The presence of glutathione S-transferase in recombinant S100A9 alters its effect on human sperm function

Abstract

In a recent study, we isolated a protein from human oviductal secretion that could bind to spermatozoa[1]. This protein was identified through chromatography and tandem mass spectrometry as human S100A9 and was detected in human tubal epithelium and oviductal secretions. S100A9 belongs to the S100 protein family[2], which has been found in various body fluids and tissues, and plays a role in extracellular functions, such as the enhancement of neutrophil extravasation, induction of proinflammatory cytokine release, antimicrobial properties through divalent ion sequestration, and modulation of cellular proliferation, differentiation, and apoptosis, as well as acting as a chemotactic factor[3–4]. Because S100A9 is involved in various pathologies and the physiology of inflammation, research on S100A9 effects continues to grow rapidly. Recently, we have shown the presence of binding sites for S100A9 on human spermatozoa, and also found that S100A9 modulated certain sperm capacitation parameters in vitro, such as the induced acrosome reaction (AR)[1]. To continue our studies on sperm function parameters, the current study aimed to express and purify human recombinant S100A9 and to assess its effect on sperm capacitation parameters, specifically the AR.