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International Journal of Molecular... May 2024The sodium-glucose co-transporter-2 (SGLT2) inhibitor dapagliflozin is increasingly used in the treatment of diabetes and heart failure. Dapagliflozin has been...
The sodium-glucose co-transporter-2 (SGLT2) inhibitor dapagliflozin is increasingly used in the treatment of diabetes and heart failure. Dapagliflozin has been associated with reduced incidence of atrial fibrillation (AF) in clinical trials. We hypothesized that the favorable antiarrhythmic outcome of dapagliflozin use may be caused in part by previously unrecognized effects on atrial repolarizing potassium (K) channels. This study was designed to assess direct pharmacological effects of dapagliflozin on cloned ion channels K11.1, K1.5, K4.3, K2.1, K2.1, K3.1, and K17.1, contributing to , , , , and K currents. Human channels coded by , , , , , , and were heterologously expressed in oocytes, and currents were recorded using the voltage clamp technique. Dapagliflozin (100 µM) reduced K11.1 and K1.5 currents, whereas K2.1, K2.1, and K17.1 currents were enhanced. The drug did not significantly affect peak current amplitudes of K4.3 or K3.1 K channels. Biophysical characterization did not reveal significant effects of dapagliflozin on current-voltage relationships of study channels. In conclusion, dapagliflozin exhibits direct functional interactions with human atrial K channels underlying , , , and currents. Substantial activation of K2.1 and K17.1 currents could contribute to the beneficial antiarrhythmic outcome associated with the drug. Indirect or chronic effects remain to be investigated in vivo.
Topics: Humans; Glucosides; Sodium-Glucose Transporter 2 Inhibitors; Benzhydryl Compounds; Animals; Xenopus laevis; Potassium Channels; Oocytes; Sodium-Glucose Transporter 2
PubMed: 38891889
DOI: 10.3390/ijms25115701 -
Cells May 2024Reduced oxygen during embryo culture in human ART prevents embryo oxidative stress. Oxidative stress is also the major mechanism by which maternal diabetes impairs...
Reduced oxygen during embryo culture in human ART prevents embryo oxidative stress. Oxidative stress is also the major mechanism by which maternal diabetes impairs embryonic development. This study employed induced hyperglycemia prepubertal mice to mimic childhood diabetes to understand the effects of varying oxygen tension during in vitro embryonic development. The oocytes were fertilized and cultured at low (≈5%) oxygen (LOT) or atmospheric (≈20%) oxygen tension (HOT) for up to 96 h. Embryo development, apoptosis in blastocysts, inner cell mass (ICM) outgrowth proliferation, and expression were assessed. Though the oocyte quality and meiotic spindle were not affected, the fertilization rate (94.86 ± 1.18 vs. 85.17 ± 2.81), blastocyst rate (80.92 ± 2.92 vs. 69.32 ± 2.54), and ICM proliferation ability (51.04 ± 9.22 vs. 17.08 ± 3.05) of the hyperglycemic embryos were significantly higher in the LOT compared to the HOT group. On the other hand, blastocysts from the hyperglycemic group, cultured at HOT, had a 1.5-fold increase in apoptotic cells compared to the control and lower transcripts in ICM outgrowths compared to the LOT. Increased susceptibility of embryos from hyperglycemic mice to higher oxygen tension warrants the need to individualize the conditions for embryo culture systems in ART clinics, particularly when an endogenous maternal pathology affects the ovarian environment.
Topics: Animals; Female; Oxygen; Mice; Hyperglycemia; Embryonic Development; Apoptosis; Blastocyst; Hypoxia-Inducible Factor 1, alpha Subunit; Oocytes; Embryo, Mammalian; Cell Proliferation
PubMed: 38891086
DOI: 10.3390/cells13110954 -
Comptes Rendus Biologies Jun 2024Fertility is declining worldwide and many couples are turning towards assisted reproductive technologies (ART) to conceive babies. Organisms that propagate via sexual... (Review)
Review
Fertility is declining worldwide and many couples are turning towards assisted reproductive technologies (ART) to conceive babies. Organisms that propagate via sexual reproduction often come from the fusion between two gametes, an oocyte and a sperm, whose qualities seem to be decreasing in the human species. Interestingly, while the sperm mostly transmits its haploid genome, the oocyte transmits not only its haploid set of chromosomes but also its huge cytoplasm to its progeny. This is what can be defined as the maternal inheritance composed of chromosomes, organelles, lipids, metabolites, proteins and RNAs. To decipher the decline in oocyte quality, it is essential to explore the nature of the maternal inheritance, and therefore study the last stages of murine oogenesis, namely the end of oocyte growth followed by the two meiotic divisions. These divisions are extremely asymmetric in terms of the size of the daughter cells, allowing to preserve the maternal inheritance accumulated during oocyte growth within these huge cells to support early embryo development. Studies performed in Marie-Hélène Verlhac's lab have allowed to discover the unprecedented impact of original acto-myosin based mechanisms in the constitution as well as the preservation of this maternal inheritance and the consequences when these processes go awry.
