REDOX PROTEOMIC ANALYSIS of HUMAN SPERMATOZOA

Abstract

Infertility is a global issue affecting nearly 15 % of all couples within the reproductive age where 50% of infertility cases are contributed by the male factors. The majority of male infertility cases remains unexplained and is considered as idiopathic infertility. However, 30-80% cases of idiopathic infertility are suggested to be due to oxidative stress. Oxidative stress is a cellular state where reactive oxygen species (ROS) generation predominates cellular antioxidant defence. At higher levels ROS causes lipid peroxidation, DNA damage, alteration in protein function and apoptosis. Though always attributed as a noxious agent ROS being highly reactive, autocatalytic, and nonspecific, qualify to be good signalling molecules. ROS are essential for normal sperm physiology as redox regulated events are crucial in reproductive processes such as spermatogenesis and steroidogenesis in the testis as well as regulation of sperm function in post-testicular stages including motility, capacitation, sperm-zona interaction, acrosome reaction and sperm-oocyte fusion. Since spermatozoa are essentially silent in terms of transcription and translation, yet the sperm proteome is dynamic and its profile varies from its site of production in the testes through epididymal maturation until the fertilization events. Therefore, in the present investigation the sperm proteome in general and with respect to ROS in particular is largely targeted for the discovery of biomarkers to address underlying mechanism(s) of idiopathic males. The high throughput shotgun proteomics by labelfree liquid chromatography tandem mass spectroscopy (LC/MSMS) followed by bioinformatics identification of nodal proteins and their validation by western blotting along with differential immune-detection of oxidatively modified proteins in the spermatozoa of idiopathic infertile men was used to prove the hypothesis. newlineIt is evidenced from a number of published literature that redox active environmental toxicants are a major source of ROS and their presence in u