Leucine mediates autophagosome-lysosome fusion and improves sperm motility by activating the PI3K/Akt pathway

In vitro effect of granulocyte-macrophage colony-stimulating factor (GM-CSF) on the expression of genes related to sperm motility and energy metabolism and intracytoplasmic sperm injection outcomes in obstructive azoospermic patients

BACKGROUND

The presence of granulocyte-macrophage colony-stimulating factor (GM-CSF) and its receptor in various testicular cells and spermatozoa suggests a potential role in enhancing spermatogonial and postmeiotic cell development. Moreover, GM-CSF activates the pivotal pathways implicated in sperm motility regulation and glucose metabolism. However, the impact of GM-CSF on testicular biopsies from patients with obstructive azoospermia (OA) remains unexplored. Therefore, this study aimed to investigate the in vitro effects of GM-CSF on the expression of genes related to glucose transporters and signaling pathways, sperm motility, and viability in testicular biopsies.

METHODS AND RESULTS

Following testicular sperm extraction from 20 patients diagnosed with OA, each sample was divided into two parts: the experimental samples were incubated with medium containing 2 ng/ml GM-CSF at 37 °C for 60 min, and the control samples were incubated with medium without GM-CSF. Subsequently, the oocytes retrieved from the partner were injected with sperm from the treatment and control groups. The sperm parameters (motility and viability), the expression levels of sperm motility-related genes (PIK3R1, PIK3CA, and AKT1), and the expression levels of sperm energy metabolism-related genes (GLUT1, GLUT3, and GLUT14) were assessed. Furthermore, the fertilization and day 3 embryo development rate and embryo quality were evaluated. Compared with those in the nontreated group, the motility parameters and the mRNA expression levels of PIK3R1, AKT1, and GLUT3 in testicular sperm supplemented with GM-CSF were significantly greater (p < 0.05). However, no significant differences in the mRNA expression of PIK3CA, GLUT1, or GLUT14 were detected. According to the ICSI results, compared with the control group, the GM-CSF treatment group exhibited significantly greater fertilization rates (p = 0.027), Day 3 embryo development rate (p = 0.001), and proportions of good-quality embryos (p = 0.002).

CONCLUSIONS

GM-CSF increased the expression of genes related to motility and the energy metabolism pathway and effectively promoted the motility of testis-extracted spermatozoa, consequently yielding positive clinical outcomes.

Scriptaid is a prospective agent for improving human asthenozoospermic sample quality and fertilization rate in vitro

ABSTRACT

Male infertility is a global issue caused by poor sperm quality, particularly motility. Enhancement of the sperm quality may improve the fertilization rate in assisted reproductive technology (ART) treatment. Scriptaid, with a novel human sperm motility-stimulating activity, has been investigated as a prospective agent for improving sperm quality and fertilization rate in ART. We evaluated the effects of Scriptaid on asthenozoospermic (AZS) semen, including its impact on motility stimulation and protective effects on cryopreservation and duration of motility, by computer-aided sperm analysis (CASA). Sperm quality improvement by Scriptaid was characterized by increased hyaluronan-binding activity, tyrosine phosphorylation, adenosine triphosphate (ATP) concentration, mitochondrial membrane potential, and an ameliorated AZS fertilization rate in clinical intracytoplasmic sperm injection (ICSI) experiments. Furthermore, our identification of active Scriptaid analogs and different metabolites induced by Scriptaid in spermatozoa lays a solid foundation for the future biomechanical exploration of sperm function. In summary, Scriptaid is a potential candidate for the treatment of male infertility in vitro as it improves sperm quality, prolongs sperm viability, and increases the fertilization rate.

Rats Orally Administered with Ethyl Alcohol for a Prolonged Time Show Histopathology of the Epididymis and Seminal Vesicle Together with Changes in the Luminal Metabolite Composition

Prolonged ethanol (EtOH) consumption is associated with male infertility, with a decreased spermatogenesis rate as one cause. The defective maturation and development of sperm during their storage in the cauda epididymis and transit in the seminal vesicle can be another cause, possibly occurring before the drastic spermatogenesis disruption. Herein, we demonstrated that the cauda epididymis and seminal vesicle of rats, orally administered with EtOH under a regimen in which spermatogenesis was still ongoing, showed histological damage, including lesions, a decreased height of the epithelial cells and increased collagen fibers in the muscle layer, which implicated fibrosis. Lipid peroxidation (shown by malondialdehyde (MDA) levels) was observed, indicating that reactive oxygen species (ROS) were produced along with acetaldehyde during EtOH metabolism by CYP2E1. MDA, acetaldehyde and other lipid peroxidation products could further damage cellular components of the cauda epididymis and seminal vesicle, and this was supported by increased apoptosis (shown by a TUNEL assay and caspase 9/caspase 3 expression) in these two tissues of EtOH-treated rats. Consequently, the functionality of the cauda epididymis and seminal vesicle in EtOH-treated rats was impaired, as demonstrated by a decreases in 1H NMR-analyzed metabolites (e.g., carnitine, fructose), which were important for sperm development, metabolism and survival in their lumen.

