Centromere pairing is crucial for synapsis in meiosis. This study delves into the Skp1-Cullin1-F-box protein (SCF) E3 ubiquitin ligase complex, specifically focusing on F-box protein 47 (FBXO47), in mouse meiosis. Here, we revealed that FBXO47 is localized at the centromere and it regulates centromere pairing cooperatively with SKP1 to ensure proper synapsis in pachynema. The absence of FBXO47 causes defective centromeres, resulting in incomplete centromere pairing, which leads to corruption of SC at centromeric ends and along chromosome axes, triggering premature dissociation of chromosomes and pachytene arrest. FBXO47 deficient pachytene spermatocytes exhibited drastically reduced SKP1 expression at centromeres and chromosomes. Additionally, FBXO47 stabilizes SKP1 by down-regulating its ubiquitination in HEK293T cells. In essence, we propose that FBXO47 collaborates with SKP1 to facilitate centromeric SCF formation in spermatocytes. In summary, we posit that the centromeric SCF E3 ligase complex regulates centromere pairing for pachynema progression in mice.

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Meiosis is a critical process in sexual reproduction, and errors during this cell division can significantly impact fertility. Successful meiosis relies on the coordinated action of numerous genes involved in DNA replication, strand breaks, and subsequent rejoining. DNA topoisomerase enzymes play a vital role by regulating DNA topology, alleviating tension during replication and transcription. To elucidate the specific function of DNA topoisomerase 1α ( A t T O P 1 α ) in male reproductive development of Arabidopsis thaliana, we investigated meiotic cell division in Arabidopsis flower buds. Combining cytological and biochemical techniques, we aimed to reveal the novel contribution of A t T O P 1 α to meiosis. Our results demonstrate that the absence of A t T O P 1 α leads to aberrant chromatin behavior during meiotic division. Specifically, the top1α1 mutant displayed altered heterochromatin distribution and clustered centromere signals at early meiotic stages. Additionally, this mutant exhibited disruptions in the distribution of 45s rDNA signals and a reduced frequency of chiasma formation during metaphase I, a crucial stage for genetic exchange. Furthermore, the atm-2×top1α1 double mutant displayed even more severe meiotic defects, including incomplete synapsis, DNA fragmentation, and the presence of polyads. These observations collectively suggest that A t T O P 1 α plays a critical role in ensuring accurate meiotic progression, promoting homologous chromosome crossover formation, and potentially functioning in a shared DNA repair pathway with ATAXIA TELANGIECTASIA MUTATED (ATM) in Arabidopsis microspore mother cells.

BACKGROUND: Non-obstructive azoospermia (NOA) is the most severe form of male infertility and affects approximately 1% of men worldwide. Fanconi anemia (FA) genes were known for their essential role in DNA repair and growing evidence showed the crucial role of FA pathway in NOA. However, the underlying mechanisms for Fance deficiency lead to a serious deficit and delayed maturation of male germ cells remain unclear.
METHODS: We used Fance deficiency mouse model for experiments, and collected testes or epididymides from mice at 8 weeks (8W), 17.5 days post coitum (dpc), and postnatal 11 (P11) to P23. The mice referred to three genotypes: wildtype (Fance +/+), heterozygous (Fance +/-), and homozygous (Fance -/-). Hematoxylin and eosin staining, immunofluorescence staining, and surface spread of spermatocytes were performed to explore the mechanisms for NOA of Fance -/- mice. Each experiment was conducted with a minimum of three biological replicates and Kruskal-Wallis with Dunn\'s correction was used for statistical analysis.
RESULTS: In the present study, we found that the adult male Fance -/- mice exhibited massive germ cell loss in seminiferous tubules and dramatically decreased sperms in epididymides. During the embryonic period, the number of Fance -/- prospermatogonia decreased significantly, without impacts on the proliferation (Ki-67, PCNA) and apoptosis (cleaved PARP, cleaved Caspase 3) status. The DNA double-strand breaks (γH2AX) increased at the cellular level of Fance -/- prospermatogonia, potentially associated with the increased nonhomologous end joining (53BP1) and decreased homologous recombination (RAD51) activity. Besides, Fance deficiency impeded the progression of meiotic prophase I of spermatocytes. The mechanisms entailed the reduced recruitment of the DNA end resection protein RPA2 at leptotene and recombinases RAD51 and DMC1 at zygotene. It also involved impaired removal of RPA2 at zygotene and FANCD2 foci at pachytene. And the accelerated initial formation of crossover at early pachytene, which is indicated by MLH1.
CONCLUSIONS: Fance deficiency caused massive male germ cell loss involved in the imbalance of DNA damage repair in prospermatogonia and altered dynamics of proteins in homologous recombination, DNA end resection, and crossover, providing new insights into the etiology and molecular basis of NOA.

