title: Mitochondrial aquaporin-8-mediated hydrogen peroxide transport is essential for teleost spermatozoon motility.
abstract: Reactive oxygen species (ROS), particularly hydrogen peroxide (H2O2), cause oxidative cell damage and inhibit sperm function. In most oviparous fishes that spawn in seawater (SW), spermatozoa may be exposed to harmful ROS loads associated with the hyperosmotic stress of axonemal activation and ATP synthesis from mitochondrial oxidative phosphorylation. However, it is not known how marine spermatozoa can cope with the increased ROS levels to maintain flagellar motility. Here, we show that a marine teleost orthologue of human aquaporin-8, termed Aqp8b, is rapidly phosphorylated and inserted into the inner mitochondrial membrane of SW-activated spermatozoa, where it facilitates H2O2 efflux from this compartment. When Aqp8b intracellular trafficking and mitochondrial channel activity are immunologically blocked in activated spermatozoa, ROS levels accumulate in the mitochondria leading to mitochondrial membrane depolarisation, the reduction of ATP production, and the progressive arrest of sperm motility. However, the decreased sperm vitality underlying Aqp8b loss of function is fully reversed in the presence of a mitochondria-targeted antioxidant. These findings reveal a previously unknown detoxification mechanism in spermatozoa under hypertonic conditions, whereby mitochondrial Aqp8b-mediated H2O2 efflux permits fuel production and the maintenance of flagellar motility.
authors.affiliation: 1] Institut de Recerca i Tecnologia Agroalimentàries (IRTA)-Institut de Ciències del Mar, Consejo Superior de Investigaciones Científicas (CSIC), 08003 Barcelona, Spain [2] Department of Biology, Bergen High Technology Centre, University of Bergen, 5020 Bergen, Norway.
authors.forename: François
authors.initials: F
authors.lastname: Chauvigné
authors.affiliation: Institut de Recerca i Tecnologia Agroalimentàries (IRTA)-Institut de Ciències del Mar, Consejo Superior de Investigaciones Científicas (CSIC), 08003 Barcelona, Spain.
authors.forename: Mónica
authors.initials: M
authors.lastname: Boj
authors.affiliation: 1] Department of Biology, Bergen High Technology Centre, University of Bergen, 5020 Bergen, Norway [2] Institute of Marine Research, Nordnes, 5817 Bergen, Norway.
authors.forename: Roderick Nigel
authors.initials: RN
authors.lastname: Finn
authors.affiliation: Institut de Recerca i Tecnologia Agroalimentàries (IRTA)-Institut de Ciències del Mar, Consejo Superior de Investigaciones Científicas (CSIC), 08003 Barcelona, Spain.
authors.forename: Joan
authors.initials: J
authors.lastname: Cerdà
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D000906:Antibodies / Q000494:pharmacology; D000975:Antioxidants / Q000494:pharmacology; D020346:Aquaporins / Q000378:metabolism*; D001692:Biological Transport / Q000187:drug effects; D015153:Blotting, Western; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D003497:Cyclic N-Oxides / Q000494:pharmacology; D005260:Female; D006861:Hydrogen Peroxide / Q000378:metabolism*; D008297:Male; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism*; D009865:Oocytes / Q000187:drug effects / Q000378:metabolism; D010085:Oxidative Phosphorylation / Q000187:drug effects; D010766:Phosphorylation / Q000187:drug effects; D021541:Sea Bream / Q000378:metabolism*; D012623:Seawater; D013081:Sperm Motility / Q000187:drug effects; D013094:Spermatozoa / Q000187:drug effects / Q000378:metabolism; D014982:Xenopus laevis
chemical_list: D000906:Antibodies; D000975:Antioxidants; D020346:Aquaporins; D003497:Cyclic N-Oxides; C108330:aquaporin 8; D000255:Adenosine Triphosphate; D006861:Hydrogen Peroxide; C003959:TEMPO