c-kit and its related genes in spermatogonial differentiation

Determining the optimal time interval between sample acquisition and cryopreservation when processing immature testicular tissue to preserve fertility

The cryopreservation of immature testicular tissue (ITT) prior to gonadotoxic therapy is crucial for fertility preservation in prepubertal boys with cancer. However, the optimal holding time between tissue collection and cryopreservation has yet to be elucidated. Using the bovine model, we investigated four holding times (1, 6, 24, and 48 h) for ITTs before cryopreservation. Biopsies from two-week-old calves were stored in transport medium and cryopreserved following a standard slow-freezing clinical protocol. Thawed samples were then assessed for viability, morphology, and gene expression by haematoxylin and eosin (H&E) staining, immunohistochemistry and real-time quantitative reverse transcription-polymerase chain reaction (RT-qPCR). Analysis failed to identify any significant changes in cell viability when compared between the different groups. Sertoli (Vimentin+) and proliferating cells (Ki67+) were well-preserved. The expression of genes related to germ cells, spermatogenesis (STRA8, PLZF, GFRα-1, C-KIT, THY1, UCHL-1, NANOG, OCT-4, CREM), and apoptosis (HSP70-2) remained stable over 48 h. However, seminiferous cord detachment increased significantly in the 48-h group (p < 0.05), with associated cord and SSC shrinkage. Collectively, our analyses indicate that bovine ITTs can be stored for up to 48 h prior to cryopreservation with no impact on cell viability and the expression levels of key genes. However, to preserve the morphology of frozen-thawed tissue, the ideal processing time would be within 24 h. Testicular tissues obtained from patients for fertility preservation often need to be transported over long distances to be cryopreserved in specialist centres. Our findings highlight the importance of determining optimal tissue transport times to ensure tissue quality in cryopreservation.

Molecular mechanisms of cellular dysfunction in testes from men with non-obstructive azoospermia

Male factor infertility affects 50% of infertile couples worldwide; the most severe form, non-obstructive azoospermia (NOA), affects 10-15% of infertile males. Treatment for individuals with NOA is limited to microsurgical sperm extraction paired with in vitro fertilization intracytoplasmic sperm injection. Unfortunately, spermatozoa are only retrieved in ~50% of patients, resulting in live birth rates of 21-46%. Regenerative therapies could provide a solution; however, understanding the cell-type-specific mechanisms of cellular dysfunction is a fundamental necessity to develop precision medicine strategies that could overcome these abnormalities and promote regeneration of spermatogenesis. A number of mechanisms of cellular dysfunction have been elucidated in NOA testicular cells. These mechanisms include abnormalities in both somatic cells and germ cells in NOA testes, such as somatic cell immaturity, aberrant growth factor signalling, increased inflammation, increased apoptosis and abnormal extracellular matrix regulation. Future cell-type-specific investigations in identifying modulators of cellular transcription and translation will be key to understanding upstream dysregulation, and these studies will require development of in vitro models to functionally interrogate spermatogenic niche dysfunction in both somatic and germ cells.

Na+/H+ Exchangers (NHEs) in Mammalian Sperm: Essential Contributors to Male Fertility

Na+/H+ exchangers (NHEs) are known to be important regulators of pH in multiple intracellular compartments of eukaryotic cells. Sperm function is especially dependent on changes in pH and thus it has been postulated that NHEs play important roles in regulating the intracellular pH of these cells. For example, in order to achieve fertilization, mature sperm must maintain a basal pH in the male reproductive tract and then alkalize in response to specific signals in the female reproductive tract during the capacitation process. Eight NHE isoforms are expressed in mammalian testis/sperm: NHE1, NHE3, NHE5, NHE8, NHA1, NHA2, NHE10, and NHE11. These NHE isoforms are expressed at varying times during spermatogenesis and localize to different subcellular structures in developing and mature sperm where they contribute to multiple aspects of sperm physiology and male fertility including proper sperm development/morphogenesis, motility, capacitation, and the acrosome reaction. Previous work has provided evidence for NHE3, NHE8, NHA1, NHA2, and NHE10 being critical for male fertility in mice and NHE10 has recently been shown to be essential for male fertility in humans. In this article we review what is known about each NHE isoform expressed in mammalian sperm and discuss the physiological significance of each NHE isoform with respect to male fertility.

Preventing/Reversing Adverse Effects of Endocrine Disruption on Mouse Testes by Normalizing Tissue Resident VSELs

Reproductive health of men is declining in today's world due to increased developmental exposure to endocrine-disrupting chemicals (EDCs). We earlier reported that neonatal exposure to endocrine disruption resulted in reduced numbers of seminiferous tubules in Stage VIII, decreased sperm count, and infertility along with testicular tumors in 65% of diethylstilbestrol (DES) treated mice. Epigenetic changes due to EDCs, pushed the VSELs out of a quiescent state to enter cell cycle and undergo excessive self-renewal while transition of c-KIT- stem cells into c-KIT + germ cells was blocked due to altered MMR axis (Np95, Pcna, Dnmts), global hypomethylation (reduced expression of 5-methylcytosine) and loss of imprinting at Igf2-H19 and Dlk1-Meg3 loci. The present study was undertaken to firstly show similar defects in FACS sorted VSELs from DES treated testis and to further explore the reversal of these testicular pathologies by (i) oral administration of XAR (a nano-formulation of resveratrol) or (ii) inter-tubular transplantation of mesenchymal stromal cells (MSCs). Similar defects as reported earlier in the testes were evident, based on RNAseq data, on FACS sorted VSELs from DES treated mice. Both strategies were found effective, improved spermatogenesis, increased number of tubules in Stage VIII, normalized numbers of VSELs and c-KIT + cells, improved epigenetic status of VSELs to restore quiescent state, and reduced cancer incidence from 65% after DES to 13.33% and 20% after XAR treatment or MSCs transplantation respectively. Results provide a basis for initiating clinical studies and the study falls under the umbrella of United Nations Sustainable Development Goal 3 to ensure healthy lives and well-being for all of all ages.

Carob extract induces spermatogenesis in an infertile mouse model via upregulation of Prm1, Plzf, Bcl-6b, Dazl, Ngn3, Stra8, and Smc1b

ETHNOPHARMACOLOGICAL RELEVANCE

Ethnopharmacological studies for drug discovery from natural compounds play an important role for developing current therapeutical platforms. Plants are a group of natural sources which have been served as the basis in the treatment of many diseases for centuries. In this regard, Ceratonia siliqua (carob) is one of the herbal medicine which is traditionally used for male infertility treatments. But so far the main mechanisms for effects of carob are unknown. Here, we intend to investigate the ability of carob extract to induce spermatogenesis in an azoospermia mouse model and determine the mechanisms that underlie its function.

AIM OF THE STUDY

This is a pre-clinical animal model study to evaluate the effect of carob extract in spermatogenesis recovery.

METHODS

We established an infertile mouse model with the intent to examine the ability of carob extract as a potential herbal medicine for restoration of male fertility. Sperm parameters, as well as gene expression dynamics and levels of spermatogenesis hormones, were evaluated 35 days after carob administration.

RESULTS

Significant enhanced sperm parameters (P < 0.05) showed that the carob extract could induce spermatogenesis in the infertile mouse model. Our data suggested an anti-apototic and inducer role in the expressions of cell cycle regulating genes. Carob extract improved the spermatogenesis niche by considerable affecting Sertoli and Leydig cells (P < 0.05). The carob-treated mice were fertile and contributed to healthy offspring that matured. Our data confirmed that this extract triggered the hormonal system, the spermatogenesis-related gene expression network, and signaling pathways to induce and promote sperm production with notable level (P < 0.05). We found that the aqueous extract consisted of a polar and mainly well water-soluble substance. Carob extract might upregulate spermatogenesis hormones via its amino acid components, which were detected in the extract by liquid chromatography-mass spectrometry (LC-MS).

CONCLUSION

Our results strongly suggest that carob extract might be a promising future treatment option for male infertility. This finding could pave the way for clinical trials in infertile men. This is the first study that has provided reliable, strong pre-clinical evidence for carob extract as an effective candidate for fertility recovery in cancer-related azoospermia.

