Recently, male reproductive health has attracted extensive attention, with the adverse effects of circadian disruption on male fertility gradually gaining recognition. However, the mechanism by which circadian disruption leads to damage to male reproductive system remains unclear. In this review, we first summarized the dual regulatory roles of circadian clock genes on the male reproductive system: (1) circadian regulation of testosterone synthesis via the hypothalamic-pituitary-testicular (HPT) and hypothalamic-pituitary-adrenal (HPA) axes; (2) non-circadian regulation of spermatogenesis. Next, we further listed the possible mechanisms by which circadian disruption impairs male fertility, including interference with the oscillatory function of the reproductive system, i.e., synchronization of the HPT axis, crosstalk between the HPT axis and the HPA axis, as well as direct damage to germ cells by disturbing the non-oscillatory function of the reproductive system. Future research using spatiotemporal omics, epigenomic assays, and neural circuit mapping in studying the male reproductive system may provide new clues to systematically unravel the mechanisms by which circadian disruption affects male reproductive system through circadian clock genes.
Male ; Humans ; Animals ; Circadian Clocks/physiology* ; Hypothalamo-Hypophyseal System/physiology* ; Circadian Rhythm/genetics* ; Spermatogenesis/physiology* ; Pituitary-Adrenal System/physiology* ; Testis/physiology* ; Testosterone/biosynthesis* ; CLOCK Proteins ; Infertility, Male/physiopathology*

Infertility has become one of the most serious diseases worldwide, and 50% of this disease can be attributed to male-related factors. Spermatogenesis, by definition, is a complex process by which spermatogonial stem cells (SSCs) self-renew to maintain stem cell population within the testes and differentiate into mature spermatids. It is of great significance to uncover gene regulation and signaling pathways that are involved in the fate determinations of SSCs with aims to better understand molecular mechanisms underlying human spermatogenesis and identify novel targets for gene therapy of male infertility. Significant achievement has recently been made in demonstrating the signaling molecules and pathways mediating the fate decisions of mammalian SSCs. In this review, we address key gene regulation and crucial signaling transduction pathways in controlling the self-renewal, differentiation, and apoptosis of SSCs, and we illustrate the networks of genes and signaling pathways in SSC fate determinations. We also highlight perspectives and future directions in SSC regulation by genes and their signaling pathways. This review could provide novel insights into the genetic regulation of normal and abnormal spermatogenesis and offer molecular targets to develop new approaches for gene therapy of male infertility.
Humans ; Male ; Signal Transduction/physiology* ; Apoptosis/physiology* ; Spermatogenesis/physiology* ; Cell Differentiation ; Adult Germline Stem Cells/physiology* ; Spermatogonia/cytology* ; Gene Expression Regulation ; Animals ; Infertility, Male/genetics* ; Cell Self Renewal/genetics*

Spermatozoa have a highly complex RNA profile. Several of these transcripts are suggested as biomarkers for male infertility and contribute to early development. To analyze the differences between sperm RNA quantity and expression of protamine ( PRM1 and PRM2 ) and testis-specific histone 2B ( TH2B ) genes, spermatozoa from 33 patients who enrolled in assisted reproduction treatment (ART) program were analyzed. Sperm RNA of teratozoospermic (T), oligoteratozoospermic (OT), and normozoospermic (N) samples was extracted, and the differences in transcript levels among the study groups were analyzed by quantitative real-time polymerase chain reaction (qRT-PCR). The correlations of total RNA per spermatozoon and the expression of the transcripts were evaluated in relation to sperm characteristics and preimplantation embryo development. The mean (±standard deviation) RNA amount per spermatozoon was 28.48 (±23.03) femtogram in the overall group and was significantly higher in the OT group than that in N and T groups. Total sperm RNA and gene expression of PRM1 and PRM2 genes were related to preimplantation embryo development and developmental arrest. Specific sperm characteristics were correlated with the expressions of PRM1 , PRM2 , or TH2B genes. We conclude that the sperm RNA amount and composition are important factors and might influence early embryonic development and also differ in different cases of male infertility.
Male ; Humans ; Protamines/metabolism* ; Spermatozoa/metabolism* ; Embryonic Development/genetics* ; Adult ; RNA/genetics* ; Histones/genetics* ; Infertility, Male/genetics* ; Teratozoospermia/genetics* ; Oligospermia/genetics*

