GDF-5在脂肪细胞分化过程中对PPARγ、Smads通路的作用及其分子机制研究

Adipocytes over-differentiation, proliferation and increase in cell size consist of the basis of obesity. When we studied the growth differentiation factor 5 (GDF 5) gene single nucleotide polymorphisms' correlation with adult height, we are surprised to found that one SNP rs 143384 of GDF 5 gene was significantly correlated with male body weight and BMI. We subsequently tested GDF 5 gene expression profile in high-fat diet-induced obese rats fat tissue, we found that GDF 5 gene expression is significantly higher in the high-fat diet treated mice. Then, we observed the 3T3-L1 preadipocytes differentiation procedure, we found that GDF 5 gene expression profile demonstrates significant phase characteristics like PPAR γ. We treated 3T3-L1 preadipocytes with recombinant GDF 5 protein, we found that GDF 5 protein can induce significantly increased PPARγ, C / EBPα gene expression and promote 3T3-L1 preadipocytes differentiation. The above results suggest that GDF 5 gene can promote preadipocyte differentiation, these findings have not been reported yet. We intend to build aP2 promoter specificity GDF 5 transgenic mice, and analyze the characteristics of white and brown fat cell biological and in vivo metabolic changes of the transgenic mice. We also will analyze the effect of GDF 5 shRNA interference on the differentiation procedure of 3T3-L1 preadipocytes and its potential signaling pathways like PPARγ,Smads pathway. Finally, we intend to analyze the effect of recombination GDF 5 protein on mesenchymal pluripotent cells C3H10T1 / 2 differentiation tendency to brown or white fat cells, based on the above experiments, we will be able to unveil the effect of GDF 5 gene on adipocyte differentiation more completely and find the key signaling pathways.

脂肪细胞过度分化增殖和体积增大是肥胖发生的基础。我们在研究生长分化因子GDF 5 SNP与成年身高的关系时意外发现rs 143384与男性BMI相关，随后发现高脂饮食诱导的肥胖大鼠GDF 5基因表达显著增高，在3T3-L1前脂肪细胞诱导分化过程中GDF 5的表达存在显著的时相性特征， GDF 5重组蛋白可诱导3T3-L1前脂肪细胞PPARγ、C/EBPα基因的高表达并促进其分化，提示GDF 5对脂肪细胞分化起促进作用，上述发现未见报道。我们拟构建aP2为启动子的脂肪组织特异性GDF 5高表达转基因小鼠，分析其白色和棕色脂肪细胞生物学特点及体内代谢变化；分析GDF 5 shRNA干扰对3T3-L1前脂肪细胞分化、PPARγ、Smads等关键信号通路的影响；结合GDF 5对间充质多能干细胞C3H10T1/2分化倾向性的影响分析，较完整的揭示GDF 5促进脂肪细胞分化的作用和关键信号通路。

脂肪细胞的数量、大小和脂质沉积的多寡是肥胖形成的共同基础。从脂肪细胞分化调控机制研究的角度出发，研究脂肪细胞数量变化的调控机制，不仅对寻求合理的措施干预儿童期肥胖十分重要，对预防成年期肥胖及MS的发生同样有特别重要的意义。本1年期资助课题研究了：1.GDF5重组蛋白在脂肪细胞分化过程中对棕色脂肪分化相关基因亦有促进作用；2.采用GDF5 shRNA慢病毒转染3T3-L1前脂肪细胞后，脂肪细胞分化受阻，脂肪分化相关基因表达下调；3.GDF5重组蛋白能够部分挽救GW9662对脂肪细胞分化的抑制作用，说明GDF5可能通过PPARg通路调控脂肪分化。从而进一步证明了GDF5对脂肪细胞分化具有促进作用，为进一步研究GDF5参与肥胖的形成奠定了重要理论基础，具有良好的创新性和潜在的临床实用性。

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