GC-1 Cells Research Articles

Down-regulation of miR-138-5p in PP2A KO mice promoted apoptosis of spermatocytes.

Protein phosphatase 2A (PP2A) is known to have a pivotal and diverse functions in various physiological processes. In the previous study, we utilized the cre-loxp system to generate germ cell-specific knockout mice for the PP2A catalytic subunit alpha subunit (Ppp2cacKO). Using high-throughput miRNA sequencing of testis tissues and real‑time PCR, we have identified a notable decrease in the expression of miR-138-5p in the testes of Ppp2cacKO mice. Our findings indicate that miR-138-5p plays a role in the regulation of apoptosis and proliferation of GC2 cells. Furthermore, bioinformatics analyses suggested that miR-138- 5p may target the transcriptional repressor Trps1. Consistent with these predictions, we observed a significant upregulation of Trps1 in the testes of Ppp2cacKO mice. Through transfection experiments, we have validated the negative regulation of Trps1 expression by miR-138-5p in GC2 cells. Our study indicates that the down-regulation of miR-138-5p in PP2A KO mice, which targets Trps1 to promote spermatocyte apoptosis.

Melatonin protects spermatogenic cells against DNA damage and necroptosis induced by atrazine

Atrazine (ATZ), a widely used triazine herbicide, has been shown to disrupt reproductive development in organisms. Melatonin (MLT) is a natural hormone and has been shown to have strong antioxidant properties. Due to its lipophilicity, it can cross biological barriers freely and act on germ cells directly. However, the mechanism through which melatonin affects atrazine-induced damage to male sperm cells remains unclear. This study aimed to investigate the effects of ATZ on spermatocyte development and to elucidate MLT's role in preventing ATZ-induced spermatogenesis failure. Pubertal mice were randomly divided into four groups: blank control group (Con), 5 mg/kg melatonin group (MLT), 170 mg/kg atrazine group (ATZ), and ATZ + MLT group. GC-1 cell culture was employed to access the in vitro effects of MLT and ATZ on spermatogonia. The results indicate that atrazine affected protein and metabolite composition, and reduced sperm viability, sperm motility (VAP, VSL and VCL) and levels of proteins related to spermatogenesis function in the mice testis. Melatonin alleviated the development of cellular DNA damage and necroptosis caused by atrazine both in vivo and in vitro. Moreover, we proposed that it was GC-1 cells developing necroptosis, but not other cell types in the testis. In conclusion, this study suggests that atrazine disrupts the development process, causing DNA damage in spermatozoa during spermatogenesis. Additionally, ATZ-induced necroptosis specifically targets spermatogenic cells. Notably, melatonin alleviates atrazine-induced necroptosis and DNA damage in spermatogenic cells. This study provides new insights into potential therapeutic strategies for atrazine-induced male infertility.

SPP1+ macrophages and FAP+ fibroblasts promote the progression of pMMR gastric cancer

Immunotherapy has become a primary and secondary treatment for gastric cancer (GC) patients with mismatch repair deficiency (dMMR), and is used in both perioperative and advanced stages. The tumor immune microenvironment (TiME) is crucial for immunotherapy efficacy, yet the impact of MMR status on TiME remains understudied. We employed single-cell RNA sequencing (scRNA-seq) to analyze 33 fresh tissue samples from 25 patients, which included 10 normal tissues, 6 dMMR tumor tissues, and 17 pMMR tumor tissues, aiming to characterize the cellular and molecular components of the TiME. The proficient mismatch repair (pMMR) group displayed a significantly higher prevalence of a specific GC cell type, termed GC2, characterized by increased hypoxia, epithelial-mesenchymal transition (EMT), and angiogenic activities compared to the dMMR group. GC2 cells overexpressed BEX3 and GPC3, and they significantly correlated with poorer survival. The pMMR group also showed increased infiltration of SPP1 + macrophages and FAP + fibroblasts, exhibiting strong hypoxic and pro-angiogenic features. Furthermore, a higher proportion of E2 endothelial cells, involved in extracellular matrix (ECM) remodeling and showing heightened VEGF pathway, HIF pathway, and angiogenesis activity, were identified in pMMR patients. Intercellular communication analyses revealed that GC2 cells, SPP1 + macrophages, FAP + fibroblasts, and E2 endothelial cells interact through VEGF, SPP1, and MIF signals, forming a TiME characterized by hypoxia, pro-angiogenesis, and ECM remodeling. This study uncovered TiME heterogeneity among GC patients with different MMR states, highlighting that the pMMR TiME is distinguished by hypoxia, pro-angiogenesis, and ECM remodeling, driven by the presence of GC2 cells, SPP1 + macrophages, FAP + fibroblasts, and E2 endothelial cells. These findings are pivotal for developing targeted immunotherapies for GC patients with pMMR.

