Effects of androgen-binding protein (ABP) on spermatid Tnp1 gene expression in vitro

Transition nuclear protein 1 as a novel biomarker in patients with fertilization failure

OBJECTIVE

Although intracytoplasmic sperm injection (ICSI) is a way to deal with in vitro fertilization failure, 3% of couples still experience repeated fertilization failure after attempted ICSI, despite having sperm within normal parameters. These patients are a challenging group whose sperm cannot fertilize the egg during ICSI. Unfortunately, no test can predict the risk of fertilization failure. Phospholipase C zeta (PLCζ) and transition nuclear proteins (TNPs) are essential factors for chromatin packaging during sperm maturation. This study aimed to assess PLCζ1 and TNP1 expression in the sperm of patients with fertilization failure and the correlations among the DNA fragmentation index, PLCζ1 and TNP1 gene and protein expression, and the risk of fertilization failure.

METHODS

In this study, 12 infertile couples with low fertilization rates (<25%) and complete failure of fertilization in their prior ICSI cycles despite normal sperm parameters were chosen as the case group. Fifteen individuals who underwent ICSI for the first time served as the control group. After sperm analysis and DNA fragmentation assays, quantitative reverse-transcription polymerase chain reaction (qRT-PCR) and Western blot analyses were performed to compare the gene and protein expression of PLCζ and TNP1 in both groups.

RESULTS

DNA fragmentation was significantly higher in the fertilization failure group. The qRT-PCR and Western blot results demonstrated significantly lower PLCζ and TNP1 gene and protein expression in these patients than in controls.

CONCLUSION

The present study showed that fertilization failure in normozoospermic men was probably due to deficient DNA packaging and expression of TNP1.

Differentiation-linked changes in the biosynthesis and turnover of sphingomyelins in rat male germ cells: Genes involved and effects of testosterone

In rodents, sphingomyelins (SMs) species with very-long-chain polyunsaturated fatty acid (VLCPUFA) are required for normal spermatogenesis. Data on the expression of enzymes with roles in their biosynthesis and turnover during germ cell differentiation and on possible effects on such expression of testosterone (Tes), known to promote this biological process, were lacking. Here we quantified, in isolated pachytene spermatocytes (PtS), round spermatids (RS), and later spermatids (LS), the mRNA levels from genes encoding ceramide (Cer), glucosylceramide (GlcCer), and SM synthases (Cers3, Gcs, Sms1, and Sms2) and sphingomyelinases (aSmase, nSmase) and assessed products of their activity in cells in culture using nitrobenzoxadiazole (NBD)-labeled substrates and [³H]palmitate as precursor. Transcript levels from Cers3 and Gcs were maximal in PtS. While mRNA levels from Sms1 increased with differentiation in the direction PtS→RS→LS, those from Sms2 increased between PtS and RS but decreased in LS. In turn, the nSmase transcript increased in the PtS→RS→LS order. During incubations with NBD-Cer, spermatocytes produced more GlcCer and SM than did spermatids. In total germ cells cultured for up to 25 h with NBD-SM, not only abundant NBD-Cer but also NBD-GlcCer were formed, demonstrating SM→Cer turnover and Cer recycling. After 20 h with [³H]palmitate, PtS produced [³H]SM and RS formed [³H]SM and [³H]Cer, all containing VLCPUFA, and Tes increased their labeling. In total germ cells, Tes augmented in 5 h the expression of genes with roles in VLCPUFA synthesis, decreased the mRNA from Sms2, and increased that from nSmase. Thus, Tes enhanced or accelerated the metabolic changes occurring to VLCPUFA-SM during germ cell differentiation.

Autophagy: A Double-Edged Sword in Male Reproduction

Autophagy, an evolutionarily conserved cell reprogramming mechanism, exists in all eukaryotic organisms. It is a fundamental and vital degradation/recycling pathway that removes undesirable components, such as cytoplasmic organelles, misfolded proteins, viruses, and intracellular bacteria, to provide energy and essential materials for organisms. The success of male reproduction depends on healthy testes, which are mainly composed of seminiferous tubules and mesenchyme. Seminiferous tubules are composed of Sertoli cells (SCs) and various germ cells, and the main functional part of mesenchyme are Leydig cells (LCs). In recent years, a large amount of evidence has confirmed that autophagy is active in many cellular events associated with the testes. Autophagy is not only important for testicular spermatogenesis, but is also an essential regulatory mechanism for the ectoplasmic specialization (ES) integrity of SCs, as well as for the normal function of the blood-testes barrier (BTB). At the same time, it is active in LCs and is crucial for steroid production and for maintaining testosterone levels. In this review, we expanded upon the narration regarding the composition of the testes; summarized the regulation and molecular mechanism of autophagy in SCs, germ cells, and LCs; and concluded the roles of autophagy in the process of spermatogenesis and testicular endocrinology. Through integrating the latest summaries and advances, we discuss how the role of autophagy is a double-edged sword in the testes and may provide insight for future studies and explorations on autophagy in male reproduction.

