Animal Reproduction and Biotechnology Laboratory, Department of Biomedical Sciences, Colorado State University, 1351 Rampart Rd, Fort Collins, CO, 80525, USA.
Animal Breeding and Husbandry Group, Institute of Animal Science, University of Bonn, Bonn, Germany.
Sci Rep. 2020 Sep 25;10(1):15824. doi: 10.1038/s41598-020-72706-z.
Elevated summer temperature is reported to be the leading cause of stress in dairy and beef cows, which negatively affects various reproductive functions. Follicular cells respond to heat stress (HS) by activating the expression of heat shock family proteins (HSPs) and other antioxidants. HS is reported to negatively affect the bi-directional communication between the follicular cells and the oocyte, which is partly mediated by follicular fluid extracellular vesicles (EVs) released from surrounding cells. As carriers of bioactive molecules (DNA, RNA, protein, and lipids), the involvement of EVs in mediating the stress response in follicular cells is not fully understood. Here we used an in vitro model to decipher the cellular and EV-coupled miRNAs of bovine granulosa cells in response to HS. Moreover, the protective role of stress-related EVs against subsequent HS was assessed. For this, bovine granulosa cells from smaller follicles were cultured in vitro and after sub-confluency, cells were either kept at 37 °C or subjected to HS (42 °C). Results showed that granulosa cells exposed to HS increased the accumulation of ROS, total oxidized protein, apoptosis, and the expression of HSPs and antioxidants, while the viability of cells was reduced. Moreover, 14 and 6 miRNAs were differentially expressed in heat-stressed granulosa cells and the corresponding EVs, respectively. Supplementation of stress-related EVs in cultured granulosa cells has induced adaptive response to subsequent HS. However, this potential was not pronounced when the cells were kept under 37 °C. Taking together, EVs generated from granulosa cells exposed to HS has the potential to shuttle bioactive molecules to recipient cells and make them robust to subsequent HS.
夏季高温被报道是导致奶牛和肉牛应激的主要原因，这会对各种生殖功能产生负面影响。卵泡细胞通过激活热休克家族蛋白（HSPs）和其他抗氧化剂的表达来应对热应激（HS）。据报道，HS 会对卵泡细胞和卵母细胞之间的双向通讯产生负面影响，这部分是由周围细胞释放的卵泡液细胞外囊泡（EVs）介导的。作为生物活性分子（DNA、RNA、蛋白质和脂质）的载体，EVs 在介导卵泡细胞应激反应中的作用尚不完全清楚。在这里，我们使用体外模型来破译牛颗粒细胞对 HS 反应的细胞和 EV 偶联 miRNA。此外，还评估了与应激相关的 EV 对随后 HS 的保护作用。为此，从小卵泡中分离出牛颗粒细胞进行体外培养，在达到亚汇合状态后，将细胞保持在 37°C 或进行 HS（42°C）处理。结果表明，暴露于 HS 的颗粒细胞增加了 ROS、总氧化蛋白、细胞凋亡以及 HSPs 和抗氧化剂的表达，而细胞活力降低。此外，在热应激的颗粒细胞和相应的 EV 中分别有 14 个和 6 个 miRNA 表达差异。在培养的颗粒细胞中补充应激相关的 EV 可诱导其对随后的 HS 产生适应性反应。然而，当细胞保持在 37°C 时，这种潜力并不明显。总之，暴露于 HS 的颗粒细胞产生的 EV 具有向受体细胞传递生物活性分子的潜力，并使它们对随后的 HS 具有更强的抵抗力。
