Reproduction最新文献

In brief: Mitochondrial uncoupling proteins (UCPs) regulate mitochondrial activity and reactive oxygen species production through the transport of protons and metabolites. This study identified the expression of UCPs in human Sertoli cells, which proved to be modulators of their mitochondrial activity.

Abstract: Mitochondrial uncoupling proteins (UCPs) are mitochondrial channels responsible for the transport of protons and small molecular substrates across the inner mitochondrial membrane. Altered UCP expression or function is commonly associated with mitochondrial dysfunction and increased oxidative stress, which are both known causes of male infertility. However, UCP expression and function in the human testis remain to be characterized. This study aimed to assess the UCP homologs (UCP1-6) expression and function in primary cultures of human Sertoli cells (hSCs). We identified the mRNA expression of all UCP homologs (UCP1-6) and protein expression of UCP1, UCP2, and UCP3 in hSCs. UCP inhibition by genipin for 24 h decreased hSCs proliferation without causing cytotoxicity (n = 6). Surprisingly, the prolonged UCP inhibition for 24 h decreased mitochondrial membrane potential, oxygen consumption rate (OCR), and endogenous reactive oxygen species (ROS) production. The metabolism of hSCs was also affected as UCP inhibition shifted their metabolism toward an increased pyruvate consumption. Taken together, these findings demonstrate that UCPs play a role as regulators of the mitochondrial function in hSCs, emphasizing their potential as targets in the study of male (in)fertility.

In brief: Porcine endometrial organoids (EOs) were isolated and characterized, revealing distinctive features such as unique extracellular matrix formation, fusion into uterine bud-like structures, and facilitation of embryo elongation. The yield of EOs was significantly enhanced by cryopreservation medium supplemented with the rock inhibitor (Y-27632), resulting in reduced expression of apoptotic mRNAs and microRNAs.

Abstract: Endometrial organoids (EOs) are acceptable models for understanding maternal-embryonic cross talk. This study was conducted to generate EOs and optimize their cryopreservation and provide coculture modeling with embryos. The endometrial tissues were used for culturing the organoids inside domes of Matrigel®. To improve the long-term storage of EOs, 10 µM ROCK inhibitor (RI) was added to the cryopreservation medium. Day 7 parthenogenetically activated embryos were cocultured with EOs or EO outgrowths, and embryonic cell numbers and embryo attachment were monitored. Spherical EOs 100-300 µm in size can be retrieved on day 7 of culture, and larger EOs, approximately 1.5 mm in diameter, can be maintained in the Matrigel® dome for 21 days. The nuclear expression of Ki67 indicates that more than 80% of EOs nuclei were proliferative. EOs exhibit unique novel characters such as formation of extracellular matrix and ability for fusion. RI increased the yield and quality of organoids after freezing or thawing. The cell number of cocultured embryos increased five-fold, and the proportion of trophoblast outgrowths increased seven-fold compared with those of control embryos. The embryos cultured with EO-conditioned medium showed a better attachment rate than the other models, and - for the first time - we report embryonic elongation. Immunofluorescence staining of the attached embryos showed CDX2 in the periphery of EOs outgrowths. The 3D assembly and cryopreservation of EOs was optimized, and EO coculture supported embryo attachment, trophoblast outgrowth, and elongation, which would provide a valuable tool for studying the intricate processes involved in porcine embryo implantation.

In brief: Oocyte vitrification leads to DNA hypomethylation, which results in defect in early embryo development. This study reveals that oocyte vitrification impairs the DNA methylation pattern by influencing protein O-GlcNAcylation.

Abstract: Oocyte vitrification leads to decreased DNA methylation levels, which impairs the quality and the developmental potential of oocytes. However, the underlying molecular mechanism still need to be further revealed. In this study, mouse metaphase II (M II) oocytes were frozen by vitrification technology, while fresh oocytes were used as the control group. The effect of oocyte vitrification on protein O-GlcNAcylation and its impact on the developmental potential of oocytes were elucidated. We found that the protein O-GlcNAcylation levels were significantly increased in vitrified oocytes. Increase of protein O-GlcNAcylation levels in control oocytes by PUGNAc (an O-GlcNAcase inhibitor) decreases blastocyst rate after parthenogenetic activation (20.82% in PUGNAc-treated group; 53.82% in control group, P < 0.05). We also discovered that DNA methylation was disrupted in two-cell embryos derived from vitrified oocytes, resulting in decreased 5mC and increased 5hmC, showing similar phenotypes to that derived from PUGNAc-treated oocytes. In vitrified and PUGNAc-treated oocytes, O-GlcNAcylated TET3 was significantly increased. Notably, by inhibiting protein O-GlcNAcylation in vitrified oocytes using OSMI1 (an O-GlcNAc transferase inhibitor) we restored the DNA methylation in two-cell embryos and ameliorated the developmental defects in early embryo. Thus, elevated protein O-GlcNAcylation in vitrified oocytes is an essential contributor to their declining embryonic developmental potential. Modulation of protein O-GlcNAcylation improves the developmental potential of vitrified oocytes.

