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Asynchronous nuclear and cytoplasmic maturation in human oocytes is believed to cause morphological anomalies after controlled ovarian hyperstimulation. Vacuolar protein sorting 34 (VPS34) is renowned for its pivotal role in regulating autophagy and endocytic trafficking. To investigate its impact on oocyte development, oocyte‐specific knockout mice (ZcKO) are generated, and these mice are completely found infertile, with embryonic development halted at 2‐ to 4‐cell stage. This infertility is related with a disruption on autophagic/mitophagic flux in ZcKO oocytes, leading to subsequent failure of zygotic genome activation (ZGA) in derived 2‐cell embryos. The findings further elucidated the regulation of VPS34 on the activity and subcellular translocation of RAS‐related GTP‐binding protein 7 (RAB7), which is critical not only for the maturation of late endosomes and lysosomes, but also for initiating mitophagy via retrograde trafficking. VPS34 binds directly with RAB7 and facilitates its activity conversion through TBC1 domain family member 5 (TBC1D5). Consistent with the cytoplasmic vacuolation observed in ZcKO oocytes, defects in multiple vesicle trafficking systems are also identified in vacuolated human oocytes. Furthermore, activating VPS34 with corynoxin B (CB) treatment improved oocyte quality in aged mice. Hence, VPS34 activation may represent a novel approach to enhance oocyte quality in human artificial reproduction. [ABSTRACT FROM AUTHOR]

Epigenetic modifiers that accumulate in oocytes, play a crucial role in steering the developmental program of cleavage embryos and initiating life. However, the identification of key maternal epigenetic regulators remains elusive. In the findings, the essential role of maternal Ep400, a chaperone for H3.3, in oocyte quality and early embryo development in mice is highlighted. Depletion of Ep400 in oocytes resulted in a decline in oocyte quality and abnormalities in fertilization. Preimplantation embryos lacking maternal Ep400 exhibited reduced major zygotic genome activation (ZGA) and experienced developmental arrest at the 2‐to‐4‐cell stage. The study shows that EP400 forms protein complex with NFYA, occupies promoters of major ZGA genes, modulates H3.3 distribution between euchromatin and heterochromatin, promotes transcription elongation, activates the expression of genes regulating mitochondrial functions, and facilitates the expression of rate‐limiting enzymes of the TCA cycle. This intricate process driven by Ep400 ensures the proper execution of the developmental program, emphasizing its critical role in maternal‐to‐embryonic transition. [ABSTRACT FROM AUTHOR]

In mammals, ovarian function is dependent on the primordial follicle pool and the rate of primordial follicle activation determines a female's reproductive lifespan. Ovarian ageing is characterised by chronic low‐grade inflammation with accelerated depletion of primordial follicles and deterioration of oocyte quality. Macrophages (Mφs) play critical roles in multiple aspects of ovarian functions; however, it remains unclear whether Mφs modulate the primordial follicle pool and what is their role in ovarian ageing. Here, by using super‐ or naturally ovulated mouse models, we demonstrated for the first time that ovulation‐induced local inflammation acted as the driver for selective activation of surrounding primordial follicles in each estrous cycle. This finding was related to infiltrating Mφs in ovulatory follicles and the dynamic changes of the two polarised Mφs, M1 and M2 Mφs, during the process. Further studies on newborn ovaries cocultured with different subtypes of Mφs demonstrated the stimulatory effect of M1 Mφs on primordial follicles, whereas M2 Mφs maintained follicles in a dormant state. The underlying mechanism was associated with the differential regulation of the Phosphatidylinositol 3‐kinase/Mechanistic target of rapamycin (PI3K/mTOR) signaling pathway through secreted extracellular vesicles (EVs) and the containing specific miRNAs miR‐107 (M1 Mφs) and miR‐99a‐5p (M2 Mφs). In aged mice, the intravenous injection of M2‐EVs improved ovarian function and ameliorated the inflammatory microenvironment within the ovary. Thus, based on the anti‐ageing effects of M2 Mφs in old mice, M2‐EVs may represent a new approach to improve inflammation‐related infertility in women. [ABSTRACT FROM AUTHOR]

CDC42 is a member of the Rho‐GTPase family and is involved in a variety of cellular functions including regulation of cell cycle progression, constitution of the actin backbone and membrane transport. In particular, CDC42 plays a key role in the establishment of polarity in female vertebrate oocytes, and essential to this major regulatory role is its local occupation of specific regions of the cell to ensure that the contractile ring is assembled at the right time and place to ensure proper gametogenesis. The multifactor controlled 'inactivation‐activation' process of CDC42 also allows it to play an important role in the multilevel signalling network, and the synergistic regulation of multiple genes ensures maximum precision during gametogenesis. The purpose of this paper is to review the role of CDC42 in the control of gametogenesis and to explore its related mechanisms, with the aim of further understanding the great research potential of CDC42 in female vertebrate germ cells and its future clinical translation. [ABSTRACT FROM AUTHOR]

The senescence of bone marrow mesenchymal stem cells (BMSCs) contributes to the development of degenerative skeletal conditions. To date, the molecular mechanism resulting in BMSC senescence has not been fully understood. In this study, we identified a small non‐coding RNA, miR‐203‐3p, the expression of which was elevated in BMSCs from aged mice. On the other hand, overexpression of miR‐203‐3p in BMSCs from young mice reduced cell growth and enhanced their senescence. Mechanistically, PDZ‐linked kinase (PBK) is predicted to be the target of miR‐203‐3p. The binding of miR‐203‐3p to Pbk mRNA could decrease its expression, which in turn inhibited the ubiquitination‐mediated degradation of p53. Furthermore, the intravitreal injection of miR‐203‐3p‐inhibitor into the bone marrow cavity of aged mice attenuated BMSC senescence and osteoporosis in aged mice. Collectively, these findings suggest that targeting miR‐203‐3p to delay BMSC senescence could be a potential therapeutic strategy to alleviate age‐related osteoporosis. [ABSTRACT FROM AUTHOR]