Primary ciliary dyskinesia (PCD) is a clinically rare, genetically and phenotypically heterogeneous condition characterized by chronic respiratory tract infections, male infertility, tympanitis, and laterality abnormalities. PCD is typically resulted from variants in genes encoding assembly or structural proteins that are indispensable for the movement of motile cilia. Here, we identified a novel nonsense mutation, c.466G>T, in cilia- and flagella-associated protein 300 ( CFAP300 ) resulting in a stop codon (p.Glu156*) through whole-exome sequencing (WES). The proband had a PCD phenotype with laterality defects and immotile sperm flagella displaying a combined loss of the inner dynein arm (IDA) and outer dynein arm (ODA). Bioinformatic programs predicted that the mutation is deleterious. Successful pregnancy was achieved through intracytoplasmic sperm injection (ICSI). Our results expand the spectrum of CFAP300 variants in PCD and provide reproductive guidance for infertile couples suffering from PCD caused by them.
Adult ; Female ; Humans ; Male ; Pregnancy ; China ; Ciliary Motility Disorders/genetics* ; Codon, Nonsense ; East Asian People/genetics* ; Exome Sequencing ; Homozygote ; Infertility, Male/genetics* ; Kartagener Syndrome/genetics* ; Pedigree ; Sperm Injections, Intracytoplasmic ; Cytoskeletal Proteins/genetics*

Multiple morphological abnormalities of the flagella (MMAF) represent a severe form of sperm defects leading to asthenozoospermia and male infertility. In this study, we identified a novel homozygous splicing mutation (c.871-4 ACA>A) in the adenylate kinase 7 (AK7) gene by whole-exome sequencing in infertile individuals. Spermatozoa from affected individuals exhibited typical MMAF characteristics, including coiled, bent, short, absent, and irregular flagella. Transmission electron microscopy analysis showed disorganized axonemal structure and abnormal mitochondrial sheets in sperm flagella. Immunofluorescence staining confirmed the absence of AK7 protein from the patients' spermatozoa, validating the pathogenic nature of the mutation. This study provides direct evidence linking the AK7 gene to MMAF-associated asthenozoospermia in humans, expanding the mutational spectrum of AK7 and enhancing our understanding of the genetic basis of male infertility.
Humans ; Male ; Sperm Tail/ultrastructure* ; Homozygote ; Consanguinity ; Asthenozoospermia/pathology* ; Infertility, Male/genetics* ; Mutation ; Pakistan ; Adenylate Kinase/genetics* ; Adult ; Pedigree ; RNA Splicing ; Exome Sequencing ; Spermatozoa

This study primarily aimed to investigate the prevalence of human papillomavirus (HPV) and other common pathogens of sexually transmitted infections (STIs) in spermatozoa of infertile men and their effects on semen parameters. These pathogens included Ureaplasma urealyticum, Ureaplasma parvum, Chlamydia trachomatis, Mycoplasma genitalium , herpes simplex virus 2, Neisseria gonorrhoeae, Enterococcus faecalis, Streptococcus agalactiae, Pseudomonas aeruginosa , and Staphylococcus aureus . A total of 1951 men of infertile couples were recruited between 23 March 2023, and 17 May 2023, at the Department of Reproductive Medicine of The First People's Hospital of Yunnan Province (Kunming, China). Multiplex polymerase chain reaction and capillary electrophoresis were used for HPV genotyping. Polymerase chain reaction and electrophoresis were also used to detect the presence of other STIs. The overall prevalence of HPV infection was 12.4%. The top five prevalent HPV subtypes were types 56, 52, 43, 16, and 53 among those tested positive for HPV. Other common infections with high prevalence rates were Ureaplasma urealyticum (28.3%), Ureaplasma parvum (20.4%), and Enterococcus faecalis (9.5%). The prevalence rates of HPV coinfection with Ureaplasma urealyticum, Ureaplasma parvum, Chlamydia trachomatis, Mycoplasma genitalium , herpes simplex virus 2, Neisseria gonorrhoeae, Enterococcus faecalis, Streptococcus agalactiae , and Staphylococcus aureus were 24.8%, 25.4%, 10.6%, 6.4%, 2.4%, 7.9%, 5.9%, 0.9%, and 1.3%, respectively. The semen volume and total sperm count were greatly decreased by HPV infection alone. Coinfection with HPV and Ureaplasma urealyticum significantly reduced sperm motility and viability. Our study shows that coinfection with STIs is highly prevalent in the semen of infertile men and that coinfection with pathogens can seriously affect semen parameters, emphasizing the necessity of semen screening for STIs.
Humans ; Male ; Infertility, Male/epidemiology* ; Coinfection/microbiology* ; Papillomavirus Infections/virology* ; Adult ; Sexually Transmitted Diseases/complications* ; China/epidemiology* ; Staphylococcus aureus/isolation & purification* ; Chlamydia trachomatis/isolation & purification* ; Prevalence ; Mycoplasma genitalium/isolation & purification* ; Ureaplasma urealyticum/isolation & purification* ; Neisseria gonorrhoeae/isolation & purification* ; Enterococcus faecalis/isolation & purification* ; Streptococcus agalactiae/isolation & purification* ; Herpesvirus 2, Human/genetics* ; Pseudomonas aeruginosa/isolation & purification* ; Semen/virology* ; Sperm Motility ; Spermatozoa/microbiology* ; Human Papillomavirus Viruses