Oligoasthenozoospermia is alleviated in a mouse model by [Gly14]-humanin-mediated attenuation of oxidative stress and ferroptosis.

Oligoasthenozoospermia is a common cause of male infertility, for which effective treatments are urgently needed. Humanin (HN) is a peptide associated with this condition. To investigate the ameliorative effect of [Gly14]-Humanin (HNG) on oligoasthenozoospermia and the mechanisms. Mice were treated with cyclophosphamide (CP) to construct a mice model of oligoasthenozoospermia. The resulting model mice were treated with saline or HNG. Subsequently, the testis weights, organ indices, testicular structure, sperm counts and motilities, litter sizes, and serum testosterone concentrations of the mice were determined. Differential gene expression in testicular tissues was determined by RNA sequencing. TM3, TM4, GC1, and GC2 cells were exposed to erastin to induce ferroptosis, followed by treatment with HNG or HNG + ML385 (a nuclear factor erythroid 2-related factor 2 inhibitor). Levels of reactive oxygen species (ROS), malondialdehyde (MDA), glutathione (GSH), and ferrous ions (Fe2+) were determined and their expression of ferroptosis-related proteins was determined by immunofluorescence and western blot. The HNG treatment improved testis and sperm parameters and increased litter size and serum testosterone concentrations in model mice. Kyoto Encyclopaedia of Genes and Genomes pathway enrichment analysis revealed significant differential expression of ferroptosis-related genes. The expression of ferroptosis-related proteins increased in testicular tissues after the HNG treatment. The concentrations of ROS, MDA, and Fe2+ decreased and the concentrations of GSH increased in testicular tissues and in TM3 and TM4 cells after HNG treatment. In vitro experiments confirmed that HNG activated the nuclear factor erythroid 2-related factor 2/glutathione peroxidase 4 (Nrf2/GPX4) pathway. However, these effects of HNG were blocked by ML385 treatment. HNG demonstrated a therapeutic effect on oligoasthenozoospermia in a mouse model by reducing oxidative stress and ferroptosis. In TM3 and TM4 cells, HNG attenuated cellular oxidative stress and inhibited ferroptosis via the Nrf2/GPX4 pathway.

Deficiency in the Rab25 gene leads to a decline in male fertility and testicular injury: Impact on the regulation of germ cell proliferation and apoptosis

BackgroundRab25 is a member of the Rab family, functioning as a regulatory molecule in intracellular transport. Although its involvement in cellular functions and disease development is well-established, its precise roles in male reproductive physiology remain elusive. MethodsTo explore the specific roles of Rab25 in testicular development and spermatogenesis, we established the Rab25−/− mouse model and Rab25 knockdown germ cell line (GC-2). We compared the fertility, sperm analysis, and testicular tissues between Rab25−/− and wild-type male mice. To delve deeper into potential mechanisms, we employed immunohistochemistry, TUNEL assay, Western Blotting, CCK-8 assay, etc. to evaluate cell proliferation and apoptosis in testicular tissues and GC-2 cells. ResultsOur findings indicated that Rab25 was expressed in germ cells and Leydig cells in the testes. Although the weight of Rab25−/− mice testes exhibited no significant changes, fertility was compromised, with a decrease in sperm quantity and reduced motility. HE staining revealed a disorganized arrangement of germ cells and vacuolization. Additionally, chromatin marginalization and nuclear pyknosis were observed in the Rab25−/− mice. In both Rab25−/− mice testes and Rab25 knockdown GC-2 cells, we found that germ cell proliferation was reduced, while apoptosis was increased. ConclusionsIn conclusion, our study proposes that Rab25 plays a vital role in spermatogenesis by regulating the proliferation and apoptosis of germ cells.

