50 years of spermatogenesis: Sertoli cells and their interactions with germ cells

AMPK regulates immature boar Sertoli cell proliferation through affecting CDK4/Cyclin D3 pathway and mitochondrial function

Sertoli cell (SC) proliferation plays an important role in sperm production and quality; however, the regulatory mechanism of SC proliferation is not well understood. This study investigated the role of adenosine monophosphate-activated protein kinase (AMPK) in the regulation of immature boar SC activity. Cell counting kit-8, Seahorse XFe96, mitochondrial respiratory enzyme-related assay kits, and transmission electron microscopy were used to detect SC proliferative viability, oxygen consumption rate (OCR), mitochondrial respiratory enzyme activity, and the ultrastructure of primary cultured SCs in vitro from the testes of 21-day-old boars. A dual luciferase reporter assay was performed to determine the miRNA-mRNA target interaction. Western blotting was used to analyze cell proliferation-related protein expression of p38, p21, proliferating cell nuclear antigen (PCNA), Cyclin-dependent kinase 4 (CDK4), Cyclin D3, and phosphorylated retinoblastoma protein (Rb). Each experiment had a completely randomized design, with three replicates in each experiment. The results showed that the AMPK inhibitor (Compound C, 20 μM-24 h) increased cell proliferation viability, ATP production, and maximal respiration of SCs by 0.64-, 0.12-, and 0.08-fold (p < 0.05), respectively; increased the SC protein expression of PCNA, CDK4, Cyclin D3, and p-Rb by 0.13-, 0.09-, 0.88-, and 0.12-fold (p < 0.05), respectively; and decreased the SC protein expression of p38 and p21 by 0.36- and 0.27-fold (p < 0.05), respectively. The AMPK agonist AICAR (2 mM-6 h) significantly inhibited SC ultrastructure, OCR, mitochondrial respiratory enzyme activity, and cell proliferation-related protein levels. AMPK was validated to be a target gene of miR-1285 based on the result in which the miR-1285 mimic inhibited the luciferase activity of wild-type AMPK by 0.54-fold (p < 0.001). MiR-1285 mimic promoted the OCR of SCs, with 0.45-, 0.15-, 0.21-, and 0.30-fold (p < 0.01) increases in ATP production, basal and maximal respiration, and spare capacity, respectively. MiR-1285 mimic increased the mitochondrial respiratory enzyme activity of SCs, with 0.63-, 0.70-, and 0.97-fold (p < 0.01) increases in NADH-Q oxidoreductase, cytochrome c oxidase, and ATP synthase, respectively. Moreover, the miR-1285 mimic increased the protein expression of PCNA, CDK4, Cyclin D3, and p-Rb by 0.24-, 0.30-, 0.22-, and 0.13-fold (p < 0.05), respectively, and reduced the protein expression of p38 and p21 by 0.58- and 0.66-fold (p < 0.001). MiR-1285 inhibitor showed opposite effects on the above indicators and induced numerous autophagosomes and large lipid droplets in SCs. A high dose of estradiol (10 μM-6 h, showed a promotion of AMPK activation in a previous study) significantly inhibited SC ultrastructure, mitochondrial function, and proliferation-related pathways, while these adverse effects were weakened by Compound C treatment or miR-1285 mimic transfection. Our findings suggest that the activation and inhibition of AMPK induced by specific drugs or synthesized targeted miRNA fragments could regulate immature boar SC proliferative activity by influencing the CDK4/Cyclin D3 pathway and mitochondrial function; this helps to provide a basis for the prevention and treatment of male sterility in clinical practice.

Retinoic acid tiers mitochondrial metabolism to Sertoli Cell-Mediated efferocytosis via a non-RAR-dependent mechanism

Efferocytosis of massive non-viable germ cells by Sertoli cells (SCs), the specialized phagocytes, is essential for maintaining testis homeostasis. What elusive is the contribution of mitochondrial metabolism to this energy-consuming process, as SC has a preference of aerobic glycolysis. All-trans retinoic acid (ATRA, hereafter referred to as RA) is a well-known morphogen that primarily acts through the nuclear RA receptor (RAR). It sustains SC blood-testisbarrier integrity, and it's SC-derived RA sets the timing of meiotic commitment. In this study, we revisited RA in SC biology, from the perspective of SC-mediated efferocytosis. We provide evidence that RA induces transcriptional programming of multiple regulators involved in efferocytosis, which thereby represses SC-mediated efferocytosis, via a RAR-independent mechanism, as blocking pan-RAR activity fails to rescue RA-induced defective efferocytosis. RA-treated SCs exhibit alternations in mitochondrial dynamics and metabolism, and the hindered efferocytosis can be rescued by stimulating mitochondrial OXPHOS via pharmacological targeting of AMPK and PDK. We thus prefer to propose a signaling axis of RA-mitochondrial metabolism-efferocytosis. Our study uncovers a hitherto unappreciated role of RA in SC biology and tiers mitochondria metabolism to SC-mediated efferocytosis, contributing a deeper understanding of SC in male reproduction.

PTBP1 mediates Sertoli cell actin cytoskeleton organization by regulating alternative splicing of actin regulators

Spermatogenesis is a biological process within the testis that produces haploid spermatozoa for the continuity of species. Sertoli cells are somatic cells in the seminiferous epithelium that orchestrate spermatogenesis. Cyclic reorganization of Sertoli cell actin cytoskeleton is vital for spermatogenesis, but the underlying mechanism remains largely unclear. Here, we report that RNA-binding protein PTBP1 controls Sertoli cell actin cytoskeleton reorganization by programming alternative splicing of actin cytoskeleton regulators. This splicing control enables ectoplasmic specializations, the actin-based adhesion junctions, to maintain the blood-testis barrier and support spermatid transport and transformation. Particularly, we show that PTBP1 promotes actin bundle formation by repressing the inclusion of exon 14 of Tnik, a kinase present at the ectoplasmic specialization. Our results thus reveal a novel mechanism wherein Sertoli cell actin cytoskeleton dynamics is controlled post-transcriptionally by utilizing functionally distinct isoforms of actin regulatory proteins, and PTBP1 is a critical regulatory factor in generating such isoforms.

The effect of LINC9137 targeting miR-140-3p-NKAIN3 signal axis on the development of goose testis sertoli cells

Sertoli cells (SC) are a type of important cells in the testes, which can provide transport proteins, regulatory proteins, growth factors, and other cytokines for the spermatogenic process. They participate in the regulation of the maturation and differentiation of spermatogenic cells and play an important supporting role in the migration, proliferation, and differentiation of germ cells at all levels in the testes. Previous studies found differential expression of LINC9137, miR-140-3p, and Sodium/Potassium Transporting ATPase Interacting 3 (NKAIN3) genesin high and low sperm motility goose testicular tissues. This study investigated the effects of the LINC9137-miR-140-3p-NKAIN3 signal axis on the proliferation and apoptosis of goose testicular sertoli cells at the cellular level, respectively. The results showed that through acridine orange staining, oil red O staining, Alkaline phosphatase (AKP) staining, and RT qPCR assay, it was comprehensively identified that the cultured testicular sertoli cells were purified in vitro. Through the dual luciferase activity detection test, it was found that LINC9137 has a targeted binding site with miR-140-3p and NKAIN3. In addition, this study found that overexpression of miR-140-3p significantly inhibited the expression of LINC9137 and NKAIN3 in sertoli cells, and their expression was significantly increased when miR-140-3p was interfered with. By measuring cell proliferation activity and apoptosis related gene expression, it was found that overexpression of LINC9137 decreased cell proliferation activity (P > 0.05), while the expression level of apoptosis factor Bcl2 Associated X Protein (Bax)/B-cell lymphoma-2 (Bcl2) increased (P > 0.05). On the contrary, when interfering with LINC9137, the cell proliferation activity of sertoli cells was significantly increased (P < 0.01), and the expression level of apoptosis factor Bax/Bcl2 was significantly reduced (P < 0.05); The effect of miR-140-3p on the proliferation and apoptosis of sertoli cells is opposite to that of LINC9137. Meanwhile, this study co transfected overexpressed LINC9137 and miR-140-3p plasmids into sertoli cells, and found that the effect of LINC9137 overexpression on supporting cell proliferation was weakened by miR-140-3p. This study elucidates the role and function of the LINC9137 miR-140-3p-NKAIN3 signaling axis in the development of goose testes and spermatogenesis, establishes a regulatory network related to spermatogenesis, and provides a theoretical basis for studying the genetic regulation of goose spermatogenesis.

Synthetic human gonadal tissues for toxicology

The process of mammalian reproduction involves the development of fertile germ cells in the testis and ovary, supported by the surrounders. Fertilization leads to embryo development and ultimately the birth of offspring inheriting parental genome information. Any disruption in this process can result in disorders such as infertility and cancer. Chemical toxicity affecting the reproductive system and embryogenesis can impact birth rates, overall health, and fertility, highlighting the need for animal toxicity studies during drug development. However, the translation of animal data to human health remains challenging due to interspecies differences. In vitro culture systems offer a promising solution to bridge this gap, allowing the study of mammalian cells in an environment that mimics the physiology of the human body. Current advances on in vitro culture systems, such as organoids, enable the development of biomaterials that recapitulate the physiological state of reproductive organs. Application of these technologies to human gonadal cells would provide effective tools for drug screening and toxicity testing, and these models would be a powerful tool to study reproductive biology and pathology. This review focuses on the 2D/3D culture systems of human primary testicular and ovarian cells, highlighting the novel approaches for in vitro study of human reproductive toxicology, specifically in the context of testis and ovary.

