Sertoli cell survival and barrier function are regulated by miR-181c/d-Pafah1b1 axis during mammalian spermatogenesis

[Research progress on glycolipid metabolism of Sertoli cell in the development of spermatogenic cell]

Sertoli cells play an important role in the process of spermatogenesis, and the abnormalities in spermatogenesis are closely related to disruptions in glycolipid metabolism. The metabolic environment of Sertoli cells is hypoxic, with glycolysis and fatty acid β-oxidation being the primary metabolic pathways. In Sertoli cells, glycolysis produces lactate to provide energy for spermatogenic cells, while fatty acid β-oxidation generates ATP. Currently, the relationship between glycolipid metabolism in Sertoli cells and spermatogenic cell development, as well as the interplay between glucose and lipid metabolism remain unclear. Various hormones, including sex hormones, can affect glucose metabolism in Sertoli cells by endocrine regulation. The activation or inhibition of signaling pathways such as AMPK, mTOR, and Akt can alter the expression levels of glycolysis-related transporter genes and the synthesis of fatty acids, thereby affecting glycolipid metabolism in Sertoli cells. Some transcription factors such as PPARγ can regulate downstream fatty acid metabolism-related genes by directly binding to their response elements and promoting the oxidation of fatty acids in Sertoli cells. In this article we elaborate on the key factors influencing glycolipid metabolism in Sertoli cells and their interconnections, as well as their potential clinical implications, offering new insights for precisely targeted treatments of male infertility.

The microRNA-mediated apoptotic signaling axis in male reproduction: a possible and targetable culprit in male infertility

Recently, infertility has emerged as a significant and prevalent public health concern warranting considerable attention. Apoptosis, recognized as programmed cell death, constitutes a crucial process essential for the maintenance of normal spermatogenesis. Multiple investigations have illustrated that the dysregulated apoptosis of reproductive cells, encompassing spermatogonial stem cells, Sertoli cells, and Leydig cells, serves as a causative factor in male infertility. MicroRNAs represent a class of small RNA molecules that exert negative regulatory control over gene expression using direct interaction with messenger RNA transcripts. Previous studies have established that aberrant expression of miRNAs induces apoptosis in reproductive tissues, correlating with reproductive dysfunctions and infertility. In this review, we offer a comprehensive overview of miRNAs and their respective target genes implicated in the apoptotic process. As well, miRNAs are involved in multiple apoptotic signaling pathways, namely the PI3K/AKT, NOTCH, Wnt/β-catenin, and mTOR signaling cascades, exerting both negative and positive effects. We additionally elucidate the significant functions played by lncRNAs and circular RNAs as competing endogenous RNAs in the process of apoptosis within reproductive cells. We further illustrate that external factors, including silica nanoparticles, Cyclosporine A, and smoking, induce dysregulation of miRNAs, resulting in apoptosis within reproductive cells and subsequent male reproductive toxicity. Further, we discuss the implication of heat stress, hypoxia, and diabetes in reproductive cell apoptosis induced by miRNA dysregulation in male infertility. Finally, we demonstrate that the modulation of miRNAs via traditional and novel medicine could protect reproductive cells from apoptosis and be implemented as a therapeutic approach in 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.

Clinical and gonadal transcriptome analysis of 38,XX disorder of sex development pigs†

Pigs serve as a robust animal model for the study of human diseases, notably in the context of disorders of sex development (DSD). This study aims to investigate the phenotypic characteristics and molecular mechanisms underlying the reproductive and developmental abnormalities of 38,XX ovotestis-DSD (OT-DSD) and 38,XX testis-DSD (T-DSD) in pigs. Clinical and transcriptome sequencing analyses were performed on DSD and normal female pigs. Cytogenetic and SRY analyses confirmed that OT/T-DSD pigs exhibited a 38,XX karyotype and lacked the SRY gene. The DSD pigs had higher levels of follicle-stimulating hormone, luteinizing hormone, and progesterone, but lower testosterone levels when compared with normal male pigs. The reproductive organs of OT/T-DSD pigs exhibit abnormal development, displaying both male and female characteristics, with an absence of germ cells in the seminiferous tubules. Sex determination and development-related differentially expressed genes shared between DSD pigs were identified in the gonads, including WT1, DKK1, CTNNB1, WTN9B, SHOC, PTPN11, NRG1, and NXK3-1. DKK1 is proposed as a candidate gene for investigating the regulatory mechanisms underlying gonadal phenotypic differences between OT-DSD and T-DSD pigs. Consequently, our findings provide insights into the molecular pathogenesis of DSD pigs and present an animal model for studying into DSD in humans.

