Analysis of sperm nuclear protein gene polymorphisms and DNA integrity in infertile men

Abstract

Sperm nuclear proteins, the protamines (PRM) and transition nuclear proteins (TNP) play a crucial role in sperm nuclear condensation. The compact packaging of sperm DNA by protamines maintains sperm genome integrity, which is prerequisite for normal sperm function. However the effect of nucleotide variations in PRM and TNP genes on sperm DNA integrity and male fertility is not clear. This case-control study was planned to analyze PRM and TNP gene nucleotide variations and sperm DNA integrity in 100 oligozoospermic infertile men and 100 fertile controls. Protamine and TNP genes were amplified by polymerase chain reaction and sequenced. Flow cytometry-sperm chromatin structure assay (FC-SCSA) was applied to measure the DNA fragmentation index (DFI) in sperm. Semen analysis was performed as per WHO [1999] guidelines with slight modification. In total, 7 nucleotide variations including two novel changes, a non-synonymous mutation in the exon-2 of PRM2 gene (c.443C > A) and a novel insertion of T (c.396_397InsT) at the 3' UTR region of TNP1 were detected. None of the nucleotide changes were observed with increased risk frequency in the oligozoospermic infertile men compared to the controls. Though overall DFI was significantly (p < 0.0001) higher in infertile men compared to controls (36.31 ± 7.25 vs. 26.49 ± 2.78) irrespective of nucleotide changes, no such difference was observed between 100 infertile men or pooled population of 200 with and without mutations. However it was observed that two cases with novel nucleotide changes PRM2 c.443C > A and TNP1 c.396_397InsT had higher DFI value of 34.82% and 43.85%, respectively. In conclusion, our pilot study for the first time in the Indian population revealed two rare novel mutations in sperm nuclear protein genes that are perhaps associated with higher sperm DNA fragmentation.

The effect of vitamin C on the gene expression profile of sperm protamines in the male partners of couples with recurrent pregnancy loss: A randomized clinical trial

“…In human sperm cells, 85% of the histones are replaced by protamine, allowing sufficient chromatin density to be achieved [7] and reducing the availability of sites that could be harmed by DNA-damaging agents [8]. Evidence indicates that a high proportion of histones in sperm relative to protamine causes defective chromatin compaction, subsequently leading to an increased risk of male infertility [9]. A proper ratio of protamine P1 to protamine P2 (normal, 0.8-1.2) is required for normal sperm function [10].…”

Genetic association study ofRNF8andBRDTvariants with non-obstructive azoospermia in the Chinese Han population

“…Alternatively, the minor C allele of SNP rs2284922 is located in a conserved F-SNP (a web-based SNP analysis tool) sequence [Lee and Shatkay 2008]. A minor alteration of the conserved sequences could induce a phenotypic change [Venkatesh et al 2011;Westerveld et al 2004]. One must also consider that the variation of the SNP rs195434 in the 3 0 -UTR region might affect translational progress, as translational control in the 3 0 -untranslated region (3 0 -UTR) could influence protein level [de Moor et al 2005].…”

Association of single nucleotide polymorphisms in the USF1, GTF2A1L and OR2W3 genes with non-obstructive azoospermia in the Chinese population

“…During proliferation, low level of USF1 expression in Sertoli cells limited the USF recruitment to E-box motifs within the promoter regions of Nr5a1 and Shbg genes which were vital for Sertoli cell differentiation [12], therefore the progress of the spermatogenesis might be repressed as a result of the aberrant differentiation of Sertoli cells, NOA would take place; 2) We found that the minor allele C of the SNP rs2284922 located in the conserved region of USF1 gene by means of the F-SNP database [25], a web-based SNP analysis tool. Such an alteration in the gene might lead to an abnormality of gene expression or weaken the stability of gene [26]; 3) the variation of rs2516838 might relate to the initiation of spermiogenesis. There were studies revealing that the rs2516838 polymorphism of USF1 was associated with methylation of genomic DNA [27,28].…”