Li Yinxia, Li Fan, Shu Jiaao, Meng Chunhua, Zhang Jun, Zhang Jianli, Qian Yong, Wang Huili, Ding Qiang, Cao Shaoxian
Institute of Animal Science, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China; Jiangsu Province Engineering Research Center of Precision Animal Breeding, Nanjing 210014, China; Key Laboratory of Crop and Animal Integrated Farming, Ministry of Agriculture, Nanjing 210014, China.
Institute of Animal Science, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China.
Anim Reprod Sci. 2025 Jan;272:107649. doi: 10.1016/j.anireprosci.2024.107649. Epub 2024 Nov 19.
The adverse effects of heat stress on reproductive performance of sheep are becoming increasingly severe. Previous research has revealed that heat stress decreases both cholesterol and estradiol content; however, regulation of estradiol by cholesterol and its regulatory mechanism under heat stress are unclear. Mevalonate kinase (MVK), a key cholesterol synthesis pathway enzyme, binds to the luteinizing hormone receptor (LHR; a key gene regulating hormone synthesis) mRNA. In this study, ovine ovarian granulosa cells (GCs) were used in an in vitro model. To elucidate the underlying molecular mechanism, immunofluorescence, quantitative reverse transcription polymerase chain reaction, western blotting, enzyme-linked immunosorbent assay, and an RNA electrophoretic mobility shift assay (REMSA) were used to investigate whether the decrease in cholesterol caused by acute heat stress resulted in a decrease in estradiol synthesis. Acute heat stress reduced the cholesterol content in ovine ovarian GCs, which transactivated the cholesterol synthesis pathway corresponding to the gene expression of sterol regulatory element-binding protein (SREBP-1A), SREBP-2, and MVK. Upregulated MVK increased the MVK-LHR mRNA complex, which caused LHR mRNA decay and downregulation, further leading to the downregulation of CYP19A1 and a decrease in estradiol. The cholesterol synthesis inhibitor, PF-429242, alleviated the decrease in estradiol synthesis caused by acute heat stress. Overall, acute heat stress caused a decrease in total cholesterol, which transactivated the expression of cholesterol synthesis genes, such as SREBP-1A, SREBP2, and MVK, increasing the MVK-LHR complex, downregulating LHR expression, and further decreasing estradiol.
热应激对绵羊繁殖性能的不利影响日益严重。先前的研究表明，热应激会降低胆固醇和雌二醇含量；然而，胆固醇对雌二醇的调节及其在热应激下的调节机制尚不清楚。甲羟戊酸激酶（MVK）是胆固醇合成途径的关键酶，可与促黄体生成素受体（LHR；调节激素合成的关键基因）mRNA结合。在本研究中，使用绵羊卵巢颗粒细胞（GCs）建立体外模型。为阐明潜在的分子机制，采用免疫荧光、定量逆转录聚合酶链反应、蛋白质免疫印迹、酶联免疫吸附测定和RNA电泳迁移率变动分析（REMSA），研究急性热应激导致的胆固醇降低是否会引起雌二醇合成减少。急性热应激降低了绵羊卵巢GCs中的胆固醇含量，这激活了与固醇调节元件结合蛋白（SREBP-1A）、SREBP-2和MVK基因表达相对应的胆固醇合成途径。上调的MVK增加了MVK-LHR mRNA复合物，导致LHR mRNA降解和下调，进而导致CYP19A1下调和雌二醇减少。胆固醇合成抑制剂PF-429242减轻了急性热应激引起的雌二醇合成减少。总体而言，急性热应激导致总胆固醇降低，激活了胆固醇合成基因如SREBP-1A、SREBP2和MVK的表达，增加了MVK-LHR复合物，下调了LHR表达，并进一步降低了雌二醇。