CD147 mediates S protein pseudovirus of SARS-CoV-2 infection and its induction of spermatogonia apoptosis.

Male cases diagnosed COVID-19 with more complications and higher mortality compared with females, and the overall consequences of male sex hormones and semen parameters deterioration were observed in COVID-19 patients, whereas the involvement and mechanism for spermatogenic cell remains unclear. The study was aimed to investigate the infection mode of S protein (D614G) pseudovirus (pseu-S-D614G) to spermatogenic cells, as well as the influence on cell growth. Both mouse spermatogonia (GC-1 cell, immortalized spermatogonia) and spermatocyte (GC-2 cell, immortalized spermatocytes) were used to detect the infection of pseu-S-D614G of SARS-CoV-2, and further explored the effect of SARS-CoV-2-spike protein (S-protein) and SARS-CoV-2-spike protein (omicron) (O-protein) on GC-1 cell apoptosis and proliferation. The data showed that the pseu-S-D614G invaded into GC-1 cells through either human ACE2 (hACE2) or human CD147 (hCD147), whereas GC-2 cells were insensitive to viral infection. In addition, the apoptosis and proliferation suppression inflicted by S-protein and O-protein on GC-1 cells was through Bax-Caspase3 signaling rather than arresting cell cycle progression. These findings suggest that CD147, apart from ACE2, may be a potential receptor for SARS-CoV-2 infection in testicular tissues, and that the apoptotic effect was induced in spermatogonia cells by S-protein or O-protein, eventually resulted in the damage to male fertility.

Association of seminal plasma zinc levels with human semen quality and its toxic effects on sperm motility

Infertility has become one of the most common chronic diseases among reproductive- aged individuals, and male factors account for about 50 %. Zinc is a trace element that is essential for sperm quality and male reproductive system. Although several current studies with small sample sizes have investigated this relationship, the conclusions have been still controversial. Here, using a large population sample involved 25,915 participants from Changzhou Maternity and Child Health Care Hospital, we revealed an inverted “U”-shaped trend between seminal plasma zinc concentrations and sperm motility PR/PR + NP (PR, progressive motility; NP, non-progressive motility). The results showed that the highest values of sperm PR/PR + NP observed in the group with intermediate concentrations of zinc (Group 2, 0.25–2.11 mmol/L). The mean values were 43.17 ± 19.03 % and 56.64 ± 20.28 %, respectively. And the lowest values came out in the highest zinc levels group (Group 4, > 3.04 mmol/L). In vitro cell experiments also showed that zinc caused dose-dependent cytotoxicity for GC-2 cells at a threshold value. Furthermore, RNA-seq analysis demonstrated that high concentrations of zinc exerted toxic effects on GC-2 cells through immune injury. Taken together, our findings suggested that moderate amounts of zinc are crucial for human reproduction and excessive concentrations may have adverse effects on male fertility.

TRIM59 is required for mouse GC-1 cell maintenance through modulating the ubiquitination of AXIN1

Tripartite motif-containing protein 59 (TRIM59) is a biomarker for multiple tumors with crucial roles. However, the specific role of TRIM59 in germ cells remains largely unknown. Here, we investigated the effects and underlying regulatory mechanisms of TRIM59 on germ cells using the mouse spermatogonial cell line GC-1. Our results demonstrated that TRIM59 promoted proliferation and inhibited apoptosis of GC-1 cells. Mechanistically, TRIM59 maintained GC-1 cell behaviors through ubiquitination of AXIN1 to activate β-catenin signaling. Furthermore, activation of β-catenin signaling reversed the effects mediated by Trim59 knockdown in GC-1 cells. Collectively, our study revealed a major role and regulatory mechanism of TRIM59 in GC-1 cells, which sheds new light on the molecular pathogenesis of defects in spermatogenesis and may provide therapeutic targets for treatment of male infertility.