Microfluidic chips as a method for sperm selection improve fertilization rate in couples with fertilization failure

PURPOSE

Sperm quality plays a vital role in successful fertilization and pregnancy. Patients with fertilization failure (total failure or low-fertilization rate) despite having normal semen parameters are a challenging group whose sperm cannot fertilize the oocyte via the intracytoplasmic sperm injection (ICSI) technique. Microfluidics is offered as a new method for proper sperm sorting.

METHODS

This study aimed to evaluate sperm parameters, DNA fragmentation index (DFI), expression of phospholipase C zeta 1 (PLCZ1), and transition nuclear proteins 1 (TNP1) mRNAs in sperm selected by microfluidic sperm sorting (MSS) chip compared with conventional density gradient centrifugation technique in patients with fertilization failure following ICSI. Subsequence fertilization rate and embryo quality were assayed.

RESULTS

Normal morphology and total motility were significantly higher, and DFI was significantly lower in sperm selected by the MSS chip in fertilization failure and control groups. The RT-PCR results demonstrated a significant increase in the expression of PLCZ1 and TNP1 genes in sperm of both groups selected by MSS chips compared to the DGC method. In addition, with the selected sperm by MSS chip, an increase in fertilization rate and improvement of embryo quality was obtained.

CONCLUSION

The present study findings show that sperm sorting by the microfluidic method improves fertilization rate in patients with poor fertilization outcomes following ICSI.

Seasonal Expression of Gonadotropin Genes in the Pituitary and Testes of Male Plateau Zokor (Eospalax baileyi)

The gonadotropins, luteinizing hormone (LH) and follicle stimulating hormone (FSH), are glycoprotein hormones in the hypothalamic-pituitary-gonadal (HPG) axis and regulate mammalian reproduction. The expression of these genes in the plateau zokor (Eospalax baileyi) is poorly understood. We characterized the immunolocalization of the luteinizing hormone receptor (LHR) and follicle stimulating hormone receptor (FSHR) in the testes and evaluated the positive immunohistochemical results and the relative mRNA expression of gonadotropin genes. During the non-breeding season (September), the relative testes weight and the seminiferous tubule diameter were significantly reduced. All germ cell types were observed during the breeding season (May), whereas only spermatogonia were observed during the non-breeding season. LHR was present in the Leydig cells whereas FSHR was present in the Sertoli cells. The mean optical density was higher during the breeding season. The mRNA expression of LHβ and FSHβ was lower in the pituitary but LHR and FSHR genes expression were higher in the testes during the breeding season. These data elucidate the expression of gonadotropin genes in the HPG axis of the male plateau zokor and suggest that gonadotropins play a vital role in the regulation of seasonal breeding.

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].