Y chromosome microdeletions are an important cause of male infertility. At present, research on the Y chromosome is mainly focused on analyzing the loss of large segments of the azoospermia factor a/b/c (AZFa/b/c) gene, and few studies have reported the impact of unit point deletion in the AZF band on fertility. This study analyzed the effect of sperm quality after sY1192 loss in 116 patients. The sY1192-independent deletion accounted for 41.4% (48/116). Eight patterns were found in the deletions associated with sY1192. The rate of sperm detection was similar in the semen of patients with the independent sY1192 deletion and the combined sY1192 deletions (52.1% vs 50.0%). The patients with only sY1192 gene loss had a higher probability of sperm detection than the patients whose sY1192 gene locus existed, but other gene loci were lost (52.1% vs 32.0%). The hormone levels were similar in patients with sY1192 deletion alone and in those with sY1192 deletion and other types of microdeletions in the presence of the sY1192 locus. After multiple intracytoplasmic sperm injection (ICSI) attempts, the pregnancy rate of spouses of men with sY1192-independent deletions was similar to that of other types of microdeletions, but the fertilization and cleavage rates were higher. We observed that eight deletion patterns were observed for sY1192 microdeletions of AZFb/c, dominated by the independent deletion of sY1192. After ICSI, the fertilization rate and cleavage rate of the sY1192-independent microdeletion were higher than those of other Y chromosome microdeletion types, but there was no significant difference in pregnancy outcomes.
Humans ; Female ; Pregnancy ; Male ; Chromosomes, Human, Y/genetics* ; Adult ; Chromosome Deletion ; Pregnancy Outcome/genetics* ; Infertility, Male/genetics* ; Spermatozoa/physiology* ; Semen Analysis ; Sex Chromosome Disorders of Sex Development/genetics* ; Sperm Injections, Intracytoplasmic ; Azoospermia/genetics* ; Sex Chromosome Aberrations

We aim to study the semen carriage of human papillomavirus (HPV) and evaluate its association with patient characteristics. We conduct a single-center cohort study at Amiens University Hospital Center (Amiens, France). From May 1 to October 31, 2021, 461 men consulting for infertility and with semen analysis data were included. Each participant gave his written informed consent for the use of laboratory, demographic, clinical, and lifestyle data. A proportion of the semen samples were sent to a virology laboratory for HPV screening in a polymerase chain reaction (PCR) assay. In univariate and multivariate analyses with a logistic regression model, HPV + and HPV - groups were compared with regard to semen characteristics (including the DNA fragmentation index and the sperm decondensation index) and demographic, clinical, and lifestyle variables. Semen HPV carriage was detected in 22.3% of the patients. High-oncogenic-risk HPV genotypes were predominant (57.6%). Multivariate analysis showed that HPV carriage was significantly associated with the presence of at least one abnormal spermogram dinging (according to the 6 th World Health Organization criteria), with an adjusted odds ratio (OR) of 4.10 (95% confidence interval [CI]: 2.32-7.25, P < 0.001). A statistically significant association was also found for the type of infertility (OR: 1.61, 95% CI: 1.00-2.57, P = 0.05), the presence of varicocele (OR: 3.99, 95% CI: 1.48-10.71, P = 0.01), and a history of cryptorchidism, testicular ectopia, or monorchidism (OR: 3.54, 95% CI: 1.07-11.66, P = 0.04). Infection with a single HPV genotype or multiple HPV genotypes was significantly associated with at least one abnormal spermogram finding for all HPV oncogenic risk groups (OR: 3.93, 95% CI: 2.08-7.41, P < 0.001; and OR: 4.11, 95% CI: 1.58-10.68, P = 0.01, respectively). The association between sperm HPV carriage and the risk of infertility was statistically significant in a multivariate analysis (OR: 5.63, 95% CI: 3.16-10.01, P < 0.001) and after adjustment for the propensity score (OR: 6.10, 95% CI: 3.33-11.21, P < 0.001). Our results suggest that semen HPV carriage has an impact on male fertility. Sperm screening for HPV might be a useful addition to the work-up for male infertility.
Humans ; Male ; Adult ; Infertility, Male/epidemiology* ; Papillomavirus Infections/complications* ; Semen/virology* ; Semen Analysis ; Prevalence ; Papillomaviridae/genetics* ; Cohort Studies ; Spermatozoa/virology* ; Middle Aged ; France/epidemiology* ; Human Papillomavirus Viruses