Meiotic progression requires coordinated assembly and disassembly of protein complexes involved in chromosome synapsis and meiotic recombination. Mouse TRIP13 and its ortholog Pch2 are instrumental in remodeling HORMA domain proteins. HORMAD proteins are associated with unsynapsed chromosome axes but depleted from the synaptonemal complex (SC) of synapsed homologs. Here we report that TRIP13 localizes to the synapsed SC in early pachytene spermatocytes and to telomeres throughout meiotic prophase I. Loss of TRIP13 leads to meiotic arrest and thus sterility in both sexes. Trip13-null meiocytes exhibit abnormal persistence of HORMAD1 and HOMRAD2 on synapsed SC and chromosome asynapsis that preferentially affects XY and centromeric ends. These major phenotypes are consistent with reported phenotypes of Trip13 hypomorph alleles. Trip13 heterozygous mice exhibit meiotic defects that are less severe than the Trip13-null mice, showing that TRIP13 is a dosage-sensitive regulator of meiosis. Localization of TRIP13 to the synapsed SC is independent of SC axial element proteins such as REC8 and SYCP2/SYCP3. Terminal FLAG-tagged TRIP13 proteins are functional and recapitulate the localization of native TRIP13 to SC and telomeres. Therefore, the evolutionarily conserved localization of TRIP13/Pch2 to the synapsed chromosomes provides an explanation for dissociation of HORMA domain proteins upon synapsis in diverse organisms.

The sclerotia of Wolfiporia hoelen are one of the most important traditional Chinese medicines and foods commonly used in China, Japan, Korea, and other Asian countries. To provide a high-quality reference genome and deepen our understanding of the genome of W. hoelen to elucidate various biological phenomena. In this study, we assembled three genomes of W. hoelen using a combination of Nanopore and Illumina sequencing strategies. The fifteen-chromosome genome L7 of W. hoelen was assembled with two-sided telomere and rDNA sequences for the first time. The chromosome count was subsequently confirmed through collinearity analysis, correcting the previous belief that W. hoelen had only fourteen chromosomes. Moreover, the aneuploid genome was discovered in W. hoelen for the first time through sequencing depth analysis of different chromosomes, and only some strains of W. hoelen exhibit aneuploid genomes. According to the genome analysis of homokaryotic offspring and protoplast-isolated strains, a potential variation in chromosome allocation patterns was revealed. Moreover, the gene function enrichment analysis of genes on reduplicated chromosomes demonstrated that aneuploidy in the genome may be the result of environmental adaptation for W. hoelen. The discovery of an aneuploid genome also provides new ideas for genetic improvement of W. hoelen.