MicroRNAs in spermatogenesis dysfunction and male infertility: clinical phenotypes, mechanisms and potential diagnostic biomarkers

Infertility affects approximately 10-15% of couples worldwide who are attempting to conceive, with male infertility accounting for 50% of infertility cases. Male infertility is related to various factors such as hormone imbalance, urogenital diseases, environmental factors, and genetic factors. Owing to its relationship with genetic factors, male infertility cannot be diagnosed through routine examination in most cases, and is clinically called 'idiopathic male infertility.' Recent studies have provided evidence that microRNAs (miRNAs) are expressed in a cell-or stage-specific manner during spermatogenesis. This review focuses on the role of miRNAs in male infertility and spermatogenesis. Data were collected from published studies that investigated the effects of miRNAs on spermatogenesis, sperm quality and quantity, fertilization, embryo development, and assisted reproductive technology (ART) outcomes. Based on the findings of these studies, we summarize the targets of miRNAs and the resulting functional effects that occur due to changes in miRNA expression at various stages of spermatogenesis, including undifferentiated and differentiating spermatogonia, spermatocytes, spermatids, and Sertoli cells (SCs). In addition, we discuss potential markers for diagnosing male infertility and predicting the varicocele grade, surgical outcomes, ART outcomes, and sperm retrieval rates in patients with non-obstructive azoospermia (NOA).

Inhibition of miR-143-3p Restores Blood-Testis Barrier Function and Ameliorates Sertoli Cell Senescence

Due to the increasing trend of delayed childbirth, the age-related decline in male reproductive function has become a widely recognized issue. Sertoli cells (SCs) play a vital role in creating the necessary microenvironment for spermatogenesis in the testis. However, the mechanism underlying Sertoli cell aging is still unclear. In this study, senescent Sertoli cells showed a substantial upregulation of miR-143-3p expression. miR-143-3p was found to limit Sertoli cell proliferation, promote cellular senescence, and cause blood-testis barrier (BTB) dysfunction by targeting ubiquitin-conjugating enzyme E2 E3 (UBE2E3). Additionally, the TGF-β receptor inhibitor SB431542 showed potential in alleviating age-related BTB dysfunction, rescuing testicular atrophy, and reversing the reduction in germ cell numbers by negatively regulating miR-143-3p. These findings clarified the regulatory pathways underlying Sertoli cell senescence and suggested a promising therapeutic approach to restore BTB function, alleviate Sertoli cell senescence, and improve reproductive outcomes for individuals facing fertility challenges.

Analysis of circRNA-miRNA-mRNA regulatory network of embryonic gonadal development in Mulard duck

The aim of the study was to explore the regulatory mechanism of differences in embryonic gonadal development between intergeneric distance hybrid offspring Mulard ducks and parent ducks. The morphological differences gonadal tissues of Muscovy ducks, Pekin ducks and Mulard ducks at 12.5-day embryonic age were observed by sectioning and hematoxylin-eosin (HE) staining. Then followed by transcriptome sequencing to screen for gonadal development-related differentially expressed circRNAs and mRNAs to construct a competitive endogenous RNA (ceRNA) regulatory network. Finally, qRT-PCR and luciferase reporter system were used to verify the sequencing data and targeting relationship of ceRNA pairs. The results showed that the seminiferous tubule lumen of Mulard ducks was not obvious, while there were obvious seminiferous tubules and tubular structures in testis of Pekin ducks and Muscovy ducks, with number and shape indicating maturity. There were 18 upregulated circRNAs and 16 downregulated circRNAs in Mulard ducks and Pekin ducks, respectively, and 39 upregulated circRNAs and 1 downregulated circRNA in Mulard ducks and Muscovy ducks, respectively. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis found that genes involves in dorso-ventral axis formation, for example, neurogenic locus notch homolog protein 1 (NOTCH1), were significantly enriched (P < 0.05). The novel_circ_0002265-gga-miR-122-5p-PAFAH1B2 regulatory network was constructed. The qRT-PCR results showed that the sequencing results were reliable. The dual-luciferase reporter assay showed that gga-miR-122-5p exists binding site of circ_0002265 and PAFAH1B2, indicating circ_0002265-gga-miR-122-5p-PAFAH1B2 targeting relationship. In summary, the embryonic gonadal development of intergeneric hybrid Mulard ducks may be regulated by differentially expressed circRNAs and genes, such as novel_circ_0000519, novel_circ_0003537, NOTCH1, FGFR2, PAFAH1B1, and PAFAH1B2, among which circ_0002265-gga-miR-122-5p-PAFAH1B2 may participate in the targeted regulation of gonadal development in Mulard ducks. The findings of this study are helpful for analyzing the mechanism of embryonic gonadal development differences in avians.