Autophagy in male reproduction

Autophagy is a fundamental process that exists in all eukaryotic organisms, with a primary function of catabolizing undesirable components to provide energy and essential materials. Increasing evidence illustrates that autophagy is invovled in a broad range of cellular events within the male reproductive system. In the process of spermatogenesis, autophagy is crucial for the formation of specific structures that guarantee successful spermatogenesis, as well as for the degradation of certain constituents. The underlying connections between autophagy and androgen binding protein, lipid metabolism and testosterone biosynthesis would increase our understanding of male testicular endocrinology. Moreover, cumulative studies reveal that autophagy is a double-edged sword when the organism suffers from endocrine disrupting chemicals. This review contains a collection of the current literature concerning the above aspects of autophagy, which may provide insights for future study and exploration. Abbreviations: 3-MA: 3-methyladenine; ABP: androgen-binding protein; AKT: protein kinase B; AMPK: adenosine monophosphate-activated protein kinase; ART: assisted reproductive technologies; Atg: autophagy-related gene; CE: cholesteryl ester; CL: corpus luteum; CQ: chloroquine; CYP11A1: cholesterol side chain cleavage enzyme; CytC: cytochrome C; DEHP: di-2-ethylhexyl phthalate; DFCP1: double FYVE-containing protein 1; EDCs: endocrine-disrupting chemicals; ERK1/2: extracellular signal-regulated kinase 1/2; ES: ectoplasmic specialization; FC: free cholesterol; FIP2000: focal adhesion kinase family interacting protein of 200kDa; FSH: follicle stimulating hormone; HDL: high-density lipoprotein; IVF: in vitro fertilization; LC3: microtubule-associated protein light chain 3; LD: lipid droplet; LH: luteinising hormone; MC-LR: microcystin-LR; MEFs: mouse embryonic fibroblast cells; MT: microtubule; mtDNA: mitochondrial DNA; mTOR: mammalian target of rapamycin; NHERF2: Na⁺/H⁺ exchanger regulatory factor 2; NMR: naked mole-rat; PCD: programmed cell death; PDLIM1: PDZ and LIM domain 1; PGCs: primordial germ cells; PGF_2α: prostaglandin F_2α; PI3K: phosphatidylinositol-3-kinase; PI3P: phosphatidylinositol-3-phosphate; ROS: reactive oxygen species; SCG10: superior cervical ganglia protein 10; SR-BI: scavenger receptor class B, type I; StAR protein: steroidogenic acute regulatory protein; TC: total cholesterol; TEM: transmission electron microscopy; TUNEL: terminal deoxynucleotidyl transferase mediated dUTP nick end labeling; ULK1: mammalian uncoordinated-51-like kinase 1; WIPI: WD-repeat domain phosphoinositide-interacting.

Genetically Inherited Obesity and High-Fat Diet-Induced Obesity Differentially Alter Spermatogenesis in Adult Male Rats

Obesity is a multifactorial disorder with predominantly genetic and/or environmental causes. Our aim was to delineate effects of genetically inherited and high-fat diet-induced obesity on fertility and spermatogenesis using two Wistar rat models: genetically inherited obese (GIO) WNIN/Ob rats and diet-induced obese (DIO) rats, which received a high-fat diet. The terminal body weights were similar in both groups, but there was a significant difference in metabolic and hormone profiles between the groups. Fertility assessment revealed a significant decrease in the litter size due to increased pre- and postimplantation loss in the DIO group, whereas the rats in the GIO group were infertile due to lack of libido. Significantly decreased sperm counts were observed in the GIO group compared with the DIO group. Enumeration of testicular cells on the basis of ploidy and cell type-specific expression markers, to study the effect of obesity on spermatogenesis, demonstrated that the GIO and DIO states affected mitosis: spermatogonia and S-phase population were increased. However, distinctive effects were observed on meiosis and spermiogenesis in both the groups. Differential effects of GIO and DIO on fertility and spermatogenesis could be due to the significant difference in white adipose tissue accumulation between the groups and not due to high body weights. The differential effects of obesity suggest male obesity-induced infertility observed in humans could be a combination of genetic and environmental factors.

Exploration of intrinsic and extrinsic apoptotic pathways in zearalenone-treated rat sertoli cells

Zearalenone (ZEA) is a nonsteroidal estrogenic mycotoxin produced mainly by Fusarium. ZEA causes reproductive disorders and is both cytotoxic and genotoxic in animals; however, little is known regarding the molecular mechanism(s) leading to ZEA toxicity. Sertoli cells are somatic cells that support the development of spermatogenic cells. The objective of this study was to explore the effects of ZEA on the proliferation, apoptosis, and necrosis of rat Sertoli cells to uncover signaling pathways underlying ZEA cytotoxicity. ZEA reduced the proliferation of rat Sertoli cells in a dose-dependent manner, as indicated by a CCK8 assay, while flow cytometry revealed that ZEA caused both apoptosis and necrosis. Immunoblotting revealed that ZEA treatment increased the ratio of Bax/Bcl-2, as well as the expression of FasL and caspases-3, -8, and -9, in a dose-dependent manner. Collectively, these data suggest that ZEA induced apoptosis and necrosis in rat Sertoli cells via extrinsic and intrinsic apoptotic pathways. This study provides new insights into the molecular mechanisms by which ZEA exhibits cytotoxicity. © 2015 Wiley Periodicals, Inc. Environ Toxicol 31: 1731-1739, 2016.