The Role of Promyelocytic Leukemia Zinc Finger (PLZF) and Glial-Derived Neurotrophic Factor Family Receptor Alpha 1 (GFRα1) in the Cryopreservation of Spermatogonia Stem Cells

The cryopreservation of spermatogonia stem cells (SSCs) has been widely used as an alternative treatment for infertility. However, cryopreservation itself induces cryoinjury due to oxidative and osmotic stress, leading to reduction in the survival rate and functionality of SSCs. Glial-derived neurotrophic factor family receptor alpha 1 (GFRα1) and promyelocytic leukemia zinc finger (PLZF) are expressed during the self-renewal and differentiation of SSCs, making them key tools for identifying the functionality of SSCs. To the best of our knowledge, the involvement of GFRα1 and PLZF in determining the functionality of SSCs after cryopreservation with therapeutic intervention is limited. Therefore, the purpose of this review is to determine the role of GFRα1 and PLZF as biomarkers for evaluating the functionality of SSCs in cryopreservation with therapeutic intervention. Therapeutic intervention, such as the use of antioxidants, and enhancement in cryopreservation protocols, such as cell encapsulation, cryoprotectant agents (CPA), and equilibrium of time and temperature increase the expression of GFRα1 and PLZF, resulting in maintaining the functionality of SSCs. In conclusion, GFRα1 and PLZF have the potential as biomarkers in cryopreservation with therapeutic intervention of SSCs to ensure the functionality of the stem cells.

Unraveling the effect of the inflammatory microenvironment in spermatogenesis progression

Experimental autoimmune orchitis (EAO) is a chronic inflammatory disorder that causes progressive spermatogenic impairment. EAO is characterized by high intratesticular levels of nitric oxide (NO) and tumor necrosis factor alpha (TNFα) causing germ cell apoptosis and Sertoli cell dysfunction. However, the impact of this inflammatory milieu on the spermatogenic wave is unknown. Therefore, we studied the effect of inflammation on spermatogonia and preleptotene spermatocyte cell cycle progression in an EAO context and through the intratesticular DETA-NO and TNFα injection in the normal rat testes. In EAO, premeiotic germ cell proliferation is limited as a consequence of the undifferentiated spermatogonia (CD9⁺) cell cycle arrest in G2/M and the reduced number of differentiated spermatogonia (c-kit⁺) and preleptotene spermatocytes that enter in the meiotic S-phase. Although inflammation disrupts spermatogenesis in EAO, it is maintained in some seminiferous tubules at XIV and VII-VIII stages of the epithelial cell cycle, thereby guaranteeing sperm production. We found that DETA-NO (2 mM) injected in normal testes arrests spermatogonia and preleptotene spermatocyte cell cycle; this effect reduces the number of proliferative spermatogonia and the number of preleptotene spermatocytes in meiosis S-phase (36 h after). The temporal inhibition of spermatogonia clonal amplification delayed progression of the spermatogenic wave (5 days after) finally altering spermatogenesis. TNFα (0.5 and 1 µg) exposure did not affect premeiotic germ cell cycle or spermatogenic wave. Our results show that in EAO the inflammatory microenvironment altered spermatogenesis kinetics through premeiotic germ cell cycle arrest and that NO is a sufficient factor contributing to this phenomenon.

scATAC-Seq reveals heterogeneity associated with spermatogonial differentiation in cultured male germline stem cells

Spermatogonial stem cells are the most primitive spermatogonia in testis, which can self-renew to maintain the stem cell pool or differentiate to give rise to germ cells including haploid spermatids. All-trans-retinoic acid (RA), a bioactive metabolite of vitamin A, plays a fundamental role in initiating spermatogonial differentiation. In this study, single-cell ATAC-seq (scATAC-seq) was used to obtain genome-wide chromatin maps of cultured germline stem cells (GSCs) that were in control and RA-induced differentiation states. We showed that different subsets of GSCs can be distinguished based on chromatin accessibility of self-renewal and differentiation signature genes. Importantly, both progenitors and a subset of stem cells are able to respond to RA and give rise to differentiating cell subsets with distinct chromatin accessibility profiles. In this study, we identified regulatory regions that undergo chromatin remodeling and are associated with the retinoic signaling pathway. Moreover, we reconstructed the differentiation trajectory and identified novel transcription factor candidates enriched in different spermatogonia subsets. Collectively, our work provides a valuable resource for understanding the heterogeneity associated with differentiation and RA response in GSCs.

miRNA Profiling of Major Testicular Germ Cells Identifies Stage-Specific Regulators of Spermatogenesis

Spermatogenesis is tightly controlled at transcriptional, post-transcriptional, and epigenetic levels by various regulators, including miRNAs. This study deals with the identification of miRNAs critical to the three important stages of germ cell development (spermatocytes, round spermatids, and mature sperm) during spermatogenesis. We used high-throughput transcriptome sequencing to identify the differentially expressed miRNAs in the pachytene spermatocytes, round spermatids, and mature sperm of rat. We identified 1843 miRNAs that were differentially expressed across the three stages of germ cell development. These miRNAs were further categorized into three classes according to their pattern of expression during spermatogenesis: class 1 - miRNAs found exclusively in one stage and absent in the other two stages; class 2 - miRNAs found in any two stages but absent in the third stage; class 3 - miRNAs expressed in all the three stages. Six hundred forty-six miRNAs were found to be specific to one developmental stage, 443 miRNAs were found to be common across any two stages, and 754 miRNAs were common to all the three stages. Target prediction for ten most abundant miRNAs specific to each category identified miRNA regulators of mitosis, meiosis, and cell differentiation. The expression of each miRNA is specific to a particular developmental stage, which is required to maintain a significant repertoire of target mRNAs in the respective stage. Thus, this study provided valuable data that can be used in the future to identify the miRNAs involved in spermatogenic arrest at a particular stage of the germ cell development.

Long-Term Wi-Fi Exposure From Pre-Pubertal to Adult Age on the Spermatogonia Proliferation and Protective Effects of Edible Bird’s Nest Supplementation

Children are vulnerable to the radiofrequency radiation (RFR) emitted by Wi-Fi devices. Nevertheless, the severity of the Wi-Fi effect on their reproductive development has been sparsely available. Therefore, this study was conducted to evaluate the Wi-Fi exposure on spermatogonia proliferation in the testis. This study also incorporated an approach to attenuate the effect of Wi-Fi by giving concurrent edible bird’s nest (EBN) supplementation. It was predicted that Wi-Fi exposure reduces spermatogonia proliferation while EBN supplementation protects against it. A total of 30 (N = 30) 3-week-old Sprague Dawley weanlings were divided equally into five groups; Control, Control EBN, Wi-Fi, Sham Wi-Fi, and Wi-Fi + EBN. 2.45 GHz Wi-Fi exposure and 250 mg/kg EBN supplementation were conducted for 14 weeks. Findings showed that the Wi-Fi group had decreased in spermatogonia mitosis status. However, the mRNA and protein expression of c-Kit-SCF showed no significant decrease. Instead, the reproductive hormone showed a reduction in FSH and LH serum levels. Of these, LH serum level was decreased significantly in the Wi-Fi group. Otherwise, supplementing the Wi-Fi + EBN group with 250 mg/kg EBN resulted in a significant increase in spermatogonia mitotic status. Even though EBN supplementation improved c-Kit-SCF mRNA and protein expression, the effects were insignificant. The improvement of spermatogonia mitosis appeared to be associated with a significant increase in blood FSH levels following EBN supplementation. In conclusion, the long-term Wi-Fi exposure from pre-pubertal to adult age reduces spermatogonia proliferation in the testis. On the other hand, EBN supplementation protects spermatogonia proliferation against Wi-Fi exposure.

