Responses of cultrued bovine mammary epithelial cells to heat stress | 高温诱导体外培养奶牛乳腺上皮细胞的应激响应

Chinese. 实验以体外培养的奶牛乳腺上皮细胞为模型，研究不同时间高温(42 ℃)热处理对细胞热休克蛋白HSP、细胞凋亡、乳脂肪和乳蛋白合成相关基因mRNA表达丰度的影响。结果发现，热休克转录子hsf-1和热休克蛋白基因hsp27、hsp70和hsp90在高温处理0.5 h后mRNA表达上调，其中hsp70转录水平有急剧上调过程，且随热处理时间延长均表现出先上升后下降的趋势；标志细胞凋亡的Bax基因从处理的0.5 h开始mRNA表达下调，随后升高；但细胞凋亡Bcl-2 mRNA表达上调；在检测的热处理过程中，αS1-酪蛋白(CSN1S1)基因转录先上调后下降，而β-酪蛋白(CSN2)和嗜乳脂蛋白(BTN)基因转录均下调；与脂肪酸合成和调控相关的基因乙酰辅酶A羧化酶(ACACA)、过氧化物酶激活受体-γ(PPARG)和固醇调节元件转录因子-1(SREBF-1)基因表达显著上调，而过氧化物酶激活受体-α(PPARA)基因mRNA转录没有明显变化。本实验结果证明热应激诱导了奶牛乳腺上皮细胞的应激反应，对细胞的乳蛋白和乳脂肪合成功能产生了显著影响，细胞产生热耐受。

English. The experiment was conducted to study the response of bovine mammary epithelial cells induced by heat stress. Bovine mammary epithelial cells were exposed to 42 ℃ as the heat stress model and 38℃ as control, the transcription of targeted genes including heat shock proteins(HSPs) family, apoptosis, mlik protein and fatty acid biosynthesis, were detected by RT-qPCR. Results showed that the mRNA expression level of hsp27, hsp70 and hsp90, and heat shock factor-1(hsf-1) increased after 0.5 h at 42 ℃, and among them hsp70 increased sharply, then decreased with the extended time of treatment. The apoptosis genes Bcl-2 and Bax had different transcription, Bcl-2 upregulated during 24 h, while Bax upregulated first and downregulated later. Heat stress decreased the mRNA level of milk protein and fatty acids genes (α- and β-casein(CSN2), butyrophilin(BTN), and fatty acid synthase), increased transcription of fatty acid biosynthesis correlative genes (acetyl CoA carboxylase (ACACA), proxiomepro liferater activatedreceptor-gama (PPARG), and sterol response element binding protein (SREBF-1)), but did not influence the expression of roxiomepro liferater activatedreceptor-alfa(PPARA). It is suggested that heat shock induced the stress responses of bovine mammary peithelial cells, remarkably impacted the secretion of milk protein and fat, and arose tolerance of cell itself.