NOX5 in human spermatozoa: expression, function, and regulation

• Published in: The Journal of biological chemistry Vol. 287; no. 12; pp. 9376 - 9388
• Main Authors: Musset, Boris, Clark, Robert A, DeCoursey, Thomas E, Petheo, Gabor L, Geiszt, Miklos, Chen, Yumin, Cornell, John E, Eddy, Carlton A, Brzyski, Robert G, El Jamali, Amina
• Format: Journal Article
• Language: English
• Published: United States American Society for Biochemistry and Molecular Biology 16-03-2012
• Subjects: Cell Biology; Cell Line; Gene Expression Regulation, Enzymologic; Humans; Male; Membrane Proteins - genetics; Membrane Proteins - metabolism; NADPH Oxidase 5; NADPH Oxidases - genetics; NADPH Oxidases - metabolism; Sperm Motility; Spermatozoa - cytology; Spermatozoa - enzymology; Spermatozoa - metabolism; Superoxides - metabolism
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M111.314955

Physiological and pathological processes in spermatozoa involve the production of reactive oxygen species (ROS), but the identity of the ROS-producing enzyme system(s) remains a matter of speculation. We provide the first evidence that NOX5 NADPH oxidase is expressed and functions in human spermatozoa. Immunofluorescence microscopy detected NOX5 protein in both the flagella/neck region and the acrosome. Functionally, spermatozoa exposed to calcium ionophore, phorbol ester, or H(2)O(2) exhibited superoxide anion production, which was blocked by addition of superoxide dismutase, a Ca(2+) chelator, or inhibitors of either flavoprotein oxidases (diphenylene iododonium) or NOX enzymes (GKT136901). Consistent with our previous overexpression studies, we found that H(2)O(2)-induced superoxide production by primary sperm cells was mediated by the non-receptor tyrosine kinase c-Abl. Moreover, the H(V)1 proton channel, which was recently implicated in spermatozoa motility, was required for optimal superoxide production by spermatozoa. Immunoprecipitation experiments suggested an interaction among NOX5, c-Abl, and H(V)1. H(2)O(2) treatment increased the proportion of motile sperm in a NOX5-dependent manner. Statistical analyses showed a pH-dependent correlation between superoxide production and enhanced sperm motility. Collectively, our findings show that NOX5 is a major source of ROS in human spermatozoa and indicate a role for NOX5-dependent ROS generation in human spermatozoa motility.