几种抑制剂的调节。ANA是一种抗增殖分子，属于Tob/BTG家族，但其在骨代谢中的活性尚不清楚。在这里，我们研究了ANA对BMP异位骨形成活性的作用。在ana缺陷小鼠和野生型小鼠中，植入BMP2诱导肌肉异位骨形成。基于3D-mu CT分析，与野生型相比，ANA缺乏增加了体内新形成骨的质量。ANA mRNA在体内骨和体外成骨细胞中均有表达。BMP2处理后MC3T3-E1成骨细胞中ANA mRNA水平升高。在这些细胞中，ANA的过表达抑制BMP诱导的与BMP反应元件相关的荧光素酶报告基因的表达。相反，小干扰RNA敲低ANA mRNA可增强BMP依赖性BMP反应元件报告因子的表达。它还增强了bmp诱导的肌源性C2C12细胞的成骨细胞分化。免疫沉淀实验表明，ANA与Smad8相互作用。因此，ANA是BMP诱导的异位骨形成的抑制因子，这种抑制ANA活性是BMP功能负反馈调节的一部分。
Ectopic bone formation after joint replacement or brain injury in humans is a serious complication that causes immobility of joints and severe pain. However, mechanisms underlying such ectopic bone formation are not fully understood. Bone morphogenetic protein (BMPs) are defined as inducers of ectopic bone formation, and they are regulated by several types of inhibitors. ANA is an antiproliferative molecule that belongs to Tob/BTG family, but its activity in bone metabolism has not been known. Here, we examined the role of ANA on ectopic bone formation activity of BMP. In ANA-deficient and wild-type mice, BMP2 was implanted to induce ectopic bone formation in muscle. ANA deficiency increased mass of newly formed bone in vivo compared with wild-type based on 3D-mu CT analyses. ANA mRNA was expressed in bone in vivo as well as in osteoblastic cells in vitro. Such ANA mRNA levels were increased by BMP2 treatment in MC3T3-E1 osteoblastic cells. Overexpression of ANA suppressed BMP-induced expression of luciferase reporter gene linked to BMP response elements in these cells. Conversely, ANA mRNA knockdown by small interference RNA enhanced the BMP-dependent BMP response element reporter expression. It also enhanced BMP-induced osteoblastic differentiation in muscle-derived C2C12 cells. Immunoprecipitation assay indicated that ANA interacts with Smad8. Thus, ANA is a suppressor of ectopic bone formation induced by BMP, and this inhibitory ANA activity is a part of the negative feedback regulation of BMP function.