Mangiferin mitigates di-(2-ethylhexyl) phthalate-induced testicular injury in rats by modulating oxidative stress-mediated signals, inflammatory cascades, apoptotic pathways, and steroidogenesis

Di-(2-ethylhexyl) phthalate (DEHP) is an endocrine disruptor that causes reproductive defects in male animal models. This study was conducted to explore the plausible modulatory effects of mangiferin (MF) against DEHP-induced testicular injury in rats. Thirty-two adult male albino rats were allocated into four groups. Two groups were given DEHP (2 g/kg/day, p.o) for 14 days. One of these groups was treated with MF (20 mg/kg/day, i.p) for 7 days before and 14 days after DEHP administration. A vehicle-treated control was included, and another group of rats was given MF only. Results revealed that MF treatment suppressed oxidative testicular injury by amplifying the mRNA expression of nuclear factor-erythroid 2 related factor-2 (Nrf2) and increasing hemoxygenase-1 (HO-1), glutathione, and total antioxidant capacity (TAC) levels. This treatment also enhanced superoxide dismutase activity, but it decreased malondialdehyde and nitric oxide levels. MF had an anti-inflammatory characteristic, as demonstrated by the downregulation of the mRNA of the nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB). The content of tumor necrosis factor-alpha also decreased. MF modulated the apoptotic pathway by suppressing the mRNA of cytochrome c (Cyt c), Fas ligand content, Bax IHC expression, caspase-3 activity and cleaved caspase-3 IHC expression. It also upregulated the expression levels of heat-shock protein 70 (HSP70) and B-cell lymphoma 2. Moreover, MF upregulated the mRNA expression levels of HSP70 and c-kit and enriched the content of steroidogenic acute regulatory (StAR) protein, which were reflected in serum testosterone levels. This result indicated that MF played crucial roles in steroidogenesis and spermatogenesis. Besides, the activities of testicular marker enzymes, namely, acid and alkaline phosphatases, and lactate dehydrogenase, significantly increased. Histopathological observations provided evidence supporting the biochemical and molecular measurements. In conclusion, MF provided protective mechanisms against the DEHP-mediated deterioration of testicular functions partially through its antioxidant, anti-inflammatory, and anti-apoptotic properties. It also involved the restoration of steroidogenesis and spermatogenesis through the modulation of Nrf2/HO-1, NF-κB/Cyt c/HSP70, and c-Kit signaling cascades.

MicroRNA-30a-5p promotes differentiation in neonatal mouse spermatogonial stem cells (SSCs)

BACKGROUND

The importance of spermatogonial stem cells (SSCs) in spermatogenesis is crucial and intrinsic factors and extrinsic signals mediate fate decisions of SSCs. Among endogenous regulators, microRNAs (miRNAs) play critical role in spermatogenesis. However, the mechanisms which individual miRNAs regulate self- renewal and differentiation of SSCs are unknown. The aim of this study was to investigate effects of miRNA-30a-5p inhibitor on fate determinations of SSCs.

METHODS

SSCs were isolated from testes of neonate mice (3-6 days old) and their purities were performed by flow cytometry with ID4 and Thy1 markers. Cultured cells were transfected with miRNA- 30a-5p inhibitor. Evaluation of the proliferation (GFRA1, PLZF and ID4) and differentiation (C-Kit & STRA8) markers of SSCs were accomplished by immunocytochemistry and western blot 48 h after transfection.

RESULTS

Based on the results of flow cytometry with ID4 and Thy1 markers, percentage of purity of SSCs was about 84.3 and 97.4 % respectively. It was found that expression of differentiation markers after transfection was significantly higher in miRNA-30a- 5p inhibitor group compared to other groups. The results of proliferation markers evaluation also showed decrease of GFRA1, PLZF and ID4 protein in SSCs transfected with miRNA-30a-5p inhibitor compared to the other groups.

CONCLUSIONS

It can be concluded that inhibition of miRNA-30a-5p by overexpression of differentiation markers promotes differentiation of Spermatogonial Stem Cells.

β-estradiol promotes the growth of primary human fetal spermatogonial stem cells via the induction of stem cell factor in Sertoli cells

BACKGROUND

Mammalian spermatogenesis is responsible for male fertility and is supported by the self-renewal and differentiation of spermatogonial stem cells (SSCs). Sertoli cells provide a supportive microenvironment for SSCs, in part by the production of stem cell factor (SCF), which is a potent regulator of spermatogonia proliferation and survival.

METHODS

We investigated the novel role of β-estradiol in modulating the proliferation and apoptosis of fetal SSCs via the regulation of SCF secretion in Sertoli cells isolated from human fetal testes. The proliferation of SSCs in the co-culture system was determined by colony formation and BrdU incorporation assays. TUNEL assay was used to measure SSC apoptosis in co-culture in response to treatment with control, β-estradiol, or the combination of β-estradiol and the estrogen receptor inhibitor ICI 182780.

RESULTS

In the system with purified human fetal Sertoli cells (MIS+/c-Kit-/AP-), β-estradiol upregulated the production of SCF in a dose- and time-dependent manner. In the co-culture system of primary human fetal SSCs (c-Kit+/SSEA-4+/Oct-4+/AP+) and Sertoli cells (MIS+), β-estradiol markedly increased the proliferation of SSCs. Moreover, SSC apoptosis was significantly inhibited by β-estradiol and was completely reversed by the combination of β-estradiol and ICI 182780.

CONCLUSION

Here we report, for the first time, that β-estradiol can induce the increase of SCF expression in human fetal Sertoli cells and regulates the growth and survival of human fetal SSCs. These novel findings provide new perspectives on the current understanding of the role of estrogen in human spermatogenesis.

The association between testicular toxicity induced by Li2Co3 and protective effect of Ganoderma lucidum: Alteration of Bax & c-Kit genes expression

Ganoderma lucidum has received a lot of attention recently due to its medicinal potential activities. The aim of this designed experiment was to evaluate the beneficial effects of Ganoderma lucidum extract against lithium carbonate induced testicular toxicity and related lesions in mice testis. For this purpose, lithium carbonate at a dose of 30 mg/kg, followed by 75, 150 mg/kg Ganoderma lucidum extract orally were administered for 35 days. The results were obtained from Ganoderma lucidum extract analysis prove contained a large amount of polysaccharides, triterpenoids and poly phenols based on spectrophotometric assay. Also, DPPH assay for Ganoderma lucidum extract showed high level of radical scavenging activity. The hematoxylin & eosin cross section from lithium carbonate treated group exhibited significant alterations in seminiferous tubules. Moreover, lithium carbonate induced oxidative stress via lipid peroxidation and generate MDA (P < 0.001). In addition, lithium carbonate initiated germ cells apoptosis via increase Bax expression (p < 0.001) and reduce germ cells differentiation through down-regulation of c-Kit expression (p < 0.05). Results from CASA showed that sperm parameters like count, motility and viability significantly decreased in lithium treated group (p < 0.001). It is clear that lithium carbonate induce severe damage on male reproductive system and histopathological damages via generation oxidative stress but supplementation with Ganoderma lucidum extract exhibited prevention effects and repaired induced damages.

Phosphatidylinositol 3-Kinase δ-Specific Inhibitor-Induced Changes in the Ovary and Testis in the Sprague Dawley Rat and Cynomolgus Monkey

Phosphatidylinositol 3-kinase (PI3K) δ is a lipid kinase primarily found in leukocytes, which regulates important cell functions. AMG2519493 was a PI3K δ-specific inhibitor in development for treatment of various inflammatory diseases. AMG2519493-related changes in the male and/or female reproductive organs were observed in the 1- and 3-month oral repeat dose toxicology studies in the rat and cynomolgus monkey. Hemorrhagic corpora lutea cysts and increased incidence of corpora lutea cysts without hemorrhage were observed in the ovaries at supra pharmacological doses in the rat. A decrease in seminiferous germ cells in the testis, indicative of spermatogenesis maturation arrest, was observed in both the rat and cynomolgus monkey. Although the characteristics were comparable, the drug systemic exposures associated with the testicular changes were very different between the 2 species. In the rat, the testicular change was only observed at supra pharmacologic exposure. Isotype assessment of PI3K signaling in rat spermatogonia in vitro indicated a role for PI3K β, but not δ, in the c Kit/PI3K/protein kinase B signaling pathway. Therefore, changes in both the ovary and testis of the rat were considered due to off target effect as they only occurred at suprapharmacologic exposure. In contrast, the testicular changes in the cynomolgus monkey (decrease in seminiferous germ cells) occurred at very low doses associated with PI3K δ-specific inhibition, indicating that the PI3K δ isoform may be important in spermatogenesis maturation in the cynomolgus monkey. Our results suggest species-related differences in PI3K isoform-specific control on reproductive organs.

