Identification and Characterization of MicroRNAs by High Through-Put Sequencing in Mesenchymal Stem Cells and Bone Tissue from Mice of Age-Related Osteoporosis

The functional deficiencies of bone marrow-derived mesenchymal stem cells (MSCs) may contribute to the aging process and age-related diseases, such as osteoporosis. Although it has been reported that microRNAs (miRNAs) played an important role in mechanisms of gene regulation of aging, and their expression profiles in MSCs osteogenic differentiation were established in recent years, but it is still elusive for the dynamic patterns of miRNAs in aging process. Importantly, the miRNAs in aged bone tissue had not been yet reported so far. Here, we combined high through-put sequencing with computational techniques to detect miRNAs dynamics in MSCs and bone tissue of age-related osteoporosis. Among the detected miRNAs, 59 identified miRNAs in MSCs and 159 in bone showed significantly differential expressions. And more importantly, there existed 8 up-regulated and 30 down-regulated miRNAs in both MSCs and bone during the aging process, with the majority having a trend of down-regulation. Furthermore, after target prediction and KEGG pathway analysis, we found that their targeted genes were significantly enriched in pathways in cancer, which are complex genetic networks, comprise of a number of age-related pathways. These results strongly suggest that these analyzed miRNAs may be negatively involved in age-related osteoporosis, given that most of them showed a decreased expression, which could lay a good foundation for further functional analysis of these miRNAs in age-related osteoporosis.

骨髓来源间充质干细胞（bone marrow-derived mesenchymal stem cells，MSCs）的功能缺陷可能参与衰老进程及骨质疏松等衰老相关疾病的发生发展。尽管已有研究证实微小RNA（microRNAs，miRNAs）在衰老的基因调控机制中发挥关键作用，且近年来学界已明确了其在MSCs成骨分化中的表达谱，但衰老过程中miRNAs的动态表达模式仍难以阐明。尤为重要的是，截至目前尚无关于衰老骨组织内miRNAs的相关研究报道。
本研究将高通量测序与计算生物学技术相结合，对衰老相关骨质疏松患者的MSCs及骨组织中的miRNAs动态表达特征进行了检测。在本次检测到的miRNAs中，MSCs内有59种、骨组织内有159种miRNAs的表达量存在显著差异。更为关键的是，在衰老进程中，MSCs与骨组织内共有8种miRNAs表达上调、30种miRNAs表达下调，其中绝大多数呈现表达下调趋势。
此外，通过靶基因预测与KEGG通路分析，本研究发现上述miRNAs的靶基因显著富集于癌症通路；该类通路作为复杂的遗传调控网络，涵盖了多条衰老相关通路。上述研究结果强烈提示，鉴于多数此类miRNAs呈现表达下调趋势，它们可能负向参与衰老相关骨质疏松的发生发展，该发现可为后续探究此类miRNAs在衰老相关骨质疏松中的功能机制奠定坚实基础。