RNA m6A modification regulates L1 retrotransposons in human spermatogonial stem cell differentiation in vitro and in vivo.

The maintenance of genome integrity in the germline is crucial for mammalian development. Long interspersed element type 1 (LINE-1, L1) is a mobile genetic element that makes up about 17% of the human genome and poses a threat to genome integrity. N6-methyl-adenosine (m6A) plays an essential role in regulating various biological processes. However, the function of m6A modification in L1 retrotransposons and human germline development remains largely unknown. Here we knocked out the m6A methyltransferase METTL3 or the m6A reader YTHDF2 in human embryonic stem cells (hESCs) and discovered that METTL3 and YTHDF2 are crucial for inducing human spermatogonial stem cells (hSSCs) from hESCs in vitro. The removal of METTL3 or YTHDF2 resulted in increased L1 retrotransposition and reduced the efficiency of SSC differentiation in vitro. Further analysis showed that YTHDF2 recognizes the METTL3-catalyzed m6A modification of L1 retrotransposons and degrades L1 mRNA through autophagy, thereby blocking L1 retrotransposition. Moreover, the study confirmed that m6A modification in human fetal germ cells promotes the degradation of L1 retrotransposon RNA, preventing the insertion of new L1 retrotransposons into the genome. Interestingly, L1 retrotransposon RNA was highly expressed while METTL3 was significantly downregulated in the seminal plasma of azoospermic patients with meiotic arrest compared to males with normal fertility. Additionally, we identified some potentially pathogenic variants in m6A-related genes in azoospermic men with meiotic arrest. In summary, our study suggests that m6A modification serves as a guardian of genome stability during human germline development and provides novel insights into the function and regulatory mechanisms of m6A modification in restricting L1 retrotransposition.

Exosomes derived from umbilical cord mesenchymal stem cells ameliorate male infertility caused by busulfan in vivo and in vitro.

Environmental pollution has emerged as a global concern due to its detrimental effects on human health. One of the critical aspects of this concern is the impact of environmental pollution on sperm quality in males. Male factor infertility accounts for approximately 40%- 50% of all infertility cases. Nonobstructive azoospermia (NOA) is the most severe type of male infertility. Human umbilical cord mesenchymal stem cell (hUCMSC) exosomes enhance proliferation and migration, playing crucial roles in tissue and organ injury repair. However, whether hUCMSC exosomes impacting on NOA caused by chemotherapeutic agents remains unknown. This study aimed to explore the functional restoration and mechanism of hUCMSC exosomes on busulfan-induced injury in GC-1 spg cells and ICR mouse testes. Our results revealed that hUCMSC exosomes effectively promoted the proliferation and migration of busulfan-treated GC-1 spg cells. Additionally, oxidative stress and apoptosis were significantly reduced when hUCMSC exosomes were treated. Furthermore, the injection of hUCMSC exosomes into the testes of ICR mice treated with busulfan upregulated the expression of mouse germ cell-specific genes, such as vasa, miwi, Stra8 and Dazl. Moreover, the expression of cellular junction- and cytoskeleton-related genes, including connexin 43, ICAM-1, ß-catenin and androgen receptor (AR), was increased in the testicular tissues treated with exosomes. Western blot analysis demonstrated significant downregulation of apoptosis-associated proteins, such as bax and caspase-3, and upregulation of bcl-2 in the mouse testicular tissues injected with hUCMSC exosomes. Further, the spermatogenesis in the experimental group of mice injected with exosomes showed partial restoration of spermatogenesis compared to the busulfan-treated group. Collectively, these findings provide evidence for the potential clinical applications of hUCMSC exosomes in cell repair and open up new avenues for the clinical treatment of NOA.

Association of urinary and seminal plasma vanadium concentrations with semen quality: A repeated-measures study of 1135 healthy men.

Although animal studies have shown the reproductive toxicity of vanadium, less is known about its effects on semen quality in humans. Among 1135 healthy men who were screened as potential semen donors, we investigated the relationships of semen quality with urinary and seminal plasma vanadium levels via inductively coupled plasma-mass spectrometry (ICP-MS). Spearman rank correlation tests and linear regression models were used to assess the correlations between average urinary and within-individual pooled seminal plasma vanadium concentrations (n = 1135). We utilized linear mixed-effects models to evaluate the associations of urinary and seminal plasma vanadium levels (n = 1135) with repeated sperm quality parameters (n = 5576). Seminal plasma vanadium concentrations were not significantly correlated with urinary vanadium concentrations (r = 0.03). After adjusting for possible confounders, we observed inverse relationships of within-individual pooled seminal plasma vanadium levels with total count, semen volume, and sperm concentration (all P values for trend < 0.05). Specifically, subjects in the highest (vs. lowest) tertile of seminal plasma vanadium concentrations had - 11.3% (-16.4%, -5.9%), - 11.1% (-19.1%, -2.4%), and - 20.9% (-29.0%, -11.8%) lower sperm volume, concentration, and total count, respectively; moreover, urinary vanadium levels appeared to be negatively associated with sperm motility. These relationships showed monotonically decreasing dose-response patterns in the restricted cubic spline analyses. Our results demonstrated a poor correlation between urinary and seminal plasma levels of vanadium, and elevated vanadium concentrations in urine and seminal plasma may be adversely related to male semen quality.

