title: Molecular and functional characterization of a novel sodium channel TipE-like auxiliary subunit from the American cockroach Periplaneta americana.
abstract: In Drosophila melanogaster, the functions of voltage-gated sodium (Nav) channels are modulated by TipE and its orthologs. Here, we describe a novel TipE homolog of the American cockroach, Periplaneta americana, called PaTipE. Like DmTipE, PaTipE mRNAs are ubiquitously expressed. Surprisingly, PaTipE mRNA was undetectable in neurosecretory cells identified as dorsal unpaired median neurons. Phylogenetic analysis placed this new sequence in TipE clade, indicating an independent evolution from a common ancestor. Contrary to previous reports, our data indicate that the auxiliary subunits of insect Nav channels are very distant from the mammalian BKCa auxiliary subunits. To decipher the functional roles of PaTipE, we characterized the gating properties of DmNav1-1 channels co-expressed with DmTipE or PaTipE, in Xenopus oocytes. Compared to DmTipE, PaTipE increased Na(+) currents by a 4.2-fold. The voltage-dependence of steady-state fast inactivation of DmNav1-1/PaTipE channels was shifted by 5.8 mV to more negative potentials than that of DmNav1-1/DmTipE channels. DmNav1-1/PaTipE channels recovered 3.2-fold slower from the fast-inactivated state than DmNav1-1/DmTipE channels. In conclusion, this study supports that the insect Nav auxiliary subunits share functional features with their mammalian counterparts, although structurally and phylogenetically distant.
authors.affiliation: Laboratoire Récepteurs et Canaux Ioniques Membranaires (RCIM), UPRES EA 2647/USC, INRA 1330, SFR QUASAV n° 4207, Université d'Angers, UFR Sciences, 2 boulevard Lavoisier, F-49045, Angers Cedex, France.
authors.forename: Céline M
authors.initials: CM
authors.lastname: Bourdin
authors.affiliation: Laboratoire de Biologie Neurovasculaire et Mitochondriale Intégrée, CNRS UMR 6214, INSERM U1083, UFR de Sciences Médicales, Université d'Angers, rue Haute de Reculée, F-49045, Angers Cedex, France; Institut de Génomique Fonctionnelle, UMR CNRS 5203, INSERM U661, Université de Montpellier, 141 rue de la Cardonille, F-34094, Montpellier Cedex 5, France.
authors.forename: Nathalie C
authors.initials: NC
authors.lastname: Guérineau
authors.affiliation: Laboratoire Récepteurs et Canaux Ioniques Membranaires (RCIM), UPRES EA 2647/USC, INRA 1330, SFR QUASAV n° 4207, Université d'Angers, UFR Sciences, 2 boulevard Lavoisier, F-49045, Angers Cedex, France; Laboratoire LIttoral ENvironnement et Sociétés (LIENSs), UMR 7266 CNRS Université de La Rochelle, Institut du Littoral et de l'Environnement, 2 rue Olympe de Gouges, F-17000, La Rochelle, France.
authors.forename: Laurence
authors.initials: L
authors.lastname: Murillo
authors.affiliation: Laboratoire Récepteurs et Canaux Ioniques Membranaires (RCIM), UPRES EA 2647/USC, INRA 1330, SFR QUASAV n° 4207, Université d'Angers, UFR Sciences, 2 boulevard Lavoisier, F-49045, Angers Cedex, France.
authors.forename: Sophie
authors.initials: S
authors.lastname: Quinchard
authors.affiliation: Department of Entomology, Genetics and Neuroscience Programs, Michigan State University, East Lansing, 106 CIPS, MI 48824, USA.
authors.forename: Ke
authors.initials: K
authors.lastname: Dong
authors.affiliation: Laboratoire de Biologie Neurovasculaire et Mitochondriale Intégrée, CNRS UMR 6214, INSERM U1083, UFR de Sciences Médicales, Université d'Angers, rue Haute de Reculée, F-49045, Angers Cedex, France. Electronic address: christian.legros@univ-angers.fr.
authors.forename: Christian
authors.initials: C
authors.lastname: Legros
mesh_terms: D000818:Animals; D055724:Electrophysiological Phenomena; D019476:Insect Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D015640:Ion Channel Gating; D008564:Membrane Potentials; D008565:Membrane Proteins / Q000737:chemistry / Q000378:metabolism*; D009865:Oocytes; D010526:Periplaneta / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D010802:Phylogeny; D015222:Sodium Channels / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D014981:Xenopus
chemical_list: D019476:Insect Proteins; D008565:Membrane Proteins; D015222:Sodium Channels
keywords: Auxiliary subunit; Insect voltage-gated sodium channel; Phylogenetic analysis; Two-electrode voltage-clamp technique; Xenopus oocyte