Extracellular vesicle-microRNAs mediated response of bovine ovaries to seasonal environmental changes

Abstract

Background Among the various seasonal environmental changes, elevated ambient temperature during the summer season is a main cause of stress in dairy and beef cows, leading to impaired reproductive function and fertility. Follicular fluid extracellular vesicles (FF-EVs) play an important role in intrafollicular cellular communication by, in part, mediating the deleterious effects of heat stress (HS). Here we aimed to investigate the changes in FF-EV miRNA cargoes in beef cows in response to seasonal changes: summer (SUM) compared to the winter (WIN) season using high throughput sequencing of FF-EV-coupled miRNAs. In addition to their biological relevance, the potential mechanisms involved in the packaging and release of those miRNAs as a response to environmental HS were elucidated. Results Sequencing analysis revealed that an average of 6.6% of the EV-RNA mapped reads were annotated to bovine miRNAs. Interestingly, miR-148a, miR-99a-5p, miR-10b, and miR-143 were the top four miRNAs in both groups accounting for approximately 52 and 62% of the total miRNA sequence reads in the SUM and WIN groups, respectively. A group of 16 miRNAs was up-regulated and 8 miRNAs were down-regulated in the SUM compared to the WIN group. Five DE-miRNAs (miR-10a, miR-10b, miR-26a, let-7f, and miR-1246) were among the top 20 expressed miRNA lists. Sequence motif analysis revealed the appearance of two specific motifs in 13 out of the 16 upregulated miRNAs under HS conditions. Both motifs were found to be potentially bonded by specific RNA binding proteins including Y-box binding proteins (YBX1 and YBX2) and RBM42. Conclusion Our findings indicate that FF EV-coupled miRNA profile varies under seasonal changes. These miRNAs could be a good indicator of the cellular mechanism in mediating HS response and the potential interplay between miRNA motifs and RNA binding proteins can be one of the mechanisms governing the packaging and release of miRNAs via EVs to facilitate cellular survival.

MicroRNA Nano-Shuttles: Engineering Extracellular Vesicles as a Cutting-Edge Biotechnology Platform for Clinical Use in Therapeutics

“…It is well-documented that the expression level of particular miRNAs are key during development [29,30] and stress responses [31,32], and that EVs play an important role in transferring miRNA cargoes between cells [33]. Alterations in the release and uptake of EVs are associated with pathologies including cancer [34] and cellular stress [32,[35][36][37][38][39].…”

Disorder of Biological Quality and Autophagy Process in Bovine Oocytes Exposed to Heat Stress and the Effectiveness of In Vitro Fertilization

“…The first symptoms of heat stress are changes in the behavior of cows, which are manifested as shorter lying periods and increased thirst [ 4 ]. It is also noted that the reproductive potential of dairy cows may be reduced due to elevated temperatures, which also reduces ovarian and corpus luteum function in summer and follicle growth and development; delays sexual maturation of individuals, extending the age of the first calving; and may also affect the retention of placenta [ 1 , 5 , 6 ]. Moreover, during heat stress in cows, there is an increase in cortisol secretion, which then interferes with the synthesis of follicle-stimulating and luteinizing hormones.…”

“…Moreover, during heat stress in cows, there is an increase in cortisol secretion, which then interferes with the synthesis of follicle-stimulating and luteinizing hormones. This may result in estrus disorders but also reduces the quality of oocytes and impairs development, growth, maturation, and functioning of dominant and preovulatory follicles [ 5 , 7 ]. Exposure to heat stress in animals can lead to atresia of the ovarian follicles and significantly reduce fertility [ 3 , 8 ].…”

“…Above these temperature indications, i.e., above 25 °C, an increase in body temperature is observed in cattle, which results in heat stress [ 8 , 11 , 12 ]. Moreover, heat stress has been shown to disrupt the production of steroid hormones, significantly alter the composition of the follicular fluid, and reduce granulosa cells (GCs), which are essential for developing oocyte competence in cows [ 1 , 5 ]. In addition, high ambient temperature causing heat stress promotes the production of reactive oxygen species (ROS), which can adversely affect the redox balance in granulosa cells [ 1 , 13 ].…”

“…The hyperthermia experienced by cows in different cycles reduces the growth of the ovarian follicle, directly affects the reduction of the oocyte pool of ovarian cells, and can also affect the oocyte, which subsequently compromises the ability of the embryo and fetus to develop [ 5 , 18 , 19 ]. Furthermore, studies have shown that the functionality of mitochondria is a crucial determinant of the development potential of oocytes affecting their quality and, thus, fertilization potential [ 20 , 21 ].…”