SPATA16 promoter hypermethylation and downregulation in male infertility

Spermatogenesis associated 16 (SPATA16) gene plays an important role in acrosome formation. In this study, we analysed SPATA16 promoter methylation in 29 oligozoospermic infertile and 16 normozoospermic fertile sperm samples and in testicular biopsy from 16 non-obstructive azoospermic and 2 obstructive azoospermic individuals. Next, we analysed SPATA16 level in sperm from 8 oligozoospermic infertile, 6 normozoospermic fertile, 9 IVF failed normozoospermic and 10 IVF successful normozoospermic samples by immunoblotting. This was followed by the analysis of SPATA16 expression in testicular biopsy from azoospermic individuals (n = 8) in comparison to normozoospermic individuals (n = 2). Oligozoospermic infertile sperm samples showed significantly higher methylation in the SPATA16 promoter region. Similarly, testicular biopsy from azoospermic men also showed significantly higher level of DNA methylation. Sub-group analysis of infertile sperm and testicular biopsy samples showed a direct correlation between DNA methylation and the degree of spermatogenic impairment. Oligozoospermic infertile samples and IVF failed samples showed reduced SPATA16 expression in comparison to normozoospermic fertile and IVF successful samples, respectively. Human biopsy analysis showed a significant decrease in SPATA16 expression in hypospermatogenesis, maturation arrest and Sertoli cell only syndrome. In conclusion, hypermethylation in SPATA16 promoter shows a highly significant correlation with infertility, which is consistent with its down-regulation in infertility.