The sequential generation of large-scale DNA fragments followed by internucleosomal chromatin fragmentation is a biochemical hallmark of apoptosis. One of the nucleases primarily responsible for genomic DNA fragmentation during apoptosis is called DNA Fragmentation Factor 40 (DFF40) or Caspase-activated DNase (CAD). DFF40/CAD is a magnesium-dependent endonuclease specific for double stranded DNA that generates double strand breaks with 3'-hydroxyl ends. DFF40/CAD is activated by caspase-3 that cuts the nuclease's inhibitor DFF45/ICAD. The nuclease preferentially attacks chromatin in the internucleosomal linker DNA. However, the nuclease hypersensitive sites can be detected and DFF40/CAD is potentially involved in large-scale DNA fragmentation as well. DFF40/CAD-mediated DNA fragmentation triggers chromatin condensation that is another hallmark of apoptosis.
The present study aimed to investigate the relationship between semen quality parameters and DNA integrity, and determine whether semen quality parameters could serve as a reliable biomarker for monitoring sperm DNA damage. Conventional semen parameters from a total of 202 male human subjects were analyzed. DNA fragmentation and 8-oxo-7,8-dihydro-2′- deoxyguanosine (8-oxoGuo) were used to assess sperm DNA integrity. DNA fragmentation was analyzed by the terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay and sperm chromatin structure assay (SCSA), while 8-oxodGuo was quantified by the liquid chromatography/tandem mass spectrometry (LC-MS/MS) coupled with an on-line solid phase system. The levels of 8-oxodGuo levels in sperm were related to the percentages of DNA fragmentation measured by both the TUNEL and SCSA (r = 0.22, p = 0.048; r = 0.12, p = 0.039). Sperm vitality, motility and morphology from all of the participants exhibited a weak correlation with the levels of 8-oxodGuo and the percentages of DNA fragmentation. Semen quality parameters may be independent of the formation of DNA fragmentation and oxidative adducts in sperm. Semen quality parameters may be insufficient to monitor sperm DNA fragmentation and oxidative damage. DNA damage in sperm is recommended to be included in routine measurements.
JavaScript is turned off in your web browser. Turn it on to take full advantage of this site, then refresh the page.