GGNBP2 regulates histone ubiquitination and methylation in spermatogenesis

ABSTRACT Gametogenetin binding protein 2 (GGNBP2) was indispensable in normal spermatids for transformation into mature spermatozoa in mice, and when Gametogenetin binding protein 2 is bound to BRCC36 and RAD51, the complex participates in repairing DNA double-strand breaks (DSB) during the meiotic progression of spermatocytes. Ggnbp2 knockout resulted in the up-regulation of H2AK119ubi and down-regulation of H2BK120ubi in GC-2 cells (mouse spermatogonia-derived cell line) and postnatal day 18 testis lysate. Our results also demonstrated that Gametogenetin binding protein 2 inducedASXL1 to activate the deubiquitinating enzyme BAP1 in deubiquitinating H2A, while Gametogenetin binding protein 2 knockout disrupted the interaction between ASXL1 and BAP1, resulting in BAP1 localization change. Furthermore, the Gametogenetin binding protein 2 deletion reduced H2B ubiquitination by affecting E2 enzymes and E3 ligase binding. Gametogenetin binding protein 2 regulated H2A and H2B ubiquitination levels and controlled H3K27 and H3K79 methylation by PRC2 subunits and histone H3K79 methyltransferase. Altogether, our results suggest that Ggnbp2 knockout increased DNA damage response by promoting H2A ubiquitination and H3K27trimethylation (H3K27me3) and reduced nucleosome stability by decreasing H2B ubiquitination and H3K79 dimethylation (H3K79me2), revealing new mechanisms of epigenetic phenomenon during spermatogenesis. Gametogenetin binding protein 2 seems critical in regulating histone modification and chromatin structure in spermatogenesis.

Retinoic Acid Regulates Spermiogenesis Via Hoxb1 and Shh Signaling in Testicular Germ Cells.

Retinoic acid (RA) regulates all four major events in spermatogenesis; spermatogonial differentiation, meiotic entry, spermiogenesis, and spermiation. For the pre-meiotic phase, Sertoli cells are the source of RA and for the post-meiotic phase, pachytene spermatocytes are the source of RA. While the entire spermatogenic process is regulated by RA, how each of these phases is regulated by RA remains completely unknown. Homeobox B1 (Hoxb1) has two retinoic acid response elements (RARE) upstream and downstream of the gene. In this study, we investigated if RA facilitates spermatogenesis by its action on Hoxb1. The expressions of the Hoxb1 and Sonic hedgehog (Shh) genes were analyzed in the post-natal mouse testes and the testicular localizations of Hoxb1, Shh and Gli1 were analyzed by immunohistochemistry in the adult rat testis. To delineate the signaling mechanisms, Hoxb1 expression was altered in vitro and in vivo using retinoic acid and miR-361-3p. Finally, the levels of miR-361-3p and HOXB1 were analyzed in infertile human sperm samples. Hoxb1 and Shh gene expressions were found to be low in the testis of post-natal Swiss mice of 7, 14, 28, 35, and 60days, after which the expressions of both spiked. Immunohistochemistry in the adult mouse testis showed the expressions of Hoxb1, Shh, and Gli1 in the elongating spermatids. Exposure of GC2 cells to RA and in vivoIP RA injection upregulated Hoxb1 andShh signaling in the testiswith increased expressions of Shh, Gli1, and Hdac1. Retinoic acid administration in Swiss mice compromised sperm production and reduced epididymal sperm count. The analysis of infertile human semen samples revealed an increased level of HOXB1 and a decreased level of miR-361-3p as compared to fertile controls. We conclude that retinoic acid regulates late stage of spermatogenesis (spermiogenesis) by affecting Hoxb1 and Shh signaling.

