Trim33对骨髓基质细胞脂堆积及脂肪特异性基因表达影响

Trim33 promotes lipid accumulation and expressions of adipocyte-specific genes in bone marrow stromal cells

目的三结构域家族33(Trim33)在调控成骨细胞分化的过程中起到了非常重要的作用,而在脂肪细胞分化过程中的作用却鲜有报道。文中以Trim33为对象探讨其对脂肪细胞分化的影响。方法以转染Trim33-pcDNA3.1过表达质粒的骨髓基质细胞ST2细胞作为实验组,以转染pc DNA3.1质粒的骨髓基质细胞ST2细胞作为对照组,将2组细胞进行成脂诱导分化后,利用油红O染色、qRT-PCR及Western blot技术分析2组细胞CCAAT增强子结合蛋白(C/EBP)α、成脂相关因子过氧化物酶体增殖物激活受体(PPAR)γ、脂肪细胞表征因子FABP4、脂肪因子adipsin等脂肪特异性基因表达的变化。结果与对照组相比,实验组Trim33表达水平显著上升(1.00±0.31 vs 88.51±14.31,P<0.01)。成脂诱导5 d后,经油红O染色,转染Trim33-pcDNA3.1过表达质粒,实验组较对照组细胞脂滴数量明显增多。A520结果与染色一致,实验组的A值明显高于对照组(0.69±0.03 vs 0.34±0.03,P<0.01)。与对照组比较,实验组PPARγ、C/EBPα、FABP4、adipsin mRNA相对表达[(1.00±0.19) vs (1.79±0.21)、(1.00±0.12) vs (2.28±0.24)、(1.00±0.01) vs (10.30±1.38)、(1.00±0.16) vs (12.50±1.96)]均明显增加(P<0.05)。实验组较对照组成脂特异性基因Trim33、PPARγ、C/EBPα、FABP4的蛋白表达上调。结论 Trim33能促进骨髓基质细胞脂堆积并增强脂肪特异性基因的表达。

Objective Tripartite motif 33 （Trim33） is known to play a very important part in regulating osteoblast differentiation, but its role in adipocyte differentiation is rarely reported. The aim of this study was to investigate the regulatory effect of Trim33 on adipocyte differentiation. Methods Bone marrow stromal cell ST2 cells transfected with the Trim33-pcDNA3.1 plasmid were included in the experimental group and those transfected with the pcDNA3.1 plasmid taken as the control. The cells of both groups were treated with adipogenic medium to induce adipocyte differentiation, followed by determination of the expressions of the adipocyte-specific genes CCAAT enhancer binding protein alpha （C/EBPα）, peroxisome proliferator-activated receptor gamma （PPARγ）, adipocyte characterizing factor FABP4, and adipocytokines adipsin by oil red O staining, qRT-PCR and Western blotting. Results The expression of Trim33 was significantly upregulated in the experimental group as compared with that in the control （88.51±14.31 vs 1.00±0.31, P 〈0.01）. After 5 days of adipogenesis induction, there were dramatically more lipid droplets in the ST2 cells and the A value was markedly higher in the former than in the latter group （0.69± 0.03 vs 0.34±0.03, P 〈0.01）. Compared with the control, the cells in the experimental group exhibited remarkable increases in the relative mRNA expressions of C/EBPα, PPARγ, FABP4 and adipsin as well as the protein expressions of Trim33, PPARγ, C/EBPα and FABP4. Conclusion Trim33 promotes lipid accumulation and upregulates the expressions of adipocyte-specific genes in bone marrow stromal cells.