Expression profile analysis of a new testis-specifically expressed gene C17ORF64 and its association with cell apoptosis in MCF-7 cells

With the increasing incidence of male infertility, identification and investigation the functions of new genes related to spermatogenesis are effective avenues to elucidate the decline of testicular function. In this study, a new gene, C17ORF64 (chromosome 17 open reading frame 64), was identified from mouse testes and its potential function was studied.RT-PCR and qRT-PCR assay showed that C17ORF64 mRNA was expressed exclusively in mouse testes and up-regulated from the 3-week old to 6-month old testes during postpartum development, which is consistent with C17ORF64 protein expression profile by western blotting analysis. Immunohistochemical analysis revealed that C17ORF64 protein was mainly localized in the cytoplasm of spermatogonia and spermatocytes, which is verified by GFP- labeled C17ORF64 gene expressed in GC-1 cells. C17ORF64 overexpression not only promoted cell apoptosis in MCF-7 cells, but also significantly decreased cell viability via MTT assay. Flow cytometric assay showed that C17ORF64 overexpression could inhibit cell cycle progression by arresting G1/S transition. Western blot and qRT-PCR analysis revealed that C17ORF64 overexpression inhibited the expression of anti-apoptotic protein bcl-2 and increased the expressions of pro-apoptotic protein caspase-3, caspase-8, caspase-9, Bax, P21 and P53. Taken together, our results confirmed C17ORF64 testis-specific expression pattern and, for the first time, demonstrated that C17ORF64 could inhibit cell viability and accelerate apoptosis in MCF-7 cells through caspase-3 regulatory pathways.

Regulation of Human Spermatogenesis

Human spermatogenesis (HS) is an intricate network of sequential processes responsible for the production of the male gamete, the spermatozoon. These processes take place in the seminiferous tubules (ST) of the testis, which are small tubular structures considered the functional units of the testes. Each human testicle contains approximately 600-1200 STs [1], and are capable of producing up to 275 million spermatozoa per day [2].

Role of pyroglutamylated RFamide peptide43 in germ cell dynamics in mice testes in relation to energy metabolism

QRFP is a neuropeptide that regulates glucose homeostasis and increases insulin sensitivity in tissues. We have previously shown that QRFP and its receptor (GPR103) are predominantly expressed in germ cells and Sertoli cells, respectively, in mice testes. In the present study, we report that QRFP caused an increase in PCNA and a decrease in p27Kip1 expressions in the testis under both in vivo and ex vivo conditions. Besides, via an in vivo study, cell cycle analysis by FACS showed an increase in 2C cells and a decrease in 1C cells. QRFP also induced expression of GDNF and phosphorylation of Akt and ERK-1/2. Together these results suggest that QRFP has a proliferative effect on germ cells in mice testes, since it caused a proportional increase in the mitotic activity and the number of spermatogonial cells. Further, observations of increased expressions of STAT-3 and Neurog3 in treated mice suggest that QRFP treatment regulates priming of undifferentiated spermatogonia to undergo differentiation, while a decrease in c-Kit expression indicate that spermatogonia at this time point are in an undifferentiated state. In addition, QRFP administration also caused an increase in intratesticular levels of glucose and lactate, and in LDH activity accompanied by increased expressions of GLUT-3 and LDH-C in the testis. Also, the phosphorylation of IR-β and expressions of p-Akt and p-mTOR were increased under ex vivo conditions in testicular tissue. In conclusion, our findings suggest that QRFP treatment caused proliferation of germ cells independently from the hypothalamic-pituitary axis via regulation of testicular energy metabolism.

A Fanci knockout mouse model reveals common and distinct functions for FANCI and FANCD2

Fanconi Anemia (FA) clinical phenotypes are heterogenous and rely on a mutation in one of the 22 FANC genes (FANCA-W) involved in a common interstrand DNA crosslink-repair pathway. A critical step in the activation of FA pathway is the monoubiquitination of FANCD2 and its binding partner FANCI. To better address the clinical phenotype associated with FANCI and the epistatic relationship with FANCD2, we created the first conditional inactivation model for FANCI in mouse. Fanci ^−/− mice displayed typical FA features such as delayed development in utero, microphtalmia, cellular sensitivity to mitomycin C, occasional limb abnormalities and hematological deficiencies. Interestingly, the deletion of Fanci leads to a strong meiotic phenotype and severe hypogonadism. FANCI was localized in spermatocytes and spermatids and in the nucleus of oocytes. Both FANCI and FANCD2 proteins co-localized with RPA along meiotic chromosomes, albeit at different levels. Consistent with a role in meiotic recombination, FANCI interacted with RAD51 and stimulated D-loop formation, unlike FANCD2. The double knockout Fanci^−/− Fancd2^−/− also showed epistatic relationship for hematological defects while being not epistatic with respect to generating viable mice in crosses of double heterozygotes. Collectively, this study highlights common and distinct functions of FANCI and FANCD2 during mouse development, meiotic recombination and hematopoiesis.

Sertoli cell-conditioned medium restores spermatogenesis in azoospermic mouse testis

The current study evaluates potential applications of Sertoli cell (SC)-conditioned medium (CM) and explores the effects of the conditioned medium on the spermatogenesis process in azoospermic mice. For this study, 40 adult mice (28-30 g) were divided into 4 experimental groups: (1) control, (2) DMSO 2% (10 μl), (3) busulfan (40 mg/kg single dose) and (4) busulfan/CM (10 μl). SCs were isolated from 4-week-old mouse testes. After using anesthetics, 10 μl of CM was injected over 3-5 min into each testis and subsequently, sperm samples were collected from the tail of the epididymis. Afterward, the animals were euthanized and testis samples were taken for histopathology experiments and RNA extraction in order to examine the expression of c-kit, STRA8 and PCNA genes. The data showed that CM notably increased the total sperm count and the number of testicular cells, such as spermatogonia, primary spermatocytes, round spermatids, SCs and Leydig cells compared with the control, DMSO and busulfan groups. Furthermore, the results showed that expression of c-kit and STRA8 was significantly decreased in the busulfan and busulfan/SC groups at 8 weeks after the last injection (p < 0.001) but no significant difference was found for PCNA compared with the control and DMSO groups (p < 0.05). These findings suggest that the Sertoli cell-conditioned medium may be beneficial as a practical approach for therapeutic strategies in reproductive and regenerative medicine.

Gene expression analysis of ovine prepubertal testicular tissue vitrified with a novel cryodevice (E.Vit)

PURPOSE

Testicular tissue cryopreservation prior to gonadotoxic therapies is a method to preserve fertility in children. However, the technique still requires development, especially when the tissue is immature and rather susceptible to stress derived from in vitro manipulation. This study aimed to investigate the effects of vitrification with a new cryodevice (E.Vit) on cell membrane integrity and gene expression of prepubertal testicular tissue in the ovine model.

METHODS

Pieces of immature testicular tissue (1 mm³) were inserted into "E.Vit" devices and vitrified with a two-step protocol. After warming, tissues were cultured in vitro and cell membrane integrity was assessed after 0, 2, and 24 h by trypan blue exclusion test. Controls consisted of non-vitrified tissue analyzed after 0, 2, and 24 h in vitro culture (IVC). Expression of genes involved in transcriptional stress response (BAX, SOD1, CIRBP, HSP90AB1), cell proliferation (KIF11), and germ- (ZBDB16, TERT, POU5F1, KIT) and somatic- (AR, FSHR, STAR) cell specific markers was evaluated 2 and 24 h after warming.

RESULTS

Post-warming trypan blue staining showed the survival of most cells, although membrane integrity immediately after warming (66.00% ± 4.73) or after 2 h IVC (59.67% ± 4.18) was significantly lower than controls (C0h 89.67% ± 1.45). Extended post-warming IVC (24 h) caused an additional decrease to 31% ± 3.46 (P < 0.05). Germ- and somatic-cell specific markers showed the survival of both cell types after cryopreservation and IVC. All genes were affected by cryopreservation and/or IVC, and moderate stress conditions were indicated by transcriptional stress response.

CONCLUSIONS

Vitrification with the cryodevice E.Vit is a promising strategy to cryopreserve prepubertal testicular tissue.

Effect of gestational exposure to perfluorononanoic acid on neonatal mice testes

Perfluoroalkyl acids (PFAAs) are widely used in commercial products and are found in many goods of daily use. Perfluorononanoic acid (PFNA) is one of the PFAAs that possesses endocrine disrupting properties and we have recently shown that PFNA affects testicular functions in Parkes mice. Exposure to environmental endocrine disruptors during fetal life is believed to affect gonadal development and they might produce reproductive abnormalities in males. Therefore, the present study examined the effect of gestational exposure to PFNA on the testes of neonatal mice offspring. Pregnant Parkes mice were orally administered PFNA (2 and 5 mg/kg body weight) or distilled water from gestational day 12 until parturition. Male pups were killed on postnatal day 3. PFNA treatment decreased testosterone biosynthesis by inhibiting expression of steroidogenic acute regulatory protein, cytochrome P450scc, and 3β- and 17β-hydroxysteroid dehydrogenase; proliferation of testicular cells was also affected in treated mice. Furthermore, a marked decrease in expression of Wilms tumor 1, steroidogenic factor 1 and insulin-like factor 3 was noted in neonatal mice testes, indicating that the PFNA treatment may affect the development of the testis. Moreover, observation of the dose-related expression of anti-müllerian hormone and c-Kit in neonatal mice testes is also suggestive of an interference with gonadal development by PFNA exposure. In conclusion, the results suggest that the gestational exposure to PFNA decreased testosterone biosynthesis and altered the expression of critical factors involved in the development of the testis, thereby advocating a potential risk of PFNA to male reproductive health.