Study on the mechanisms of defective spermatogenesis induced by TiO2 NPs based on 3D blood−testis barrier microfluidic chip

Titanium dioxide nanoparticles (TiO2 NPs) can reduce sperm number, but the mechanisms of defective spermatogenesis induced by TiO2 NPs have not been studied through cell-cell interactions at present. A kind of biomimetic three-dimensional blood−testis barrier microfluidic chip capable of intercellular communication was constructed with soft lithography techniques, including Sertoli cell (TM4), spermatogonia (GC-1) and vascular endothelial cell units, to study the mechanisms of TiO2 NPs-induced defective spermatogenesis. TM4 and GC-1 cells cultured in TiO2 NPs exposure and control chips were collected for transcriptomics and metabonomics analysis, and key proteins and metabolites in changed biological processes were validated. In TM4 cells, TiO2 NPs suppressed glucose metabolism, especially lactate production, which reduced energy substrate supply for spermatogenesis. TiO2 NPs also decreased the levels of key proteins and metabolites of lactate production. In GC-1 cells, TiO2 NPs disturbed chemokine signaling pathways regulating cell proliferation and interfered with glutathione metabolism. The Cxcl13, Stat3 and p-Stat3 levels and cell proliferation rate were decreased, and the GSR, GPX4 and GSH contents were increased in GC-1 cells in chips under TiO2 NPs treatment. The decrease in energy substrate supply for spermatogenesis and inhibition of spermatogonia proliferation could be the main mechanisms of defective spermatogenesis induced by TiO2 NPs.

Triclosan impairs spermatocyte cell proliferation and induces autophagy by regulating microRNA-20a-5 P by pargeting PTEN

BackgroundTriclosan (TCS), as an endocrine disrupter, has been found to affect male fertility. However, the potential molecular mechanism is still unknown. We aimed to investigate whether the toxic effects of TCS on spermatocyte cells was mediated by the regulation of microRNA-20a-5 P on PTEN. MethodsGC-2 and TM4 cells were treated with TCS (0.5–80 μM) for 24 or 48 hours. Effect of TCS on proliferation of GC-2 and TM4 cells was detected using a cell counting kit-8 (CCK8) assay. Expression of miR-17 family and autophagy genes were detected. The interaction between miR-20a-5 P and PTEN was determined by a dual-luciferase reporter assay. ResultsTCS decreased cell proliferation of GC-2 and TM4 cells. Expression of autophagy-related genes and miR-17 family was altered by TCS. PTEN expression was significantly increased, whereas the expression of miR-20a-5 P was significantly decreased in GC-2 and TM4 cells. As predicted in relevant databases, there is a binding site of miR-20a-5 P in PTEN. The expression of PTEN was significantly down-regulated by the miR-20a-5 P mimic. ConclusionAs a downstream target of miR-20a-5 P, PTEN functioned in the autophagy process of which TCS inhibited the proliferation of spermatocyte cells. Our results provided new ideas for revealing the molecular mechanism and protective strategy on male infertility.

P-084 Exome sequencing reveals the novel genetic mutations associated with teratospermia

Abstract Study question This research aims to explore the molecular mechanisms of genetic variations in the small acrosome sperm subtype within teratospermia and its correlation with male infertility. Summary answer Novel gene mutations associated with teratospermia were identified, providing important insights into the genetic mechanisms underlying this condition. What is known already Male infertility is a substantial challenge in reproductive medicine, impacting a significant proportion of couples globally. Teratospermia, marked by abnormal sperm morphology, is a major factor in male reproductive disorders. Unraveling the genetic foundation of teratospermia is essential for comprehending the intricate molecular mechanisms governing male fertility. Study design, size, duration This study uses exome sequencing to investigate the genetic landscape of male infertility, particularly focusing on teratospermia. Through a comprehensive examination of the exome, our goal is to uncover novel gene mutations and understand the molecular mechanisms connecting genetic changes to abnormal sperm morphology and, consequently, male infertility. Participants/materials, setting, methods Sperm DNA was extracted from 55 patients with a confirmed diagnosis of teratospermia for this study. Subsequently, comprehensive exome sequencing was performed on the extracted sperm DNA to investigate potential genetic variations associated with teratospermia.Further functional studies were conducted to unveil the potential roles of mutated genes in the development of the reproductive system and spermogenesis. Main results and the role of chance Within the known genes associated with spermatogenic dysfunction, we identified one pathogenic/likely pathogenic variant and four variants of unknown significance, all of which have not been previously reported.Cell phenotype experiments revealed that mutations in CCDC62 and KCNU1 have specific effects on the proliferation and apoptosis of GC-2 cells. Limitations, reasons for caution Further molecular experiments and pathway mechanism studies are required to enhance our understanding of the observed effects and provide a more comprehensive interpretation of the findings. Wider implications of the findings This study unveils novel genes and pathways in teratospermia, informing diagnosis, prognosis, and potential treatments for male infertility. Exploring the genetic landscape enhances our comprehension of the complex interplay between genetics and male fertility, guiding personalized approaches in reproductive medicine. Trial registration number not applicable

