m6A介导的IGFBP7-OT表达上调促进骨关节炎发生发展的机制研究

骨关节炎（OA）正成为越来越严重的社会和公共卫生问题。IGFBP7-OT和IGFBP7是本课题组筛选的在OA软骨中表达显著上调的lncRNA和mRNA。我们发现：①过表达IGFBP7-OT和IGFBP7均显著抑制软骨细胞增殖、促进凋亡和基质降解；②IGFBP7-OT可抑制IGFBP7甲基化，生信分析提示IGFBP7-OT可与DNMT1/DNMT3A结合；③IGFBP7-OT存在m6A修饰，METTL14/WTAP在OA软骨中表达均上调。由此我们推测：m6A介导的IGFBP7-OT表达上调通过抑制IGFBP7基因的甲基化而上调其表达，进而抑制软骨细胞增殖、促进凋亡和基质降解，最终导致OA的发生发展。本项目拟利用ChIP、RIP和Pull-down等技术以及小鼠OA模型构建和临床标本检测对此假说进行验证。本项目的研究结果不仅有助于OA发病分子机制的阐明，而且可以为OA的预防和治疗提供新的靶点。

Osteoarthritis (OA) is becoming a more and more serious social and public health problem. IGFBP7-OT and IGFBP7 are the lncRNA and mRNA which are significantly up-regulated in OA patients' cartilage, obtained by our group through differential expression screening. We found that overexpression of IGFBP7-OT and IGFBP7 markedly inhibited chondrocyte proliferation, promoted apoptosis and extracellular matrix degradation. In addition, overexpression of IGFBP7-OT reduced the methylation level of IGFBP7 promoter, and bioinformatics analysis indicated that IGFBP7-OT could bind with the DNA methyltransferases DNMT1/DNMT3A. Moreover, we have demonstrated that there exists m6A modification in IGFBP7-OT, and the m6A “writers” METTL14 and WTAP were up-regulated in OA patients' cartilage. Therefore, we speculate that up-regulation of IGFBP7-OT mediated by m6A modification enhances IGFBP7 expression by inhibiting the methylation of IGFBP7 gene, thereby inhibits chondrocyte proliferation, promotes its apoptosis and extracellular matrix degradation, finally leads to the occurrence and development of OA. We will verify this hypothesis through Chromatin immunoprecipitation assay (ChIP), RNA immunocoprecipitation (RIP), RNA pull-down as well as mouse OA model construction and clinical samples test, etc. Results of this project will not only help to clarify the molecular mechanism of OA, but also provide a new target for the prevention and treatment of OA.