Exposure to copper compromises the maturational competency of porcine oocytes via oxidative stress-induced DNA damage
Ontology highlight
ABSTRACT: Copper (Cu) is not only one of the essential trace elements for animal body, but also an important nutrient component for normal physiology and metabolism of animal reproductive system. Lack or excess of copper will directly or indirectly affect animal reproductive activities. However, the effect of copper on reproductive performance of boars and sows has not been studied and the effect of excessive Copper addition on reproductive performance of sows is even less, and the molecular mechanism is poorly understood. Here, we document that copper has the negative effects on the oocyte maturation and Organelle function. We show that copper exposure perturbs the porcine oocyte meiotic maturation and impair the spindle/chromosome structure, displaying an obviously defective spindle assembly, and abnormal distribution of actin dynamics and cortical granules. In addition, single-cell transcriptome analysis identifies target effectors of copper in porcine oocytes, which was further demonstrated that copper exposure affects the distribution and function of mitochondria, and high ROS levels, DNA damage, and early apoptosis in porcine oocytes. Collectively, we demonstrate that copper exposure causes abnormalities in mitochondrial function and distribution, resulting in increased oxidative stress ROS levels, DNA damage and apoptosis, ultimately leading to decreased quality of porcine oocytes.
Project description:Elevated ambient temperature results in heat stress which is a major concern for productivity and product quality due to its negative impact on animal health, productivity and product quality. As global warming becomes more and more serious, the impact of heat stress (HS) on animal husbandry cannot be ignored. However, the effect of NMN on the quality of porcine oocytes after heat stress and the prevention strategies are not yet fully understood. Here, we report that nicotinamide mononucleotide (NMN) treatment ameliorates the quality of porcine oocytes exposed to heat stress. Specifically, we found that HS caused oocyte meiosis failure by disrupting the dynamics and arrangement of meiotic organelles, showing obvious damage to cytoskeleton assembly. Furthermore, heat stress can cause damage to oocyte mitochondria, which is an indicator of oocyte cytoplasmic maturation. On the contrary, supplementation of NMN can improve this phenomenon, maintain the normal chromosome/spindle structure, and the dynamics of CGs and its core content ovastacin.
Project description:Spermidine is involved in a variety of biological processes, including DNA metabolism, autophagy and aging. Previous studies have shown that spermidine can increase the percentage of mouse oocytes developing into blastocysts after in vitro fertilization. However, none of the past studies elucidated the effects of spermidine supplementation on porcine oocyte maturation. Here, we choose appropriate dose of spermidine to be added to the maturation medium during in vitro maturation (IVM) to verify whether spermidine can actively promote the maturation of porcine oocytes. Our study provided substantial evidence that spermidine exposure promoted the porcine oocyte meiotic maturation. In addition, single-cell transcriptome analysis identified the target effectors of spermidine actions in porcine oocytes, further demonstrating that spermidine exposure enhanced mitochondrial distribution and function, leading to a reduced excessive oxidative stress-induced DNA damage and early apoptosis of porcine oocytes. These findings demonstrate that spermidine not only delays ageing and cancer treatment, but also improves the quality of germ cells, which may be less likely to suffer from sterility or infertility in humans and animals.
Project description:SIRT6, the sixth member of sirtuin family proteins, has been identified as a crucial regulator in multiple molecular pathways related to aging, including genome stability, DNA damage repair, telomere maintenance and inflammation. However, the exact roles of SIRT6 during mammalian oocyte meiosis have not yet fully clarified. Here, we investigated the critical events during porcine oocyte meiotic maturation with the treatment of SIRT6 specific inhibitor SIRT6-IN-1. We found that SIRT6 inhibition resulted in oocyte meiotic failure by displaying the poor expansion of cumulus cells and reduced rate of polar body extrusion. Meanwhile, the compromised spindle assembly, chromosome alignment and actin dynamics were also observed in SIRT6-inhibited oocytes. Moreover, inhibition of SIRT6 led to the defective cytoplasmic maturation by showing the abnormal distribution of cortical granules and their component ovastacin. Notably, we identified that expression of genes related to oocyte meiosis, oxidative phosphorylation and cellular senescence was remarkably altered in SIRT6-inhibited oocytes by transcriptome analysis, and validated that the meiotic defects caused by SIRT6 inhibition resulted from the excessive ROS-induced early apoptosis in oocytes. Taken together, our findings demonstrate that SIRT6 promotes the porcine oocyte meiotic maturation via maintaining the organelle dynamics.
Project description:We used porcine oocytes as model and found that MAL exposure significantly impaired porcine oocyte maturation in a dose dependent manner. RNA-seq analyses showed that MAL altered the mRNA level of 2917 genes in the porcine maturated oocytes and most of these genes were related to ROS, the lipid droplet process and the energy supplement.
Project description:Advanced age is a primary risk factor for female infertility due to reduced ovarian reserve and declining oocyte quality. However, as an important contributing factor, the role of metabolic regulation during reproductive aging is poorly understood. Here, we applied untargeted metabolomics to identify spermidine as a critical metabolite in ovaries to protect oocytes against aging. In particular, we found that spermidine level was reduced in aged ovaries and supplementation of spermidine promoted follicle development, oocyte maturation, early embryonic development and female fertility of aged mice. By micro-transcriptomic analysis, we further discovered that recovery of oocyte quality by spermidine was mediated by enhancement of mitophagy activity and mitochondrial function in aged mice, and this action mechanism was conserved in porcine oocytes under oxidative stress. Altogether, our findings demonstrate that spermidine supplementation is a potentially effective strategy to ameliorate oocyte quality and reproductive outcome of women at an advanced age.
