miR-214在运动防治骨质疏松中的作用机制研究

The prevalence of osteoporosis increases dramatically in recent years, becoming a public health concern in the world. However, no perfect drug had been developed for anti-osteoporosis though bisphosphonates (eg. alendronate) were wildly used to inhibit the activity of osteoclasts and estradiol were used as hormone replacement thearpy (HRT) would efficiently prevent bone loss and improve osteogenesis. As long as various side effects of bisphosphonates or HRT, these drugs were carefully chosen for prevention and treatment of osteoporosis in clinical. Previous studies have showed that physical activity or appropriate exercise can prevent or treatment the development of osteoporosis as which can helps decearse bone loss, increase bone formation. However, the mechanisms of exercise preventing osteoporosis were poorly understood. Our preliminary studies have indicated that appropriate exercise had effects in bone formation and inhibition resorption, and it may induced by activating Wnt, BMPs or OPG-RANK-RANKL signaling pathway. At the same time, we also found exercise inhibited endogenous miR-214 expression in the bone. miR-214 targets the mRNA of ATF4 and Osterix(SP7), and has been proven that was negatively correlated with bone formation. Thus, we proposed the hypothesis that exercise prevents and treatment osteoporosis through inhibiting endogenous miR-214 expression. In this program, we plan to create the ovariectomized mice of overexpression or knockdown miR-214, and then they will be assigned the treadmill running protocol, combined with mechanical stress including tension and compression for mice bone mesenchymal stem cell to test the hypothesis above. This study will greatly increase our understanding of the molecular mechanism for exercise preventing osteoporosis, and provide the potential therapy target in clinical rehabilitation.

随着骨质疏松发病率逐年升高，如何防治骨质疏松成为当前的一个热点问题。长期药物治疗的各种副作用使其临床应用受到一定限制，适宜运动可以在一定程度上防治骨质疏松，但机制尚未完全阐明。我们前期研究发现：1、适宜运动有较好的骨生成和抑制骨吸收作用，其机制可能是通过激活Wnt、BMPs、OPG-RANK-RANKL等信号通路而发挥其生物学效应；2、适宜运动抑制骨骼内源性miR-214表达。而miR-214又作用于ATF4和Osterix mRNA从而抑制骨生成，因此，我们推测抑制内源性miR-214表达从而促进骨生成作用可能是运动防治骨质疏松的部分机制。本课题拟采用过表达和敲低miR-214的去卵巢小鼠进行跑台运动、结合对小鼠间充质干细胞进行机械应力干预来明确“运动/机械应力—miR-214—骨生成”这一假说。该研究的开展不仅有助于部分揭示运动防治骨质疏松的机制，也为临床康复提供一定的理论依据。

我们前期的研究发现运动可通过调控雌激素、细胞因子、OPG-RANKL-RANK通路以及Wnt信号传导通路起到防治骨质疏松的作用。本课题在此基础上进一步探究运动对骨质疏松小鼠成骨细胞和间充质干细胞成骨分化中起着重要调控作用的非编码RNA miR-214及其下游靶基因的影响。课题拟采用在体和离体实验结合的方法进行研究。在体实验采用去卵巢手术建立骨质疏松小鼠模型，离体实验采用牵张干预的培养方法并结合miR-214激活剂和抑制剂的转染，通过检测成骨细胞和间充质干细胞中miR-214及其下游靶基因ATF4和β-catenin蛋白及基因的表达，探究运动是否通过调控内源性miR-214的表达，进而使骨生成增加，起到预防和治疗骨质疏松的作用。本研究以非编码RNA miR-214为切入点，有助于从分子水平揭示运动防治骨质疏松的作用机制。因而，本研究项目具有非常重要的理论意义。