Protective effect of dental pulp stem cells' conditioned medium against cisplatin-induced testicular damage in rats

Cisplatin is a highly effective chemotherapy drug used to treat most solid tumors. However, one of its side effects is testicular toxicity, which can lead to fertility abnormalities. This study investigated the effectiveness of dental pulp mesenchymal stem cells conditioned medium (DPSC-CM) on cisplatin-induced testicular toxicity. In this study, 36 eight-week-old male Wistar rats were randomly divided into three groups equally (n = 12). Group 1 control "CTR", which received normal saline (0.5 ml) intraperitoneally (i.p), group 2 "Cis" which received an intraperitoneal dose of cisplatin (7 mg/kg), and group 3 "Cis+CM" which received an i.p injection of DPSC-CM (0.5 mg/kg) after cisplatin injection. Biochemical, histomorphometric, and histopathological studies were performed on the testis. Our results exhibited that cis administration led to a decline in total body weight, testis weight, diameter, and volume. A decrease in testosterone and IL-6 serum levels, as well as a decrease in IL-6 and TNFα levels, the activity of catalase and SOD enzymes, and an increase in MDA in testicular tissue were detected. Testicular tissue damage was associated with a significant decrease in tube diameter, germinal epithelium height, number of spermatogonia and Sertoli cells, along with a noticeable increase in basement membrane thickness, and perivascular fibrosis. DMSC-CM improved all the mentioned parameters. Taken together, our results demonstrated that DMSC-CM due to its antioxidant and anti-inflammatory properties, could be effective in reversing cisplatin-induced testicular toxicity.

Unveiling the roles of Sertoli cells lineage differentiation in reproductive development and disorders: a review

In mammals, gonadal somatic cell lineage differentiation determines the development of the bipotential gonad into either the ovary or testis. Sertoli cells, the only somatic cells in the spermatogenic tubules, support spermatogenesis during gonadal development. During embryonic Sertoli cell lineage differentiation, relevant genes, including WT1, GATA4, SRY, SOX9, AMH, PTGDS, SF1, and DMRT1, are expressed at specific times and in specific locations to ensure the correct differentiation of the embryo toward the male phenotype. The dysregulated development of Sertoli cells leads to gonadal malformations and male fertility disorders. Nevertheless, the molecular pathways underlying the embryonic origin of Sertoli cells remain elusive. By reviewing recent advances in research on embryonic Sertoli cell genesis and its key regulators, this review provides novel insights into sex determination in male mammals as well as the molecular mechanisms underlying the genealogical differentiation of Sertoli cells in the male reproductive ridge.

Identification and characterization of dystrophin-locus-derived testis-specific protein: A testis-specific gene within the intronic region of the rat dystrophin gene

The mammalian X chromosome exhibits enrichment in genes associated with germ cell development. Previously, we generated a rat model of Becker muscular dystrophy (BMD) characterized by an in-frame mutation in the dystrophin gene, situated on the X chromosome and responsible for encoding a protein crucial for muscle integrity. Male BMD rats are infertile owing to the absence of normal spermatids in the epididymis. Within the seminiferous tubules of BMD rats, elongated spermatids displayed abnormal morphology. To elucidate the cause of infertility, we identified a putative gene containing an open reading frame situated in the intronic region between exons 6 and 7 of the dystrophin gene, specifically deleted in male BMD rats. This identified gene, along with its encoded protein, exhibited specific detection within the testes, exclusively localized in round to elongated spermatids during spermiogenesis. Consequently, we designated the encoded protein as dystrophin-locus-derived testis-specific protein (DTSP). Given the absence of DTSP in the testes of BMD rats, we hypothesized that the loss of DTSP contributes to the infertility observed in male BMD rats.

Rreb1 is a key transcription factor in Sertoli cell maturation and function and spermatogenesis in mouse

Spermatogenesis is a developmental process driven by interactions between germ cells and Sertoli cells. This process depends on appropriate gene expression, which might be regulated by transcription factors. This study focused on Rreb1, a zinc finger transcription factor, and explored its function and molecular mechanisms in spermatogenesis in a mouse model. Our results showed that RREB1 was predominantly expressed in the Sertoli cells of the testis. The decreased expression of RREB1 following injection of siRNA caused impaired Sertoli cell development, which was characterized using a defective blood-testis barrier structure and decreased expression of Sertoli cell functional maturity markers; its essential trigger might be SMAD3 destabilization. The decreased expression of RREB1 in mature Sertoli cells influenced the cell structure and function, which resulted in abnormal spermatogenesis, manifested as oligoasthenoteratozoospermia, and we believe RREB1 plays this role by regulating the transcription of Fshr and Wt1. RREB1 has been reported to activate Fshr transcription, and we demonstrated that the knockdown of Rreb1 caused a reduction in follicle-stimulating hormone receptor (FSHR) in the testis, which could be the cause of the increased sperm malformation. Furthermore, we confirmed that RREB1 directly activates Wt1 promoter activity, and RREB1 downregulation induced the decreased expression of Wt1 and its downstream polarity-associated genes Par6b and E-cadherin, which caused increased germ-cell death and reduced sperm number and motility. In conclusion, RREB1 is a key transcription factor essential for Sertoli cell development and function and is required for normal spermatogenesis.

Etiology of Male Infertility: an Update

Spermatogenesis is a complex process of germ cell division and differentiation that involves extensive cross-talk between the developing germ cells and the somatic testicular cells. Defective endocrine signaling and/or intrinsic defects within the testes can adversely affect spermatogenic progression, leading to subfertility/infertility. In recent years, male infertility has been recognized as a global public health concern, and research over the last few decades has elucidated the complex etiology of male infertility. Congenital reproductive abnormalities, genetic mutations, and endocrine/metabolic dysfunction have been demonstrated to be involved in infertility/subfertility in males. Furthermore, acquired factors like exposure to environmental toxicants and lifestyle-related disorders such as illicit use of psychoactive drugs have been shown to adversely affect spermatogenesis. Despite the large body of available scientific literature on the etiology of male infertility, a substantial proportion of infertility cases are idiopathic in nature, with no known cause. The inability to treat such idiopathic cases stems from poor knowledge about the complex regulation of spermatogenesis. Emerging scientific evidence indicates that defective functioning of testicular Sertoli cells (Sc) may be an underlying cause of infertility/subfertility in males. Sc plays an indispensable role in regulating spermatogenesis, and impaired functional maturation of Sc has been shown to affect fertility in animal models as well as humans, suggesting abnormal Sc as a potential underlying cause of reproductive insufficiency/failure in such cases of unexplained infertility. This review summarizes the major causes of infertility/subfertility in males, with an emphasis on infertility due to dysregulated Sc function.

Photoperiod-regulated mitophagy in the germ cells of Brandt's voles (Lasiopodomys brandtii)

Photoperiod is a pivotal factor in affecting testicular function and spermatogenesis in seasonal-breeding animals. Mitophagy is essential for spermatogenesis, but its association with seasonal photoperiods has not been studied extensively. To explore this, we exposed male Brandt's voles (Lasiopodomys brandtii) to long-photoperiod (LP, 16 h/day) and short-photoperiod (SP, 8 h/day) conditions from their embryonic stages. Our results indicated that testis weight, volume, and relative testes weight were all significantly increased in LP compared to SP. Additionally, blood testosterone levels were markedly higher in LP than SP. Histological examination revealed that seminiferous diameter and epithelium thickness were greater in LP, with an increased abundance of germ cell types and cell numbers compared to SP. RT-qPCR analysis showed that mitophagy-promoting genes, such as Pink1, Prkn, Tomm7, Mnf2, Lc3, Optn, Gabarap, and Nbr1 were all upregulated in LP. Fluorescence in situ hybridization indicated that Pink1 expression was present in spermatogonia in SP, while in LP, Pink1 expression extended to almost all germ cell types with significantly higher mean optical density. Prkn expression was found in all germ cell types in both LP and SP, with a significantly higher mean optical density of 10-week-old LP males. Transmission electron microscopy showed normal mitochondrial morphology with clear membranes in SP, while the LP group had reduced cristae in mitochondria and damaged mitochondria undergoing autophagy. This study suggests that mitophagy may be involved in the photoperiodic spermatogenesis in Brandt's voles, providing insights into the role of photoperiod in seasonal reproduction in wild animals.

Loss of Fshr Prevents Testicular Maturation in Atlantic Salmon (Salmo salar L.)

Early puberty poses a significant challenge for male Atlantic salmon in aquaculture due to its negative impact on growth and welfare. The regulation of puberty in vertebrates involves 2 key reproductive hormones: follicle-stimulating hormone (FSH) and luteinizing hormone (LH) and their gonadal receptors. In male mice lacking FSH receptor, testes size is reduced, but fertility is maintained, while medaka and zebrafish with a disrupted fshr gene exhibit near normal testis size and fertility. In these fishes both Fsh and Lh are present during puberty and Lh may rescue fertility, while in salmonid fish only Fsh is present in the circulation during puberty. Using CRISPR-Cas9, we produced crispants with a high prevalence of fshr mutations at the target site, which remained fertile, although more than half showed a testis development deviating from wild-type (wt) males. Crossing out these F0 crispants to each other produced a viable F1 generation showing frameshift (fshr-/-) or in-frame mutations (fshrif/if). Nearly all wt males matured while all fshr-/- males remained immature with small testes containing A spermatogonia as the furthest developed germ cell type and prepubertal plasma androgen levels. Also, the pituitary transcript levels of gnrhr2bba and lhb, but not for fshb, were reduced in the fshr-/- males compared with maturing males. More than half of the fshrif/if mutant males showed no or a delayed maturation. In conclusion, Atlantic salmon show the unique characteristic that loss of Fshr function alone results in male infertility, offering new opportunities to control precocious puberty or fertility in salmon.

