长链非编码RNA Nron抑制骨吸收对抗骨质疏松的效应及机制研究

Osteoporosis is a major disease occurred in the aged people, but its pathogenesis mechanism remains to be further investigated. We found that long noncoding RNA Nron significantly decreased after osteoclast differentiation by RNA deep sequencing. It was found that Nron inhibit osteoclast differentiation and bone resorption activity in vitro. In osteoporosis specimens derived osteoclasts, NRON level decreased and positively correlated with bone mass. Based on our precious results and recently publications, we hypothesized that Nron control bone resorption in osteoporosis. This project will use bone imaging method, bone histology method, cell biology method and molecular biology method to confirm this hypothesis. We will construct osteoclast specific Nron knockout mice and osteoclast specific Nron transgenic mice to analyzes their bone phenotypes and bone absorption ability. The binding of Nron to Mdm2 protein will be further studied for the molecular mechanisms of Nron regulating bone resorption. Then we will use osteoclast targeted delivery system to rover Nron expression and evaluate the theoretic role of Nron in osteoporotic mice. This project will provide experimental support for osteoporosis nucleic acid drug research and development.

骨质疏松是危害老年人健康的重大疾病，其发病机制有待深入研究。课题组通过RNA深度测序，发现长链非编码RNA Nron在破骨细胞分化后含量下降；Nron在体外可以显著抑制破骨细胞的分化进程和噬骨活性；在人的骨质疏松标本分离的破骨细胞中，NRON水平下降并与患者的骨量呈正相关性。基于预实验结果和文献调研，我们提出Nron通过抑制骨吸收参与骨质疏松发生发展的科学假说。本项目将采用骨影像学、骨组织学、细胞生物学、分子生物学手段，拟构建破骨细胞特异性Nron敲除小鼠和破骨细胞特异性Nron转基因小鼠，分析其整体骨表型和骨吸收能力，以明确Nron在体内对骨吸收的调控作用；以Nron新发现的结合蛋白Mdm2为切入点，深入分析Nron调控破骨细胞的分子机制；采用靶向破骨细胞的核酸递送系统增强Nron的表达水平，以评估Nron对骨质疏松小鼠的治疗作用，从而为骨质疏松新的核酸药物研发提供理论依据和实验支持。

骨质疏松是危害老年人健康的重大疾病，骨吸收激活是骨质疏松的核心发病机制之一，但lncRNA对骨吸收的调控作用尚缺乏深入研究，基于lncRNA靶向干预骨吸收进而对抗骨质疏松的研究亟待开展。通过本项目的实施，课题组发现lncRNA Nron在骨质疏松骨组织及破骨细胞分化过程中的表达水平显著下调。破骨细胞特异性敲除Nron导致小鼠骨吸收活性增加并出现骨质疏松表型。破骨细胞特异性Nron转基因小鼠骨吸收活性被抑制，同时骨量显著高于对照小鼠。分子机制研究发现Nron可通过其保守功能基序NCM2结合E3泛素连接酶CUL4B调控破骨细胞ERα的泛素化降解，进而调控破骨细胞凋亡。通过破骨细胞靶向递送Nron及NCM2至骨质疏松小鼠，发现Nron及NCM2可在体内显著抑制OVX小鼠骨吸收并提升小鼠骨量。但全长Nron治疗导致小鼠出现脾脏肿大的毒副作用，而NCM2治疗小鼠未显现出明显的毒副作用。综上所述，本项目发现Nron为体内负向调控骨吸收的关键lncRNA，而Nron功能基序NCM2有潜力成为骨质疏松基因治疗的候选核酸分子。本研究通过对lncRNA核酸药物治疗骨质疏松的初步实验探索，将为lncRNA核酸药物的临床转化提供实验依据和理论支撑。在本项目资助下，课题组于Nature Metabolism、Nature Communications、Journal of Bone and Mineral Research等国内外知名刊物共发表论文12篇，授权发明专利3件。