调控成骨细胞的OPG表达-miR-21在骨重建中的新作用机制研究

OPG/RANKL/RANK is a key immunomodulation system in the process of bone rebuilding, which maintains balance of osteoblasts and osteoclasts activity. The role of miR-21 has been illustrated in osteogenesis and osteoclastogenesis in vitro. However, it is still unclear the real function of miR-21 in bone. Our previous studies have showed that miR-21 could modulate osteogenesis through Sprouty1 in osteoporosis caused by estrogen deficiency. We have constructed miR-21 LoxP mice, and got miR-21osb-/- mice conditional knockout mice through crossing with α1(I)Col-Cre mice that osteoblasts specific expressed. The research found that osteogenesis declined but osteoclastogenesis increased obviously, and OPG expression in osteoblasts declined remarkably. Therefore, we hypothesized that the expression of miR-21 in osteoblasts may not only affect osteogenesis but also regulate osteoblasts-osteoclasts coupling mediated by OPG system. This study intends to identify the real role of miR-21 in miR-21osb-/- conditional knockout mice without or with ovariotomy. Additionally, we will analysis of the target genes of miR-21, and regulation mechanisms of OPG system. This topic will firstly reveal microRNAs regulation involved in bone reconstruction in the process of osteogenesis and molecular mechanism of osteoclasts coupling, and provides new theoretical targets for osteoporosis treatment.

OPG/RANKL/RANK系统是骨重建过程中调控成骨-破骨偶联的关键因素，而miR-21在成骨、破骨发生中均能发挥重要作用，但miR-21是否能调控成骨-破骨偶联目前并不清楚。本课题组前期研究已表明miR-21在骨质疏松病理状态下调控成骨发生，并通过构建miR-21的LoxP小鼠，利用成骨细胞特异表达的Cre小鼠得到了miR-21Osb-/-的条件敲除小鼠，研究发现该小鼠的成骨明显下降，破骨显著增强，而且成骨细胞OPG的表达明显下降，因此我们推测成骨细胞miR-21的表达还有可能通过OPG系统影响成骨-破骨偶联。本研究拟以miR-21Osb-/-条件敲除小鼠为模型，借助去势模拟绝经后骨质疏松，分析miR-21的靶基因，及对OPG系统的调控作用机制。本课题将首次从体内角度揭示microRNAs参与骨重建过程中成骨-破骨偶联的分子机理，并为骨质疏松治疗提供新的理论思路和靶点。

MicroRNAs在骨中的重要功能已经被大量的研究所证明，但绝大部分的研究均是基于体外研究所得出的结论。而体内骨的发育和改建往往牵涉到成骨系和破骨系细胞相互作用，本项目以miR-21为研究对象，揭示了microRNAs在体内参与成骨-破骨偶联的机制。在本项目中，我们证明了成骨系细胞在体内不同病理微环境下特性变化的不一致性，提示体外单一研究成骨系细胞的特性，特别是microRNAs的功能研究还不完善。基于此，我们利用miR-21的基因敲除小鼠在体内研究microRNAs的功能。目前我们已经研究了临床正畸情况下miR-21在成骨和破骨中的作用，以及雌激素缺乏、衰老等导致骨质疏松下miR-21在成骨-破骨偶联中的作用机理。并证明了miR-21在骨中体内功能的表型主要体现在破骨层面，借助适配体靶向破骨细胞，利用AntagomiR-21抑制破骨细胞中的miR-21，可以有效防治骨质疏松的发生发展。已发表第一标注论文9篇，其中国际SCI期刊5篇，平均IF=4.7；中文核心期刊4篇。在项目支持下，联合培养博士研究生3名和硕士研究生1名。.