Key Laboratory of Metabolism and Molecular Medicine, The Ministry of Education, Shanghai, People's Republic of China.
Department of Biochemistry and Molecular Biology, Fudan University Shanghai Medical College, Shanghai, People's Republic of China.
Obesity (Silver Spring). 2015 Dec;23(12):2445-53. doi: 10.1002/oby.21319. Epub 2015 Nov 5.
The recruitment and commitment of mesenchymal stem cells and their terminal differentiation into adipocytes are the main pathways for increasing adipocyte cell numbers during obesity. Our previous studies have shown that lysyl oxidase (Lox) is upregulated and functions as an essential factor during bone morphogenetic protein 4 (BMP4) -induced C3H10T1/2 cell adipocytic lineage commitment. However, the mechanism of Lox regulation during adipogenic lineage commitment has remained largely unestablished.
Samples of adipose tissue from humans with different BMI and C57BL/6 mice with a high-fat diet were used to compare microRNA-27 (miR-27) expression level associated with obesity. Taqman assays were used for miR-27 expression detection and Oil Red O staining for adipogenesis analysis.
A negative correlation was identified between Lox expression level and miR-27 expression in both BMP4-treated C3H10T1/2 cells and human subcutaneous adipose tissues. A Lox 3' UTR luciferase reporter assay showed that miR-27 directly targeted Lox. Furthermore, overexpression of miR-27 impaired BMP4-induced upregulation of Lox and adipocytic commitment, which could be rescued by overexpression of mature Lox. Conversely, miR-27 inhibition by specific inhibitors increased Lox expression and adipocytic commitment.
Taken together, these results suggest a novel role for miR-27 in repressing adipogenic lineage commitment by targeting Lox.
间充质干细胞的募集和归巢及其终末分化为脂肪细胞是肥胖过程中脂肪细胞数量增加的主要途径。我们之前的研究表明赖氨酰氧化酶（Lox）在骨形态发生蛋白 4（BMP4）诱导的 C3H10T1/2 细胞脂肪谱系定向分化中上调并发挥重要作用。然而，Lox 在脂肪谱系定向分化过程中的调节机制在很大程度上尚未确定。
使用来自不同 BMI 的人类和高脂肪饮食的 C57BL/6 小鼠的脂肪组织样本，比较与肥胖相关的 microRNA-27（miR-27）表达水平。使用 Taqman 检测试剂盒检测 miR-27 表达，用油红 O 染色进行脂肪生成分析。
BMP4 处理的 C3H10T1/2 细胞和人皮下脂肪组织中，Lox 表达水平与 miR-27 表达水平呈负相关。Lox 3'UTR 荧光素酶报告基因检测显示，miR-27 可直接靶向 Lox。此外，miR-27 的过表达抑制了 BMP4 诱导的 Lox 上调和脂肪细胞定向分化，而过表达成熟的 Lox 可挽救这一抑制作用。相反，特异性抑制剂抑制 miR-27 增加了 Lox 的表达和脂肪细胞定向分化。
综上所述，这些结果表明 miR-27 通过靶向 Lox 在抑制脂肪谱系定向分化中发挥新的作用。
