NOX5 in human spermatozoa: expression, function, and regulation

J Biol Chem. 2012 Mar 16;287(12):9376-88. doi: 10.1074/jbc.M111.314955. Epub 2012 Jan 30.

Abstract

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.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • 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*

Substances

  • Membrane Proteins
  • Superoxides
  • NADPH Oxidase 5
  • NADPH Oxidases
  • NOX5 protein, human