猪脂肪组织发育过程中Wnt/β-catenin信号通路相关基因及脂肪转录因子的时序表达

sequential expression of Wnt/β-catenin signal pathway related genes and adipocyte transcription factors during porcine adipose tissue development

摘要:

为研究Wnt/b-catenin信号通路对猪脂肪组织发育的影响, 并探讨其可能的作用机制, 以1~120日龄长白猪脂肪组织为试验材料, 采用SQ RT-PCR法检测Wnt信号通路中相关基因β-catenin、GSK3β、Fz1及主要的脂肪转录因子PPARγ、C/EBPα 和分化早期标志基因LPL mRNA的表达变化; 石蜡切片免疫组化方法定性检测β-catenin在脂肪组织发育中的时序表达变化。SQ RT-PCR结果显示, β-catenin mRNA在猪出生第1天有高水平表达, 随着个体日龄的增长, 其表达量逐渐降低, 60日龄后维持在一个较低水平。GSK3β和Fz1 mRNA的表达量也伴随脂肪组织的发育而逐渐降低。而LPL、PPARγ和C/EBPα的 mRNA表达量随着个体日龄的增长而逐渐升高, 60日龄后仍保持高水平的表达。石蜡切片免疫组化结果显示, 随着脂肪组织的发育, β-catenin蛋白的表达也随之降低, 并且β-catenin蛋白的表达部位逐渐由细胞核和细胞质共表达变为只在细胞质中表达。上述基因表达的时序变化规律提示, β-catenin在维持前体脂肪细胞的未分化状态, 抑制脂肪组织发育中具有重要作用, 其作用机制可能是通过对脂肪细胞转录因子PPARγ、C/EBPα及分化早期标志基因LPL mRNA的调控来进行的。

Abstract:

To evaluate the influence of Wnt/β-catenin signal pathway on the porcine adipose tissue development and explore the mechanism, we detected the mRNA expression of Wnt/β-catenin signal pathway related genes: β-catenin, GSK3β, Fz1 and adipogenic transcription factors: PPARγ, C/EBPα and early differentiation marker gene LPL with semi-quantitative (SQ) RT-PCR method. Immunohistochemical method (IHC) was applied to qualitatively measure the sequential expression of β-catenin protein. The results of SQ RT-PCR showed that β-catenin highly expressed at the first day after birth, then decreased to a low plateau after 60 days, the expression of GSK3β and Fz1 also decreased with the development process of the porcine adipose tissue development. However, the sequential expression of PPARγ, C/EBPα, LPL appeared to be an opposite manner and kept at a high level after 60 days. The result of IHC showed that the expression of β-catenin protein was strong in nucleus and cytoplasm at the first day after birth, then tended to decline with the process of adipose tissue development and could be only found in cytoplasm after 30-day old. These results suggest that β-catenin plays an important role in the undifferentiated state maintenance of preadipocytes and the inhibition of porcine adipose tissue development, the mechanism maybe due to its regulation function on the adipogenic transcription factors PPARγ, C/EBPα and early differentiation marker gene LPL.