Triptolide induced spermatogenesis dysfunction via ferroptosis activation by promoting K63-linked GPX4 polyubiquitination in spermatocytes

Triptolide (TP) is a major bioactive compound derived from Tripterygium wilfordii Hook. F. (TwHF) known for its medicinal properties, but it also exhibits potential toxic effects. It has been demonstrated to induce severe male reproductive toxicity, yet the precise mechanism behind this remains unclear, which limits its broad clinical application. This study aimed to investigate the mechanisms underlying testicular damage and spermatogenesis dysfunction induced by TP in mice, using both mouse models and the spermatocyte-derived cell line GC-2spd. In the present study, it was found that TP displayed significant testicular microstructure damaged and spermatogenesis defects including lower concentration and abnormal morphology by promoting ROS formation, MDA production and restraining GSH level, glutathione peroxidase 4 (GPX4) expression in vivo. Furthermore, Ferrostatin-1 (FER-1), a ferroptosis inhibitor, was found to significantly reduce the accumulation of lipid peroxidation, alleviate testicular microstructural damage, and enhance spermatogenic function in mice. Besides, notably decreased cell viability, collapsed mitochondrial membrane potential, and elevated DNA damage were observed in vitro. The above-mentioned phenomenon could be reversed by pre-treatment of FER-1, indicating that ferroptosis participated in the TP-mediated spermatogenesis dysfunction. Mechanistically, TP could enhance GPX4 ubiquitin degradation via triggering K63-linked polyubiquitination of GPX4, thereby stimulating ferroptosis in spermatocytes. Functionally, GPX4 deletion intensified ferroptosis and exacerbated DNA damage in GC-2 cells, while GPX4 overexpression mitigated ferroptosis induced by TP. Overall, these findings for the first time indicated a vital role of ferroptosis in TP induced-testicular injury and spermatogenic dysfunction through promoting GPX4 K63-linked polyubiquitination, which hopefully offers a potential therapeutic avenue for TP-related male reproductive damage. In addition, this study also provides a theoretical foundation for the improved clinical application of TP or TwHF in the future.

The Olfactory Receptor Olfr25 Mediates Sperm Dysfunction Induced by Low-Dose Bisphenol A through the CatSper-Ca2+ Signaling Pathway.

Bisphenol A (BPA), a typical endocrine disruptor, is known to have various adverse effects on the male reproductive system. However, the toxic effects and mechanisms of low-dose BPA have not yet been fully explored. In this study, male Kunming mice were orally administered low-dose BPA (0.03, 0.3 and 3 mg/kg/d) for ten consecutive weeks. Pathological sections of testicular tissue showed no significant morphological differences after BPA exposure. An analysis of the functional parameters of sperm revealed that exposure to low-dose BPA significantly decreased sperm motility, chemotaxis, and the acrosome reaction. An in vitro BPA exposure model combined with an omics data analysis showed that the olfactory receptor-related pathway was significantly enriched after BPA treatment. Subsequent experiments verified the reduced mRNA level of a novel olfactory receptor gene, Olfr25, in vivo and in vitro exposure models. Meanwhile, exposure to low-dose BPA reduced the intracellular calcium ion concentration and the mRNA levels of pore-forming subunits of the CatSper channel in sperm. Importantly, the knockdown of Olfr25 inhibited calcium ion levels and CatSper subunit expression in GC-2 cells. Olfr25 overexpression attenuated the BPA-induced downregulation of CatSper subunit expression in GC-2 cells. These findings indicate that Olfr25 might participate in low-dose BPA-induced sperm dysfunction by affecting the CatSper-Ca2+ signaling pathway. This study reveals a new mechanism underlying the effects of low-dose BPA on sperm function and provides a reference for assessing the safety of low-dose BPA exposure.