Dietary Guanidinoacetic acid modulates testicular histology and expression of c-Kit and STRA8 genes in roosters

Decline in semen quality is considered as a major contributing factor in age-related subfertility of broiler breeder flocks. This study was aimed to investigate the effect of dietary supplementation of Guanidinoacetic acid (GAA), as an alternative energy source along with antioxidant potential, on testicular histology and relative gene expression of some spermatogonial markers (c-Kit and STRA8) in aged roosters. Sixteen 24-week-old male broiler breeders were randomly allocated into four groups and fed a basal diet supplemented with increasing levels of GAA including 0 (GAA-0), 600 (GAA-600), 1200 (GAA-1200) or 1800 (GAA-1800) mg/kg diet/day for 26 successive weeks. At the end of the experiment, all the birds were killed and two ipsilateral testicle samples were taken to either quantify relative gene expression or do histology. Except for seminiferous tubules' diameter, testicular weight, and the number of blood vessels, dietary supplementation of GGA improved the epithelium thickness of seminiferous tubules, the number of spermatogonia and Leydig cells and the relative gene expression of c-Kit and STRA8 (P < 0.01). Increasing levels of GAA cubically affected (P < 0.01) the diameter of seminiferous tubules and their epithelium thickness as well as the number of spermatogonia. However, number of Leydig cells and relative expression of c-Kit were linearly, and relative expression of STRA8 was quadratically (P < 0.01) enhanced in response to graded levels of GAA supplementation. Taking all parameters into account, daily supplementation of 1300-1450 mg of GAA/kg diet was estimated as an optimum dosage maximizing the evaluated traits.

Cloning of a new testis-enriched gene C4orf22 and its role in cell cycle and apoptosis in mouse spermatogenic cells

Spermatogenesis is a complicated and dynamic cellular differentiation process mainly regulated by genes, steroid hormones and environmental factors. Although a number of genes involved in spermatogenesis have been identified, there are still a lot of genes underlying spermatogenesis remained unexplained. Here, a novel gene C4orf22, also known as 1700007G11Rik or Cfap299 was identified from mouse testis. C4orf22 protein contains 233 amino acid residues and is highly conserved in metazoan species. C4orf22 mRNA was predominantly expressed in mouse testis and increased from 2-week-old testes to 8-week-old testes during the developing testes by RT-PCR and qRT-PCR. Immunohistochemical analysis indicated that C4orf22 protein was mainly distributed in the cytoplasm of spermatogonia and primary spermatocytes, which was further confirmed by C4orf22-tagged with GFP in the GC-1 and GC-2 cells. Over-expression of pEGFP-C3-C4orf22 significantly inhibited GC-1 cells apoptosis and promoted cell cycle progression with an increase in the cell number of S and G2 phase. Conversely, small interfering RNA (siRNA) silencing C4orf22 in GC-1 cells could cause an increase in the number of apoptosis cells and the cell cycle was arrested at G2/M phase. Western blot analysis and qRT-PCR results showed that C4orf22 over-expression significantly increased the expressions of anti-apoptotic bcl-2 and decreased the expression of caspase-3, caspase-8 and Bax. Our results suggest that C4orf22 may be involved in spermatogenesis, and for the first time, unravels its potential role in regulating cell apoptosis through bcl-2 regulatory pathway in GC-1 cells.

Cped1 promotes chicken SSCs formation with the aid of histone acetylation and transcription factor Sox2

Spermatogonial stem cells (SSCs) may apply to gene therapy, regenerative medicine in place of embryonic stem cells (ESCs). However, the application of SSCs was severely limited by the low induction efficiency and the lack of thorough analysis of the regulatory mechanisms of SSCs formation. Current evidences have demonstrated multiple marker genes of germ cells, while genes that specifically regulate the formation of SSCs have not been explored. In our study, cadherin-like and PC-esterase domain containing 1 (Cped1) expressed specifically in SSCs based on RNA-seq data analysis. To study the function of Cped1 in the formation of SSCs, we successfully established a CRISPR/Cas9 knockout system. The gene disruption frequency is 37% in DF1 and 25% in ESCs without off-target effects. Knockout of Cped1 could significantly inhibit the formation of SSCs in vivo and in vitro The fragment of -1050 to -1 bp had the activity as Cped1 gene promoter. Histone acetylation could regulate the expression of Cped1. We added 5-azaeytidi (DNA methylation inhibitors) and TSA (histone deacetylase inhibitors) respectively during the cultivation of SSCs. TSA was validated to promote the transcription of Cped1. Dual-luciferase reporter assay revealed that active control area of the chicken Cped1 gene is -296 to -1 bp. There are Cebpb, Sp1, and Sox2 transcription factor binding sites in this region. Point-mutation experiment results showed that Sox2 negatively regulates the transcription of Cped1. Above results demonstrated that Cped1 is a key gene that regulates the formation of SSCs. Histone acetylation and transcription factor Sox2 participate in the regulation of Cped1.

Expression profiling of c-kit and its impact after esiRNA silencing during gonadal development in catfish

Receptor, c-Kit is a member of a family of growth factor receptors that have tyrosine kinase activity, and are involved in the transduction of growth regulatory signals across plasma membrane by activation of its ligand, kitl/scf. The present study analyzed mRNA and protein expression profiles of c-kit in the gonads of catfish, Clarias gariepinus, using real time PCR, in situ hybridization and immunohistochemistry. Tissue distribution analysis revealed higher expression mainly in the catfish gonads. Ontogeny studies showed minimal expression during early developmental stages and highest during 50-75 days post hatch, and the dimorphic expression in gonads decreased gradually till adulthood, which might suggest an important role for this gene around later stages of sex differentiation and gonadal development. Expression of c-kit was analyzed at various phases of gonadal cycle in both male and female, which showed minimal expression during the resting phase, and higher expression during the pre-spawning phase in male compared to females. In vitro and in vivo induction using human chorionic gonadotropin elevated the expression of c-kit indicating the regulatory influence of hypothalamo-hypophyseal axis. In vivo transient gene silencing using c-kit-esiRNA in adult catfish during gonadal recrudescence showed a decrease in c-kit expression, which affected the expression levels of germ cell meiotic marker sycp3, as well as several factors and steroidogenic enzyme genes that are involved in germ cell development. Decrease in the levels of 11-ketotestosterone and testosterone in serum were also observed after esiRNA silencing. The findings suggests that c-kit has an important role in the process of germ cell proliferation, development and maturation during gonadal development and recrudescence in catfish.

Retinoic acid triggers c-kit gene expression in spermatogonial stem cells through an enhanceosome constituted between transcription factor binding sites for retinoic acid response element (RARE), spleen focus forming virus proviral integration oncogene (SPFI1) (PU.1) and E26 transformation-specific (ETS)

Restricted availability of retinoic acid (RA) in the testicular milieu regulates transcriptional activity of c-kit (KIT, CD117), which aids in the determination of spermatogonial stem-cell differentiation. The effect of RA on c-kit has been reported previously, but its mode of genomic action remains unresolved. We studied the molecular machinery guiding RA responsiveness to the c-kit gene using spermatogonial stem-cell line C18-4 and primary spermatogonial cells. A novel retinoic acid response element (RARE) positioned at -989 nucleotides upstream of the transcription start site (TSS) was identified, providing a binding site for a dimeric RA receptor (i.e. retinoic acid receptor gamma (RARγ) and retinoic X receptor). RA treatment influenced c-kit promoter activity, along with endogenous c-kit expression in C18-4 cells. A comprehensive promoter deletion assay using the pGL3B reporter system characterised the region spanning -271bp and -1011bp upstream of the TSS, which function as minimal promoter and maximal promoter, respectively. In silico analysis predicted that the region -1011 to +58bp comprised the distal enhancer RARE and activators such as spleen focus forming virus proviral integration oncogene (SPFI1) (PU.1), specificity protein 1 (SP1) and four E26 transformation-specific (ETS) tandem binding sites at the proximal region. Gel retardation and chromatin immunoprecipitation (ChIP) assays showed binding for RARγ, PU.1 and SP1 to the predicted consensus binding sequences, whereas GABPα occupied only two out of four ETS binding sites within the c-kit promoter region. We propose that for RA response, an enhanceosome is orchestrated through scaffolding of a CREB-binding protein (CBP)/p300 molecule between RARE and elements in the proximal promoter region, controlling germ-line expression of the c-kit gene. This study outlines the fundamental role played by RARγ, along with other non-RAR transcription factors (PU.1, SP1 and GABPα), in the regulation of c-kit expression in spermatogonial stem cells in response to RA.

