title: Expression and differential cell distribution of low-threshold Ca(2+) channels in mammalian male germ cells and sperm.
abstract: Numerous sperm functions including the acrosome reaction (AR) are associated with Ca(2+) influx through voltage-gated Ca(2+) (Ca(V)) channels. Although the electrophysiological characterization of Ca(2+) currents in mature sperm has proven difficult, functional studies have revealed the presence of low-threshold (Ca(V)3) channels in spermatogenic cells. However, the molecular identity of these proteins remains undefined. Here, we identified by reverse transcription polymerase chain reaction the expression of Ca(V)3.3 mRNA in mouse male germ cells, an isoform not previously described in these cells. Immunoconfocal microscopy revealed the presence of the three Ca(V)3 channel isoforms in mouse spermatogenic cells. In mature mouse sperm only Ca(V)3.1 and Ca(V)3.2 were detected in the head, suggesting its participation in the AR. Ca(V)3.1 and Ca(V)3.3 were found in the principal and the midpiece of the flagella. All Ca(V)3 channels are also present in human sperm, but only to a minor extent in the head. These findings were corroborated by immunogold transmission electron microscopy. Tail localization of Ca(V)3 channels suggested they may participate in motility, however, mibefradil and gossypol concentrations that inhibit Ca(V)3 channels did not significantly affect human sperm motility. Only higher mibefradil doses that can block high-threshold (HVA) Ca(V) channels caused small but significant motility alterations. Antibodies to HVA channels detected Ca(V)1.3 and Ca(V)2.3 in human sperm flagella.
authors.affiliation: Department of Genetics of Development and Molecular Physiology, Institute of Biotechnology, UNAM, Avenida Universidad #2001, Col. Chamilpa, CP 62210, Cuernavaca, Mor., Mexico.
authors.forename: Claudia L
authors.initials: CL
authors.lastname: Treviño
authors.forename: Ricardo
authors.initials: R
authors.lastname: Felix
authors.forename: Laura E
authors.initials: LE
authors.lastname: Castellano
authors.forename: Carolina
authors.initials: C
authors.lastname: Gutiérrez
authors.forename: Delany
authors.initials: D
authors.lastname: Rodríguez
authors.forename: Judith
authors.initials: J
authors.lastname: Pacheco
authors.forename: Ignacio
authors.initials: I
authors.lastname: López-González
authors.forename: Juan Carlos
authors.initials: JC
authors.lastname: Gomora
authors.forename: Victor
authors.initials: V
authors.lastname: Tsutsumi
authors.forename: Arturo
authors.initials: A
authors.lastname: Hernández-Cruz
authors.forename: Tatiana
authors.initials: T
authors.lastname: Fiordelisio
authors.forename: Allison L
authors.initials: AL
authors.lastname: Scaling
authors.forename: Alberto
authors.initials: A
authors.lastname: Darszon
mesh_terms: D000818:Animals; D002121:Calcium Channel Blockers / Q000494:pharmacology; D020747:Calcium Channels, T-Type / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D019084:Fluorescent Antibody Technique, Indirect; D005854:Germ Cells / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D006801:Humans; D015640:Ion Channel Gating / Q000502:physiology; D008297:Male; D020748:Mibefradil / Q000494:pharmacology; D051379:Mice; D008815:Mice, Inbred Strains; D018408:Patch-Clamp Techniques; D016133:Polymerase Chain Reaction; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D013081:Sperm Motility / Q000187:drug effects; D013094:Spermatozoa / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure
chemical_list: D002121:Calcium Channel Blockers; D020747:Calcium Channels, T-Type; D020033:Protein Isoforms; D012333:RNA, Messenger; D020748:Mibefradil