BACKGROUND: Sterigmatocystin (STE) is a mycotoxin widely found in contaminated food and foodstuffs, and excessive long-term exposure to STE is associated with several health issues, including infertility. However, there is little information available regarding the effects of STE toxin on the female reproductive system, particularly concerning oocyte maturation.
METHODS: In the present study, we investigated the toxic effects of STE on mouse oocyte maturation. We also used Western blot, immunofluorescence, and image quantification analyses to assess the impact of STE exposure on the oocyte maturation progression, mitochondrial distribution, oxidative stress, DNA damages, oocyte ferroptosis and asymmetric division defects.
RESULTS: Our results revealed that STE exposure disrupted mouse oocyte maturation progression. When we examined the cellular changes following 100 µM STE treatment, we found that STE adversely affected polar body extrusion and induced asymmetric division defects in oocytes. RNA-sequencing data showed that STE exposure affects the expression of several pathway-correlated genes during oocyte meiosis in mice, suggesting its toxicity to oocytes. Based on the RNA-seq data, we showed that STE exposure induced oxidative stress and caused DNA damage in oocytes. Besides, ferroptosis and α-tubulin acetylation were also found in STE-exposed oocytes. Moreover, we determined that STE exposure resulted in reduced RAF1 protein expression in mouse oocytes, and inhibition of RAF1 activity also causes defects in asymmetric division of mouse oocytes.
CONCLUSIONS: Collectively, our research provides novel insights into the molecular mechanisms whereby STE contributes to abnormal meiosis.

The ubiquitination is crucial for controlling cellular homeostasis and protein modification, in which ubiquitin-conjugating enzyme (E2) acts as the central player in the ubiquitination system. Ubiquitin-conjugating enzymes, which have special domains that catalyse substrates, have sequence discrepancies and modulate various pathophysiological processes in different cells of multiple organisms. E2s take part in the mitosis of primordial germ cells, meiosis of spermatocytes and the formation of mature haploid spermatids to maintain normal male fertility. In this review, we summarize the various types of E2s and their functions during distinct stages of spermatogenesis.

Calcium ions (Ca2+) regulate cell proliferation and differentiation and participate in various physiological activities of cells. The calcium transfer protein inositol 1,4,5-triphosphate receptor (IP3R), located between the endoplasmic reticulum (ER) and mitochondria, plays an important role in regulating Ca2+ levels. However, the mechanism by which IP3R1 affects porcine meiotic progression and embryonic development remains unclear. We established a model in porcine oocytes using siRNA-mediated knockdown of IP3R1 to investigate the effects of IP3R1 on porcine oocyte meiotic progression and embryonic development. The results indicated that a decrease in IP3R1 expression significantly enhanced the interaction between the ER and mitochondria. Additionally, the interaction between the ER and the mitochondrial Ca2+ ([Ca2+]m) transport network protein IP3R1-GRP75-VDAC1 was disrupted. The results of the Duolink II in situ proximity ligation assay (PLA) revealed a weakened pairwise interaction between IP3R1-GRP75 and VDAC1 and a significantly increased interaction between GRP75 and VDAC1 after IP3R1 interference, resulting in the accumulation of large amounts of [Ca2+]m. These changes led to mitochondrial oxidative stress, increased the levels of reactive oxygen species (ROS) and reduced ATP production, which hindered the maturation and late development of porcine oocytes and induced apoptosis. Nevertheless, after treat with [Ca2+]m chelating agent ruthenium red (RR) or ROS scavenger N-acetylcysteine (NAC), the oocytes developmental abnormalities, oxidative stress and apoptosis caused by Ca2+ overload were improved. In conclusion, our results indicated IP3R1 is required for meiotic progression and embryonic development by regulating mitochondrial calcium and oxidative damage.

In mammals, the transition from mitosis to meiosis facilitates the successful production of gametes. However, the regulatory mechanisms that control meiotic initiation remain unclear, particularly in the context of complex histone modifications. Herein, we show that KDM2A, acting as a lysine demethylase targeting H3K36me3 in male germ cells, plays an essential role in modulating meiotic entry and progression. Conditional deletion of Kdm2a in mouse pre-meiotic germ cells results in complete male sterility, with spermatogenesis ultimately arrested at the zygotene stage of meiosis. KDM2A deficiency disrupts H3K36me2/3 deposition in c-KIT+ germ cells, characterized by a reduction in H3K36me2 but a dramatic increase in H3K36me3. Furthermore, KDM2A recruits the transcription factor E2F1 and its co-factor HCFC1 to the promoters of key genes required for meiosis entry and progression, such as Stra8, Meiosin, Spo11, and Sycp1. Collectively, our study unveils an essential role for KDM2A in mediating H3K36me2/3 deposition and controlling the programmed gene expression necessary for the transition from mitosis to meiosis during spermatogenesis.