The constructive and destructive impact of autophagy on both genders' reproducibility, a comprehensive review

Reproduction is characterized by a series of massive renovations at molecular, cellular, and tissue levels. Recent studies have strongly tended to reveal the involvement of basic molecular pathways such as autophagy, a highly conserved eukaryotic cellular recycling, during reproductive processes. This review comprehensively describes the current knowledge, updated to September 2022, of autophagy contribution during reproductive processes in males including spermatogenesis, sperm motility and viability, and male sex hormones and females including germ cells and oocytes viability, ovulation, implantation, fertilization, and female sex hormones. Furthermore, the consequences of disruption in autophagic flux on the reproductive disorders including oligospermia, azoospermia, asthenozoospermia, teratozoospermia, globozoospermia, premature ovarian insufficiency, polycystic ovarian syndrome, endometriosis, and other disorders related to infertility are discussed as well.Abbreviations: AKT/protein kinase B: AKT serine/threonine kinase; AMPK: AMP-activated protein kinase; ATG: autophagy related; E2: estrogen; EDs: endocrine disruptors; ER: endoplasmic reticulum; FSH: follicle stimulating hormone; FOX: forkhead box; GCs: granulosa cells; HIF: hypoxia inducible factor; IVF: in vitro fertilization; IVM: in vitro maturation; LCs: Leydig cells; LDs: lipid droplets; LH: luteinizing hormone; LRWD1: leucine rich repeats and WD repeat domain containing 1; MAP1LC3: microtubule associated protein 1 light chain 3; MAPK: mitogen-activated protein kinase; MTOR: mechanistic target of rapamycin kinase; NFKB/NF-kB: nuclear factor kappa B; P4: progesterone; PCOS: polycystic ovarian syndrome; PDLIM1: PDZ and LIM domain 1; PI3K: phosphoinositide 3-kinase; PtdIns3P: phosphatidylinositol-3-phosphate; PtdIns3K: class III phosphatidylinositol 3-kinase; POI: premature ovarian insufficiency; ROS: reactive oxygen species; SCs: Sertoli cells; SQSTM1/p62: sequestosome 1; TSGA10: testis specific 10; TST: testosterone; VCP: vasolin containing protein.

Genotypic and Allelic Prevalence of the TGF- Β1 +869 C/T SNP and Their Relationship to Seminogram in Infertile Males

Background

The influence of cytokine in the reproductive system is becoming increasingly important. The polymorphisms of the transforming growth factor-β1 (TGF-β1) gene are involved in male infertility. This study aimed to demonstrate the association between TGF-β1 and infertility and to investigate its impact on semen quality.

Methods

In this case-control study, serum TGF-β1 concentration was measured in 144 patients diagnosed with infertility and 40 fertile males by enzyme-linked immunosorbent assay (ELISA). The tetra-amplification refractory mutation system-PCR (T-ARMS-PCR) analysis was performed to detect the genotyping of the TGF-β1 (+869 C/T) (rs1800470) SNPs gene.

Results

Serum concentration of TGF-β1 was less in infertile males compared to fertile ones. The detected and more effective genotypes and alleles of TGF-β1 gene polymorphic on male infertility were, in normozoospermic group, CT genotype, probability (p)= 0.45, relative risk (RR)= 1.56, confidence intervals (CI): 0.58-4.22, and T allele (p= 0.46, RR= 1.32, CI: 0.65-2.69), in oligozoospermic and azoospermic groups, CC genotype (p= 0.32, RR= 1.58, CI: 0.73-3.41), (p= 0.013, RR= 3.50, CI: 1.40-8.73), and allele C (p= 0.44, RR= 1.32, CI: 0.73-2.38), (p= 0.06, RR= 2.14, CI: 1.02-4.50), respectively. The recessive model (TT+CT) showed increased risk among normozoospermic group (p=0.44, RR=1.67, CI:0.60-4.62). The serum concentration of TGF-β1 with CT and TT genotypes was less than that of CC genotype. TGF-β1 C/T genotype correlated with low sperm number, high immotile sperm, and high abnormal sperm morphology.

Conclusions

Our study revealed that the TGF-β1(rs1800470) gene polymorphisms are associated negatively with semen quality.

Metabolomic analysis of seminal plasma to identify goat semen freezability markers

Factors affecting sperm freezability in goat seminal plasma were investigated. Based on the total motility of thawed sperm, goats were divided into a high-freezability (HF) group with &gt;60% total motility (n = 8) and a low-freezability (LF) group with &lt;45% total motility (n = 8). Sperm and seminal plasma from the HF and LF groups were separated, HF seminal plasma was mixed with LF spermatozoa, LF seminal plasma was mixed with HF sperm, and the products were subjected to a freeze-thaw procedure. Semen from individual goats exhibited differences in freezability. HF semen had higher sperm motility parameters and plasma membrane and acrosome integrity after thawing; this difference could be related to the composition of seminal plasma. Seminal plasma from the HF and LF groups was evaluated using metabolomic analysis, and multivariate statistical analysis revealed a clear separation of metabolic patterns in the seminal plasma of goats with different freezability classifications. Forty-one differential metabolites were identified using the following screening conditions: variable importance in the projection &gt; 1 and 0.05 &lt; P-value &lt; 0.1. Kyoto Encyclopedia of Genes and Genomes pathway analysis revealed significant enrichment of central carbon metabolism in cancer, protein digestion and absorption, aminoacyl-tRNA, and other pathways and significant differences in the abundance of seven differential metabolites, including L-glutamine, L-aspartate, L-arginine, phenylpyruvate, benzoic acid, ketoisocaproic acid, and choline between seminal plasma from the HF and LF groups (P-value &lt; 0.05). These significantly differentially-expressed metabolites may be potential biomarkers for sperm freezability. L-glutamine, L-aspartate, and L-arginine may directly affect sperm freezability. Benzoic acid, ketoisocaproic acid, and choline may regulate sperm freezability by participating in anabolic processes involving phenylalanine, leucine, and phosphatidylcholine in sperm.

