miR-130b通过作用于PPARG调控人骨髓间充质干细胞成骨和成脂分化平衡的作用机制研究

Senile osteoporosis shows an increase in adipocytes in the bone marrow accompanied by bone loss. A balance between the differentiation of adipocytes and osteoblasts in the bone marrow must be maintained for the growth of dynamic connective bone tissue. The balance in differentiation can be disrupted, and an excessive accumulation of bone marrow adipocytes and a decrease in bone volume are observed, resulting in osteoporosis. Recent evidence has documented a functional contribution of specific miRNAs to stem cell differentiation and development in various tissues and organs. In the previous study, we have found that the expression of miR-130b was increased during osteoblast differentiation of MSC, whereas it was decreased during adipocyte differentiation, but no evidence of its functions and mechanism has been documented. Furthermore，we performed a bioinformatics analysis for the putative mRNA targets of miR-130b, and the target associated with adipocyte and osteoblast predicted was PPARG. Thus, in the present study, we will aim to investigate the expression of miR-130b during osteoblast and adipocyte differentiation of MSC, show that miR-130b could act as a mediator of adipoosteogenic differentiation，and demonstrate that miR-130b act as important endogenous negative regulators of PPARG, which promote osteogenesis and inhibit adipogenesis of MSC derived from bone marrow. This raises a possibility that miR-130b may be a promising early diagnosis and therapeutic agent for osteoporosis.

老年性骨质疏松的特点是骨量减少和骨髓中脂肪蓄积，这是由骨形成和脂肪形成的平衡紊乱所造成的。研究表明这种紊乱源于间充质干细(MSC)成骨和成脂分化的失衡。申请人通过前期研究工作发现：miR-130b参与MSC的成骨和成脂分化过程，但其具体调控作用及机制尚不清楚；作为MSC成脂和成骨分化双向调控因子的PPARG，可能是miR-130b的一个潜在靶基因。由此本项目拟通过研究：①验证miR-130b在MSC成骨分化和成脂分化过程中的差异表达趋势；②证明上调miR-130b的表达，可以促进MSC的成骨分化，而抑制其成脂分化；③明确miR-130b是通过抑制PPARG的表达来调控MSC的成骨和成脂分化。由此阐明miR-130b参与调控MSC成骨成脂分化平衡的作用机制，丰富MSC分化失衡解释老年性骨质疏松发病机制的理论，为今后利用这些分子进行骨质疏松的早期诊断及靶向治疗提供新的途径和研究思路。

老年性骨质疏松的特点是骨量减少和骨髓中脂肪蓄积，这是由骨形成和脂肪形成的平衡紊乱所造成的。研究表明这种紊乱源于间充质干细(MSC)成骨和成脂分化的失衡。申请人通过前期研究工作发现：miR-130b参与MSC的成骨和成脂分化过程，但其具体调控作用及机制尚不清楚；作为MSC成脂和成骨分化双向调控因子的PPARG，可能是miR-130b的一个潜在靶基因。本项目在建立人骨髓MSC及成骨成脂分化诱导体系的基础上，验证了miR-130b在MSC成骨分化和成脂分化过程中的差异表达趋势；然后通过病毒感染上调MSC内miR-130b的表达水平，证明了上调miR-130b的表达，可以促进MSC的成骨分化，而抑制其成脂分化；最后通过荧光素酶报告系统明确了miR-130b是通过抑制PPARG的表达来调控MSC的成骨和成脂分化。由此阐明miR-130b参与调控MSC成骨成脂分化平衡的作用机制，丰富MSC分化失衡解释老年性骨质疏松发病机制的理论，为今后利用这些分子进行骨质疏松的早期诊断及靶向治疗提供新的途径和研究思路。