The marker of alkyl DNA base damage, N7-methylguanine, is associated with semen quality in men

DNA damage in prepared semen is negatively associated with semen quality and fertilisation rate in assisted reproduction technology (ART) treatment

Sperm DNA contains strand breaks and base damage that can potentially affect reproductive health. This study aims to determine to what extent sperm DNA integrity and alkylation is associated with semen quality and assisted reproduction technology (ART) treatment outcomes, in particular fertilisation and cleavage rates. Male partners of couples attending for infertility treatment were recruited. DNA integrity (% tail DNA, sperm with either low (LDD) or high (HDD) damage levels) was measured by a neutral Comet assay and N7-methyldeoxyguanosine (N7-MedG) DNA levels by an immunoslotblot in sperm prepared by density gradient centrifugation. Associations between DNA damage, semen quality and ART treatment outcomes were assessed. N7-MedG levels were lower and the proportion of LDD sperm higher in prepared than in neat sperm samples. The proportion of HDD sperm and % tail DNA were significantly negatively associated and the proportion of LDD sperm positively associated with semen quality. Fertilisation, but not cleavage, rate nor live birth, was significantly negatively associated with N7-MedG levels, the proportion of HDD sperm and % tail DNA and was positively associated with the proportion of LDD sperm. These results confirm that DNA damage, even in prepared sperm, is associated with adverse semen quality and suggest that sperm DNA damage affects the early stages of embryo formation.

Quantification of Intracellular DNA-Protein Cross-Links with N7-Methyl-2'-Deoxyguanosine and Their Contribution to Cytotoxicity

The major product of DNA-methylating agents, N7-methyl-2'-deoxyguanosine (MdG), is a persistent lesion in vivo, but it is not believed to have a large direct physiological impact. However, MdG reacts with histone proteins to form reversible DNA-protein cross-links (DPCMdG), a family of DNA lesions that can significantly threaten cell survival. In this paper, we developed a tandem mass spectrometry method for quantifying the amounts of MdG and DPCMdG in nuclear DNA by taking advantage of their chemical lability and the concurrent release of N7-methylguanine. Using this method, we determined that DPCMdG is formed in less than 1% yield based upon the levels of MdG in methyl methanesulfonate (MMS)-treated HeLa cells. Despite its low chemical yield, DPCMdG contributes to MMS cytotoxicity. Consequently, cells that lack efficient DPC repair by the DPC protease SPRTN are hypersensitive to MMS. This investigation shows that the downstream chemical and biochemical effects of initially formed DNA damage can have significant biological consequences. With respect to MdG formation, the initial DNA lesion is only the beginning.

Advanced molecular approaches in male infertility diagnosis

In the recent years a special attention has been given to a major health concern namely to male infertility, defined as the inability to conceive after 12 months of regular unprotected sexual intercourse, taken into account the statistics that highlight that sperm counts have dropped by 50-60% in recent decades. According to the WHO, infertility affects approximately 9% of couples globally, and the male factor is believed to be present in roughly 50% of cases, with exclusive responsibility in 30%. The aim of this manuscript is to present an evidence-based approach for diagnosing male infertility that includes finding new solutions for diagnosis and critical outcomes, retrieving up-to-date studies and existing guidelines. The diverse factors that induce male infertility generated in a vast amount of data that needed to be analysed by a clinician before a decision could be made for each individual. Modern medicine faces numerous obstacles as a result of the massive amount of data generated by the molecular biology discipline. To address complex clinical problems, vast data must be collected, analysed, and used, which can be very challenging. The use of artificial intelligence (AI) methods to create a decision support system can help predict the diagnosis and guide treatment for infertile men, based on analysis of different data as environmental and lifestyle, clinical (sperm count, morphology, hormone testing, karyotype, etc.) and "omics" bigdata. Ultimately, the development of AI algorithms will assist clinicians in formulating diagnosis, making treatment decisions, and predicting outcomes for assisted reproduction techniques.

Epigenetics of Male Infertility: The Role of DNA Methylation

In recent years, a number of studies focused on the role of epigenetics, including DNA methylation, in spermatogenesis and male infertility. We aimed to provide an overview of the knowledge concerning the gene and genome methylation and its regulation during spermatogenesis, specifically in the context of male infertility etiopathogenesis. Overall, the findings support the hypothesis that sperm DNA methylation is associated with sperm alterations and infertility. Several genes have been found to be differentially methylated in relation to impaired spermatogenesis and/or reproductive dysfunction. Particularly, DNA methylation defects of MEST and H19 within imprinted genes and MTHFR within non-imprinted genes have been repeatedly linked with male infertility. A deep knowledge of sperm DNA methylation status in association with reduced reproductive potential could improve the development of novel diagnostic tools for this disease. Further studies are needed to better elucidate the mechanisms affecting methylation in sperm and their impact on male infertility.