Germ cell-intrinsic requirement for the homeodomain transcription factor PKnox1/Prep1 in adult spermatogenesis

PKnox1 (also known as Prep1) belongs to the TALE family of homeodomain transcription factors that are critical for regulating growth and differentiation during embryonic and postnatal development in vertebrates. We demonstrate here that PKnox1 is required for adult spermatogenesis in a germ cell-intrinsic manner. Tamoxifen-mediated PKnox1 loss in the adult testes, as well as its germ cell-specific ablation, causes testis hypotrophy with germ cell apoptosis and, as a consequence, compromised spermatogenesis. In PKnox1-deficient testes, spermatogenesis was arrested at the c-Kit⁺ spermatogonia stage, with a complete loss of the meiotic spermatocytes, and was accompanied by compromised differentiation of the c-Kit⁺ spermatogonia. Taken together, these results indicate that PKnox1 is a critical regulator of maintenance and subsequent differentiation of the c-Kit⁺ stage of spermatogonia in the adult testes.

Exploring the molecular aspects associated with testicular germ cell tumors: a review

Testicular germ cell tumors (TGCTs) represent the most common solid tumors affecting young men. They constitute a distinct entity because of their embryonic origin and their unique biological behavior. Recent preclinical data regarding biological signaling machinery as well as genetic and epigenetic mechanisms associated with molecular patterns of tumors have contribute to explain the pathogenesis and the differentiation of TGCTs and to understand the mechanisms responsible for the development of resistance to treatment. In this review, we discuss the main genetic and epigenetic events associated with TGCTs development in order to better define their role in the pathogenesis of these tumors and in cisplatin-acquired resistance.

Comparative Expression Analysis of HSP70, HSP90, IL-4, TNF, KITLG and KIT-receptor Gene between Varicocele-Induced and Non-Varicocele Testes of Dog

Background

This study was designed to create an experimental varicocele model by a simple surgical procedure in dog with minimum invasion and to investigate the effect of varicocele-induced infertility on the expression of six related genes (HSP90, HSP70, IL-4, TNF, KITLG and KIT receptor).

Materials and Methods

In this experimental study, the proximal part of the pampini-form plexus of dog testes was partially occluded without abdominal incision which was confirmed by venographic examination. To evaluate varicocele in its acute form, dogs were castrated after 15 days and testes were dissected. Histopathologic evaluation was undertaken and the relative expression of the six genes was assessed by quantitative realtime polymerase chain reaction (PCR).

Results

Microscopic changes showed tubule degeneration. The Johnson score was significantly decreased in the varicocele testes when compared with non-varicocele testes. Expressions of HSP90, TNF, KITLG and the KIT-receptor gene were significantly downregulated (P=0.029, 0.047, 0.004 and 0.035 respectively) in varicocele-induced testes while HSP70 was upregulated (P=0.018). IL-4 did not show differential expression (P=0.377).

Conclusion

We conclude that partial occlusion of the proximal part of the pampiniform plexus induces varicocele in the testis of dog. Differential expression of the mentioned genes may be responsible for the pathophysiology of varicocele and related subfertility.

Spermatogonial deubiquitinase USP9X is essential for proper spermatogenesis in mice

USP9X (ubiquitin-specific peptidase 9, X chromosome) is the mammalian orthologue of Drosophila deubiquitinase fat facets that was previously shown to regulate the maintenance of the germ cell lineage partially through stabilizing Vasa, one of the widely conserved factors crucial for gametogenesis. Here, we demonstrate that USP9X is expressed in the gonocytes and spermatogonia in mouse testes from newborn to adult stages. By using Vasa-Cre mice, germ cell-specific conditional deletion of Usp9x from the embryonic stage showed no abnormality in the developing testes by 1 week and no appreciable defects in the undifferentiated and differentiating spermatogonia at postnatal and adult stages. Interestingly, after 2 weeks, Usp9x-null spermatogenic cells underwent apoptotic cell death at the early spermatocyte stage, and then, caused subsequent aberrant spermiogenesis, which resulted in a complete infertility of Usp9x conditional knockout male mice. These data provide the first evidence of the crucial role of the spermatogonial USP9X during transition from the mitotic to meiotic phases and/or maintenance of early meiotic phase in Usp9x conditional knockout testes.

Aberrant expressions of stem cell factor/c-KIT in rat testis with varicocele

BACKGROUND/PURPOSE

Varicocele (VC) is considered by the World Health Organization as the main cause of male infertility. Studies have shown that VC can affect spermatogenesis and then result in male infertility. But the exact mechanism by which VC affects spermatogenesis is still unclear. Stem cell factor (SCF) and c-KIT receptor are crucial molecules during spermatogenesis in testis. This study aims to investigate whether SCF/c-KIT signaling is involved in the pathophysiology of VC on spermatogenesis.

METHODS

Rat models of VC were built (n = 13), and sham-operated rats were used as controls (n = 8). The seminiferous tubules of the testis were observed with hematoxylin and eosin staining, expression of SCF was analyzed via enzyme-linked immunosorbent assay and Western blot, and expression of c-KIT was assessed with Western blot and immunofluorescence.

RESULTS

Compared with controls, the seminiferous epithelium was disorganized and had significantly fewer cells in the testes of rats with VC. Expression of SCF increased in testes of VC rats, while expression of c-KIT was decreased.

CONCLUSION

These results suggest that sperm counts in seminiferous epithelium are affected by VC, and the SCF/c-KIT system is aberrantly expressed in VC testis, which could be involved in male infertility caused by VC.

The regulatory repertoire of PLZF and SALL4 in undifferentiated spermatogonia

Spermatogonial stem cells (SSCs) maintain spermatogenesis throughout adulthood through balanced self-renewal and differentiation, yet the regulatory logic of these fate decisions is poorly understood. The transcription factors Sal-like 4 (SALL4) and promyelocytic leukemia zinc finger (PLZF; also known as ZBTB16) are known to be required for normal SSC function, but their targets are largely unknown. ChIP-seq in mouse THY1(+) spermatogonia identified 4176 PLZF-bound and 2696 SALL4-bound genes, including 1149 and 515 that were unique to each factor, respectively, and 1295 that were bound by both factors. PLZF and SALL4 preferentially bound gene promoters and introns, respectively. Motif analyses identified putative PLZF and SALL4 binding sequences, but rarely both at shared sites, indicating significant non-autonomous binding in any given cell. Indeed, the majority of PLZF/SALL4 shared sites contained only PLZF motifs. SALL4 also bound gene introns at sites containing motifs for the differentiation factor DMRT1. Moreover, mRNA levels for both unique and shared target genes involved in both SSC self-renewal and differentiation were suppressed following SALL4 or PLZF knockdown. Together, these data reveal the full profile of PLZF and SALL4 regulatory targets in undifferentiated spermatogonia, including SSCs, which will help elucidate mechanisms controlling the earliest cell fate decisions in spermatogenesis.

Mechanisms Regulating Spermatogonial Differentiation

Mammalian spermatogenesis is a complex and highly ordered process by which male germ cells proceed through a series of differentiation steps to produce haploid flagellated spermatozoa. Underlying this process is a pool of adult stem cells, the spermatogonial stem cells (SSCs), which commence the spermatogenic lineage by undertaking a differentiation fate decision to become progenitor spermatogonia. Subsequently, progenitors acquire a differentiating spermatogonia phenotype and undergo a series of amplifying mitoses while becoming competent to enter meiosis. After spermatocytes complete meiosis, post-meiotic spermatids must then undergo a remarkable transformation from small round spermatids to a flagellated spermatozoa with extremely compacted nuclei. This chapter reviews the current literature pertaining to spermatogonial differentiation with an emphasis on the mechanisms controlling stem cell fate decisions and early differentiation events in the life of a spermatogonium.

