Key Laboratory for Major Obstetric Diseases of Guangdong Province, Third Affiliated Hospital of Guangzhou Medical University, Guangzhou 510150, China.
J Mol Med (Berl). 2012 Nov;90(11):1333-42. doi: 10.1007/s00109-012-0914-z. Epub 2012 May 31.
Defective spermatogenesis, which severely impairs male fertility, can be caused by excessive reactive oxygen species (ROS). Nuclear factor erythroid 2-related factor 2 (Nrf2) regulates transcription of genes encoding enzymes important for protection against ROS. In human seminal plasma and spermatozoa, superoxide dismutase isoenzymes (SOD) and glutathione S-transferases (GST) are key antioxidant enzymes. We hypothesized that decreased function of the Nrf2-antioxidant response element (ARE) pathway might predispose individuals to male infertility. In this study, we identified three functional single nucleotide polymorphisms (SNPs) in the Nrf2 promoter regions of 196 idiopathic asthenozoospermic patients, 140 idiopathic oligoasthenozoospermic patients, and 295 controls. We found that two of the Nrf2 SNPs (-617 G > T and -653 T > C) were associated with oligoasthenozoospermia (p = 0.001) and individuals with 617 TT and 653 TT genotypes had higher risk of oligoasthenozoospermia (p = 0.006 and p = 0.002). Four haplotypes of Nrf2 promoters were identified, and two of them (GCC and TCT) had different frequencies in oligoasthenozoospermic patients than in controls (p = 0.019 and p = 0.011). In vitro reporter assay indicated that oligoasthenozoospermia associated genotypes of Nrf2 had significantly decreased transcriptional capabilities. The GCC and TCT haplotypes both showed lower Nrf2 mRNA expression in spermatozoa than GCT. TCT also showed decreased levels of antioxidant gene GSTM1 and SOD2 mRNA. Analysis of total seminal SOD activity elucidated that oligoasthenozoospermic patients had less SOD activity than controls. This study is the first to demonstrate a strong association between functional polymorphisms in Nrf2 promoters with defective spermatogenesis in humans.
精子发生缺陷严重损害男性生育能力，其原因可能是活性氧（ROS）过多。核因子红细胞 2 相关因子 2（Nrf2）调节编码对抗 ROS 的酶的基因的转录。在人精液和精子中，超氧化物歧化酶同工酶（SOD）和谷胱甘肽 S-转移酶（GST）是关键的抗氧化酶。我们假设 Nrf2-抗氧化反应元件（ARE）通路功能下降可能使个体易患男性不育症。在这项研究中，我们在 196 名特发性少弱精子症患者、140 名特发性少弱精子症患者和 295 名对照者的 Nrf2 启动子区域中鉴定出三个功能单核苷酸多态性（SNP）。我们发现 Nrf2 的两个 SNP（-617 G>T 和 -653 T>C）与少弱精子症有关（p=0.001），并且 617 TT 和 653 TT 基因型个体发生少弱精子症的风险更高（p=0.006 和 p=0.002）。鉴定出 Nrf2 启动子的四个单倍型，其中两个（GCC 和 TCT）在少弱精子症患者中的频率与对照组不同（p=0.019 和 p=0.011）。体外报告基因检测表明，与少弱精子症相关的 Nrf2 基因型的转录能力显著降低。GCC 和 TCT 单倍型在精子中的 Nrf2 mRNA 表达均低于 GCT。TCT 还显示抗氧化基因 GSTM1 和 SOD2 mRNA 水平降低。总精液 SOD 活性分析表明，少弱精子症患者的 SOD 活性低于对照组。这项研究首次证明 Nrf2 启动子的功能多态性与人类精子发生缺陷之间存在很强的关联。