Insulin-like growth factor 2 (IGF2) is a critical endocrine mediator implicated in male reproductive physiology. To investigate the correlation between IGF2 protein levels and various aspects of male infertility, specifically focusing on sperm quality, inflammation, and DNA damage, a cohort of 320 male participants was recruited from the Women's Hospital, Zhejiang University School of Medicine (Hangzhou, China) between 1 st January 2024 and 1 st March 2024. The relationship between IGF2 protein concentrations and sperm parameters was assessed, and Spearman correlation and linear regression analysis were employed to evaluate the independent associations between IGF2 protein levels and risk factors for infertility. Enzyme-linked immunosorbent assay (ELISA) was used to measure IGF2 protein levels in seminal plasma, alongside markers of inflammation (tumor necrosis factor-alpha [TNF-α] and interleukin-1β [IL-1β]). The relationship between seminal plasma IGF2 protein levels and DNA damage marker phosphorylated histone H2AX (γ-H2AX) was also explored. Our findings reveal that IGF2 protein expression decreased notably in patients with asthenospermia and teratospermia. Correlation analysis revealed nuanced associations between IGF2 protein levels and specific sperm parameters, and low IGF2 protein concentrations correlated with increased inflammation and DNA damage in sperm. The observed correlations between IGF2 protein levels and specific sperm parameters, along with its connection to inflammation and DNA damage, underscore the importance of IGF2 in the broader context of male reproductive health. These findings lay the groundwork for future research and potential therapeutic interventions targeting IGF2-related pathways to enhance male fertility.
Humans ; Male ; Insulin-Like Growth Factor II/metabolism* ; Infertility, Male/genetics* ; DNA Damage ; Adult ; Inflammation/metabolism* ; Spermatozoa/metabolism* ; Semen Analysis ; Semen/metabolism* ; Tumor Necrosis Factor-alpha/metabolism* ; Histones/metabolism* ; Interleukin-1beta/metabolism*

Male infertility can result from impaired sperm motility caused by multiple morphological abnormalities of the flagella (MMAF). Distinct projections encircling the central microtubules of the spermatozoal axoneme play pivotal roles in flagellar bending and spermatozoal movement. Mammalian sperm-associated antigen 17 ( SPAG17 ) encodes a conserved axonemal protein of cilia and flagella, forming part of the C1a projection of the central apparatus, with functions related to ciliary/flagellar motility, skeletal growth, and male fertility. This study investigated two novel homozygous SPAG17 mutations (M1: NM_206996.2, c.829+1G>T, p.Asp212_Glu276del; and M2: c.2120del, p.Leu707*) identified in four infertile patients from two consanguineous Pakistani families. These patients displayed the MMAF phenotype confirmed by Papanicolaou staining and scanning electron microscopy assays of spermatozoa. Quantitative real-time polymerase chain reaction (PCR) of patients' spermatozoa also revealed a significant decrease in SPAG17 mRNA expression, and immunofluorescence staining showed the absence of SPAG17 protein signals along the flagella. However, no apparent ciliary-related symptoms or skeletal malformations were observed in the chest X-rays of any of the patients. Transmission electron microscopy of axoneme cross-sections from the patients showed incomplete C1a projection and a higher frequency of missing microtubule doublets 1 and 9 compared with those from fertile controls. Immunofluorescence staining and Western blot analyses of spermatogenesis-associated protein 17 (SPATA17), a component of the C1a projection, and sperm-associated antigen 6 (SPAG6), a marker of the spring layer, revealed disrupted expression of both proteins in the patients' spermatozoa. Altogether, these findings demonstrated that SPAG17 maintains the integrity of spermatozoal flagellar axoneme, expanding the phenotypic spectrum of SPAG17 mutations in humans.
Humans ; Male ; Infertility, Male/pathology* ; Sperm Tail/ultrastructure* ; Homozygote ; Microtubule-Associated Proteins/genetics* ; Axoneme/genetics* ; Spermatozoa/ultrastructure* ; Adult ; Mutation ; Sperm Motility/genetics* ; Pedigree ; Microtubules ; Microtubule Proteins/genetics*