In brief: The causes of subfertility and recurrent pregnancy loss are often unclear. This study shows that endometrial gland cilia from women with subfertility have ultrastructural defects.

Abstract: Endometrial glands secrete products into the endometrium and are necessary for embryo implantation and successful pregnancy. However, structural and functional abnormalities in endometrial gland cilia from women with reproductive failure remain poorly understood. This was a cross-sectional study where endometrial biopsies were collected at days 19-23 of the menstrual cycle from women with unexplained recurrent pregnancy loss (n = 15), unexplained subfertility (n = 11) or from egg donor control participants (n = 10). Endometrial gland cilia ultrastructure was imaged by transmission electron microscopy and cilia defects assessed by an electron-microscopist from a national primary ciliary dyskinesia diagnostic centre. Endometrial glands were isolated, and the cilia beat frequency recorded by high speed video. Subfertile women have proportionately lower ultrastructurally normal cilia (P < 0.05); higher frequency of absent dynamin arms (P < 0.01) or inner arm defects (P < 0.01) and lower cilia beat frequency (P < 0.05). The mechanisms underlying these obversions have yet to be determined. Recent studies have identified cilia related gene expression changes associated with reproductive failure and this study adds to the growing body of literature revealing structural and functional changes. The observation that cilia defects occurred at a higher frequency in endometrial glands of subfertile women raises the question of its mechanistic role in implantation.

In brief: Although common in many commercial extenders, supraphysiological concentrations of glucose in the media may be detrimental to stallion spermatozoa. In this study, we present evidence that these elevated glucose levels may predispose spermatozoa to ferroptosis.

Abstract: Stallion spermatozoa depend on oxidative phosphorylation as their major source of ATP; however, the metabolism of these cells is complex and a great degree of metabolic plasticity exists. The composition of the media in which the spermatozoa are extended, or exposed to in the mare's reproductive tract, exerts a profound effect on sperm function and may even accelerate cell demise. Recent research indicates that high concentrations of glucose in the media, although common in commercial extenders, may be detrimental. To determine if supraphysiological glucose concentration may induce or predispose to ferroptosis (a caspase-independent form of programmed cell death, triggered by oxidative stress), stallion spermatozoa were incubated under different concentrations of glucose, 67 mM (HG) or 1 mM plus 10 mM pyruvate (LG-HP), in the presence or absence of known inductors of ferroptosis. Furthermore, we developed a single-cell flow metabolic assay to identify different metabolic phenotypes in spermatozoa. Storage and incubation of spermatozoa under high glucose concentrations led to an increase in the percentage of necrotic spermatozoa (P < 0.0001). Moreover, ferroptosis was induced more intensely in sperm in media with high glucose concentrations (P < 0.0001). Finally, we observed that induction of ferroptosis modified two proteins (oxoglutarate dehydrogenase and superoxide dismutase 2) in spermatozoa incubated in media containing 67 mM glucose but not in media containing 1 mM glucose and 10 mM pyruvate. The composition of the media, especially the concentration of glucose, exerts a major impact on the functionality and life span of the spermatozoa. The results reported here may pave the way for improvements in existing semen extenders.

In brief: The impact of HVJ-E employed in mitochondrial replacement techniques (MRTs) on embryonic development remains uncertain. This study has exhibited the influence of HVJ-E utilized in MRTs on embryonic development and has devised a novel HVJ-E-induced fusion approach to curtail the amount of HVJ-E employed in MRTs. Abstract: Mitochondrial replacement techniques (MRTs) provide a viable option for women carrying pathogenic mitochondrial DNA (mtDNA) variants to conceive disease-free offspring with a genetic connection. In comparison to electrofusion, HVJ-E-induced fusion has been identified as the most promising approach for clinical translation of MRTs due to its absence of electrical interference. However, despite confirmation of the absence of RNA activity in HVJ-E, a reduction in blastocyst quality has been observed in various MRTs studies utilizing the HVJ-E-induced fusion scheme. Recent investigations have revealed a dose-dependent elevation of reactive oxygen species (ROS) levels in various cancer cells incubated with HVJ-E. However, the impact of HVJ-E as a sole determinant on embryonic development in MRTs remains unverified. This investigation establishes that the augmented concentration of HVJ-E utilized in the conventional HVJ-E fusion protocol is an autonomous variable that influences embryonic development in MRTs. This effect may be attributed to amplified DNA damage resulting from heightened levels of ROS in reconstructed embryos. To mitigate the presence of HVJ-E in reconstructed zygotes while maintaining optimal fusion efficiency in MRTs, a novel HVJ-E-induced fusion approach was devised, namely, press-assisted fusion. This technique offers potential advantages in reducing detrimental factors that impede embryo development in MRTs.