Wuzi Yanzong administration alleviates Sertoli cell injury by recovering AKT/mTOR-mediated autophagy and the mTORC1-mTROC2 balance in aging-induced testicular dysfunction

ETHNOPHARMACOLOGICAL RELEVANCE

Wuzi Yanzong Prescription (WZ), a classic traditional Chinese medicine formula, has the properties of kidney nourishing and essence strengthening, and it is widely used to treat male infertility with a long history. Sertoli cells are injured with aging, resulting in testicular dysfunction, and WZ effectively rejuvenates the age-related decline of testicular function. However, whether the therapeutic effects of WZ on aging-related testicular dysfunction are dependent on the restoration of Sertoli cell function remains unclear.

AIM OF THE STUDY

In a mouse model of natural aging, we explored the protective effects of WZ and its potential mechanisms.

MATERIALS AND METHODS

Fifteen-month-old C57BL/6 mice were randomized to receive either standard diet or WZ (2 and 8 g/kg) for 3 months. Meanwhile, 10 1-month-old mice were considered the adult control group and received standard diet for 3 months. The testis and epididymis were rapidly collected, and the sperm quality, testicular histology, Sertoli cell numbers, tight junction (TJ) ultrastructure, and blood-testis barrier-associated protein expression and localization were assessed.

RESULTS

WZ significantly increased sperm concentration and sperm viability, improved the degenerative histomorphology and elevated the seminiferous epithelium height. Furthermore, WZ increased the number of Sertoli cells, restored the ultrastructure of the Sertoli cell TJ, and upregulated the expression of TJ-associated proteins (zonula occludens-1 and Claudin11), ectoplasm specialized-associated proteins (N-Cadherin, E-Cadherin and β-Catenin), and gap junction-associated protein (connexin 43), but did not affect the expression of Occludin and cytoskeletal protein (Vimentin). In addition, WZ did not change the localization of zonula occludens-1 and β-Catenin in aged testis. Moreover, WZ increased the expression of autophagy-associated proteins (light chain 3 beta and autophagy related 5) and decreased the expression of p62, phosphorylated mammalian target of rapamycin, and phosphorylated AKT in Sertoli cells. Finally, we found that WZ attenuated mTOR complex 1 (mTORC1) activity and upregulated mTORC2 activity, as evidenced by inhibition of the expression of the regulatory-associated protein of mTOR, phosphorylated p70 S6K, and phosphorylated ribosomal protein s6 and enhancement of the expression of Rictor in the Sertoli cells of aging mice.

CONCLUSIONS

WZ improves the injury of Sertoli cells by restoring AKT/mTOR-mediated autophagy and the mTORC1-mTROC2 balance in Sertoli cells during aging. Our findings provide a new mechanism of WZ in the treatment of aging-induced testicular dysfunction.

Protective effect of Moringa oleifera leaf ethanolic extract against uranyl acetate-induced testicular dysfunction in rats

Uranyl acetate (UA) is used in civilian and military applications, predisposing it to wide dispersion in ecosystems. Using high-performance liquid chromatography, gas chromatography-mass spectrometry, and 2,2-Diphenyl-1-picrylhydrazyl scavenging radical analysis, we confirmed that Moringa oleifera leaf ethanolic extract (MLEE) is rich in biologically active phytochemicals. Thus, this study aims to investigate the possible defensive effect of MLEE against UA-induced testicular dysfunction. To achieve this, rats were divided randomly and evenly into three groups for 14 days. The control group received no treatment, while the UA group received a single intraperitoneal injection of UA at a dose of 5 mg/kg BW dissolved in saline on the 12th day of the experiment, followed by no treatment the following day. The MLEE + UA group received daily oral administration of MLEE (300 mg/kg BW) dissolved in distilled water before exposure to UA intoxication. The disruption observed in the pituitary-gonadal axis of UA-intoxicated rats was characterized by a significant decrease in luteinizing hormone, follicle-stimulating hormone, testosterone, and estradiol 17beta levels. Additionally, there was a notable increase in malondialdehyde and a decrease in catalase, superoxide dismutase, reduced glutathione, and nitric oxide, accompanied by an up-regulation in the immuno-expression of nuclear factor-kappa B, indicating a disturbance in the redox balance. The TUNEL assay confirmed a substantial rise in apoptotic cell numbers in the UA group. Testicular histopathological changes, excessive collagen deposition, and reduced glycogen content were evident following UA exposure. However, supplementation with MLEE effectively countered these mentioned abnormalities. MLEE is proposed to combat the toxicological molecular targets in the UA-affected testis by restoring the balance between oxidants and antioxidants while obstructing the apoptotic cascade. MLEE contains an abundance of redox-stabilizing and cytoprotective phytochemicals that have the potential to counteract the mechanistic pathways associated with UA exposure. These findings encourage further research into other plausible protective aspects of Moringa oleifera against the UA challenge.

Integration of RRBS and RNA-seq unravels the regulatory role of DNMT3A in porcine Sertoli cell proliferation

DNMT3A participates in de novo methylation, yet its impact on the proliferation of testicular Sertoli cells remains unclear. Development-specific methylation has been proven to be associated with cellular development. Therefore, in this study, we simulated DNMT3A expression pattern during testicular development by DNMT3A interference. Then, RRBS and RNA-seq were used to decipher DNMT3A regulatory mechanisms on Sertoli cell proliferation. Immunofluorescence staining revealed the expression of DNMT3A in the Sertoli cells of the prepubertal testis. DNMT3A was demonstrated to inhibit the cell cycle and proliferation of Sertoli cells, while promoting cell apoptosis. After transfected with DNMT3A interference, a total of 560 DEGs and 2,091 DMGs produced by DNMT3A interference were identified between two treated groups, respectively. Integrating the results from RRBS and RNA-seq, the overlapping genes between DMGs and DEGs were found to be enriched in the Gene Ontology (GO) terms related to cellular development and the Apelin signaling pathway. The present study demonstrated the impact of DNMT3A on the proliferation of porcine testicular Sertoli cells, suggesting that DNMT3A primarily acts through the Apelin signaling pathway. These findings provide valuable insights into how DNMT3A influences testicular development and health, offering new perspectives.

Retinoic acid signaling in development and differentiation commitment and its regulatory topology

Retinoic acid (RA), the derivative of vitamin A/retinol, is a signaling molecule with important implications in health and disease. It is a well-known developmental morphogen that functions mainly through the transcriptional activity of nuclear RA receptors (RARs) and, uncommonly, through other nuclear receptors, including peroxisome proliferator-activated receptors. Intracellular RA is under spatiotemporally fine-tuned regulation by synthesis and degradation processes catalyzed by retinaldehyde dehydrogenases and P450 family enzymes, respectively. In addition to dictating the transcription architecture, RA also impinges on cell functioning through non-genomic mechanisms independent of RAR transcriptional activity. Although RA-based differentiation therapy has achieved impressive success in the treatment of hematologic malignancies, RA also has pro-tumor activity. Here, we highlight the relevance of RA signaling in cell-fate determination, neurogenesis, visual function, inflammatory responses and gametogenesis commitment. Genetic and post-translational modifications of RAR are also discussed. A better understanding of RA signaling will foster the development of precision medicine to improve the defects caused by deregulated RA signaling.

Localization and expression of phospholipase A2 and polyunsaturated fatty acid profile in the testis tissues of Hu sheep

The fatty acid content and the localization and expression of phospholipase A2 (PLA2) in the testis of Hu sheep were investigated. A total of 18 six-month-old Hu sheep were divided into small group (S, with left testis weight < 50 g), medium group (M, with left testis weight among 90-110 g), and large group (L, with left testis weight >160 g), which had six individuals each. The expression of PLA2 in testicular tissues of different sizes was analyzed by immunohistochemistry, RT-qPCR, and Western blot. The fatty acid profile was detected by gas chromatography. Immunohistochemical labeling determined that PLA2 protein was expressed in the Leydig and Sertoli cells of testis, and the immunohistochemical average optional density in the S group was significantly greater than the L group (P < 0.05). RT-qPCR and Western blot analysis showed that PLA2 in the S group was greater than that in the L group (P < 0.05). Docosahexaenoic acid, ω-3 polyunsaturated fatty acid (PUFA), and total PUFA content in the testis of the L group were significantly less than those of the S and M groups (P < 0.01). This study showed that PLA2 content in the S group was greater than that in the L group.

Loss of NR5A1 in mouse Sertoli cells after sex determination changes cellular identity and induces cell death by anoikis

To investigate the role of the nuclear receptor NR5A1 in the testis after sex determination, we analyzed mice lacking NR5A1 in Sertoli cells (SCs) from embryonic day (E) 13.5 onwards. Ablation of Nr5a1 impaired the expression of genes characteristic of SC identity (e.g. Sox9 and Amh), caused SC death from E14.5 onwards through a Trp53-independent mechanism related to anoikis, and induced disorganization of the testis cords. Together, these effects caused germ cells to enter meiosis and die. Single-cell RNA-sequencing experiments revealed that NR5A1-deficient SCs changed their molecular identity: some acquired a 'pre-granulosa-like' cell identity, whereas other reverted to a 'supporting progenitor-like' cell identity, most of them being 'intersex' because they expressed both testicular and ovarian genes. Fetal Leydig cells (LCs) did not display significant changes, indicating that SCs are not required beyond E14.5 for their emergence or maintenance. In contrast, adult LCs were absent from postnatal testes. In addition, adult mutant males displayed persistence of Müllerian duct derivatives, decreased anogenital distance and reduced penis length, which could be explained by the loss of AMH and testosterone synthesis due to SC failure.