Spermatogenesis in humans and its affecting factors

Spermatogenesis is an extraordinary complex process. The differentiation of spermatogonia into spermatozoa requires the participation of several cell types, hormones, paracrine factors, genes and epigenetic regulators. Recent researches in animals and humans have furthered our understanding of the male gamete differentiation, and led to clinical tools for the better management of male infertility. There is still much to be learned about this intricate process. In this review, the critical steps of human spermatogenesis are discussed together with its main affecting factors.

Testosterone regulates the autophagic clearance of androgen binding protein in rat Sertoli cells

Dysregulation of androgen-binding protein (ABP) is associated with a number of endocrine and andrology diseases. However, the ABP metabolism in Sertoli cells is largely unknown. We report that autophagy degrades ABP in rat Sertoli cells, and the autophagic clearance of ABP is regulated by testosterone, which prolongs the ABP biological half-life by inhibiting autophagy. Further studies identified that the autophagic clearance of ABP might be selectively regulated by testosterone, independent of stress (hypoxia)-induced autophagic degradation. These data demonstrate that testosterone up-regulates ABP expression at least partially by suppressing the autophagic degradation. We report a novel finding with respect to the mechanisms by which ABP is cleared, and by which the process is regulated in Sertoli cells.

Estradiol affects androgen-binding protein expression and fertilizing ability of spermatozoa in adult male rats

The estrogenicity of certain environmental pollutants is being increasingly correlated to decline in sperm counts and fertility of the males. Qualitative effects, if any, of estrogen(s) on terminal differentiation of spermatids have been less reported. The present study suggests that exposure to estrogen(s) can also alter the status of condensed chromatin in testicular spermatozoa and reduce their fertilizing potential. A significant reduction was evident in the serum gonadotropins, testosterone, weights of reproductive organs, sperm counts and litters sired by male rats after 10 days of estradiol exposure to a dose of 0.1mg/kg/day. Estradiol treatment led to retardation of in vitro decondensation rates of sperm chromatin, reduction in the uptake of acridine orange dye by chromatin, reduction in susceptibility of chromatin to acid denaturation in vitro, reduced uptake of thiol reactive monobromobimane dye and reduced levels of immunoreactive protamine 1 in caput epididymal sperms. Concomitantly, testicular levels of immunoreactive protamine 1, transition proteins 1/2 and cyclic adenosyl response element modulator-tau (CREMtau) were significantly reduced whilst their mRNA levels were unaffected after estradiol treatment. A significant increase was observed in the testicular mRNA levels of androgen-binding protein (ABP) in estradiol treated sires. An inverse correlation was observed between ABP mRNA levels and uptake of acridine orange by estradiol treated caput sperm chromatin. The results suggest that estradiol-induced increase in ABP mRNA underlies the mechanism(s) involved in the reduction in levels of certain proteins involved in nuclear chromatin condensation during spermiogenesis.

Cyproterone acetate affects protamine gene expression in the testis of adult male rat

The temporal effects of oral administration of cyproterone acetate (CPA), a progestational androgen receptor blocker, were studied on the fertility of adult male rat sires, at a dose of 20 mg kg-1 day-1 after 15 days of gavage. The treatment reduced the fertility and weights of accessory sex glands, without altering the serum levels of luteinizing hormone, follicle-stimulating hormone (FSH) and testosterone (T). Sperm counts were significantly reduced after treatment. Several changes were evident in caput epididymal sperm chromatin in treated rats. The in vitro decondensation rates of sperm chromatin and total fluorescent acridine orange (AO) dye uptake were enhanced. The fluorescent AO dye uptake by the double- and single-stranded sperm chromatin increased. The uptake of thiol-specific monobromobimane fluorescent dye by sperm chromatin was significantly reduced. Sperm of treated rats exhibited hypoprotamination. Protamine levels in the testis were significantly reduced after treatment. Androgen-binding protein (ABP) expression was significantly reduced in testis after treatment. A slight but significant increase was observed in cyclic AMP immunoexpression in testis after treatment. The expression and levels of transition proteins 1 (TP1) and 2 (TP2) as well as cyclic AMP response element modulator protein-tau were maintained at control levels in the testis of treated rats. The present study reports that androgen receptor occupation by CPA preferentially reduces the levels of spermatidal protamine in testis and spermatozoa involved in nuclear chromatin condensation. It is inferred that ABP could be mediating the effects of T in modulating the sequential expression of TPs and protamines during nuclear chromatin condensation. It is likely that indirect effects of T involve its aromatization in spermatids.