The positive impact of the NtTAS14-like1 gene on osmotic stress response in Nicotiana tabacum.

KEY MESSAGE: NtTAS14-like1 enhances osmotic tolerance through coordinately activating the expression of osmotic- and ABA-related genes. Osmotic stress is one of the most important limiting factors for tobacco (Nicotiana tabacum) growth and development. Dehydrin proteins are widely involved in plant adaptation to osmotic stress, but few of these proteins have been functionally characterized in tobacco. Here, to identify genes required for osmotic stress response in tobacco, an encoding dehydrin protein gene NtTAS14-like1 was isolated based on RNA sequence data. The expression of NtTAS14-like1 was obviously induced by mannitol and abscisic acid (ABA) treatments. Knock down of NtTAS14-like1 expression reduced osmotic tolerance, while overexpression of NtTAS14-like1 conferred tolerance to osmotic stress in transgenic tobacco plants, as determined by physiological analysis of the relative electrolyte leakage and malonaldehyde accumulation. Further expression analysis by quantitative real-time PCR indicated that NtTAS14-like1 participates in osmotic stress response possibly through coordinately activating osmotic- and ABA-related genes expression, such as late embryogenesis abundant (NtLEA5), early responsive to dehydration 10C (NtERD10C), calcium-dependent protein kinase 2 (NtCDPK2), ABA-responsive element-binding protein (NtAREB), ABA-responsive element-binding factor 1 (NtABF1), dehydration-responsive element-binding genes (NtDREB2A), xanthoxin dehydrogenase/reductase (NtABA2), ABA-aldehyde oxidase 3 (NtAAO3), 9-cis-epoxycarotenoid dioxygenase (NtNCED3). Together, this study will facilitate to improve our understandings of molecular and functional properties of plant TAS14 proteins and to improve genetic evidence on the involvement of the NtTAS14-like1 in osmotic stress response of tobacco.

Safety and effectiveness evaluation of a uterine direct visualization system in induced abortion. A multicenter clinical trial.

OBJECTIVES: While the decision of abortion is undeniably complex, there are situations where it becomes a necessary choice. In such circumstances, a secure abortion procedure is essential to safeguard the physical and mental well-being of women. A uterine direct visualization system was designed to fulfill the requirements and this study undertook an assessment of the system's safety and effectiveness within a medical facility setting. MATERIALS AND METHODS: Induced abortion requested women in 17 institutions across the country between December 2016 and February 2017 were enrolled. Subjects were separated to the study and control group randomly. Induced abortion was conducted by a uterine direct visualization system and an ultrasound-guided system in the study and control group, respectively. The clinical indexes collected during intra- and post-procedures were analyzed and compared between groups. RESULTS: Overall, 392 and 339 subjects were included in the study and control group, respectively. The baseline demographic and clinical characteristics were similar between two groups. Subjects in the study group had significant smaller number of uterine cavity entry (p < 0.001), less 2-h and 14-days postoperative bleeding (all p < 0.001), and less 14-days postoperative abdominal pain (p < 0.001). Significantly higher ratio of normal menstruation, in terms of incidence and duration after 60-days of operation, was observed in the study group (all p < 0.001). CONCLUSIONS: Induced abortion with uterine direct visualization system generate better outcome and less complication than the conventional ultrasound-guided abortion procedures.

Transcriptome analysis of meiotic and post-meiotic spermatogenic cells reveals the potential hub genes of aging on the decline of male fertility.

Genetic and epigenetic changes in sperm caused by male aging may be essential factors affecting semen parameters, but the effects and specific molecular mechanisms of aging on male reproduction have not been fully clarified. In this study, to explore the effect of aging on male fertility and seek the potential molecular etiology, we performed high-throughput RNA-sequencing in isolated spermatogenic cells, including pachytene spermatocytes (marked by the completion of chromosome synapsis) and round spermatids (produced by the separation of sister chromatids) from the elderly and the young men. Functional enrichment analysis of differentially expressed genes (DEGs) in round spermatids between the elderly and young showed that they were significantly enriched in gamete generation, spindle assembly, and cilium movement involved in cell motility. In addition, the expression levels of DEGs in round spermatids (post-meiotic cells) were found to be more susceptible to age. Furthermore, ten genes (AURKA, CCNB1, CDC20, CCNB2, KIF2C, KIAA0101, NR5A1, PLK1, PTTG1, RAD51AP1) were identified to be the hub genes involved in the regulation of sperm quality in the elderly through Protein-Protein Interaction (PPI) network construction and measuring semantic among GO terms and gene products. Our data provide aging-related molecular alterations in meiotic and post-meiotic spermatogenic cells, and the information gained from this study may explain the abnormal aging-related male fertility decline.