Zinc oxide nanoparticles-induced testis damage at single-cell resolution: Depletion of spermatogonia reservoir and disorder of Sertoli cell homeostasis

The widespread application of zinc oxide nanoparticles (ZnO NPs) in our daily life has initiated an enhanced awareness of their biosafety concern. An incredible boom of evidence of organismal disorder has accumulated for ZnO NPs, yet there has been no relevant study at the single-cell level. Here, we profiled > 28,000 single-cell transcriptomes and assayed > 25,000 genes in testicular tissues from two healthy Sprague Dawley (SD) rats and two SD rats orally exposed to ZnO NPs. We identified 10 cell types in the rat testis. ZnO NPs had more deleterious effects on spermatogonia, Sertoli cells, and macrophages than on the other cell types. Cell-cell communication analysis indicated a sharp decrease of interaction intensity for all cell types except macrophages in the ZnO NPs group than in the control group. Interestingly, two distinct maturation states of spermatogonia were detected during pseudotime analysis, and ZnO NPs induced reservoir exhaustion of undifferentiated spermatogonia. Mechanically, ZnO NPs triggered fatty acid accumulation in GC-1 cells through protein kinase B (Akt)/mammalian target of rapamycin (mTOR) signaling and peroxisome proliferator-activated receptor alpha (PPARα)/acyl-CoA oxidase 1 (Acox1) axis, contributing to cell apoptosis. In terms of Sertoli cells, downregulated genes were highly enriched for tight junction. In vitro and in vivo experiments verified that ZnO NPs disrupted blood-testis barrier formation and growth factors synthesis, which subsequently inhibited the proliferation and induced the apoptosis of spermatogonia. As for the macrophages, ZnO NPs activated oxidative stress of Raw264.7 cells through nuclear factor erythroid 2-related factor 2 (Nrf2)/heme oxygenase-1 (HO-1) pathway and promoted cell apoptosis through extracellular signal-regulated kinase (ERK) 1/2 pathway. Collectively, our work reveals the cell type-specific and cellularly heterogenetic mechanism of ZnO NPs-induced testis damage and paves the path for identifying putative biomarkers and therapeutics against this disorder.

Autophagy regulation and protein kinase activity of PIK3C3 controls sertoli cell polarity through its negative regulation on SCIN (scinderin)

Sertoli cells are highly polarized testicular cells that provide a nurturing environment for germ cell development and maturation during spermatogenesis. The class III phosphatidylinositol 3-kinase (PtdIns3K) plays core roles in macroautophagy in various cell types; however, its role in Sertoli cells remains unclear. Here, we generated a mouse line in which the gene encoding the catalytic subunit, Pik3c3, was specifically deleted in Sertoli cells (cKO) and found that after one round of normal spermatogenesis, the cKO mice quickly became infertile and showed disruption of Sertoli cell polarity and impaired spermiogenesis. Subsequent proteomics and phosphoproteomics analyses enriched the F-actin cytoskeleton network involved in the disorganized Sertoli-cell structure in cKO testis which we identified a significant increase of the F-actin negative regulator SCIN (scinderin) and the reduced phosphorylation of HDAC6, an α-tubulin deacetylase. Our results further demonstrated that the accumulation of SCIN in cKO Sertoli cells caused the disorder and disassembly of the F-actin cytoskeleton, which was related to the failure of SCIN degradation through the autophagy-lysosome pathway. Additionally, we found that the phosphorylation of HDAC6 at site S59 by PIK3C3 was essential for its degradation through the ubiquitin-proteasome pathway. As a result, the HDAC6 that accumulated in cKO Sertoli cells deacetylated SCIN at site K189 and led to a disorganized F-actin cytoskeleton. Taken together, our findings elucidate a new mechanism for PIK3C3 in maintaining the polarity of Sertoli cells, in which both its autophagy regulation or protein kinase activities are required for the stabilization of the actin cytoskeleton.Abbreviations: ACTB: actin, beta; AR: androgen receptor; ATG14: autophagy related 14; BafA1: bafilomycin A1; BECN1: beclin 1, autophagy related; BTB: blood-testis barrier; CASP3: caspase 3; CDC42: cell division cycle 42; CDH2: cadherin 2; CHX: cycloheximide; CTNNA1: catenin (cadherin associated protein), alpha 1; CYP11A1: cytochrome P450, family 11, subfamily A, polypeptide 1; EBSS: Earle's balanced salt solution; ES: ectoplasmic specialization; FITC: fluorescein isothiocyanate; GAPDH: glyceraldehyde-3-phosphate dehydrogenase; GCNA: germ cell nuclear acidic protein; GJA1: gap junction protein, alpha 1; H2AX: H2A.X variant histone; HDAC6: histone deacetylase 6; KIT: KIT proto-oncogene, receptor tyrosine kinase; LAMP1: lysosomal associated membrane protein 1; MAP3K5: mitogen-activated protein kinase kinase kinase 5; MAP1LC3B: microtubule associated protein 1 light chain 3 beta; OCLN: occludin; PIK3C3: phosphatidylinositol 3-kinase catalytic subunit type 3; PIK3R4: phosphoinositide-3-kinase regulatory subunit 4; PNA: arachis hypogaea lectin; RAC1: Rac family small GTPase 1; SCIN: scinderin; SQSTM1/p62: sequestosome 1; SSC: spermatogonia stem cell; STK11: serine/threonine kinase 11; TJP1: tight junction protein 1; TubA: tubastatin A; TUBB3: tubulin beta 3 class III; TUNEL: TdT-mediated dUTP nick-end labeling; UB: ubiquitin; UVRAG: UV radiation resistance associated gene; VIM: vimentin; WT1: WT1 transcription factor; ZBTB16: zinc finger and BTB domain containing 16.

Molecular characterization, expression patterns and cellular localization of BCAS2 gene in male Hezuo pig

Background

Breast carcinoma amplified sequence 2 (BCAS2) participates in pre-mRNA splicing and DNA damage response, which is implicated in spermatogenesis and meiosis initiation in mouse. Nevertheless, the physiological roles of BCAS2 in the testes of large mammals especially boars remain largely unknown.

Methods

In this study, testes were collected from Hezuo pig at three development stages including 30 days old (30 d), 120 days old (120 d), and 240 days old (240 d). BCAS2 CDS region was firstly cloned using RT-PCR method, and its molecular characteristics were identified using relevant bioinformatics software. Additionally, the expression patterns and cellular localization of BCAS2 were analyzed by quantitative real-time PCR (qRT-PCR), Western blot, immunohistochemistry and immunofluorescence.

Results

The cloning and sequence analysis indicated that the Hezuo pig BCAS2 CDS fragment encompassed 678 bp open reading frame (ORF) capable of encoding 225 amino acid residues, and possessed high identities with some other mammals. The results of qRT-PCR and Western blot displayed that BCAS2 levels both mRNA and protein were age-dependent increased (p < 0.01). Additionally, immunohistochemistry and immunofluorescence results revealed that BCAS2 protein was mainly observed in nucleus of gonocytes at 30 d testes as well as nucleus of spermatogonia and Sertoli cells at 120 and 240 d testes. Accordingly, we conclude that BCAS2 is critical for testicular development and spermatogenesis of Hezuo pig, perhaps by regulating proliferation or differentiation of gonocytes, pre-mRNA splicing of spermatogonia and functional maintenance of Sertoli cells, but specific mechanism still requires be further investigated.

Glutamine protects mouse spermatogonial stem cells against NOX1-derived ROS for sustaining self-renewal division in vitro

Reactive oxygen species (ROS) are generated from NADPH oxidases and mitochondria; they are generally harmful for stem cells. Spermatogonial stem cells (SSCs) are unique among tissue-stem cells because they undergo ROS-dependent self-renewal via NOX1 activation. However, the mechanism by which SSCs are protected from ROS remains unknown. Here, we demonstrate a crucial role for Gln in ROS protection using cultured SSCs derived from immature testes. Measurements of amino acids required for SSC cultures revealed the indispensable role of Gln in SSC survival. Gln induced Myc expression to drive SSC self-renewal in vitro, whereas Gln deprivation triggered Trp53-dependent apoptosis and impaired SSC activity. However, apoptosis was attenuated in cultured SSCs that lacked NOX1. In contrast, cultured SSCs lacking Top1mt mitochondria-specific topoisomerase exhibited poor mitochondrial ROS production and underwent apoptosis. Gln deprivation reduced glutathione production; supra-molar Asn supplementation allowed offspring production from SSCs cultured without Gln. Therefore, Gln ensures ROS-dependent SSC-self-renewal by providing protection against NOX1 and inducing Myc.

Rhox8 homeobox gene ablation leads to rete testis abnormality and male subfertility in mice†

The reproductive homeobox X-linked (Rhox) genes encode transcription factors that are expressed selectively in reproductive tissues including the testis, epididymis, ovary, and placenta. While many Rhox genes are expressed in germ cells in the mouse testis, only Rhox8 is expressed exclusively in the Sertoli cells during embryonic and postnatal development, suggesting a possible role of Rhox8 in embryonic gonad development. Previously, Sertoli cell-specific knockdown of RHOX8 resulted in male subfertility due to germ cell defects. However, this knockdown model was limited in examining the functions of Rhox8 as RHOX8 knockdown occurred only postnatally, and there was still residual RHOX8 in the testis. In this study, we generated new Rhox8 knockout (KO) mice using the CRISPR/Cas9 system. Sex determination and fetal testis development were apparently normal in mutant mice. Fertility analysis showed a low fecundity in Rhox8 KO adult males, with disrupted spermatogenic cycles, increased germ cell apoptosis, and reduced sperm count and motility. Interestingly, Rhox8 KO testes showed an increase in testis size with dilated seminiferous tubules and rete testis, which might be affected by efferent duct (ED) Rhox8 ablation dysregulating the expression of metabolism and transport genes in the EDs. Taken together, the data presented in this study suggest that Rhox8 in the Sertoli cells is not essential for sex determination and embryonic testis differentiation but has an important role in complete spermatogenesis and optimal male fertility.