Dietary Leucine Improves Fish Intestinal Barrier Function by Increasing Humoral Immunity, Antioxidant Capacity, and Tight Junction

This study attempted to evaluate the possible impact and mechanism of leucine (Leu) on fish intestinal barrier function. One hundred and five hybrid Pelteobagrus vachelli ♀ × Leiocassis longirostris ♂ catfish were fed with six diets in graded levels of Leu 10.0 (control group), 15.0, 20.0, 25.0, 30.0, 35.0, and 40.0 g/kg diet for 56 days. Results showed that the intestinal activities of LZM, ACP, and AKP and contents of C3, C4, and IgM had positive linear and/or quadratic responses to dietary Leu levels. The mRNA expressions of itnl1, itnl2, c-LZM, g-LZM, and β-defensin increased linearly and/or quadratically (p < 0.05). The ROS, PC, and MDA contents had a negative linear and/or quadratic response, but GSH content and ASA, AHR, T-SOD, and GR activities had positive quadratic responses to dietary Leu levels (p < 0.05). No significant differences on the CAT and GPX activities were detected among treatments (p > 0.05). Increasing dietary Leu level linearly and/or quadratically increased the mRNA expressions of CuZnSOD, CAT, and GPX1α. The GST mRNA expression decreased linearly while the GCLC and Nrf2 mRNA expressions were not significantly affected by different dietary Leu levels. The Nrf2 protein level quadratically increased, whereas the Keap1 mRNA expression and protein level decreased quadratically (p < 0.05). The translational levels of ZO-1 and occludin increased linearly. No significant differences were indicated in Claudin-2 mRNA expression and protein level. The transcriptional levels of Beclin1, ULK1b, ATG5, ATG7, ATG9a, ATG4b, LC3b, and P62 and translational levels of ULK1, LC3Ⅱ/Ⅰ, and P62 linearly and quadratically decreased. The Beclin1 protein level was quadratically decreased with increasing dietary Leu levels. These results suggested that dietary Leu could improve fish intestinal barrier function by increasing humoral immunity, antioxidative capacities, and tight junction protein levels.

Enhancing Milk Production by Nutrient Supplements: Strategies and Regulatory Pathways

The enhancement of milk production is essential for dairy animals, and nutrient supplements can enhance milk production. This work summarizes the influence of nutrient supplements-including amino acids, peptides, lipids, carbohydrates, and other chemicals (such as phenolic compounds, prolactin, estrogen and growth factors)-on milk production. We also attempt to provide possible illuminating insights into the subsequent effects of nutrient supplements on milk synthesis. This work may help understand the strategy and the regulatory pathway of milk production promotion. Specifically, we summarize the roles and related pathways of nutrients in promoting milk protein and fat synthesis. We hope this review will help people understand the relationship between nutritional supplementation and milk production.

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.

Metabolomics analysis of buck semen cryopreserved with trehalose

Trehalose is commonly used as an impermeable cryoprotectant for cryopreservation of cells, but its cryoprotective mechanism has now not but been determined. This study investigated the cryopreservation impact of trehalose on buck semen cryopreservation and finished metabolic profiling of freeze-thawed media by way of the GC–MS-based metabolomics for the first time. Metabolic pattern recognition and metabolite identification by means of principal component analysis (PCA), partial least squares discriminant analysis (PLS-DA) and metabolic pathway topology analysis revealed the results of trehalose on buck sperm metabolism at some point of cryopreservation. The results confirmed that trehalose drastically progressed sperm motility parameters and structural integrity after thawing. PCA and PLS-DA analysis discovered that the metabolic patterns of the freezing-thawing media of buck semen cryopreserved with trehalose (T group) or without trehalose (G group, Control) were certainly separated. Using screening conditions of VIP >1.5 and p vaule <0.05, a total of 48 differential metabolites have been recognized, whithin l-isoleucine, L-leucine, L-threonine, and dihydroxyacetone were notably enriched in valine, leucine and isoleucine biosynthesis, glycerolipid metabolism, and aminoacyl-tRNA biosynthesis pathways. In brief, trehalose can efficiently improve membrane structural integrity and motion parameters in buck sperm after thawing, and it exerts a cryoprotective impact with the aid of changing sperm amino acid synthesis and the glycerol metabolism pathway.

Effects of dietary L-leucine supplementation on testicular development and semen quality in boars

Sperm and seminal plasma are rich in leucine, and leucine can promote the protein synthesis. This property makes it an interesting amino acid to increase sperm quality of human and livestock spermatogenesis. The goal of this study was to explore the effects of dietary leucine supplementation on testicular development and semen quality in boars from weaning to 10 months of age. 30 pure-bred, weaned Duroc boars (8.0 ± 1.0 kg) were randomly divided into two groups: control group (CON; fed the basal diet) and leucine group (LEU; fed the basal diet supplemented with 1.2% leucine); then, their body weight and testicular volume were recorded every 4 weeks. Testes were collected for histological and genes expression analysis from 150-day-old boars. Semen was collected and analyzed. Amino acids contents of blood plasma, seminal plasma, sperm, and testes were determined. Dietary supplementation with leucine increased the testicular volume and weight of boars, compared with CON. Sperm viability, sperm count per ejaculation, and average curve speed of sperm in leucine-supplemented boars were increased. Furthermore, leucine supplementation increased the blood plasma and seminal plasma leucine concentrations, and enhanced the gene expressions of branch chain amino acid transaminase, protein kinase B, mammalian target of rapamycin (mTOR), and cyclinb1 in the testes. Interestingly, the expressions of the p-mTOR and mTOR proteins in the testes were also upregulated. Thus, dietary leucine supplementation increased leucine absorption and utilization in the testes, promoted testicular development, and improved semen quality of boars, partly through the mTOR signaling pathway.

