Proteomic analysis of sperm proteins in infertile men with high levels of reactive oxygen species

Oxidative stress is a significant risk factor for male infertility. A pro-oxidant testicular environment may alter the expression profile of functional sperm proteins and result in poor sperm quality. Patients and donors were divided into ROS (-) and ROS (+) groups. Using computational studies, and data mining of available literature on spermatozoa, oxidative stress and proteomics, we identified three core regulatory proteins angiotensin-converting enzyme (ACE), heat-shock protein (Hsp70) family A member 2 (HSPA2) and ribosomal protein subunit 27A (RPS27A) and seven interlink proteins NOS2, SUMO2, UBL4A, FBXO25, MAP3K3, APP and UBC. HSPA2 was validated by Western Blot, while the localisation of ACE, RPS27A, MAP3K3 and APP was identified by immunocytochemistry. The obtained results showed that HSPA2 was 1.2 (ROS+) and 2.1 (ROS-) fold downregulated in spermatozoa from patients with high levels of reactive oxygen species (ROS). ACE and APP were localised in the post-acrosomal region of spermatozoa, whereas RPS27A and MAP3K3 were localised either in the tail or sperm neck area. Our data show that these proteins may play a role in ROS-induced male infertility.