Effects of exposure to PM2.5 during pregnancy on the multigenerational reproductive outcomes of male mouse offspring and the role of Sertoli cells

There is a paucity of studies on the multigenerational reproductive toxicity of fine particle matter (PM2.5) exposure during pregnancy on male offspring and the underlying mechanisms. This study explored the effects of PM2.5 exposure during pregnancy on the spermatogenesis of three consecutive generations of male mouse offspring. We randomized pregnant C57BL/6 mice into the control group, the Quartz Fiber Membrane control group, and two experimental groups exposed to different concentrations of PM2.5 (4.8 and 43.2 mg/kg B.Wt.). Pregnant mice from experimental groups received intratracheal instillation of PM2.5 of different doses on a three-day basis until birth. F1 mature male offspring from PM2.5-exposed pregnant mice were mated with normal female C57BL/6 mice. Likewise, their F2 mature male followed the same to produce the F3 generation. The results showed that PM2.5 exposure during pregnancy led to decreased body and tail length, body weight, and survival rates, decreased sperm concentration and sperm motility, and increased sperm abnormality rates significantly in F1 male offspring. We barely observed significant impacts of PM2.5 on the birth number, survival rates, and index of testes in the F2 and F3 offspring. Further exploration showed that PM2.5 exposure during pregnancy caused the morphological abnormality of Sertoli cells, downregulated androgen receptor (AR) and connexin43, upregulated anti-Müllerian hormone (AMH), cytokeratin-18 (CK-18), caspase-3, and cleaved caspase-3, decreased thyroid-stimulating hormone (TSH) and testosterone (T), and increased triiodothyronine (T3) in F1 male mouse offspring. Overall, we hypothesize that PM2.5 exposure during pregnancy mainly negatively impacts spermatogenesis in the F1 offspring. The possible mechanism could be that PM2.5 exposure during pregnancy disrupts endocrine hormone release in the F1 generation, thereby influencing the maturation and proliferation of their Sertoli cells and hindering spermatogenesis. This study for the first time investigates the role of Sertoli cells in the reproductive toxicity of PM2.5 on offspring.

Melatonin improves oxidative state and lactate metabolism in rodent Sertoli cells

Antioxidant actions of melatonin and its impact on testicular function and fertility have already been described. Considering that Sertoli cells contribute to provide structural support and nutrition to germ cells, we evaluated the effect of melatonin on oxidative state and lactate metabolism in the immature murine TM4 cell line and in immature hamster Sertoli cells. A prooxidant stimulus applied to rodent Sertoli cells expressing MT1/MT2 receptors, increased lipid peroxidation whereas decreased antioxidant enzymes (superoxide dismutase 1, catalase, peroxiredoxin 1) expression and catalase activity. These changes were prevented by melatonin. Furthermore, melatonin stimulated lactate dehydrogenase (LDH) expression/activity via melatonin receptors, and increased intracellular lactate production in rodent Sertoli cells. Interestingly, oral melatonin supplementation in infertile men positively regulated LDHA testicular mRNA expression. Overall, our work provides insights into the potential benefits of melatonin on Sertoli cells contributing to testicular development and the future establishment of a sustainable spermatogenesis.

Effects of Heparan sulfate acetyl-CoA: Alpha-glucosaminide N-acetyltransferase (HGSNAT) inactivation on the structure and function of epithelial and immune cells of the testis and epididymis and sperm parameters in adult mice

Heparan sulfate (HS), an abundant component of the apical cell surface and basement membrane, belongs to the glycosaminoglycan family of carbohydrates covalently linked to proteins called heparan sulfate proteoglycans. After endocytosis, HS is degraded in the lysosome by several enzymes, including heparan-alpha-glucosaminide N-acetyltransferase (HGSNAT), and in its absence causes Mucopolysaccharidosis III type C (Sanfilippo type C). Since endocytosis occurs in epithelial cells of the testis and epididymis, we examined the morphological effects of Hgsnat inactivation in these organs. In the testis, Hgsnat knockout (Hgsnat-Geo) mice revealed statistically significant decrease in tubule and epithelial profile area of seminiferous tubules. Electron microscopy (EM) analysis revealed cross-sectional tubule profiles with normal and moderately to severely altered appearances. Abnormalities in Sertoli cells and blood-testis barrier and the absence of germ cells in some tubules were noted along with altered morphology of sperm, sperm motility parameters and a reduction in fertilization rates in vitro. Along with quantitatively increased epithelial and tubular profile areas in the epididymis, EM demonstrated significant accumulations of electrolucent lysosomes in the caput-cauda regions that were reactive for cathepsin D and prosaposin antibodies. Lysosomes with similar storage materials were also found in basal, clear and myoid cells. In the mid/basal region of the epithelium of caput-cauda regions of KO mice, large vacuolated cells, unreactive for cytokeratin 5, a basal cell marker, were identified morphologically as epididymal mononuclear phagocytes (eMPs). The cytoplasm of the eMPs was occupied by a gigantic lysosome suggesting an active role of these cells in removing debris from the epithelium. Some eMPs were found in proximity to T-lymphocytes, a feature of dendritic cells. Taken together, our results reveal that upon Hgsnat inactivation, morphological alterations occur to the testis affecting sperm morphology and motility parameters and abnormal lysosomes in epididymal epithelial cells, indicative of a lysosomal storage disease.

Comprehensive Analysis of the Transcriptome-Wide m6A Methylome in Shaziling Pig Testicular Development

RNA N6-methyladenosine (m6A) modification is one of the principal post-transcriptional modifications and plays a dynamic role in testicular development and spermatogenesis. However, the role of m6A in porcine testis is understudied. Here, we performed a comprehensive analysis of the m6A transcriptome-wide profile in Shaziling pig testes at birth, puberty, and maturity. We analyzed the total transcriptome m6A profile and found that the m6A patterns were highly distinct in terms of the modification of the transcriptomes during porcine testis development. We found that key m6A methylated genes (AURKC, OVOL, SOX8, ACVR2A, and SPATA46) were highly enriched during spermatogenesis and identified in spermatogenesis-related KEGG pathways, including Wnt, cAMP, mTOR, AMPK, PI3K-Akt, and spliceosome. Our findings indicated that m6A methylations are involved in the complex yet well-organized post-transcriptional regulation of porcine testicular development and spermatogenesis. We found that the m6A eraser ALKBH5 negatively regulated the proliferation of immature porcine Sertoli cells. Furthermore, we proposed a novel mechanism of m6A modification during testicular development: ALKBH5 regulated the RNA methylation level and gene expression of SOX9 mRNA. In addition to serving as a potential target for improving boar reproduction, our findings contributed to the further understanding of the regulation of m6A modifications in male reproduction.

The relevance of the use of plant extracts on testicular cells: A systematic review

This review aims to establish an association between traditional and scientific knowledge to allow the evaluation of the effectiveness of medicinal plants, as well as their risks based on the testicular microenvironment. A systematic search was performed using PRISMA guidelines. The descriptors were structured based on search filters built for three domains: Animals, Plants, and Testis. The filters on the PubMed/Medline platform were constructed using a hierarchical distribution of the MeSH Terms. Methodological quality assessments were performed using the SYRCLE risk bias tool. Data on testicular cells, hormones and biochemistry, sperm, and sexual behavior were evaluated and compared. The search came out with 2644 articles, and 36 articles met the inclusion criteria and were used in this review. The included studies analyzed testicular cells from murine models treated with crude plant extracts. Plant extracts act directly on the hypothalamic-pituitary axis and/or directly on testicular cells, inhibiting and stimulating the reproductive process, thus causing alterations in fertility rates. Apiaceae and the Cucurbitaceae families are the most used in male reproductive biology experiments, being Apiaceae described as sexual stimulants, while Cucurbitaceae are the main sources of deleterious effects on the male reproductive system.

Comparing the adult and pre-pubertal testis: Metabolic transitions and the change in the spermatogonial stem cell metabolic microenvironment

BACKGROUND

Survivors of childhood cancer often suffer from infertility. While sperm cryopreservation is not feasible before puberty, the patient's own spermatogonial stem cells could serve as a germ cell reservoir, enabling these patients to father their own children in adulthood through the isolation, in vitro expansion, and subsequent transplantation of spermatogonial stem cells. However, this approach requires large numbers of stem cells, and methods for successfully propagating spermatogonial stem cells in the laboratory are yet to be established for higher mammals and humans. The improvement of spermatogonial stem cell culture requires deeper understanding of their metabolic requirements and the mechanisms that regulate metabolic homeostasis.

AIM

This review gives a summary on our knowledge of spermatogonial stem cell metabolism during maintenance and differentiation and highlights the potential influence of Sertoli cell and stem cell niche maturation on spermatogonial stem cell metabolic requirements during development.

RESULTS AND CONCLUSIONS

Fetal human spermatogonial stem cell precursors, or gonocytes, migrate into the seminiferous cords and supposedly mature to adult stem cells within the first year of human development. However, the spermatogonial stem cell niche does not fully differentiate until puberty, when Sertoli cells dramatically rearrange the architecture and microenvironment within the seminiferous epithelium. Consequently, pre-pubertal and adult spermatogonial stem cells experience two distinct niche environments potentially affecting spermatogonial stem cell metabolism and maturation. Indeed, the metabolic requirements of mouse primordial germ cells and pig gonocytes are distinct from their adult counterparts, and novel single-cell RNA sequencing analysis of human and porcine spermatogonial stem cells during development confirms this metabolic transition. Knowledge of the metabolic requirements and their changes and regulation during spermatogonial stem cell maturation is necessary to implement laboratory-based techniques and enable clinical use of spermatogonial stem cells. Based on the advancement in our understanding of germline metabolism circuits and maturation events of niche cells within the testis, we propose a new definition of spermatogonial stem cell maturation and its amendment in the light of metabolic change.