Genom-wide analysis identifies single nucleotide polymorphism variations and altered pathways associated with poor semen quality in breeding bulls

The reason for poor semen quality among the breeding bulls is not well understood. In the present study, we performed high-throughput RNAseq analysis of spermatozoa to identify the SNPs present in good and poor-quality semen-producing Holstein Friesian breeding bulls. A total of 21,360 and 44,650 SNPs were identified in good and poor-quality semen with a minimum read depth of 20, among which 4780 and 8710 novel variants were observed in good and poor-quality semen, respectively. Greater SNPs and indels variations were observed in poor compared to good-quality semen. In poor-quality semen, SNP variations were observed in ZNF280B, SLC26A2, DMXL1, OR52A1, MACROD2 and REV1 genes, which are associated with regulation of spermatogenesis, post-testicular maturation, Cl^- channel activity, V-ATPase-mediated intracellular vesicle acidification, a mono-ADP-ribosyl hydrolase and ATR-Chk1 checkpoint activation. GO analysis of filtered genes with significant variations between good and poor-quality semen showed enrichment in important pathways related to semen quality such as MAPK signalling pathway, Akt signalling pathway, focal adhesion, cAMP signalling pathway, and Rap1 signalling pathway. Network analysis of filtered genes in poor-quality semen showed variations in pathways of purine metabolism, pyrimidine metabolism, prolactin signalling pathway and RNA cap-binding complex. It is inferred that SNP in genes involved in maintaining sperm functions could be the reason for poor-quality semen production in bulls, and the identified SNPs hold potential to be used as biomarkers for semen quality in bulls.

Proteomic Study on the Reproductive Toxicity of Tripterygium Glycosides in Rats

Tripterygium glycoside tablet (TGT) is a common clinically used and effective non-steroidal immunosuppressant. However, its reproductive toxicity limits its application in pediatric immune diseases, warranting the study of the molecular mechanism behind its reproductive toxicity. In the present study, 4-week-old male Sprague Dawley (SD) rats were provided TGT through continuous gavage with a clinically equivalent dose of 12 mg/kg for 12 weeks. The reproductive toxicity of TGT was recorded, and its toxicity mechanism was verified through experimental validation and proteomics analyses. Our results demonstrated that TGT could significantly reduce the testosterone level in the serum as well as the concentration and survival rate of sperms. Pathological sections of the testis revealed that TGT could reduce spermatocytes at different levels and make the convoluted meridians vacuolated. Based on tandem mass tag (TMT)-labeled quantitative rats testicular tissue proteomics, 34 differential proteins were screened, involving protein digestion and absorption, PPAR signaling pathway, PI3K-Akt, and other pathways, among which PI3K-Akt plays an important role in the study of reproductive injury. Western blotting results revealed that TGT could significantly downregulate the Col1A1, Col1A2, p-PI3K, and p-Akt expressions and inhibit the expression of proteins related to the PI3K-Akt signaling pathway. In summary, the clinically equivalent dose of TGT induced reproductive toxicity of 4-week-old male SD rats, possibly in relation to the inhibition of the PI3K-Akt pathway expression.

GM-CSF (granulocyte-macrophage colony-stimulating factor) treatment improves sperm parameters in men with oligoasthenoteratospermia via PI3K/AKT pathway

Poor sperm quality in oligoasthenoteratospermia patients negatively affects assisted reproductive technology outcomes. Therefore, the development of sperm media is necessary to improve sperm parameters. This study investigated the effect of GM-CSF via PI3K/AKT pathway on sperm quality in OAT patients. Semen samples were collected from 20 OAT patients, and each sample was divided into two groups: Experiment and Control. In the experimental group, the samples were incubated with medium containing GM-CSF, and control samples were incubated without GM-CSF. Sperm parameters, mitochondrial membrane potential, acrosome reaction and DFI were studied; in addition, gene expression of PI3KR1, PI3KCA, GLUT1, GLUT3 and AKT1 was analysed, evaluation of PAKT/TAKT, and expression of GLUT 1, 3 was examined; subsequent fertilization rate and embryo quality were assessed. Our data showed that GM-CSF supplementation could significantly increase motility, mitochondrial activity, gene expression of PI3KCA, AKT1, the protein level of PAKT/TAKT and expression of GLUT 1, 3 while it decreases DNA fragmentation. The fertilization rate and embryo quality significantly improved in the treatment group. LY294002 had adverse effects on sperm motility and the PAKT/TAKT ratio. GM-CSF can improve in vitro sperm quality and could be a suitable supplement to sperm media for OAT patients.

Melatonin mitigates Chloroquine-induced defects in porcine immature Sertoli cells

Chloroquine (CQ) could function as a lysosomotropic agent to inhibit the endolysosomal trafficking in the autophagy pathway, and is widely used on malarial, tumor and recently COVID-19. However, the effect of CQ treatment on porcine immature Sertoli cells (iSCs) remains unclear. Here we showed that CQ could reduce iSC viability in a dose-dependent manner. CQ treatment (20 μM) on iSCs for 36h could elevate oxidative stress, damage mitochondrial function and promote apoptosis, which could be partially rescued by melatonin (MT) (10 nM). Transcriptome profiling identified 1611 differentially expressed genes (DEGs) (776 up- and 835 down-regulated) (20 μM CQ vs. DMSO), mainly involved in MAPK cascade, cell proliferation/apoptosis, HIF-1, PI3K-Akt and lysosome signaling pathways. In contrast, only 467 (224 up- and 243 down-regulated) DEGs (CQ + MT vs. DMSO) could be found after MT (10 nM) addition, enriched in cell cycle, regulation of apoptotic process, lysosome and reproduction pathways. Therefore, the partial rescue effects of MT on CQ treatment were confirmed by multiple assays (cell viability, ROS level, mitochondrial function, apoptosis, and mRNA levels of selected genes). Collectively, CQ treatment could impair porcine iSC viability by deranging the signaling pathways related to apoptosis and autophagy, which could be partially rescued by MT supplementation.

Autophagy: a multifaceted player in the fate of sperm

BACKGROUND

Autophagy is an intracellular catabolic process of degrading and recycling proteins and organelles to modulate various physiological and pathological events, including cell differentiation and development. Emerging data indicate that autophagy is closely associated with male reproduction, especially the biosynthetic and catabolic processes of sperm. Throughout the fate of sperm, a series of highly specialized cellular events occur, involving pre-testicular, testicular and post-testicular events. Nonetheless, the most fundamental question of whether autophagy plays a protective or harmful role in male reproduction, especially in sperm, remains unclear.