Effects of tamoxifen citrate on gene expression during nuclear chromatin condensation in male rats

AIM

To evaluate the effects of tamoxifen citrate on gene expression during nuclear chromatin condensation in male rats.

METHODS

The effects of an oral dose of 0.4 kg/(kg.d) tamoxifen citrate on rates of in vitro chromatin decondensation, acridine orange (AO) dye uptake, concentration of thiol-groups, levels and/or expression of transition proteins 1, 2 (TP1, TP2), protamine 1 (P1), cyclic AMP response element modulator-tau (CREMtau), androgen-binding protein (ABP) and cyclic adenosine 3',5' monophosphate (cAMP) were evaluated after 60 days of exposure in adult male rats. Controls received the vehicle.

RESULTS

Tamoxifen citrate enhanced the rates of chromatin decondensation, increased AO dye uptake and reduced free thiols in caput epididymal sperms and reduced the levels of TP1, TP2, P1, and CREMtau in the testis, while cAMP was unaffected. P1 deposition was absent in the sperm. The transcripts of TP1, TP2 were increased, of P1 and ABP decreased, while those of CREMtau unaffected in the testis.

CONCLUSION

Tamoxifen citrate reduced caput epididymal sperm chromatin compaction by reducing the testicular levels of proteins TP1, TP2 and P1 and the CREMtau involved in chromatin condensation during spermiogenesis. Tamoxifen citrate affects the expression of these genes at both the transcriptional and post-transcriptional levels.

Hyperprolactinemia affects spermiogenesis in adult male rats

The mechanisms underlying the antifertility effects of hyperprolactinemia have yet to be established in an appropriate experimental model. Hyperprolactinemia is a known side effect of fluphenazine, a broad spectrum, long-acting phenothiazine known to be dopamine type-D2 receptor antagonist. In our earlier study in adult male rats, we reported that fluphenazine at a dose of 3 mg/kg/day suppressed serum FSH but not testosterone (T) through increasing dopamine (DA) metabolism in the pituitary gland, within 60 days. Fluphenazine treatment affected sperm quality and male rats treated with fluphenazine sired fewer litters. The effects of fluphenazine-induced hyperprolactinemia on sperm quality appeared to be related to reduced FSH. We now report that FSH suppression enhanced the uptake of acridine orange (AO), a DNA intercalating, fluorescent dye by the fluphenazine-treated caput epididymal sperms with concomitant reduction in the uptake of thiol-specific monobromobimane (mBBr) fluorescent dye in vitro, suggesting greater accessibility of DNA intercalating dye to sperm chromatin and reduction in free sperm protein thiols. The concomitant increase in AO and decrease in mBBr fluorescence was suggestive of loose chromatin packaging in caput epididymal sperms after treatment with fluphenazine at 3 mg/kg/day for 60 days. The suppression in levels of protamine (P1) in caput epididymal sperms suggested that chromatin hypocompaction was due to reduced deposition of protamines in sperm chromatin. Reduction in testicular levels of cyclic adenosyl 3', 5' monophosphate response element modulator (CREMtau) and P1 further suggested that reduced deposition was indeed due to reduced synthesis. The concomitant reduction in testicular levels of transition protein 1 (TP1) and transition protein 2 (TP2) also suggested that hypoprotamination was due to reduced synthesis of these proteins crucial for facilitating P1 deposition. The effect appeared to have occurred at the level of translation of CREMtau, since its transcript levels were unaffected whereas those of TP1, TP2 and P1 and protamine were upregulated. The study led to the view that the effects of FSH suppression were manifest on the posttranscriptional modifications of CREMtau, as also on transcript repression of TP1, TP2, P1, which do the RNA- binding proteins bring about. Reduction in FSH did not decrease ABP expression in the testis, which has recently been implicated in the expression of transition protein 1 in vitro. However, a significant reduction was evident after fluphenazine treatment, in the immunoexpression of testicular cAMP, the mediator of FSH effects in the Sertoli cells and putative mediator of ABP effects in the spermatids. The study suggests that fluphenazine-induced hyperprolactinemia suppressed FSH and affected a putative cAMP-dependent mechanism underlying posttranscriptional modification of spermatidal genes involved in chromatin condensation, presumably by reducing the availability/secretion of ABP, a paracrine regulator of spermiogenesis in vitro.