miR-26b 调控脂肪酸结合蛋白4 介导脂肪细胞分化的分子机制.

BACKGROUND: The roles of miR-26b, PTEN-PI3K-AKT pathway and fatty acid-binding protein 4 (FABP4) in the process of adipocyte differentiation have been confirmed, but whether there is an interaction and their molecular mechanisms have not been reported yet. OBJECTIVE: To investigate the molecular mechanism by which miR-26b regulates FABP4-mediated adipocyte differentiation through the PTEN-PI3K-AKT pathway. METHODS: 3T3-L1 preadipocytes were set as control group, 3T3-L1 cells maturely differentiated as differentiation group, 3T3-L1 cells transfected with miR- 26b inhibitor as transfection group, and 3T3-L1 cells that were transfected with miR-26b inhibitor and then induced to differentiate were used as transfected differentiation group. Oil red O staining observed lipid droplets in mature adipocytes in the differentiation group and transfected differentiation group. Fluorescence quantitative PCR was used to detect the mRNA expression of miR-26b and FABP4, PTEN, PI3K and AKT in the cells. Western blot assay was used to identify the protein expression of FABP4, PTEN, PI3K and AKT in the cells. RESULTS AND CONCLUSION: (1) The expression of miR-26b was significantly increased after 3T3-L1 cell differentiation (P < 0.05), suggesting that it may be involved in the regulation of cell differentiation. Inhibiting the level of miR-26b in the cells could inhibit the differentiation of 3T3-L1 cells into adipocytes and reduce the accumulation of intracellular lipid droplets. (2) The mRNA and protein expression of PI3K, AKT, and FABP4 in the 3T3-L1 cells increased significantly after differentiation (P < 0.01). Although PTEN mRNA expression increased (P < 0.05), the protein level did not change obviously (P > 0.05), suggesting that during the differentiation of 3T3-L1 cells, the PI3K-AKT pathway in the cells is activated and the level of FABP4 is increased. (3) Compared with normal differentiated cells, the mRNA and protein expressions of FABP4, PI3K, and AKT in differentiated cells in which the level of intracellular miR-26b was downregulated were significantly decreased (P < 0.01), while the mRNA and protein expressions of PTEN increased (P < 0.05), suggesting that inhibition of miR-26b significantly promoted mRNA and protein expression of PTEN, thereby inhibited PI3K-AKT pathway, reduced mRNA and protein expression of FABP4, and then inhibited 3T3-L1 cell differentiation. [ABSTRACT FROM AUTHOR]