title: Speract, a sea urchin egg peptide that regulates sperm motility, also stimulates sperm mitochondrial metabolism.
abstract: Sea urchin sperm have only one mitochondrion, that in addition to being the main source of energy, may modulate intracellular Ca(2+) concentration ([Ca(2+)]i) to regulate their motility and possibly the acrosome reaction. Speract is a decapeptide from the outer jelly layer of the Strongylocentrotus purpuratus egg that upon binding to its receptor in the sperm, stimulates sperm motility, respiration and ion fluxes, among other physiological events. Altering the sea urchin sperm mitochondrial function with specific inhibitors of this organelle, increases [Ca(2+)]i in an external Ca(2+) concentration ([Ca(2+)]ext)-dependent manner (Ardón, et al., 2009. BBActa 1787: 15), suggesting that the mitochondrion is involved in sperm [Ca(2+)]i homeostasis. To further understand the interrelationship between the mitochondrion and the speract responses, we measured mitochondrial membrane potential (ΔΨ) and NADH levels. We found that the stimulation of sperm with speract depolarizes the mitochondrion and increases the levels of NADH. Surprisingly, these responses are independent of external Ca(2+) and are due to the increase in intracellular pH (pHi) induced by speract. Our findings indicate that speract, by regulating pHi, in addition to [Ca(2+)]i, may finely modulate mitochondrial metabolism to control motility and ensure that sperm reach the egg and fertilize it.
authors.affiliation: Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Apdo. Postal 510-3, Cuernavaca, Morelos C.P. 62210, México.
authors.forename: Juan
authors.initials: J
authors.lastname: García-Rincón
authors.affiliation: Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Apdo. Postal 510-3, Cuernavaca, Morelos C.P. 62210, México. Electronic address: darszon@ibt.unam.mx.
authors.forename: Alberto
authors.initials: A
authors.lastname: Darszon
authors.affiliation: Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Apdo. Postal 510-3, Cuernavaca, Morelos C.P. 62210, México. Electronic address: beltran@ibt.unam.mx.
authors.forename: Carmen
authors.initials: C
authors.lastname: Beltrán
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone / Q000494:pharmacology; D002334:Carnitine O-Palmitoyltransferase / Q000502:physiology; D006863:Hydrogen-Ion Concentration; D008297:Male; D008928:Mitochondria / Q000187:drug effects* / Q000378:metabolism; D009243:NAD / Q000032:analysis; D009842:Oligopeptides / Q000494:pharmacology*; D006180:Proton-Translocating ATPases / Q000378:metabolism; D013081:Sperm Motility / Q000187:drug effects*; D013094:Spermatozoa / Q000378:metabolism*
chemical_list: D009842:Oligopeptides; D009243:NAD; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone; C028364:speract; D002334:Carnitine O-Palmitoyltransferase; D006180:Proton-Translocating ATPases; D002118:Calcium
keywords: Carnitine palmitoyl transferase-I; Intracellular pH; Mitochondrial membrane potential; NADH; Speract; Sperm