OBJECTIVE AND RATIONALE

We summarize the functional roles of autophagy in the pre-testicular (hypothalamic–pituitary–testis (HPG) axis), testicular (spermatocytogenesis, spermatidogenesis, spermiogenesis, spermiation) and post-testicular (sperm maturation and fertilization) processes according to the timeline of sperm fate. Additionally, critical mechanisms of the action and clinical impacts of autophagy on sperm are identified, laying the foundation for the treatment of male infertility.

SEARCH METHODS

In this narrative review, the PubMed database was used to search peer-reviewed publications for summarizing the functional roles of autophagy in the fate of sperm using the following terms: ‘autophagy’, ‘sperm’, ‘hypothalamic–pituitary–testis axis’, ‘spermatogenesis’, ‘spermatocytogenesis’, ‘spermatidogenesis’, ‘spermiogenesis’, ‘spermiation’, ‘sperm maturation’, ‘fertilization’, ‘capacitation’ and ‘acrosome’ in combination with autophagy-related proteins. We also performed a bibliographic search for the clinical impact of the autophagy process using the keywords of autophagy inhibitors such as ‘bafilomycin A1’, ‘chloroquine’, ‘hydroxychloroquine’, ‘3-Methyl Adenine (3-MA)’, ‘lucanthone’, ‘wortmannin’ and autophagy activators such as ‘rapamycin’, ‘perifosine’, ‘metformin’ in combination with ‘disease’, ‘treatment’, ‘therapy’, ‘male infertility’ and equivalent terms. In addition, reference lists of primary and review articles were reviewed for additional relevant publications. All relevant publications until August 2021 were critically evaluated and discussed on the basis of relevance, quality and timelines.

OUTCOMES

(i) In pre-testicular processes, autophagy-related genes are involved in the regulation of the HPG axis; and (ii) in testicular processes, mTORC1, the main gate to autophagy, is crucial for spermatogonia stem cell (SCCs) proliferation, differentiation, meiotic progression, inactivation of sex chromosomes and spermiogenesis. During spermatidogenesis, autophagy maintains haploid round spermatid chromatoid body homeostasis for differentiation. During spermiogenesis, autophagy participates in acrosome biogenesis, flagella assembly, head shaping and the removal of cytoplasm from elongating spermatid. After spermatogenesis, through PDLIM1, autophagy orchestrates apical ectoplasmic specialization and basal ectoplasmic specialization to handle cytoskeleton assembly, governing spermatid movement and release during spermiation. In post-testicular processes, there is no direct evidence that autophagy participates in the process of capacitation. However, autophagy modulates the acrosome reaction, paternal mitochondria elimination and clearance of membranous organelles during fertilization.

WIDER IMPLICATIONS

Deciphering the roles of autophagy in the entire fate of sperm will provide valuable insights into therapies for diseases, especially male infertility.

Proteomics study reveals the molecular mechanisms underlying cryotolerance induced by mild sublethal stress in human sperm

The preconditioning of human sperm with sublethal nitrosative stress before cryopreservation can potentially improve the thawed sperm quality. However, the underlying mechanisms behind this protective strategy are not entirely understood. We compared the cryosurvival of human sperm exposed to 0.01 μM nitric oxide (NO) throughout the cryopreservation and used multiplexed quantitative proteomics approach to identify changes in the proteome profile of preconditioned sperm cells. Semen samples were obtained from 30 normospermia donors and then each sample was divided into three equal parts: fresh (F), frozen-control (C), and frozen exposed to nitric oxide (NO). The sperm undergoing mild sublethal stress showed higher values for motility and viability compared to the frozen control sperm. Moreover, out of 2912 identified proteins, 248 proteins were detected as differentially abundant proteins (DAPs) between cryopreserved groups and fresh group (F) (p < 0.05). Gene ontology (GO) analysis of differentially abundant proteins indicated that the abundance of proteins associated with glycolysis, gluconeogenesis, and fertilization processes was reduced while oxidative phosphorylation pathway was increased in abundance in cryopreserved sperm compared to the fresh sperm. Moreover, redox protein such as thioredoxin 17 was increased in abundance in the NO group compared to the control freezing group. Therefore, the pre-conditioning of sperm prior to cryopreservation may play an important role in maintaining the redox balance in mitochondria of sperm after freezing. Overall, our results indicate that arylsulfatase A (ARSA), serine protease 37 (PRSS37), and sperm surface protein (SP17) may potentially serve as protein biomarkers associated with screening the fertilization potential of the thawed sperm.

Differentially expressed miRNAs and potential therapeutic targets for asthenospermia

Asthenozoospermia is detected in 40% of infertile men, and characterised by low sperm motility. MicroRNAs (miRNAs) play essential roles in spermatogenesis, but little is known regarding the function of seminal plasma miRNAs in asthenozoospermia. In this study, we collected seminal plasma samples from patients with asthenospermia and healthy men and employed high-throughput sequence technology to identify differentially expressed miRNAs. Thirteen altered miRNAs were confirmed by qRT-PCR. Six of these miRNAs were upregulated, and seven were downregulated. Five of the miRNAs (hsa-miR-34c-5p, hsa-miR-34b-5p, hsa-miR-146b-5p, hsa-miR-449a and has-miR-765) had been characterised previously, and eight of the others (miR-5000-3p, miR-4289, miR-6514-3p, miR-6882-5p and miR-6739-5p, miR-135a-5p, miR-509-3p and miR-196b-5p) were identified in asthenospermia for the first time in this study. These miRNAs were significantly associated with PI3K-Akt signaling pathway, MAPK signaling pathway, HIF-1 signaling pathway and FoxO signaling pathway. The identified dysregulated miRNA may be the key to the development of new and enhanced diagnosis and prognosis technologies for asthenospermia, and may also provide new therapeutic possibilities in the field of personalised medicine.