Project description:Oocyte quality, which is directly related to reprogramming competence, is a major important limiting factor in animal cloning efficiency. Compared with oocytes matured in vivo, in vitro matured (IVM) oocytes exhibit lower oocyte quality and reprogramming competence primarily because of their higher levels of reactive oxygen species (ROS). In this study, we investigate whether supplementing the oocyte maturation medium with melatonin, a free radical scavenger, could improve oocyte quality and reprogramming competence. We found that 10−9 M melatonin effectively alleviated oxidative stress, markedly decreased early apoptosis levels, recovered the integrity of mitochondria, ameliorated the spindle assembly and chromosome alignment in oocytes, and significantly promoted subsequent cloned embryo development in vitro. We also analyzed the effects of melatonin on epigenetic modifications in bovine oocytes. Melatonin increased the global H3K9 acetylation levels, reduced the H3K9 methylation levels, and minimally affected DNA methylation and hydroxymethylation. Genome-wide expression analysis of genes affected by melatonin during oocyte maturation was conducted by high-throughput scRNA sequencing. We found that several important genes altered by melatonin were involved in oocyte stress defense. These genes included GSTP1, mitochondrial DNA polymerase POLG, mitochondrial ATP synthase ATP5E, centriole-enriched gene CEP295, spindle assembly-related gene TCTP, cytoprotection, and anti-apoptosis-related gene HSP27. Our results indicated critical roles of melatonin during bovine oocyte maturation and development.
Project description:Advanced maternal age, defined as 35 years or older, is associated with a decline in both ovarian reserve and oocyte quality, which leads to the female infertility, pregnancy loss, fetal anomalies, stillbirth, and obstetric complications. At present, the effective approaches to counteract the maternal age-related decay of oocyte quality are still not fully determined. Here, we report that in vivo supplementation of nicotinamide mononucleotide (NMN) efficaciously ameliorates the quality of oocytes from naturally aged mice by recovering nicotinamide adenine dinucleotide (NAD + ) levels in oocytes. NMN supplementation increases the number of antral follicles, ovulated oocytes and matured oocytes from aged mice. Specifically, NMN supplementation maintains the normal spindle/chromosome structure and dynamics of cortical granule component ovastacin to ensure the meiotic competency and fertilization ability of aged oocytes. Moreover, single cell transcriptome analysis shows that the beneficial effect of NMN on the aged oocytes is mediated by the restoration of the mitochondrial function, thereby reducing the accumulated ROS to suppress the occurrence of apoptosis. To sum up, our data reveal that supplementation of NMN is a feasible approach to prevent oocyte quality from advanced maternal age-related deterioration, contributing to improve the reproductive outcome of aged women and the assisted reproductive technology.
Project description:The oocytes of many species, both invertebrate and vertebrate, contain a large collection of localized determinants in the form of proteins and translationally inactive maternal mRNAs. However, it is unknown whether mouse oocytes contain localized MmRNA determinants and what mechanisms might be responsible for their control. We collected intact MII oocytes, enucleated MII oocyte cytoplasts (with the spindle removed), and spindle-chromosome complexes which had been microsurgically removed. RNA was extracted, amplified, labeled, and applied to microarrays to determine if any MmRNA determinants were localized to the SCC. We used microarrays to determine whether maternal mRNAs in mouse oocytes are enriched in the meiotic spindle
Project description:Bisphenol S (BPS) is widely used to replace earlier-eliminated BPA. We evaluated the effect of acute in vivo BPS exposure on oocyte quality using eight-weeks-old ICR female mice (N = 15 per experimental group), exposed to vehicle or BPS1-BPS4 (0.001, 0.1, 10, and 100 ng BPS x g bw-1 x day-1, respectively). Oocytes were isolated and matured in vitro. Thereafter, we observed that BPS exposure increases aberrant spindle formation in mature oocytes and induces DNA damage. Moreover, BPS3 significantly increases chromatin repressive marks 5-methyl cytosine (5meC) and H3K27me2 in immature oocytes. In the BPS2 group (0.1 ng x g bw-1 x day-1), the increase in 5meC arises during oocyte maturation. Transcriptome analysis shows differential expression of early embryonic development transcripts in BPS2-exposed oocytes. These findings indicate that the biological effect of BPS is non-monotonic, affecting oocyte quality even at concentrations that are orders of magnitude below those measured in humans. We used microarray aproach to unravel gene expression differences triggered by the administration of BPS at different concentrations in mouse oocytes.
Project description:Postovulatory aging leads to the decline in oocyte quality and subsequent impairment of embryonic development, thereby reducing the success rates of assisted reproductive technology (ART). Nevertheless, potential preventative strategies to improve aging oocytes quality and the associated underlying mechanisms warrant further investigation. In this study, we identify cordycepin, an natural nucleoside analogue, as having the potential to restore the postovulatory aging-induced decline in oocyte quality, including aspects such as oocyte fragmentation, embryonic developmental competence, spindle/chromosomes morphology and mitochondrial function. Proteomic and RNA sequencing analyses revealed that cordycepin inhibited the degradation of several crucial maternal proteins and mRNAs caused by aging. Mechanistically, cordycepin was found to suppress the elevation of DCP1A protein levels by inhibiting polyadenylation during postovulatory aging, consequently impeding the decapping of maternal mRNAs. In humans, the increased degradation of DCP1A and total mRNA during aging was also inhibited by cordycepin. Collectively, our findings demonstrate that cordycepin may prevent postovulatory aging of mammalian oocytes by inhibition of maternal mRNAs degradation via DCP1A polyadenylation suppression, thereby promoting the successful rates of ART procedure.