Effects of 4-Hydroxy-2-Nonenal, a Marker of Oxidative Stress, on Spermatogenesis and Expression of p53 Protein in Male Infertility

Abstract

Oxidative stress is involved in male infertility. However, little is known about how it impairs spermatogenesis. We investigated the presence of oxidative stress in human testes by studying the generation of 4-hydroxy-2-nonenal modified proteins and expressions of proliferating cell nuclear antigen and p53. A total of 47 testicular biopsies from patients with varicocele, obstructive azoospermia and idiopathic infertility were included. Localization and generation of 4-hydroxy-2-nonenal modified proteins were determined by immunohistochemistry and Western blotting. The expressions of proliferating cell nuclear antigen and p53 were assessed by Western blotting. The interaction between 4-hydroxy-2-nonenal modified proteins and p53 was examined by immunoprecipitation. Data were compared to clinicopathological parameters. 4-Hydroxy-2-nonenal modified proteins were strongly positive in spermatogonia, primary spermatocytes and Sertoli's cells, and generation was inversely correlated with expression of proliferating cell nuclear antigen. The expression of p53 was increased in testes with varicocele (p <0.01) and obstructive azoospermia (p <0.05), and there was a positive or inverse correlation with 4-hydroxy-2-nonenal modified proteins and proliferating cell nuclear antigen. Immunoprecipitated p53 was detected by anti-4-hydroxy-2-nonenal modified protein antibody. 4-Hydroxy-2-nonenal impairs the proliferation of germ cells through the up-regulation of p53 protein, especially in testes with varicocele. Modification by 4-hydroxy-2-nonenal might alter normal function and stabilization of p53 protein.