The Role of microRNA in Spermatogenesis: Is There a Place for Fertility Preservation Innovation?

Oncological treatments have dramatically improved over the last decade, and as a result, survival rates for cancer patients have also improved. Quality of life, including concerns about fertility, has become a major focus for both oncologists and patients. While oncologic treatments are often highly effective at suppressing neoplastic growth, they are frequently associated with severe gonadotoxicity, leading to infertility. For male patients, the therapeutic option to preserve fertility is semen cryopreservation. In prepubertal patients, immature testicular tissue can be sampled and stored to allow post-cure transplantation of the tissue, immature germ cells, or in vitro spermatogenesis. However, experimental techniques have not yet been proven effective for restoring sperm production for these patients. MicroRNAs (miRNAs) have emerged as promising molecular markers and therapeutic tools in various diseases. These small regulatory RNAs possess the unique characteristic of having multiple gene targets. MiRNA-based therapeutics can, therefore, be used to modulate the expression of different genes involved in signaling pathways dysregulated by changes in the physiological environment (disease, temperature, ex vivo culture, pharmacological agents). This review discusses the possible role of miRNA as an innovative treatment option in male fertility preservation-restoration strategies and describes the diverse applications where these new therapeutic tools could serve as fertility protection agents.

Seasonal patterns of miRNA and mRNA expression profiles in the testes of plateau zokors (Eospalax baileyi)

The gonads of seasonal breeding animals undergo periodic annual changes in morphology, physiological hormones, and gene expression levels. To clarify the regulatory mechanism of miRNAs in the seasonal testicular development and spermatogenesis of plateau zokors, the miRNA expression profiles in their testicles during breeding and non-breeding seasons were analyzed. In total, 447 miRNAs, including 366, 81, and 167 known, novel, and differentially expressed (DE) miRNAs, respectively, were determined in the testes. Compared to the non-breeding season, 90 DE miRNAs were upregulated and 77 DE miRNAs were downregulated during the breeding season. By analysing the miRNA and mRNA expression profiles, we predicted 2096 significant target mRNAs. According to the miRNA-mRNA interaction network, target mRNAs with DE miRNAs were related to testicular development and spermatogenesis. GO indicated that target mRNAs were enriched in spermatogenesis, cell differentiation, multicellular biological development, and flagellated sperm movement and were associated with regulating testicular development and spermatogenesis. KEGG suggested that target mRNAs were enriched in lipid and fructose metabolism and provided energy and material for spermatogenesis. The target mRNA of rno-miR-24-3p was determined to be Polyubiquitin-B (UBB). Our results provide a reference for revealing the mechanism by which miRNAs regulate testicular development and spermatogenesis in plateau zokors, which has important implications for understanding the regulation of seasonal reproduction in animals.

Mitochondrial dysfunction and endoplasmic reticulum stress induced by activation of PPARα leaded testicular to apoptosis in SD rats explored to di-(2-ethylhexyl) phthalate (DEHP)

Di-2-ethylhexyl phthalate (DEHP), as a common endocrine disrupting chemicals, can induce toxicity to reproductive system. However, the mechanism remains to be explored. In our study, DEHP exposure induced testicular injury in rats. The high throughput transcriptional sequencing was performed to identify differentially expressed genes (DEGs) between the treatment and control groups. KEGG analysis revealed that DEGs were enriched in apoptosis, PPARα, and ER stress pathway. DEHP up-regulated the expression of PPARα, Bax, Bim, caspase-4. GRP78, PERK, p-PERK, eIF2α, p-eIF2α, ATF4 and CHOP. This view has also been confirmed in TM3 and TM4 cells. In vitro, after pre-treatment with GW6471 (an inhibitor of PPARα) or GSK (an inhibitor of PERK), the apoptosis was inhibited and mitochondrial dysfunction was improved. Moreover, the improvement of mitochondrial dysfunction decreased the expression of PERK pathway by using SS-31(a protective agent for mitochondrial function). Interestingly, ER stress promoted the accumulation of ROS by ERO1L (the downstream of CHOP during ER stress), and the ROS further aggravated the ER stress, thus forming a feedback loop during the apoptosis. In this process, a vicious cycle consisting of PERK, eIF2α, ATF4, CHOP, ERO1L, ROS was involved. Taken together, our results suggested that mitochondrial dysfunction and ER stress-ROS feedback loop caused by PPARα activation played a crucial role in DEHP-induced apoptosis. This work provides insight into the mechanism of DEHP-induced reproductive toxicity.