Inhibition of HSP90AA1 induces abnormalities in bovine oocyte maturation and embryonic development

In brief: HSP90AA1 is a ubiquitous molecular chaperone that can resist cellular stress, such as oxidative stress and apoptosis, and mediate the efficacy and protein folding of normal cells during heat stress, as well as many other functions. This study further reveals the role of HSP90AA1 in bovine oocytes maturation and early embryonic development. Abstract: HSP90AA1, a highly abundant and ubiquitous molecular chaperone, plays important roles in various cellular processes including cell cycle control, cell survival, and hormone signaling pathways. In this study, we investigated the functions of HSP90AA1 in bovine oocyte and early embryo development. We found that HSP90AA1 was expressed at all stages of development, but was mainly located in the cytoplasm, with a small amount distributed in the nucleus. We then evaluated the effect of HSP90AA1 on the in vitro maturation of bovine oocytes using Tanespimycin (17-AAG), a highly selective inhibitor of HSP90AA1. The results showed that inhibition of HSP90AA1 decreased nuclear and cytoplasmic maturation of oocytes, disrupted spindle assembly and chromosome distribution, significantly increased acetylation levels of α-tubulin in oocytes and affected epigenetic modifications (H3K27me3 and H3K27ac). In addition, H3K9me3 was increased at various stages during early embryo development. Finally, the impact of HSP90AA1 on early embryo development was explored. The results showed that inhibition of HSP90AA1 reduced the cleavage and blastocyst formation rates, while increasing the fragmentation rate and decreasing blastocyst quality. In conclusion, HSP90AA1 plays a crucial role in bovine oocyte maturation as well as early embryo development.