Dysregulation of Immature Sertoli Cell Functions by Exposure to Acetaminophen and Genistein in Rodent Cell Models

Sertoli cells are essential for germ cell development and function. Their disruption by endocrine disrupting chemicals (EDCs) or drugs could jeopardize spermatogenesis, contributing to male infertility. Perinatal exposure to EDCs and acetaminophen (APAP) disrupts male reproductive functions in animals and humans. Infants can be exposed simultaneously to the dietary soy phytoestrogen genistein (GEN) and APAP used for fever or pain relief. Our goal was to determine the effects of 10-100 µM APAP and GEN, alone or mixed, on immature Sertoli cells using mouse TM4 Sertoli cell line and postnatal-day 8 rat Sertoli cells, by measuring cell viability, proliferation, prostaglandins, genes and protein expression, and functional pathways. A value of 50 µM APAP decreased the viability, while 100 µM APAP and GEN decreased the proliferation. Sertoli cell and eicosanoid pathway genes were affected by GEN and mixtures, with downregulation of Sox9, Cox1, Cox2, and genes relevant for Sertoli cell function, while genes involved in inflammation were increased. RNA-seq analysis identified p53 and TNF signaling pathways as common targets of GEN and GEN mixture in both cell types. These results suggest that APAP and GEN dysregulate immature Sertoli cell function and may aid in elucidating novel EDC and drug targets contributing to the etiology of male infertility.

Identification of follicle-stimulating hormone-responsive genes in Sertoli cells during early postnatal mouse testis development

BACKGROUND

In the mouse testis, Sertoli cells rapidly divide during a narrow window of time pre-pubertally and differentiate thereafter. The number of Sertoli cells determines the testis size and germ cell-carrying capacity. Follicle-stimulating hormone (FSH) binds its cognate FSH-receptors expressed on Sertoli cells and acts as a mitogen to regulate their proliferation. Fshb-/- mutant adult male mice have reduced Sertoli cell number and testis size and reduced sperm number and motility. However, FSH-responsive genes in early postnatal mouse Sertoli cells are unknown.

OBJECTIVES

To identify FSH-responsive genes in early postnatal mouse Sertoli cells.

MATERIALS AND METHODS

A fluorescence-activated cell sorting method was developed to rapidly purify Sertoli cells from control and Fshb-/- mice carrying a Sox9 GfpKI allele. These pure Sertoli cells were used for large-scale gene expression analyses.

RESULTS

We show that mouse Sertoli cells rarely divide beyond postnatal day 7. Our in vivo BrdU labeling studies indicate loss of FSH results in a 30% reduction in Sertoli cell proliferation in mice at 5 days of age. Flowsorted GFP+ Sertoli cells with maximal Fshr expression were 97%-98% pure and mostly devoid of Leydig and germ cells as assessed by Taqman qPCR quantification of gene expression and immunolabeling of the corresponding cell-specific markers. Large-scale gene expression analysis identified several differentially regulated genes in flow-sorted GFP+ Sertoli cells obtained from testis of control and Fshb-/- mice at 5 days of age. The top 25 networks identified by pathway analysis include those related to the cell cycle, cell survival and most importantly, carbohydrate and lipid metabolism and molecular transport.

DISCUSSION

Several of the FSH-responsive genes identified in this study could serve as useful markers for Sertoli cell proliferation in normal physiology, toxicant-induced Sertoli cell/testis injury, and other pathological conditions.

CONCLUSION

Our studies reveal that FSH-regulates macromolecular metabolism and molecular transport networks of genes in early postnatal Sertoli cells most likely in preparation for establishment of functional associations with germ cells to successfully coordinate spermatogenesis.

Transcriptome analysis reveals dysregulated gene expression networks in Sertoli cells of cattle-yak hybrids

Cattle-yak, the hybrid offspring of yak and taurine cattle, exhibits male sterility with normal female fertility. Spermatogenesis is arrested in adult cattle-yak, and apoptosis is elevated in spermatogenic cells. Currently, the mechanisms underlying these defects remain elusive. Sertoli cells are the only somatic cells that directly interact with spermatogenic cells in the seminiferous tubules and play essential roles in spermatogenesis. The present study was designed to investigate gene expression signatures and potential roles of Sertoli cells in hybrid sterility in cattle-yak. Immunohistochemical analysis showed that the 5 mC and 5hmC signals in Sertoli cells of cattle-yaks were significantly different from those of age-matched yaks (P < 0.05). Transcriptome profiling of isolated Sertoli cells identified 402 differentially expressed genes (DEGs) between cattle-yaks and yaks. Notably, niche factor glial cell derived neurotrophic factor (GDNF) was upregulated, and genes involved in retinoic acid (RA) biogenesis were changed in Sertoli cells of cattle-yak, suggesting possible impairments of spermatogonial fate decisions. Further studies showed that the numbers of proliferative gonocytes and undifferentiated spermatogonia in cattle-yak were significantly higher than those in yak (P < 0.01). Exogenous GDNF significantly promoted the proliferation of UCHL1-positive spermatogonia in yaks. Therefore, we concluded that altered GDNF expression and RA signaling impacted the fate decisions of undifferentiated spermatogonia in cattle-yak. Together, these findings highlight the role of Sertoli cells and their derived factors in hybrid sterility.

Oral administration of Turnera diffusa willd. ex Schult. extract ameliorates steroidogenesis and spermatogenesis impairment in the testes of rats with type-2 diabetes mellitus

ETHNOPHARMACOLOGICAL RELEVANCE

Turnera diffusa Willd. ex Schult. (T. diffusa) has traditionally been used to treat male reproductive dysfunction and have aphrodisiac properties.

AIMS OF THE STUDY

This study aims to investigate the ability of T. diffusa to ameliorate the impairment in testicular steroidogenesis and spermatogenesis in DM that might help to improve testicular function, and subsequently restore male fertility.

MATERIALS AND METHODS

DM-induced adult male rats were given 100 mg/kg/day and 200 mg/kg/day T. diffusa leaf extract orally for 28 consecutive days. Rats were then sacrificed; sperm and testes were harvested and sperm parameter analysis were performed. Histo-morphological changes in the testes were observed. Biochemical assays were performed to measure testosterone and testicular oxidative stress levels. Immunohistochemistry and double immunofluorescence were used to monitor oxidative stress and inflammation levels in testes as well as Sertoli and steroidogenic marker proteins' expression.

RESULTS

Treatment with T. diffusa restores sperm count, motility, and viability near normal and reduces sperm morphological abnormalities and sperm DNA fragmentation in diabetic rats. T. diffusa treatment also reduces testicular NOX-2 and lipid peroxidation levels, increases testicular antioxidant enzymes (SOD, CAT, and GPx) activities, ameliorates testicular inflammation via downregulating NF-ΚB, p-Ikkβ and TNF-α and upregulating IκBα expression. In diabetic rats, T. diffusa treatment increases testicular steroidogenic proteins (StAR, CYP11A1, SHBG, and ARA54, 3 and 17β-HSD) and plasma testosterone levels. Furthermore, in diabetic rats treated with T. diffusa, Sertoli cell marker proteins including Connexin 43, N-cadherin, and occludin levels in the testes were elevated.

CONCLUSION

T. diffusa treatment could help to ameliorate the detrimental effects of DM on the testes, thus this plant has potential to be used to restore male fertility.

Gold nanoparticles retrogradely penetrate through testicular barriers via Sertoli-cells mediated endocytosis/exocytosis and induce immune response in mouse

Despite the rapidly growing interest in nanoparticle-mediated controllable male contraception and recovery of male fertility, novel applications of nanoparticles in these processes are limited by a knowledge gap regarding their transport and distribution in the testes. Here, we investigated the fate of gold nanoparticles in the mouse testes using two injection methods, namely, interstitial testicular injection (IT-AuNPs, AuNPs exposure in the interstitial compartment of the testes) and rete testis injection (RT-AuNPs, AuNPs exposure in the adluminal compartment of the seminiferous tubules). In this study, we used 100 nm spherical AuNPs and microinjected with 5 μL AuNPs (30 mg/mL) for the experiments. For IT-AuNP injection, we found that AuNPs could not penetrate through the Sertoli cell-mediated blood-testis barrier (BTB) of the seminiferous tubules, and no male reproductive toxicity was observed. For RT-AuNP injection, AuNPs could be retrogradely transported from the adluminal compartment to the interstitial compartment of the testes via Sertoli cell-mediated endocytosis/exocytosis, resulting in damage and the release of inflammatory cytokines in the mouse testis. Our results highlight a retrograde nanoparticle transport function of Sertoli cells, thereby providing a mechanistic overview of the development and use of nanobiotechnology in male reproduction. SYNOPSIS: This study provides new insights into male reproductive immunotoxicity for AuNPs exposure and elucidates a mechanism via Sertoli cell-mediated endocytosis/exocytosis.

Cytoskeletal orchestration of glucose uptake in Sertoli cell to support efferocytosis of apoptotic germ cells

Efferocytosis of non-viable germ cells by Sertoli cells (SCs) constitutes a sentinel for testis homeostasis, yet how SCs signal for the metabolic and cytoskeletal adaption to this energetically costly process remains unexplored. Spectrin is membrane-associated periodic skeleton assembled into an actin-spectrin-based cytoskeletal structure with an interaction with glucose transporter Glut1. The contribution of spectrin to glucose uptake and efferocytosis is unknown. In this study, we identified a cross-regulation between glucose metabolism and efferocytosis in SCs. Pharmacological or genetic inhibition of glucose uptake or glycolysis compromises efferocytosis activity. We further found that βII-spectrin is a hitherto unappreciated regulator of glucose metabolism and cytoskeletal architecture. βII-spectrin deficiency impairs glucose uptake and lactate production in SCs. Moreover, a defective assembly of cytoskeleton and a loss of blood-testis barrier integrity are also featured by SCs deficient in βII-spectrin. The disruption in glucose metabolism and cytoskeletal organization synergistically lead to a defective efferocytosis. In vivo siRNA-mediated targeting of βII-spectrin in testis causes an obvious morphological aberration in seminiferous epithelium with the presence of exfoliated germ cells and multinucleated giant cells. Importantly, a decrease in expression of αII/βII-spectrin was observed in testes of Adjudin-induced infertility model. By exploring the functional relevance of βII-spectrin to the metabolic and cytoskeletal regulation of efferocytosis, our study proposes a potential link between βII-spectrin deregulation and male infertility.