Topics: Animals; Female; Humans; Mice; Maternal Inheritance; Meiosis; Oocytes; Oogenesis
PubMed: 38888193
DOI: 10.5802/crbiol.155 -
Frontiers in Endocrinology 2024Anti-Müllerian hormone (AMH) is a key paracrine/autocrine factor regulating folliculogenesis in the postnatal ovary. As antral follicles mature to the preovulatory...
Anti-Müllerian hormone (AMH) is a key paracrine/autocrine factor regulating folliculogenesis in the postnatal ovary. As antral follicles mature to the preovulatory stage, AMH production tends to be limited to cumulus cells. Therefore, the present study investigated the role of cumulus cell-derived AMH in supporting maturation and competence of the enclosed oocyte. Cumulus-oocyte complexes (COCs) were isolated from antral follicles of rhesus macaque ovaries for maturation with or without AMH depletion. Oocyte meiotic status and embryo cleavage after fertilization were assessed. maturation with AMH depletion was also performed using COCs from antral follicles of human ovarian tissue. Oocyte maturation and morphology were evaluated. The direct AMH action on mural granulosa cells of the preovulatory follicle was further assessed using human granulosa cells cultured with or without AMH supplementation. More macaque COCs produced metaphase II oocytes with AMH depletion than those of the control culture. However, preimplantation embryonic development after fertilization was comparable between oocytes derived from COCs cultured with AMH depletion and controls. Oocytes resumed meiosis in human COCs cultured with AMH depletion and exhibited a typical spindle structure. The confluency and cell number decreased in granulosa cells cultured with AMH supplementation relative to the control culture. AMH treatment did not induce cell death in cultured human granulosa cells. Data suggest that reduced AMH action in COCs could be beneficial for oocyte maturation. Cumulus cell-derived AMH is not essential for supporting oocyte competence or mural granulosa cell viability.
Topics: Anti-Mullerian Hormone; Oocytes; Female; Cumulus Cells; Animals; Humans; In Vitro Oocyte Maturation Techniques; Macaca mulatta; Oogenesis; Cells, Cultured; Fertilization in Vitro; Meiosis; Granulosa Cells; Ovarian Follicle; Embryonic Development
PubMed: 38887270
DOI: 10.3389/fendo.2024.1365260 -
Communications Biology Jun 2024Many insects and other animals carry microbial endosymbionts that influence their reproduction and fitness. These relationships only persist if endosymbionts are... (Comparative Study)
Comparative Study
Many insects and other animals carry microbial endosymbionts that influence their reproduction and fitness. These relationships only persist if endosymbionts are reliably transmitted from one host generation to the next. Wolbachia are maternally transmitted endosymbionts found in most insect species, but transmission rates can vary across environments. Maternal transmission of wMel Wolbachia depends on temperature in natural Drosophila melanogaster hosts and in transinfected Aedes aegypti, where wMel is used to block pathogens that cause human disease. In D. melanogaster, wMel transmission declines in the cold as Wolbachia become less abundant in host ovaries and at the posterior pole plasm (the site of germline formation) in mature oocytes. Here, we assess how temperature affects maternal transmission and underlying patterns of Wolbachia localization across 10 Wolbachia strains diverged up to 50 million years-including strains closely related to wMel-and their natural Drosophila hosts. Many Wolbachia maintain high transmission rates across temperatures, despite highly variable (and sometimes low) levels of Wolbachia in the ovaries and at the developing germline in late-stage oocytes. Identifying strains like closely related wMel-like Wolbachia with stable transmission across variable environmental conditions may improve the efficacy of Wolbachia-based biocontrol efforts as they expand into globally diverse environments.