The lncRNA Gm8097 is associated with hypospermatogenesis

Objective: To investigate whether long non-coding RNA (lncRNA) Gm8097 (LncGm8097) is associated with male infertility.Methods: The expression and bilogical role of LncGm8097 were investigated.Results: LncGm8097 expression was down-regulated in the testis tissues with moderate and severe hypospermatogenesis compared with those with normal spermatogenesis and mild hypospermatogenesis (<i>p</i><0.05). LncGm8097 down-regulation significantly promoted apoptosis and inhibited proliferation in GC1 and GC2 cells. In addition, LncGm8097 was significantly down-regulated in mouse model of hypospermatogenesis and correlated with cell apoptosis and proliferation. LncGm8097 was located immediately upstream of PRPS2, and correlated with Bcl-2/P53/caspase 6/caspase 9 signal pathway.Conclusion: LncGm8097 down-regulation correlates with hypospermatogenesis, which may offer new insights into the pathogenesis of male infertility.

DCAF2 regulates the proliferation and differentiation of mouse progenitor spermatogonia by targeting p21 and thymine DNA glycosylase.

DDB1-Cullin-4-associated factor-2 (DCAF2, also known as DTL or CDT2), a conserved substrate recognition protein of Cullin-RING E3 ligase 4 (CRL4), recognizes and degrades several substrate proteins during the S phase to maintain cell cycle progression and genome stability. Dcaf2 mainly expressed in germ cells of human and mouse. Our study found that Dcaf2 was expressed in mouse spermatogonia and spermatocyte. The depletion of Dcaf2 in germ cells by crossing Dcaf2fl/fl mice with stimulated by retinoic acid gene 8(Stra8)-Cre mice caused a reduction in progenitor spermatogonia and differentiating spermatogonia, eventually leading to the failure of meiosis initiation and male infertility. Further studies showed that depletion of Dcaf2 in germ cells caused abnormal accumulation of the substrate proteins, cyclin-dependent kinase inhibitor 1A (p21) and thymine DNA glycosylase (TDG), decreasing of cell proliferation, increasing of DNA damage and apoptosis. Overexpression of p21 or TDG attenuates proliferation and increases DNA damage and apoptosis in GC-1 cells, which is exacerbated by co-overexpression of p21 and TDG. The findings indicate that DCAF2 maintains the proliferation and differentiation of progenitor spermatogonia by targeting the substrate proteins p21 and TDG during the S phase.

Rsad2 mediates Bisphenol A-induced actin cytoskeletal disruption in mouse spermatocytes.

Bisphenol A (BPA) is widely exposed in populations worldwide and has negative effects on spermatogenesis both in animals and humans. The homeostasis of the actin cytoskeleton in the spermatogenic epithelium is crucial for spermatogenesis. Actin cytoskeleton destruction in the seminiferous epithelium is one of the important reasons for BPA-induced spermatogenesis disorder. However, the underlying molecular mechanisms remain largely unexplored. Herein, we explored the role and mechanism of Rsad2, an interferon-stimulated gene in BPA-induced actin cytoskeleton disorder in mouse GC-2 spermatocyte cell lines. After BPA exposure, the actin cytoskeleton was dramatically disrupted and the cell morphology was markedly altered accompanied by a significant increase in Rsad2 expression both in mRNA and protein levels in GC-2 cells. Furthermore, the phalloidin intensities and cell morphology were restored obviously when interfering with the expression of Rsad2 in BPA-treated GC-2 cells. In addition, we observed a significant decrease in intracellular ATP levels after BPA treatment, while the ATP level was obviously upregulated when knocking down the expression of Rsad2 in BPA-treated cells compared to cells treated with BPA alone. Moreover, Rsad2 relocated to mitochondria after BPA exposure in GC-2 cells. BPA promoted Rsad2 expression by activating type I IFN-signaling in GC-2 cells. In summary, Rsad2 mediated BPA-induced actin cytoskeletal disruption in GC-2 cells, which provided data to reveal the mechanism of BPA-induced male reproductive toxicity.

