College of Animal Science and Technology, Guangxi University, Nanning, 530004, Guangxi, China.
Cell Stress Chaperones. 2021 May;26(3):563-574. doi: 10.1007/s12192-021-01201-9. Epub 2021 Mar 20.
Heat stress (HS) results in health problems in animals. This study was conducted to investigate the effect and the underlying mechanism of HS on the proliferation and differentiation process of 3T3-L1 preadipocytes. 3T3-L1 preadipocytes were treated at 37 °C or 41.5 °C. HS up-regulated the mRNA and protein expression level of heat shock protein 70 (HSP70). Furthermore, the proliferation of 3T3-L1 preadipocytes were significantly inhibited after HS treatment for 2 days. A large number of accumulated lipid droplets were observed under the microscope after HS treatment for 8 days. Notably, the result of oil red O staining showed that the number of lipid droplets increased significantly and the differentiation ability of the cells was enhanced after HS. Moreover, after 2 and 8 d of differentiation, HS increased the transcription levels of fat synthesis genes including peroxisome proliferators activated receptor γ (PPARγ), fatty acid binding protein 2 (AP2), fatty acid synthase (FAS) and CCAAT enhancer binding protein α (CEBPα) genes, while decreasing the transcription levels of lipid decomposition genes including ATGL and HSL genes. In addition, HS reduced the expression of AMPK and PGC-1α, as well as the dephosphorylation of AMPK. 5-Aminoimidazole-4-carboxamide ribonucleotide (AICAR) can eliminate HS induced lipogenesis by activating AMPK. These results indicated that HS inhibited the proliferation of 3T3-L1 preadipocytes and promoted lipid accumulation by inhibiting the AMPK-PGC-1α signaling pathway in 3T3-L1 preadipocytes. This work lays a theoretical foundation for improving the effect of HS on meat quality of livestock and provides a new direction for the prevention of obesity caused by HS.
热应激（HS）会导致动物健康问题。本研究旨在探讨 HS 对 3T3-L1 前脂肪细胞增殖和分化过程的影响及其潜在机制。将 3T3-L1 前脂肪细胞在 37°C 或 41.5°C 下进行处理。HS 上调热休克蛋白 70（HSP70）的 mRNA 和蛋白表达水平。此外，HS 处理 2 天后，3T3-L1 前脂肪细胞的增殖明显受到抑制。HS 处理 8 天后，在显微镜下观察到大量堆积的脂滴。值得注意的是，油红 O 染色结果表明，HS 处理后细胞内脂滴数量明显增加，细胞分化能力增强。此外，在分化的第 2 天和第 8 天，HS 增加了脂肪合成基因包括过氧化物酶体增殖物激活受体γ（PPARγ）、脂肪酸结合蛋白 2（AP2）、脂肪酸合酶（FAS）和 CCAAT 增强子结合蛋白α（CEBPα）基因的转录水平，同时降低了脂肪分解基因包括脂肪甘油三酯酶（ATGL）和激素敏感脂肪酶（HSL）基因的转录水平。此外，HS 降低了 AMPK 和 PGC-1α 的表达以及 AMPK 的磷酸化水平。5-氨基咪唑-4-甲酰胺核糖核苷酸（AICAR）可以通过激活 AMPK 消除 HS 诱导的脂肪生成。这些结果表明，HS 通过抑制 3T3-L1 前脂肪细胞中的 AMPK-PGC-1α 信号通路，抑制 3T3-L1 前脂肪细胞的增殖并促进脂质积累。这项工作为改善 HS 对家畜肉质的效果奠定了理论基础，并为预防 HS 引起的肥胖提供了新的方向。