Topics: Wolbachia; Animals; Female; Ovary; Drosophila melanogaster; Aedes; Symbiosis; Temperature; Oocytes
PubMed: 38877196
DOI: 10.1038/s42003-024-06431-y -
Scientific Reports Jun 2024In mammalian females, quiescent primordial follicles serve as the ovarian reserve and sustain normal ovarian function and egg production via folliculogenesis. The loss...
In mammalian females, quiescent primordial follicles serve as the ovarian reserve and sustain normal ovarian function and egg production via folliculogenesis. The loss of primordial follicles causes ovarian aging. Cellular senescence, characterized by cell cycle arrest and production of the senescence-associated secretory phenotype (SASP), is associated with tissue aging. In the present study, we report that some quiescent primary oocytes in primordial follicles become senescent in adult mouse ovaries. The senescent primary oocytes share senescence markers characterized in senescent somatic cells. The senescent primary oocytes were observed in young adult mouse ovaries, remained at approximately 15% of the total primary oocytes during ovarian aging from 6 to 12 months, and accumulated in aged ovaries. Administration of a senolytic drug ABT263 to 3-month-old mice reduced the percentage of senescent primary oocytes and the transcription of the SASP factors in the ovary, in addition, led to increased numbers of primordial and total follicles and a higher rate of oocyte maturation. Our study provides experimental evidence that primary oocytes, a germline cell type that is arrested in meiosis, become senescent in adult mouse ovaries and that senescent cell clearance reduced primordial follicle loss and mitigated ovarian aging phenotypes.
Topics: Animals; Oocytes; Female; Cellular Senescence; Mice; Aging; Ovary; Sulfonamides; Ovarian Follicle; Aniline Compounds; Senescence-Associated Secretory Phenotype; Senotherapeutics
PubMed: 38871781
DOI: 10.1038/s41598-024-64441-6 -
Proceedings of the National Academy of... Jun 2024Hertwig's rule states that cells divide along their longest axis, usually driven by forces acting on the mitotic spindle. Here, we show that in contrast to this rule,...
Hertwig's rule states that cells divide along their longest axis, usually driven by forces acting on the mitotic spindle. Here, we show that in contrast to this rule, microtubule-based pulling forces in early embryos align the spindle with the short axis of the cell. We combine theory with experiments to reveal that in order to correct this misalignment, inward forces generated by the constricting cytokinetic ring rotate the entire cell until the spindle is aligned with the cell's long axis. Experiments with slightly compressed mouse zygotes indicate that this cytokinetic ring-driven mechanism of ensuring Hertwig's rule is general for cells capable of rotating inside a confining shell, a scenario that applies to early cell divisions of many systems.
Topics: Animals; Caenorhabditis elegans; Mice; Spindle Apparatus; Microtubules; Cytokinesis; Rotation; Zygote; Embryo, Nonmammalian; Embryonic Development; Models, Biological
PubMed: 38870057
DOI: 10.1073/pnas.2318838121 -
Genes & Development Jun 2024Genome organization can regulate gene expression and promote cell fate transitions. The differentiation of germline stem cells (GSCs) to oocytes in involves changes in...
Genome organization can regulate gene expression and promote cell fate transitions. The differentiation of germline stem cells (GSCs) to oocytes in involves changes in genome organization mediated by heterochromatin and the nuclear pore complex (NPC). Heterochromatin represses germ cell genes during differentiation, and NPCs anchor these silenced genes to the nuclear periphery, maintaining silencing to allow for oocyte development. Surprisingly, we found that genome organization also contributes to NPC formation, mediated by the transcription factor Stonewall (Stwl). As GSCs differentiate, Stwl accumulates at boundaries between silenced and active gene compartments. Stwl at these boundaries plays a pivotal role in transitioning germ cell genes into a silenced state and activating a group of oocyte genes and nucleoporins (Nups). The upregulation of these Nups during differentiation is crucial for NPC formation and further genome organization. Thus, cross-talk between genome architecture and NPCs is essential for successful cell fate transitions.
