Upregulation of miR-22 Promotes Osteogenic Differentiation and Inhibits Adipogenic Differentiation of Human Adipose Tissue-Derived Mesenchymal Stem Cells by Repressing HDAC6 Protein Expression
Upregulation of miR-22 Promotes Osteogenic Differentiation and Inhibits Adipogenic Differentiation of Human Adipose Tissue-Derived Mesenchymal Stem Cells by Repressing HDAC6 Protein Expression
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DOI：
10.1089/scd.2012.0014
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发表时间：
2012-09-01
影响因子：
4
通讯作者：
Zhao, Robert Chunhua
中科院分区：
文献类型：
--
作者：
Huang, Shan;Wang, Shihua;Zhao, Robert Chunhua
骨髓间充质干细胞（Mesenchmal stem cells，MSCs）可分化为成脂细胞和成骨细胞，成脂与成骨之间存在着相互促进的关系。已有报道多种转录因子和信号通路分别调控成脂或成骨分化，但脂肪和成骨之间细胞命运改变的分子机制仍有待阐明。microRNA是多种生物过程中的重要调节因子，通过抑制其靶蛋白的表达。在此，发现miR-22以相反的方向调节人脂肪组织来源的间充质干细胞（hADMSC）的成脂和成骨分化。我们的数据表明，miR-22在成脂分化过程中减少，但在成骨分化过程中增加。一方面，miR-22在hADMSCs中的过表达可以抑制脂滴的积聚，抑制成脂转录因子和成脂特异性基因的表达。另一方面，碱性磷酸酶活性和基质矿化的增强，以及骨特异性基因表达的增加，表明miR-22在调节成骨分化中的积极作用。通过双荧光素酶报告基因测定、蛋白质印迹和实时聚合酶链反应的靶数据库预测和验证将组蛋白脱乙酰酶6（HDAC 6）鉴定为hADMSC中miR-22的直接下游靶。通过小干扰RNA抑制内源性HDAC 6抑制脂肪生成并刺激骨生成，这与hADMSC中miR-22过表达的作用一致。总之，我们的研究结果表明，miR-22通过抑制其靶点HDAC 6，在hADMSCs的成脂和成骨分化之间起到关键的平衡调节作用。
Mesenchmal stem cells (MSCs) can be differentiated into either adipocytes or osteoblasts, and a reciprocal relationship exists between adipogenesis and osteogenesis. Multiple transcription factors and signaling pathways have been reported to regulate adipogenic or osteogenic differentiation, respectively, yet the molecular mechanism underlying the cell fate alteration between adipogenesis and osteogenesis still remains to be illustrated. MicroRNAs are important regulators in diverse biological processes by repressing protein expression of their targets. Here, miR-22 was found to regulate adipogenic and osteogenic differentiation of human adipose tissue-derived mesenchymal stem cells (hADMSCs) in opposite directions. Our data showed that miR-22 decreased during the process of adipogenic differentiation but increased during osteogenic differentiation. On one hand, overexpression of miR-22 in hADMSCs could inhibit lipid droplets accumulation and repress the expression of adipogenic transcription factors and adipogenic-specific genes. On the other hand, enhanced alkaline phosphatase activity and matrix mineralization, as well as increased expression of osteo-specific genes, indicated a positive role of miR-22 in regulating osteogenic differentiation. Target databases prediction and validation by Dual Luciferase Reporter Assay, western blot, and real-time polymerase chain reaction identified histone deacetylase 6 (HDAC6) as a direct downstream target of miR-22 in hADMSCs. Inhibition of endogenous HDAC6 by small-interfering RNAs suppressed adipogenesis and stimulated osteogenesis, consistent with the effect of miR-22 overexpression in hADMSCs. Together, our results suggested that miR-22 acted as a critical regulator of balance between adipogenic and osteogenic differentiation of hADMSCs by repressing its target HDAC6.