GH Overexpression Alters Spermatic Cells MicroRNAome Profile in Transgenic Zebrafish

Overexpression of growth hormone (GH) in gh-transgenic zebrafish of a highly studied lineage F0104 has earlier been reported to cause increased muscle growth. In addition to this, GH affects a broad range of cellular processes in transgenic fish, such as morphology, physiology, and behavior. Reports show changes such as decreased sperm quality and reduced reproductive performance in transgenic males. It is hypothesized that microRNAs are directly involved in the regulation of fertility potential during spermatogenesis. The primary aim of our study was to verify whether gh overexpression disturbs the sperm miRNA profile and influences the sperm quality in transgenic zebrafish. We report a significant increase in body weight of gh-transgenic males along with associated reduced sperm motility and other kinetic parameters in comparison to the non-transgenic group. MicroRNA transcriptome sequencing of gh-transgenic zebrafish sperms revealed expressions of 186 miRNAs, among which six miRNA were up-regulated (miR-146b, miR-200a-5p, miR-146a, miR-726, miR-184, and miR-738) and sixteen were down-regulated (miR-19d-3p, miR-126a-5p, miR-126b-5p, miR-22a-5p, miR-16c-5p, miR-20a-5p, miR-126b-3p, miR-107a-3p, miR-93, miR-2189, miR-202–5p, miR-221–3p, miR-125a, miR-125b-5p, miR-126a-3p, and miR-30c-5p) in comparison to non-transgenic zebrafish. Some of the dysregulated miRNAs were previously reported to be related to abnormalities in sperm quality and reduced reproduction ability in other species. In this study, an average of 134 differentially expressed miRNAs-targeted genes were predicted using the in silico approach. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis demonstrated that the genes of affected pathways were primarily related to spermatogenesis, sperm motility, and cell apoptosis. Our results suggested that excess GH caused a detrimental effect on sperm microRNAome, consequently reducing the sperm quality and reproductive potential of zebrafish males.

Alteration in autophagy gene expression profile correlates with low sperm quality

AIMS

Low sperm quality, a crucial factor of male infertility, is becoming a public health issue all over the world. In male reproductive system, autophagy plays an important role in maintaining physiological functions. There exist conjectures that disordered autophagy autophagy might be related to low sperm quality. However, there is no evidence can confirm that. This study aims to investigate the association between autophagy-associated genes and low sperm quality.

METHODS

Sperm samples of low sperm quality cases and matched controls were included to select differential expressed genes (DE genes) by autophagy-related functional gene microarray analysis. Then, 104 cases and 250 controls were included to validate the expression of four important autophagy genes (CXCR4, ESR1, PTEN and LC3B). Based on the obtained DE gene, gene Ontology and pathway analyses were conducted.

RESULTS

Chip results showed that expression of all 18 DE genes were decreased in the cases compared to the controls (P < 0.05). Expression of ESR1 were verified to be significantly decreased (P < 0.05).

CONCLUSION

Our results provided clues with the association among down-regulated expression of autophagy regulating and associated genes and low sperm quality. These findings revealed possible role of impaired autophagy in the mechanism of low sperm quality. Moreover, these may also provide potential targets for the treatment of low sperm quality.

Metabolite Profiling of Pig Seminal Plasma Identifies Potential Biomarkers for Sperm Resilience to Liquid Preservation

Metabolomic approaches allow the study of downstream gene expression events since metabolites are considered as the products of cell signaling pathways. For this reason, many studies in humans have already been conducted to determine the influence of the metabolites present in seminal plasma (SP) on sperm physiology, and to identify putative biomarkers. However, in livestock species, these relationships are yet to be uncovered. Thus, the present study aimed to explore: (i) if concentrations of metabolites in pig SP are related to sperm quality and functionality, and (ii) if they could predict the sperm resilience to liquid storage at 17°C. To this end, 28 ejaculates were individually collected and split into three aliquots: one was used for SP analysis through nuclear magnetic resonance (NMR) spectroscopy; another served for the evaluation of sperm concentration and morphology; and the last one was utilized to determine sperm functionality parameters using computer-assisted sperm analysis (CASA) and flow cytometry after 0 h and 72 h of liquid-storage at 17°C. NMR analysis allowed the identification and quantification of 23 metabolites present in pig SP which, except for fumarate, were not observed to follow a breed-dependent behavior. Moreover, specific relationships between metabolites and sperm variables were identified: (i) glutamate, methanol, trimethylamine N-oxide, carnitine, and isoleucine were seen to be related to some sperm quality and functionality parameters evaluated immediately after semen collection; (ii) leucine, hypotaurine, carnitine and isoleucine were found to be associated to the sperm ability to withstand liquid storage; and (iii) Bayesian multiple regression models allowed the identification of metabolite patterns for specific sperm parameters at both 0 h and 72 h. The identification of these relationships opens up the possibility of further investigating these metabolites as potential sperm functional biomarkers.

Assessment of Atg7 and LC3II/LC3, as The Markers of Autophagy, in Sperm of Infertile Men with Globozoospermia: A Case-Control Study

Objective

Assessment of relationship between LC3II/LC3 and Autophagy-related 7 (Atg7) proteins, as markers of autophagy, as well as evaluating the sperm parameters and DNA fragmentation in spermatozoa of infertile men with globozoospermia.

Materials and Methods

In this case-control study, 10 semen samples from infertile men with globozoospermia and 10 fertile individuals were collected, and the sperm parameters, sperm DNA fragmentation, and main autophagy markers (Atg7 and LC3II/LC3) were assessed according to World Health Organization (WHO) criteria, TUNEL assay, and western blot technique, respectively.

