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 oocyte 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.

The effect of L-carnitine supplementation during in vitro maturation on oocyte maturation and somatic cloned embryo development.

The quality of the recipient cytoplasm was reported as a crucial factor in maintaining the vitality of SCNT embryos and SCNT efficiency for dairy cows. Compared with oocytes matured in vivo, oocytes matured in vitro showed abnormal accumulation and metabolism of cytoplasmic lipids. L-carnitine treatment was found to control fatty acid transport into the mitochondrial ß-oxidation pathway, which improved the process of lipid metabolism. The results of this study show that 0.5 mg/ml L-carnitine significantly reduced the cytoplasmic lipid content relative to control. No significant difference was observed in the rate of oocyte nuclear maturation, but the in vitro developmental competence of SCNT embryos was improved in terms of increased blastocyst production and lower apoptotic index in the L-carnitine treatment group. In addition, the pregnancy rate with SCNT embryos in the treatment group was significantly higher than in the control group. In conclusion, the present study demonstrated that adding L-carnitine to the maturation culture medium could improve the developmental competence of SCNT embryos both in vitro and in vivo by reducing the lipid content of the recipient cytoplasm.

bta-miR-183 targets EZRIN to regulate microvilli formation and improve early development of bovine embryos.

In brief: Almost total lack of sperm-borne RNAs is regarded as one of the key factors that leads to the abnormal development of somatic cell nuclear transfer embryo. This paper reveals a need for us to further explore the roles of the paternal regulatory factors on embryonic development in early embryos. Abstract: Mature sperm contain both coding and non-coding RNAs, which can be delivered into an oocyte with the sperm at fertilization. Accumulating evidences show that these sperm-borne RNAs play crucial roles in epigenetic reprogramming, cytoskeleton remodeling, embryonic development, and offspring phenotype. Almost total lack of sperm-borne RNAs is regarded as one of the key factors that leads to the abnormal development of somatic cell nuclear transfer (SCNT) embryo. bta-miR-183 was found to be highly expressed in bovine sperm and can be delivered into oocytes during fertilization in our previous study, and in this study, EZR was confirmed as a target gene of bta-miR-183 in early embryos by bioinformatics, luciferase, and gain-of-function and loss-of-function experiments. Scanning electron microscopy showed that the density of microvilli on the surface of SCNT embryos was significantly higher than that onin vitro fertilized embryos and was significantly reduced by injection of bta-miR-183 mimic. EZR-siRNA injected into SCNT embryos had a similar effect. This indicated that the lack of bta-miR-183 might lead to abnormal changes in microvilli by downregulating ezrin protein. In addition, gain-of-function studies showed that bta-miR-183 significantly improved developmental competence of SCNT embryo in terms of cleavage (76.63% vs 64.32%, P < 0.05), blastocyst formation (43.75% vs 28.26%, P < 0.05), apoptotic index (5.21% vs 12.64%, P < 0.05), and the trophoblast ratio (32.65% vs 25.58%, P < 0.05) in day 7 blastocysts. Thus, the present study indicated that bta-miR-183 might play crucial roles in the formation of microvilli and embryo development by regulating expression of EZR mRNA.

A novel indel within the bovine SEPT7 gene is associated with ovary length.

The ovary can generate oocytes and secrete female hormones and thus is of great significance to animal fertility. In turn, the functioning of this organ has an effect on the profit margins of the livestock breeding industry. As the development-regulating gene and target gene of miR-202, SEPT7 might play an important role in ovarian growth. Therefore, we hypothesized that SEPT7 is related to ovarian traits owing to the regulation of gonad-specific miR-202. To further investigate the connection between bovine SEPT7 and ovarian development, we analyzed data from 408 samples. After genotyping and analyzing three selected loci, we found that two out of the three loci (L1 and L5) were polymorphic, of which the minimum allelic frequencies were 0.417 (L1) and 0.094 (L5). Moreover, one novel indel L1 of SEPT7 was associated with ovarian length (p < 0.05). More specifically, individuals with II and ID genotypes have longer ovaries than those with the DD genotype. Our work shows that SEPT7 can be selected as a testing marker gene for animal fertility. Our findings contribute to improving the prospects of the cattle industry and the wider use of genetic techniques in breeding.

Current understanding of metal ions in the pathogenesis of Alzheimer's disease.

Background: The homeostasis of metal ions, such as iron, copper, zinc and calcium, in the brain is crucial for maintaining normal physiological functions. Studies have shown that imbalance of these metal ions in the brain is closely related to the onset and progression of Alzheimer's disease (AD), the most common neurodegenerative disorder in the elderly. Main body: Erroneous deposition/distribution of the metal ions in different brain regions induces oxidative stress. The metal ions imbalance and oxidative stress together or independently promote amyloid-ß (Aß) overproduction by activating ß- or γ-secretases and inhibiting α-secretase, it also causes tau hyperphosphorylation by activating protein kinases, such as glycogen synthase kinase-3ß (GSK-3ß), cyclin-dependent protein kinase-5 (CDK5), mitogen-activated protein kinases (MAPKs), etc., and inhibiting protein phosphatase 2A (PP2A). The metal ions imbalances can also directly or indirectly disrupt organelles, causing endoplasmic reticulum (ER) stress; mitochondrial and autophagic dysfunctions, which can cause or aggravate Aß and tau aggregation/accumulation, and impair synaptic functions. Even worse, the metal ions imbalance-induced alterations can reversely exacerbate metal ions misdistribution and deposition. The vicious cycles between metal ions imbalances and Aß/tau abnormalities will eventually lead to a chronic neurodegeneration and cognitive deficits, such as seen in AD patients. Conclusion: The metal ions imbalance induces Aß and tau pathologies by directly or indirectly affecting multiple cellular/subcellular pathways, and the disrupted homeostasis can reversely aggravate the abnormalities of metal ions transportation/deposition. Therefore, adjusting metal balance by supplementing or chelating the metal ions may be potential in ameliorating AD pathologies, which provides new research directions for AD treatment.