Effect of Removal of Spermatogonial Stem Cells (SSCs) from In Vitro Culture on Gene Expression of Niche Factors in Bovine

BACKGROUND

Niche cells, regulating Spermatogonial Stem Cells (SSCs) fate are believed to have a reciprocal communication with SSCs. The present study was conducted to evaluate the effect of SSC elimination on the gene expression of Glial cell line-Derived Neurotrophic Factor (GDNF), Fibroblast Growth Factor 2 (FGF2) and Kit Ligand (KITLG), which are the main growth factors regulating SSCs development and secreted by niche cells, primarily Sertoli cells.

METHODS

Following isolation, bovine testicular cells were cultured for 12 days on extracellular matrix-coated plates. In the germ cell-removed group, the SSCs were removed from the in vitro culture using differential plating; however, in the control group, no intervention in the culture was performed. Colony formation of SSCs was evaluated using an inverted microscope. The gene expression of growth factors and spermatogonia markers were assessed using quantitative real time PCR.

RESULTS

SSCs colonies were developed in the control group but they were rarely observed in the germ cell-removed group; moreover, the expression of spermatogonia markers was detected in the control group while it was not observed in the germ cell-removed group, substantiating the success of SSCs removal. The expression of Gdnf and Fgf2 was greater in the germ cell-removed than control group (p<0.05), whereas the expression of Kitlg was lower in the germ cell-removed than control group (p< 0.05).

CONCLUSION

In conclusion, the results revealed that niche cells respond to SSCs removal by upregulation of GDNF and FGF2, and downregulation of KITLG in order to stimulate self-renewal and arrest differentiation.

Exposure to Brefeldin A promotes initiation of meiosis in murine female germ cells

In mammals, ontogenesis starts from a fusion of spermatozoon and oocyte, which are produced by reductive nuclear division of a diploid germ cell in a specialised but complex biological process known as meiosis. However, little is known about the mechanism of meiotic initiation in germ cells, although many factors may be responsible for meiosis both in male and female gonads. In this study, 11.5 days post coitum (dpc) female fetal mouse genital ridges were cultured in vitro with exposure to Brefeldin A (BFA) for 6h, and the changes in meiosis were detected. Synaptonemal-complex analysis implied that BFA played a positive role in meiosis initiation and this hypothesis was confirmed by quantitative PCR of meiosis-specific genes: stimulated by retinoic acid gene 8 (Stra8) and deleted in a zoospermia-like (DAZL). At the same time, mRNA expression of retinoic acid synthetase (Raldh2) and retinoic acid (RA) receptors increased in female gonads with in vitro exposure to BFA. Transplanting genital ridges treated with BFA into the kidney capsule of immunodeficient mice demonstrated that the development capacity of female germ cells was normal, while formation of primordial follicles was seen to be a result of accelerated meiosis after exposure to BFA. In conclusion, the study indicated that BFA stimulated meiosis initiation partly by RA signalling and then promoted the development of follicles.

Generation of fertile offspring from Kit(w)/Kit(wv) mice through differentiation of gene corrected nuclear transfer embryonic stem cells

Genetic mutations could cause sperm deficiency, leading to male infertility. Without functional gametes in the testes, patients cannot produce progeny even with assisted reproduction technologies such as in vitro fertilization. It has been a major challenge to restore the fertility of gamete-deficient patients due to genetic mutations. In this study, using a Kit(w)/Kit(wv) mouse model, we investigated the feasibility of generating functional sperms from gamete-deficient mice by combining the reprogramming and gene correcting technologies. We derived embryonic stem cells from cloned embryos (ntESCs) that were created by nuclear transfer of Kit(w)/Kit(wv) somatic cells. Then we generated gene-corrected ntESCs using TALEN-mediated gene editing. The repaired ntESCs could further differentiate into primordial germ cell-like cells (PGCLCs) in vitro. RFP-labeled PGCLCs from the repaired ntESCs could produce functional sperms in mouse testes. In addition, by co-transplantation with EGFP-labeled testis somatic cells into the testes where spermatogenesis has been chemically damaged or by transplantation into Kit(w)/Kit(wv) infertile testes, non-labeled PGCLCs could also produce haploid gametes, supporting full-term mouse development. Our study explores a new path to rescue male infertility caused by genetic mutations.

RA induces differentiation of multipotent P19 cells towards male germ cell

Generating male germ cells in vitro from multipotent stem cells is still a challenge for stem cell biologists. The difficulty is caused by the lack of knowledge about spermatogenesis molecular-controlling mechanisms. In vivo, PGCs differentiate into male germ cells in a very complicated environment through many middle steps. In this study, we use the pluripotent p19 cells to test their responses to different retinoic acid (RA) concentrations by evaluating markers for stem cells (bmp4, egr3), primordial germ cells (ddx4), spermatogonia (c-kit), premeiotic cells (stra8), and male germ cells (dazl and plzf). We have found that cyp26b1, which will catalyze RA, increases dramatically in p19 cells 1 d after RA treatment. Bmp3, egr3, and stra8 are stimulated after 1 d of RA treatment and then recover to normal after 3 d of RA treatment. C-kit keeps being expressed when treated with 10 nM-4 μM RA. Dazl and plzf are gained after 3 d of stimulation. The morphology of RA (100 nM-4 μM)-treated cells changes distinctively, and cell colonies are formed. Typical neural cell-like and germ cell-like morphologies appear in the 100 nM and 4 μM RA groups, respectively. We conclude that 100-500 nM RA can cause responses in p19 cells, but a high concentration of RA (1-4 μM) can drive these pluripotent cells' differentiation towards male germ cells. However, high concentrations of RA are also toxic. Some colonies that survived from 4 μM RA begin to express ddx4 and c-kit. Selection of the c-kit(+), dazl(+), and ddx4(+) cells after RA stimulation and creating a special culture medium for their propagation might benefit successful spermatogenesis induction in vitro.

Construction and quantitative evaluation of a dual specific promoter system for monitoring the expression status of Stra8 and c-kit genes

Applications of genetic constructs with multiple promoters, which are fused with reporter genes and simultaneous monitoring of various events in cells, have gained special attention in recent years. Lentiviral vectors, with their distinctive characteristics, have been considered to monitor the developmental changes of cells in vitro. In this study, we constructed a novel lentiviral vector (FUM-M), containing two germ cell-specific promoters (Stra8 and c-kit), fused with ZsGreen and DsRed2 reporter genes, and evaluated its efficiency in different cells following treatments with retinoic acid and DMSO. Several cell lines (P19, GC-1 spg and HEK293T) were transduced with this vector, and functional capabilities of the promoters were verified by flow cytometry and quantitative RT-PCR. Our results indicate that FUM-M shows dynamic behavior in the presence and absence of extrinsic factors. A correlation was also observed between the function of promoters, present in the lentiviral construct and the endogenous level of the Stra8 and c-kit mRNAs in the cells. In conclusion, we recommend this strategy, which needs further optimization of the constructs, as a beneficial and practical way to screen chemical inducers involved in cellular differentiation toward germ-like cells.

A novel Amh-Treck transgenic mouse line allows toxin-dependent loss of supporting cells in gonads

Cell ablation technology is useful for studying specific cell lineages in a developing organ in vivo. Herein, we established a novel anti-Müllerian hormone (AMH)-toxin receptor-mediated cell knockout (Treck) mouse line, in which the diphtheria toxin (DT) receptor was specifically activated in Sertoli and granulosa cells in postnatal testes and ovaries respectively. In the postnatal testes of Amh-Treck transgenic (Tg) male mice, DT injection induced a specific loss of the Sertoli cells in a dose-dependent manner, as well as the specific degeneration of granulosa cells in the primary and secondary follicles caused by DT injection in Tg females. In the testes with depletion of Sertoli cell, germ cells appeared to survive for only several days after DT treatment and rapidly underwent cell degeneration, which led to the accumulation of a large amount of cell debris within the seminiferous tubules by day 10 after DT treatment. Transplantation of exogenous healthy Sertoli cells following DT treatment rescued the germ cell loss in the transplantation sites of the seminiferous epithelia, leading to a partial recovery of the spermatogenesis. These results provide not only in vivo evidence of the crucial role of Sertoli cells in the maintenance of germ cells, but also show that the Amh-Treck Tg line is a useful in vivo model of the function of the supporting cell lineage in developing mammalian gonads.