FZD7, Regulated by Non-CpG Methylation, Plays an Important Role in Immature Porcine Sertoli Cell Proliferation

The regulatory role of non-CpG methylation in mammals has been important in whole-genome bisulfite sequencing. It has also been suggested that non-CpG methylation regulates gene expression to affect the development and health of mammals. However, the dynamic regulatory mechanisms of genome-wide, non-CpG methylation during testicular development still require intensive study. In this study, we analyzed the dataset from the whole-genome bisulfite sequencing (WGBS) and the RNA-seq of precocious porcine testicular tissues across two developmental stages (1 and 75 days old) in order to explore the regulatory roles of non-CpG methylation. Our results showed that genes regulated by non-CpG methylation affect the development of testes in multiple pathways. Furthermore, several hub genes that are regulated by non-CpG methylation during testicular development-such as VEGFA, PECAM1, and FZD7-were also identified. We also found that the relative expression of FZD7 was downregulated by the zebularine-induced demethylation of the first exon of FZD7. This regulatory relationship was consistent with the results of the WGBS and RNA-seq analysis. The immature porcine Sertoli cells were transfected with RNAi to mimic the expression patterns of FZD7 during testicular development. The results of the simulation test showed that cell proliferation was significantly impeded and that cell cycle arrest at the G2 phase was caused by the siRNA-induced FZD7 inhibition. We also found that the percentage of early apoptotic Sertoli cells was decreased by transfecting them with the RNAi for FZD7. This indicates that FZD7 is an important factor in linking the proliferation and apoptosis of Sertoli cells. We further demonstrated that Sertoli cells that were treated with the medium collected from apoptotic cells could stimulate proliferation. These findings will contribute to the exploration of the regulatory mechanisms of non-CpG methylation in testicular development and of the relationship between the proliferation and apoptosis of normal somatic cells.

Biomaterials for Testicular Bioengineering: How far have we come and where do we have to go?

Traditional therapeutic interventions aim to restore male fertile potential or preserve sperm viability in severe cases, such as semen cryopreservation, testicular tissue, germ cell transplantation and testicular graft. However, these techniques demonstrate several methodological, clinical, and biological limitations, that impact in their results. In this scenario, reproductive medicine has sought biotechnological alternatives applied for infertility treatment, or to improve gamete preservation and thus increase reproductive rates in vitro and in vivo. One of the main approaches employed is the biomimetic testicular tissue reconstruction, which uses tissue-engineering principles and methodologies. This strategy pursues to mimic the testicular microenvironment, simulating physiological conditions. Such approach allows male gametes maintenance in culture or produce viable grafts that can be transplanted and restore reproductive functions. In this context, the application of several biomaterials have been proposed to be used in artificial biological systems. From synthetic polymers to decellularized matrixes, each biomaterial has advantages and disadvantages regarding its application in cell culture and tissue reconstruction. Therefore, the present review aims to list the progress that has been made and the continued challenges facing testicular regenerative medicine and the preservation of male reproductive capacity, based on the development of tissue bioengineering approaches for testicular tissue microenvironment reconstruction.

In vitro complete differentiation of human spermatogonial stem cells to morphologic spermatozoa using a hybrid hydrogel of agarose and laminin

Spermatogenesis refers to the differentiation of the spermatogonial stem cells (SSCs) located in the base seminiferous tubules into haploid spermatozoa. Prerequisites for in vitro spermatogenesis include an extracellular matrix (ECM), paracrine factors, and testicular somatic cells which play a supporting role for SSCs. Thus, the present study evaluated the potential of co-culturing Sertoli cells and SSCs embedded in a hybrid hydrogel of agarose and laminin, the main components of the ECM. Following the three-week conventional culture of human testicular cells, the cells were cultured in agarose hydrogel or agarose/laminin one (hybrid) for 74 days. Then, immunocytochemistry, real-time PCR, electron microscopy, and morphological staining methods were applied to analyze the presence of SSCs, as well as the other cells of the different stages of spermatogenesis. Based on the results, the colonies with positive spermatogenesis markers were observed in both culture systems. The existence of the cells of all three phases of spermatogenesis (spermatogonia, meiosis, and spermiogenesis) was confirmed in the two groups, while morphological spermatozoa were detected only in the hybrid hydrogel group. Finally, a biologically improved 3D matrix can support all the physiological activities of SSCs such as survival, proliferation, and differentiation.

Reproductive genomics of the mouse: implications for human fertility and infertility

Genetic analyses of mammalian gametogenesis and fertility have the potential to inform about two important and interrelated clinical areas: infertility and contraception. Here, we address the genetics and genomics underlying gamete formation, productivity and function in the context of reproductive success in mammalian systems, primarily mouse and human. Although much is known about the specific genes and proteins required for meiotic processes and sperm function, we know relatively little about other gametic determinants of overall fertility, such as regulation of gamete numbers, duration of gamete production, and gamete selection and function in fertilization. As fertility is not a binary trait, attention is now appropriately focused on the oligogenic, quantitative aspects of reproduction. Multiparent mouse populations, created by complex crossing strategies, exhibit genetic diversity similar to human populations and will be valuable resources for genetic discovery, helping to overcome current limitations to our knowledge of mammalian reproductive genetics. Finally, we discuss how what we know about the genomics of reproduction can ultimately be brought to the clinic, informing our concepts of human fertility and infertility, and improving assisted reproductive technologies.

Seasonal spermatogenesis, epididymal storage, and creatine kinase expression in Pelodiscus sinensis

The soft-shelled turtle, Pelodiscus sinensis, is an important economic aquaculture species. Its reproduction exhibits seasonality; however, there is a lack of systematic studies focused on sperm maturation and epididymal storage. The testes and epididymides of P. sinensis were sampled from March to December. The seasonal reproduction and maturation of the spermatozoa were examined by anatomy, hematoxylin and eosin staining, AB-PAS staining, and immunohistochemistry. Spermatogenesis exhibited obvious seasonality in P. sinensis. It was found that the spermatogenic epithelium was most active during June to September, whereas the diameter of the epididymal tubules was smallest during June to October. As key enzymes of ATP metabolism, creatine kinases were highly expressed in the epididymal tubule epithelium during the breeding season, which may be important for the regulation of sperm maturation. In addition, the epididymal tubule epithelium changed with the season in June to September, the epididymal tubule epithelium proliferated to form villous structures, and secreted a large number of glycoproteins, which may be related to the rapid maturation of sperm during the breeding season. In conclusion, this study provided insights into the spermatogenesis of P. sinensis through histological analysis and enriched our understanding of reproduction in reptiles.

Sertoli cells-derived exosomal miR-30a-5p regulates ubiquitin E3 ligase Zeb2 to affect the spermatogonial stem cells proliferation and differentiation

The role of spermatogonial stem cells (SSCs) is crucial in spermatogenesis, and extracellular vesicles (EVs) have been the focus of research as an important intercellular communication mechanism. Various endogenous regulatory factors secreted by Sertoli cells (SCs) can affect the self-maintenance and regeneration of SSCs, but little is known about the roles of SCs-derived exosomal microRNAs (miRNAs) on SSCs. In this study, we aimed to explore the regulation of the SCs-derived exosomal miR-30a-5p on SSCs proliferation and differentiation. EVs from the SCs were detected by electron microscopy and nanoparticle tracking analysis (NTA). Subsequently, the SSCs were treated with the SCs-derived extracellular vesicles (SCs-EVs). CCK-8 assay and EdU staining was applied to detect the cell proliferation, and the results indicated that SCs-EVs promoted the SSCs proliferation. Western blot detection of the SSCs markers (Gfrα1, Plzf, Stra8, and C-kit) indicated that SCs-EVs promoted the SSCs differentiation. Additionally, we found that SCs-EVs secreted miR-30a-5p to show the promoting effects. Besides, we discovered that miR-30a-5p targeted zinc finger E-box binding homeobox 2 (Zeb2) to regulate the ubiquitination of fibroblast growth factor 9 (Fgf9) in SSCs. miR-30a-3p/Zeb2/Fgf9 promoted the SSCs proliferation and differentiation by activating the mitogen‑activated protein kinase (MAPK) signaling pathway. Taken together, our study showed that SCs-EVs can transport miR-30a-5p to SSCs and affect SSCs proliferation and differentiation by regulating the MAPK signaling pathway via Zeb2/Fgf9. This paper disclosed a novel molecular mechanism that regulates SSCs proliferation and differentiation, which could be valuable for the treatment of male infertility.

Sexual selection drives the coevolution of male and female reproductive traits in Peromyscus mice

When females mate with multiple partners within a single reproductive cycle, sperm from rival males may compete for fertilization of a limited number of ova, and females may bias the fertilization of their ova by particular sperm. Over evolutionary timescales, these two forms of selection shape both male and female reproductive physiology when females mate multiply, yet in monogamous systems, post-copulatory sexual selection is weak or absent. Here, we examine how divergent mating strategies within a genus of closely related mice, Peromyscus, have shaped the evolution of reproductive traits. We show that in promiscuous species, males exhibit traits associated with increased sperm production and sperm swimming performance, and females exhibit traits that are predicted to limit sperm access to their ova including increased oviduct length and a larger cumulus cell mass surrounding the ova, compared to monogamous species. Importantly, we found that across species, oviduct length and cumulus cell density are significantly correlated with sperm velocity, but not sperm count or relative testes size, suggesting that these female traits may have coevolved with increased sperm quality rather than quantity. Taken together, our results highlight how male and female traits evolve in concert and respond to changes in the level of post-copulatory sexual selection.