Results

The mean of sperm concentration and motility were significantly lower, while the percentage of abnormal spermatozoa and DNA fragmentation were significantly higher in infertile men with globozoospermia compared to fertile individuals (P<0.01). Unlike the relative expression of LC3II/LC3 that did not significantly differ between the two groups, the relative expression of ATG7 was significantly higher in infertile men with globozoospermia compared to fertile individuals (P<0.05). There was a significantly negative correlation between the sperm concentration (r=-0.679; P=0.005) and motility (r=-0.64; P=0.01) with the expression of ATG7, while a significantly positive association was founf between the percentage of DNA fragmentation and expression of ATG7 (0.841; P =0.018).

Conclusion

The increased expression of ATG7 and unaltered expression of LC3II/LC3 may indicate that the autophagy pathway is initiated but not completely executed in spermatozoa of individuals with globozoospermia. A significant correlation of ATG7 expression with increased sperm DNA fragmentation, reduced sperm concentration, and sperm motility may associate with the activation of a compensatory mechanism for promoting deficient spermatozoa to undergo cell death by the autophagy pathway. Therfore, this pathway could act as a double-edged sword that, at the physiological level, is involved in acrosome biogenesis, while, at the pathological level, such as globozoospermia, could act as a compensatory mechanism.

Prediction of 3D Protein Structure Based on The Mutation of AKAP3 and PLOD3 Genes in The Case of Non-Obstructive Azoospermia

Background

The present study has been designed with the aim of evaluating A-kinase anchoring proteins 3 (AKAP3) and Procollagen-Lysine, 2-Oxoglutarate 5-Dioxygenase 3 (PLOD3) gene mutations and prediction of 3D protein structure for ligand binding activity in the cases of non-obstructive azoospermic male.

Materials and Methods

Clinically diagnosed cases of non-obstructive azoospermia (n=111) with age matched controls (n=42) were included in the present case-control study for genetics analysis and confirmation of diagnosis. The sample size was calculated using Epi info software version 6 with 90 power and 95% confidence interval. Genomic DNA was isolated from blood (2.0 ml) and a selected case was used for whole exome sequencing (WES) using Illumina Hiseq for identification of the genes. Bioinformatic tools were used for decode the amino acid sequence from biological database (www.ncbi.nlm.nih.gov/protein). 3D protein structure of AKAP3 and PLOD3 genes was predicted using I-TASSER server and binding energy was calculated by Ramachandran plot.

Results

Present study revealed the mutation of AKAP3 gene, showing frameshift mutation at rs67512580 (ACT → -CT) and loss of adenine in homozygous condition, where, leucine changed into serine. Similarly, PLOD3 gene shows missense mutation in heterozygous condition due to loss of guanine in the sequence AGG→A-G and it is responsible for the change in post-translational event of amino acid where arginine change into lysine. 3D structure shows 8 and 4 pockets binding site in AKAP3 and PLOD3 gene encoded proteins with MTX respectively, but only one site bound to the receptor with less binding energy representing efficient model of protein structure.

Conclusion

These genetic variations are responsible for alteration of translational events of amino acid sequences, leading to protein synthesis change following alteration in the predicted 3D structure and functions during spermiogen- esis, which might be a causative “risk” factor for male infertility.

Strategy of Hepatic Metabolic Defects Induced by beclin1 Heterozygosity in Adult Zebrafish

Hepatic disorders have been increasing in recent years because of high carbohydrate diets. Hepatocytes depend mainly on the basal autophagy to maintain hepatic glucose/lipid homeostasis in mammals. However, the regulatory mechanisms of autophagy in hepatic energy metabolism are still unknown in fish species. Accordingly, mutant zebrafish lines of autophagy-related genes beclin1 and atg7 were generated by CRISPR/Cas9 gene-editing technology. Interestingly, unlike atg7+/-, male beclin1+/- zebrafish displayed liver defects in the morphology and histology, including abnormal hepatocyte proliferation, hemorrhagic and inflammatory phenotypes. A significant decrease in hepatocyte glycogen and an increase in hepatocyte lipids were detected in the histological assay that coincidence with the hepatic gene expression. Meanwhile, loss of heterozygosity for beclin1 creates a suitable microenvironment for hepatic tumorigenesis via phosphorylation of Akt kinase, which in turn affects liver autophagy. The reduction in autophagy activity in male beclin1+/- liver leads to a disturbance in the glucose/lipid metabolism and negatively regulates apoptosis accompanied by the induction of cellular proliferation and acute inflammatory response. Our findings highlight an important role of beclin1 in zebrafish liver development and energy metabolism, suggesting the crucial role of autophagy in maintaining homeostasis of the nutrient metabolism in fish species.

Effects of autophagy on macrophage adhesion and migration in diabetic nephropathy

Objective: Macrophage infiltration in kidney is a major pathological feature of diabetic nephropathy (DN), which has been demonstrated associate with macrophages autophagy homeostasis. However, the relationships between autophagy and the infiltration response related of macrophages adhesion and migration are unknown. This study aims to investigate the impact of macrophages adhesion and migration by modulating autophagy.

Methods: In vivo, rats were randomly distributed into control (NC) and DN groups. The pathological changes in renal tissue were assessed, and expression of CD68, LC3, P62 were analyzed. In vitro, RAW264.7 cells were divided into NC and high glucose (HG) groups. The capacity of macrophages adhesion migration and the expression of autophagy markers were observed with and without autophagy modulators (rapamycin, 3-methyladenine, chloroquine, and bafilomycin A1 for RAPA, 3-MA, CQ, BAFA). The macrophages autophagosome and the process of degradation and fusion of autophagosome-lysosome were observed by electron microscopy.