Laboratory studies with rodents indicate that in utero proximity of a female to male foetus can affect female's subsequent reproduction due to elevated testosterone exposure during early development. It remains unknown whether these findings can be generalised to non-laboratory species because the need for caesarean section makes it difficult to determine the intrauterine position outside laboratory conditions. As an alternative, some studies have compared the reproductive performance of individuals born in male-biased litters to those born in female-biased litters. We identified 44 of those studies in 28 viviparous species for a total of 176 relationships between litter sex composition around the time of birth and subsequent reproductive performance (fertility, fecundity, age at first reproduction, interbirth intervals or post-natal survival of offspring). Those relationships are discordant and complex both within and across species. Some factors can mask an actual association between litter sex composition and reproductive performance. Conversely, a part of significant relationships between litter sex composition and reproductive performance likely arises via pathways other than androgen- and oestrogen-transfer between foetuses of different sexes.

During pregnancy, the main role of the cervix is to isolate the fetus from outside pathogens and maintain the relatively closed system of uterine gestation. Conversely, towards the end of pregnancy, the cervix must be remodeled to increase flexibility and allow the delivery. This process is called cervical remodeling and dysregulation of the process plays a role in premature delivery. The endocannabinoidome plays an important role in several reproductive events, however its function on cervical tissue throughout pregnancy is poorly understood. The goal of this study was to evaluate the presence and participation of the endocannabinoidome in lipopolysaccharide (LPS)-induced cervical changes. Therefore, we evaluated key components of the endocannabinoidome in cervical tissue from non-pregnant mice and pregnant mice with and without LPS treatment. Using mass spectrometric analysis, we found an increase in anandamide and 2-arachidonoylglycerol in the cervix of pregnant mice when compared to non-pregnant mice. We have also found a reduction in FAAH protein expression in these tissues. Furthermore, when treated with LPS, we observed a reduction in the cervical immunostaining with anti-CB1, and anti-CB2 antibodies. Likewise, using cervix explants from pregnant mice, we found that LPS significantly increased cervical metalloprotease activity and cyclooxygenase 2, which were subsequently modulated by cannabinoid receptor antagonists.

Collectively, our findings suggest that an LPS-induced imbalance of cervix endocannabinoidome likely contributes to premature cervical remodeling, which is part of the key components that contribute to premature delivery.

The uterine epithelium is composed of a single layer of hormone responsive polarized epithelial cells that line the lumen and form tubular glands. Endometrial epithelial organoids (EEO) can be generated from uterine epithelia and recapitulate cell composition and hormone responses in vitro. As such, the development of EEO represents a major advance for facilitating mechanistic studies in vitro. However, a major limitation for the use of EEO cultured in basement membrane extract and other hydrogels is the inner location of apical membrane, thereby hindering direct access to the apical surface of the epithelium to study interactions with the embryo or infectious agents such as viruses and bacteria. Here, a straightforward strategy was developed that successfully reverses the polarity of EEO. The result is an apical-out organoid that preserves a distinct apical-basolateral orientation and remains responsive to ovarian steroid hormones. Our investigations highlight the utility of polarity-reversed EEO to study interactions with E. coli and blastocysts. This method of generating apical-out EEO lays the foundation for developing new in vitro functional assays, particularly regarding epithelial interactions with embryos during pregnancy or other luminal constituents in a pathological or diseased state.

Pyruvate, the final product of glycolysis, undergoes conversion into acetyl-CoA within the mitochondria of oocytes, serving as a primary fuel source for the tricarboxylic acid (TCA) cycle. The citrate generated in the TCA cycle can be transported to the cytoplasm and converted back into acetyl-CoA. This acetyl-CoA can either fuel lipid synthesis or act as a substrate for histone acetylation. This study aimed to investigate how pyruvate metabolism influences lysine 9 histone 3 acetylation (H3K9ac) dynamics and RNA transcription in bovine oocytes during in vitro maturation (IVM). Bovine cumulus-oocyte complexes were cultured in vitro for 24 hours, considering three experimental groups: Control (IVM medium only), DCA (IVM supplemented with sodium dichloroacetate, a stimulant of pyruvate oxidation into acetyl-CoA), or IA (IVM supplemented with sodium iodoacetate, a glycolysis inhibitor). The results revealed significant alterations in oocyte metabolism in both treatments, promoting the utilization of lipids as an energy source. These changes during IVM affected the dynamics of H3K9ac, subsequently influencing the oocyte's transcriptional activity. In the DCA and IA groups, a total of 148 and 356 differentially expressed genes were identified, respectively, compared to the control group. These findings suggest that modifications in pyruvate metabolism trigger the activation of metabolic pathways, particularly lipid metabolism, changing acetyl-CoA availability and H3K9ac levels, ultimately impacting the mRNA content of in vitro matured bovine oocytes.