TEX13B is essential for metabolic reprogramming during germ cell differentiation.

What is the functional significance of Tex13b in male germ cell development and differentiation? Tex13b regulates male germ cell differentiation by metabolic reprogramming during spermatogenesis. Studies in mice and humans suggest that TEX13B is a transcription factor and is exclusively expressed in germ cells. We sequenced the coding regions of TEX13B in 628 infertile men and 427 ethnically matched fertile control men. Further, to identify the molecular function of Tex13b, we created a Tex13b knockout and conditional overexpression system in GC-1spg (hereafter, GC-1) cells. Our recent exome sequencing study identified novel candidate genes for male infertility. TEX13B was found to be one of the potential candidates, hence we explored the role of TEX13B in male infertility within a large infertile case-control cohort. We performed functional analyses of Tex13b in a GC-1 cell line using CRISPR-Cas9. We differentially labelled the cell proteins by stable isotope labelling of amino acids in cell culture (SILAC) and performed mass spectrometry-based whole-cell proteomics to identify the differential protein regulation in knockout cells compared to wild-type cells. We found that Tex13b knockout leads to downregulation of the OXPHOS complexes and upregulation of glycolysis genes, which was further validated by western blotting. These results were further confirmed by respirometry analysis in Tex13b knockout cells. Further, we also performed a conditional overexpression of TEX13B in GC-1 cells and studied the expression of OXPHOS complex proteins by western blotting. We identified a rare variant, rs775429506 (p.Gly237Glu), exclusively in two non-obstructive-azoospermia (NOA) men, that may genetically predispose these men for infertility. Further, we demonstrated that Tex13b functions in the transcription regulation of OXPHOS complexes. N/A. We examined the function of Tex13b in GC-1 in vitro by knocking out and conditional overexpression, for understanding the function of Tex13b in germ cells. Unfortunately, this could not be replicated in either an animal model or in patient-derived tissue due to the non-availability of an animal model or patient's testis biopsies. This study identified that Tex13b plays an important role in male germ cell development and differentiation. The findings of this study would be useful for screening infertile males with spermatogenic failure and counselling them before the implementation of assisted reproduction technique(s). Funding was provided by the Council of Scientific and Industrial Research (CSIR) under the network project (BSC0101 and MLP0113) and SERB, the Department of Science and Technology, Government of India (J C Bose Fellowship: JCB/2019/000027). The authors do not have any competing interest.

AZIN2 is associated with apoptosis of germ cells in undescended testis

Undescended testis (UDT), known as cryptorchidism (CRY), is a common congenital disorder in which one or both testicles do not descend normally into the scrotum. A unilateral UDT model was established by inducing UDT in mice through surgery. The results showed that the testis in the UDT model group was abnormal; the lumen of the seminiferous tubule was atrophic; apoptosis, necrosis and shedding were observed in many of the germ cells; the level of sex hormones was abnormal; and mature sperm was reduced. Subsequently, transcriptome sequencing was conducted on the testicular tissue of UDT model mice. Through analysis and verification of differential genes, AZIN2 was identified as playing a key role in the decline in male fertility caused by cryptorchidism. AZIN2 expression and spermine content was down-regulated in the testis of the UDT group. We then used a combination of hypoxanthine and xanthine to create a GC-1 cell damage model. In this model, AZIN2 expression and spermine content was down-regulated. When si-Azin2 transfected GC-1 cells, cell viability and proliferation were decreased. However, in the GC-1 cell damage model transfected with Azin2 over-expressed plasmid, AZIN2 expression and spermine content was up-regulated, reversing the cell damage caused by hypoxanthine and xanthine, and restoring the proliferation ability of GC-1 cells. These results indicate that in UDT, down-regulated AZIN2 expression is a factor in testicular damage. This discussion of the connection between AZIN2 and germ cells has important clinical significance as it provides an important reference for the diagnosis and treatment of cryptorchidism.