The relationship between Sperm DNA fragmentation and differential expression of human sperm pro-apoptotic miR-15a/16 and anti-apoptotic BCL-2 gene

Apoptosis is one of the etiologies of sperm DNA damage. Considering the crucial role of micro RNAs in multiple pathophysiological processes, the possibility of controlling the apoptosis process in sperm DNA by micro-RNAs has been proposed. This study was performed with aim to investigate the relationship between sperm DNA fragmentation and expression level of miR-15a/16 and Anti-apoptotic BCL-2 gene.

This experimental study was performed on 30 patients referred to Tehran Taleghani Hospital infertility center in 2017. After 2-3 days of abstinence, semen was collected and analyzed based on WHO criteria. Sperm preparation was performed using density gradient centrifugation technique. To assess sperm DNA fragmentation, Sperm Chromatin Structure Assay was carried out and based on the level of DNA fragmentation, the samples were divided into two groups: DFI ≥30% and DFI<30%. The expression level of miR-15a/16 and BCL-2 was measured by quantitative Real Time -PCR. Data were analyzed using SPSS software (version 22) and independent t-test. The gene expression level was analyzed using REST 2009 software. P < 0.05 was considered statistically significant.

A significantnegative relationship was found between DFI ≥30% with motility and normal morphology of spermatozoa (p<0.05). The expression level of miR-15a/16 was significantly increased, and the expression level of BCL-2 gene was significantly decreased in patients with DFI ≥30% compared with DFI<30% (p<0.05).

Decreased expression of BCL2 following increased miR-16-1 leads to increased sperm DNA fragmentation. Assessment of miR-15a and apoptosis-related gene can be proposed as a diagnosing tool to ensure of sperm DNA integrity in male factor infertility cases in future.