The roles of testicular c-kit positive cells in de novo morphogenesis of testis

C-kit positive (c-kit⁺) cells are usual tissue-specific stem cells. However, in postnatal testis, undifferentiated spermatogonial stem cells (SSCs) are c-kit negative (c-kit⁻) and activation of c-kit represents the start of SSC differentiation, leaving an intriguing question whether other c-kit⁺ cells exist and participate in the postnatal development of testis. To this end, a feasible system for testicular reconstitution, in which a specific type of cells can be manipulated, is needed. Here, we first establish de novo morphogenesis of testis by subcutaneous injection of testicular cells from neonatal testes into the backs of nude mice. We observe testicular tissue formation and spermatogenesis from all injected sites. Importantly, functional spermatids can be isolated from these testicular tissues. Using this system, we systemically analyze the roles of c-kit⁺ cells in testicular reconstitution and identify a small population of cells (c-kit⁺:CD140a⁺:F4/80⁺), which express typical markers of macrophages, are critical for de novo morphogenesis of testis. Interestingly, we demonstrate that these cells are gradually replaced by peripheral blood cells of recipient mice during the morphogenesis of testis. Thus, we develop a system, which may mimic the complete developmental process of postnatal testis, for investigating the testicular development and spermatogenesis.

An oncofetal and developmental perspective on testicular germ cell cancer

Germ cell tumors (GCTs) represent a diverse group of tumors presumably originating from (early fetal) developing germ cells. Most frequent are the testicular germ cell cancers (TGCC). Overall, TGCC is the most frequent malignancy in Caucasian males (20-40 years) and remains an important cause of (treatment related) mortality in these young men. The strong association between the phenotype of TGCC stem cell components and their totipotent ancestor (fetal primordial germ cell or gonocyte) makes these tumors highly relevant from an onco-fetal point of view. This review subsequently discusses the evidence for the early embryonic origin of TGCCs, followed by an overview of the crucial association between TGCC pathogenesis, genetics, environmental exposure and the (fetal) testicular micro-environment (genvironment). This culminates in an evaluation of three genvironmentally modulated hallmarks of TGCC directly related to the oncofetal pathogenesis of TGCC: (1) maintenance of pluripotency, (2) cell cycle control/cisplatin sensitivity and (3) regulation of proliferation/migration/apoptosis by KIT-KITL mediated receptor tyrosine kinase signaling. Briefly, TGCC exhibit identifiable stem cell components (seminoma and embryonal carcinoma) and progenitors that show large and consistent similarities to primordial/embryonic germ cells, their presumed totipotent cells of origin. TGCC pathogenesis depends crucially on a complex interaction of genetic and (micro-)environmental, i.e. genvironmental risk factors that have only been partly elucidated despite significant effort. TGCC stem cell components also show a high degree of similarity with embryonic stem/germ cells (ES) in the regulation of pluripotency and cell cycle control, directly related to their exquisite sensitivity to DNA damaging agents (e.g. cisplatin). Of note, (ES specific) micro-RNAs play a pivotal role in the crossover between cell cycle control, pluripotency and chemosensitivity. Moreover, multiple consistent observations reported TGCC to be associated with KIT-KITL mediated receptor tyrosine kinase signaling, a pathway crucially implicated in proliferation, migration and survival during embryogenesis including germ cell development. In conclusion, TGCCs are a fascinating model for onco-fetal developmental processes especially with regard to studying cell cycle control, pluripotency maintenance and KIT-KITL signaling. The knowledge presented here contributes to better understanding of the molecular characteristics of TGCC pathogenesis, translating to identification of at risk individuals and enhanced quality of care for TGCC patients (diagnosis, treatment and follow-up).

Upregulation and nuclear translocation of testicular ghrelin protects differentiating spermatogonia from ionizing radiation injury

Proper control of apoptotic signaling is important for maintenance of testicular homeostasis after ionizing radiation (IR). Herein, we challenged the hypothesis that ghrelin, a pleiotropic modulator, is potentially involved in IR-induced germ cell injury. Lower body exposure to 2 Gy of IR induced a notable increase of ghrelin expression in the nuclear of differentiating spermatogonia at defined stages, with an impairment in the Leydig cells (LCs)-expressing ghrelin. Unexpectedly, inhibition of the ghrelin pathway by intraperitoneal injection of a specific GHS-R1α antagonist enhanced spermatogonia elimination by apoptosis during the early recovery following IR, and thereafter resulted in impaired male fertility, suggesting that the anti-apoptotic effects of evoked ghrelin, although transient along testicular IR injury, have a profound influence on the post-injury recovery. In addition, inhibition of ghrelin signaling resulted in a significant increase in the intratesticular testosterone (T) level at the end of 21 days after IR, which should stimulate the spermatogenic recovery from surviving spermatogonia to a certain extent during the late stage. We further demonstrated that the upregulation and nuclear trafficking of ghrelin, elaborately regulated by IR-elicited antioxidant system in spermatogonia, may act through a p53-dependent mechanism. The elicitation of ghrelin expression by IR stress, the regulation of ghrelin expression by IR-induced oxidative stress and the interaction between p53 and ghrelin signaling during IR injury were confirmed in cultured spermatogonia. Hence, our results represent the first evidence in support of a radioprotective role of ghrelin in the differentiating spermatogonia. The acutely, delicate regulation of local-produced ghrelin appears to be a fine-tune mechanism modulating the balance between testicular homeostasis and early IR injury.

Phosphatase of regenerating liver 2 (PRL2) deficiency impairs Kit signaling and spermatogenesis

The Phosphatase of Regenerating Liver (PRL) proteins promote cell signaling and are oncogenic when overexpressed. However, our understanding of PRL function came primarily from studies with cultured cell lines aberrantly or ectopically expressing PRLs. To define the physiological roles of the PRLs, we generated PRL2 knock-out mice to study the effects of PRL deletion in a genetically controlled, organismal model. PRL2-deficient male mice exhibit testicular hypotrophy and impaired spermatogenesis, leading to decreased reproductive capacity. Mechanistically, PRL2 deficiency results in elevated PTEN level in the testis, which attenuates the Kit-PI3K-Akt pathway, resulting in increased germ cell apoptosis. Conversely, increased PRL2 expression in GC-1 cells reduces PTEN level and promotes Akt activation. Our analyses of PRL2-deficient animals suggest that PRL2 is required for spermatogenesis during testis development. The study also reveals that PRL2 promotes Kit-mediated PI3K/Akt signaling by reducing the level of PTEN that normally antagonizes the pathway. Given the strong cancer susceptibility to subtle variations in PTEN level, the ability of PRL2 to repress PTEN expression qualifies it as an oncogene and a novel target for developing anti-cancer agents.

Effects of vitamin A on in vitro maturation of pre-pubertal mouse spermatogonial stem cells

Testicular tissue cryopreservation is the only potential option for fertility preservation in pre-pubertal boys exposed to gonadotoxic treatment. Completion of spermatogenesis after in vitro maturation is one of the future uses of harvested testicular tissue. The purpose of the current study was to evaluate the effects of vitamin A on in vitro maturation of fresh and frozen-thawed mouse pre-pubertal spermatogonial stem cells in an organ culture system. Pre-pubertal CD1 mouse fresh testes were cultured for 7 (D7), 9 (D9) and 11 (D11) days using an organ culture system. Basal medium was supplemented with different concentrations of retinol (Re) or retinoic acid (RA) alone or in combination. Seminiferous tubule morphology (tubule diameter, intra-tubular cell type), intra-tubular cell death and proliferation (PCNA antibody) and testosterone level were assessed at D7, D9 and D11. Pre-pubertal mouse testicular tissue were frozen after a soaking temperature performed at -7°C, -8°C or -9°C and after thawing, were cultured for 9 days, using the culture medium preserving the best fresh tissue functionality. Retinoic acid at 10^-6M and retinol at 3.3.10^-7M, as well as retinol 10^-6M are favourable for seminiferous tubule growth, maintenance of intra-tubular cell proliferation and germ cell differentiation of fresh pre-pubertal mouse spermatogonia. Structural and functional integrity of frozen-thawed testicular tissue appeared to be well-preserved after soaking temperature at -8°C, after 9 days of organotypic culture using 10^-6M retinol. RA and Re can control in vitro germ cell proliferation and differentiation. Re at a concentration of 10^-6M maintains intra-tubular cell proliferation and the ability of spermatogonia to initiate spermatogenesis in fresh and frozen pre-pubertal mouse testicular tissue using a soaking temperature at -8°C. Our data suggested a possible human application for in vitro maturation of cryopreserved pre-pubertal testicular tissue.