Topics: Animals; Oogenesis; Drosophila Proteins; Cell Differentiation; Nuclear Pore; Genome, Insect; Gene Expression Regulation, Developmental; Female; Drosophila melanogaster; Oocytes; Transcription Factors; Drosophila; Nuclear Pore Complex Proteins
PubMed: 38866556
DOI: 10.1101/gad.351402.123 -
Ecotoxicology and Environmental Safety Jul 20242-Ethylhexyl diphenyl phosphate (EHDPP) is a representative organophosphorus flame retardant (OPFR) that has garnered attention due to its widespread use and potential...
2-Ethylhexyl diphenyl phosphate (EHDPP) is a representative organophosphorus flame retardant (OPFR) that has garnered attention due to its widespread use and potential adverse effects. EHDPP exhibits cytotoxicity, genotoxicity, developmental toxicity, and endocrine disruption. However, the toxicity of EHDPP in mammalian oocytes and the underlying mechanisms remain poorly understood. Melatonin is a natural free radical scavenger that has demonstrated cytoprotective properties. In this study, we investigated the effect of EHDPP on mouse oocytes in vitro culture system and evaluated the rescue effect of melatonin on oocytes exposed to EHDPP. Our results indicated that EHDPP disrupted oocyte maturation, resulting in the majority of oocytes arrested at the metaphase I (MI) stage, accompanied by cytoskeletal damage and elevated levels of reactive oxygen species (ROS). Nevertheless, melatonin supplementation partially rescued EHDPP-induced mouse oocyte maturation impairment. Results of single-cell RNA sequencing (scRNA-seq) analysis elucidated potential mechanisms underlying these protective effects. According to the results of scRNA-seq, we conducted further tests and found that EHDPP primarily disrupts mitochondrial distribution and function, kinetochore-microtubule (K-MT) attachment, DNA damage, apoptosis, and histone modification, which were rescued upon the supplementation of melatonin. This study reveals the mechanisms of EHDPP on female reproduction and indicates the efficacy of melatonin as a therapeutic intervention for EHDPP-induced defects in mouse oocytes.
Topics: Animals; Melatonin; Mice; Oocytes; Mitochondria; Female; Flame Retardants; Reactive Oxygen Species; Organophosphates; DNA Damage; Apoptosis; Organophosphorus Compounds
PubMed: 38865937
DOI: 10.1016/j.ecoenv.2024.116559 -
Theriogenology May 2024There are few existing publications that describe transvaginal ultrasound-guided Ovum Pick-Up (OPU) in sows, and the impacts of the procedure for the welfare of the...
There are few existing publications that describe transvaginal ultrasound-guided Ovum Pick-Up (OPU) in sows, and the impacts of the procedure for the welfare of the animals are unknown. In this study, we evaluated the effects of OPU, performed following restraint in a claw-trimming chute, on the animal welfare and reproductive health of second parity hybrid sows. The study utilized a generalized randomized block design at a commercial sow pool. We assessed salivary cortisol levels before, during, and after the procedure to compare the physiological stress response between OPU and restraint chute procedures (control group). We found a significant increase in salivary cortisol caused by the physical restraint procedure, and that the salivary cortisol level at the end of the procedure did not differ between OPU and control groups (p = 0.51). Furthermore, we conducted a novel approach-aversion test for sows, designed to assess if a feed reward would motivate the animals to willingly participate in the OPU-procedure. The animals were trained daily to enter the chute to access a feed reward. Ten animals in each group failed to complete the training period and did not voluntarily enter the restraint chute on the experimental day. This indicates that even the short daily restraint procedure during the four-day long training period was aversive to some animals. There was no difference in aversion towards the restraint chute between OPU and control groups one day after the procedure. The reproductive performance of the animals was subsequently evaluated through oestrus synchronization and insemination of the sows after the experiment. There was no observed difference in the farrowing rate (p = 0.72) and total number of born piglets (p = 0.84) between OPU and control sows. On average, we retrieved 9.0 ± 5.9 oocytes during the OPU-sessions (N = 26). Our results show that a majority of the sows prioritize the motivation for feed over their aversion to the OPU procedure. However, the physical restraint procedure is unpleasant for the animals and elicits a temporary stress response. We suggest that transvaginal OPU may be used for the recovery of oocytes from live sows, but refinements are needed to avoid stress during the lifting procedure. Such modifications could also potentially reduce the observed inter-individual variations in oocyte recovery outcomes.
PubMed: 38865790
DOI: 10.1016/j.theriogenology.2024.05.009