Perspectives: Approaches for Studying Livestock Spermatogonia

At present, the knowledge base on characteristics and biology of spermatogonia in livestock is limited in comparison to rodents, yet the importance of studying these cells for comparative species analysis and enhancing reproductive capacity in food animals is high. Previous studies have established that although many core attributes of organ physiology and mechanisms governing essential cellular functions are conserved across eutherians, significant differences exist between mice and higher order mammals. In this chapter, we briefly discuss distinguishing aspects of testicular anatomy and the spermatogenic lineage in livestock and critical considerations for studying spermatogonial stem cell biology in these species.

Throughout in vitro first spermatogenic wave: Next-generation sequencing gene expression patterns of fresh and cryopreserved prepubertal mice testicular tissue explants

INTRODUCTION

Suitable cryopreservation procedures of pre-pubertal testicular tissue associated with efficient culture conditions are crucial in the fields of fertility preservation and restoration. In vitro spermatogenesis remains a challenging technical procedure to undergo a complete spermatogenesis.The number of haploid cells and more specifically the spermatic yield produced in vitro in mice is still extremely low compared to age-matched in vivo controls and this procedure has never yet been successfully transferred to humans.

METHODS

To evaluate the impact of in vitro culture and freezing procedure, pre-pubertal testicular mice testes were directly cultured until day 4 (D4), D16 and D30 or cryopreserved by controlled slow freezing then cultured until D30. Testes composed of a panel of 6.5 dpp (days postpartum), 10.5 dpp, 22.5 dpp, and 36.5 dpp mice were used as in vivo controls. Testicular tissues were assessed by histological (HES) and immunofluorescence (stimulated by retinoic acid gene 8, STRA8) analyses. Moreover, a detailed transcriptome evaluation study has been carried out to study the gene expression patterns throughout the first in vitro spermatogenic wave.

RESULTS

Transcriptomic analyses reveal that cultured tissues expression profiles are almost comparable between D16 and D30; highlighting an abnormal kinetic throughout the second half of the first spermatogenesis during in vitro cultures. In addition, testicular explants have shown dysregulation of their transcriptomic profile compared to controls with genes related to inflammation response, insulin-like growth factor and genes involved in steroidogenesis.

DISCUSSION

The present work first shows that cryopreservation had very little impact on gene expression in testicular tissue, either directly after thawing or after 30 days in culture. Transcriptomic analysis of testis tissue samples is highly informative due to the large number of expressed genes and identified isoforms. This study provides a very valuable basis for future studies concerning in vitro spermatogenesis in mice.

Ldha-Dependent Metabolic Programs in Sertoli Cells Regulate Spermiogenesis in Mouse Testis

Sertoli cells play indispensable roles in spermatogenesis by providing the advanced germ cells with structural, nutritional, and regulatory support. Lactate is regarded as an essential Sertoli-cell-derived energy metabolite that nurses various types of spermatogenic cells; however, this assumption has not been tested using genetic approaches. Here, we have reported that the depletion of lactate production in Sertoli cells by conditionally deleting lactate dehydrogenase A (Ldha) greatly affected spermatogenesis. Ldha deletion in Sertoli cells significantly reduced the lactate production and resulted in severe defects in spermatogenesis. Spermatogonia and spermatocytes did not show even mild impairments, but the spermiogenesis of Ldha conditional knockout males was severely disrupted. Further analysis revealed that 2456 metabolites were altered in the sperm of the knockout animals, and specifically, lipid metabolism was dysregulated, including choline, oleic acid, and myristic acid. Surprisingly, choline supplementation completely rescued the spermiogenesis disorder that was caused by the loss of Ldha activities. Collectively, these data have demonstrated that the interruption of Sertoli-cell-derived lactate impacted sperm development through a choline-mediated mechanism. The outcomes of these findings have revealed a novel function of lactate in spermatogenesis and have therapeutic applications in treating human infertility.

The potential of sertoli cells (SCs) derived exosomes and its therapeutic efficacy in male reproductive disorders

In the male reproductive system, seminiferous tubules in testis are lined by a complex stratified epithelium containing two distinct populations of cells, spermatogenic cells that develop into spermatozoa, and sertoli cells (SCs) that mainly support and nourish spermatogenic cell lineage as well as exerting powerful effect on men reproductive capacity. Different varieties of proteins, hormones, exosomes and growth factors are secreted by SCs. There are different kinds of junctions found between SCs called BTB. It was elucidated that complete absence of BTB or its dysfunction leads to infertility. To promote spermatogenesis, crosstalk of SCs with spermatogenic cells plays an important role. The ability of SCs to support germ cell productivity and development is related to its various products carrying out several functions. Exosomes (EXOs) are one of the main EVs with 30-100 nm size generating from endocytic pathway. They are produced in different parts of male reproductive system including epididymis, prostate and SCs. The most prominent characteristics of SC-based exosomes is considered mutual interaction of sertoli cells with spermatogonial stem cells and Leydig cells mainly through establishment of intercellular communication. Exosomes have gotten a lot of interest because of their role in pathobiological processes and as a cell free therapy which led to developing multiple exosome isolation methods based on different principles. Transmission of nucleic acids, proteins, and growth factors via SC-based exosomes and exosomal miRNAs are proved to have potential to be valuable biomarkers in male reproductive disease. Among testicular abnormalities, non-obstructive azoospermia and testicular cancer have been more contributed with SCs performance. The identification of key proteins and miRNAs involved in the signaling pathways related with spermatogenesis, can serve as diagnostic and regenerative targets in male infertility.

Targeting APLN/APJ restores blood-testis barrier and improves spermatogenesis in murine and human diabetic models

Type 2 diabetes mellitus is one of the most prevalent metabolic diseases presenting with systemic pathologies, including reproductive disorders in male diabetic patients. However, the molecular mechanisms that contributing to spermatogenesis dysfunction in diabetic patients have not yet been fully elucidated. Here, we perform STRT-seq to examine the transcriptome of diabetic patients' testes at single-cell resolution including all major cell types of the testis. Intriguingly, whereas spermatogenesis appears largely preserved, the gene expression profiles of Sertoli cells and the blood-testis barrier (BTB) structure are dramatically impaired. Among these deregulate pathways, the Apelin (APLN) peptide/Apelin-receptor (APJ) axis is hyper-activated in diabetic patients' testes. Mechanistically, APLN is produced locally by Sertoli cells upon high glucose treatment, which subsequently suppress the production of carnitine and repress the expression of cell adhesion genes in Sertoli cells. Together, these effects culminate in BTB structural dysfunction. Finally, using the small molecule APLN receptor antagonist, ML221, we show that blocking APLN/APJ significantly ameliorate the BTB damage and, importantly, improve functional spermatogenesis in diabetic db/db mice. We also translate and validate these findings in cultured human testes. Our findings identify the APLN/APJ axis as a promising therapeutic target to improve reproduction capacity in male diabetic patients.

Modeling mammalian spermatogonial differentiation and meiotic initiation in vitro

In mammalian testes, premeiotic spermatogonia respond to retinoic acid by completing an essential lengthy differentiation program before initiating meiosis. The molecular and cellular changes directing these developmental processes remain largely undefined. This wide gap in knowledge is due to two unresolved technical challenges: (1) lack of robust and reliable in vitro models to study differentiation and meiotic initiation; and (2) lack of methods to isolate large and pure populations of male germ cells at each stage of differentiation and at meiotic initiation. Here, we report a facile in vitro differentiation and meiotic initiation system that can be readily manipulated, including the use of chemical agents that cannot be safely administered to live animals. In addition, we present a transgenic mouse model enabling fluorescence-activated cell sorting-based isolation of millions of spermatogonia at specific developmental stages as well as meiotic spermatocytes.

Mechanism of 2,4-Dichlorophenoxyacetic acid-induced damage to rat testis via Fas/FasL pathway and the protective effect of Lycium barbarum polysaccharides

The herbicide 2,4-Dichlorophenoxyacetic acid (2,4-D) is widely used to control broadleaved weeds and has been associated with male infertility. We studied the molecular mechanisms of 2,4-D induced male reproductive system damage and the protective effects of Lycium barbarum polysaccharides (LBP) using Sprague Dawley rats and TM4 cells. Treatment with 2,4-D caused architectural and functional changes in the testis, including collapsed and atrophied seminiferous tubules with reduced number of spermatozoa, scarce sperm in the epididymal duct, low levels of serum testosterone, decreased superoxide dismutase and glutathione peroxidase activity, high malondialdehyde content, and increased apoptosis in the testis and epididymis. The expression of Fas, FasL, FADD, Pro-caspase-8, Cleaved-Caspase-8, Pro-Caspase-3, and Cleaved-Caspase-3 were significantly increased in the testicular tissue of 2,4-D-treated rats. The proliferative activity of TM4 cells decreased with an increase in dose and time of 2,4-D exposure, along with enhanced Fas/Fas ligand expression and a decreased concentration of inhibin B in TM4 cell culture medium. Depletion of Fas by specific shRNA transfection reversed the effects of 2,4-D in TM4 cells, further confirming the involvement of death receptor pathway in 2,4-D-mediated apoptosis of sertoli cells. Treatment with LBP also reversed the effects of 2,4-D in testicular cells, resulting in improved cell architecture along with enhanced proliferative capacity. Moreover, in response to LBP treatment of Sertoli cells, the content of inhibin B increased, the level of reactive oxygen species and malondialdehyde decreased, the activities of superoxide dismutase and glutathione peroxidase increased, and the rate of apoptosis as well as the expression of Fas/Fas ligand signaling pathway proteins decreased.