Results: In vivo, renal injury is aggravated in diabetic rat compared with NC group. The autophagy level is inhibited in renal tissues of DN group with the increasing expression of CD68 and P62, while expression level of LC3 decreased (p < .05). In vitro, HG and 3-MA reduce the numbers of autophagosome of macrophages to inhibit autophagy level with decrease expression of LC3 and Beclin-1, but increase expression of P62, which promote the adhesion and migration capacity of macrophages (p < .05). Moreover, CQ and BAFA suppress autophagy level by inhibiting the process of autophagosome-lysosome degradation and fusion of macrophages, as well as the expression of LC3 and Beclin-1. We notice an increase expression of P62 by CQ and BAFA stimulation (p < .05). CQ and BAFA further facilitate the adhesion and migration capacity of macrophages. However, RAPA increases the numbers of macrophages autophagosome that inhibited by HG, resulting in a recovery of autophagy level with increase expression of LC3 and Beclin-1, whereas a reduction expression of P62, which lead to inhibition of adhesion and migration of macrophages induced by HG (p < .05)

Conclusions: High glucose efficiently reduced the level of macrophage autophagy, following macrophages adhesion and migration enhanced when autophagy is suppressed. Activation of autophagosome improve the level of autophagy, but leading to a reduction of the macrophages adhesion and migration. While, inhibiting the process of degradation and fusion of autophagosome-lysosome suppress the level of autophagy and promote the macrophages adhesion and migration. These results indicate that high glucose may play an important role in macrophages adhesion and migration through modulating autophagy activities in diabetic nephropathy.

Leucine Promotes Milk Synthesis in Bovine Mammary Epithelial Cells via the PI3K-DDX59 Signaling

Leucine is an essential amino acid in the milk production of bovine mammary glands, but the regulatory roles and molecular mechanisms of leucine are still not known well. This study investigated the roles of leucine on milk synthesis and explored the corresponding mechanism in bovine mammary epithelial cells (BMECs). Leucine (0, 0.25, 0.5, 0.75, 1.0, and 1.25 mM) was added to BMECs that were cultured in FBS-free OPTI-MEM medium. Leucine significantly promoted milk protein and milk fat synthesis and also increased phosphorylation of mTOR signaling protein and the protein expression levels of SREBP-1c, with the most significant effects at 0.75 mM concentration. Leucine increased the expression and nuclear localization of DDX59, and loss and gain of gene function experiments further reveal that DDX59 mediates the stimulation of leucine on the mRNA expression variation of mTOR and SREBP-1c genes. PI3K inhibition experiment further detected that leucine upregulated expression of DDX59 and its downstream signaling via PI3K activation. ChIP-qPCR analysis further proved the binding of DDX59 to the promoter regions of mTOR and SREBP-1c. In summary, these data prove that DDX59 positively regulates the mTOR and SREBP-1c signaling pathways leading to synthesis of milk, and leucine regulates these two signaling pathways through the PI3K-DDX59 signaling.

Induction of sperm hypermotility through membrane progestin receptor alpha (mPRα): A teleost model of rapid, multifaceted, nongenomic progestin signaling

Rapid progestin effects on sperm physiology have been described in a variety of vertebrate species. Here, we briefly review the signaling pathways mediating rapid progestin induction of sperm hypermotility and increased fertility in two teleost species, Atlantic croaker and southern flounder. Acute in vitro treatment of teleost sperm with the progestin hormone, 20β-S, causes activation of progestin membrane receptor alpha (mPRα, or Paqr7) coupled to a stimulatory olfactory G protein (G_olf), resulting in increased cAMP and calcium concentrations and hypermotility upon activation in a hyperosmotic medium. Pharmacological tools were used to investigate the involvement of mPRα and several intracellular signaling pathways in the hypermotility response. Evidence was obtained using the specific mPRα agonist, Org OD 02-0, that this progestin action is mediated through mPRα and not through the nuclear PR. The results indicate that progestins induce hypermotility through activation of a membrane adenylyl cyclase (Acy)/cAMP pathway, an epidermal growth factor receptor (Egfr)/Mapkinase pathway, and a Pi3kinase/Akt/phosphodiesterase (Pde) pathway which result in increased sperm calcium concentrations within 10 s. The finding that inhibition of any one of these pathways is sufficient to prevent hypermotility along with the calcium increase suggests that activation of all of them and the associated calcium increase are required for the progestin hypermotility response. On the basis of these findings a model of progestin induction of sperm hypermotility in teleosts is proposed. As teleosts lack CatSper, the model described here is a non-CatSper mediated one and may therefore be applicable to a wide variety of nonmammalian vertebrates.

Dydrogesterone Causes Male Bias and Accelerates Sperm Maturation in Zebrafish ( Danio rerio)

Synthetic progestins are widely used in human and veterinary medicine. They can enter aquatic environments mainly via wastewater discharge and agricultural runoff, thus affecting fish populations in receiving waters. Here, we investigated the chronic effects of dydrogesterone (DDG) on zebrafish from 21 to 140 days post-fertilization (dpf) at 3.39, 33.1, and 329 ng L^-1. The results showed that the male ratio increased with the exposure concentration, and after 120 days of exposure to 329 ng L^-1, 98% of the fish were males. The DDG exposure during sex differentiation significantly increased the transcription of dmrt1 (1.83-fold) and apoptosis-related genes but suppressed the transcription of cyp19a1a (3.16-fold). Histological analysis showed that the exposure to DDG at 329 ng L^-1 caused 61.5% of mature spermatocytes in males, while the exposure to DDG at 33.1 ng L^-1 resulted in 14.7% of atretic follicles in females. Microarray analysis identified spermatogenesis-related gene ontology (endothelial barrier and immune response) in the testes at all concentrations. Genes from phagosome, lysosome, and sphingolipid metabolism pathways were enriched and could be responsible for sperm maturation. The findings from this study demonstrate that DDG in the aquatic environment can cause male bias and accelerate sperm maturation in zebrafish, resulting in potential high ecological risks to fish populations.