dGNaC1, a Gonad-Specific Amiloride-Sensitive Na+ Channel

J Biol Chem. 1998 Apr 17;273(16):9424-9. doi: 10.1074/jbc.273.16.9424.

Abstract

Amiloride-sensitive sodium channels have been implicated in reproductive and early developmental processes of several species. These include the fast block of polyspermy in Xenopus oocytes that follows the sperm binding to the egg or blastocoel expansion in mammalian embryo. We have now identified a gene called dGNaC1 that is specifically expressed in the gonads and early embryo in Drosophila melanogaster. The corresponding protein belongs to the superfamily of cationic channels blocked by amiloride that includes Caenorhabditis elegans degenerins, the Helix aspersa FMRF-amide ionotropic receptor (FaNaC), the mammalian epithelial Na+ channel (ENaC), and acid-sensing ionic channels (ASIC, DRASIC, and MDEG). Expression of dGNaC1 in Xenopus oocytes generates a constitutive current that does not discriminate between Na+ and Li+, but is selective for Na+ over K+. This current is blocked by amiloride (IC50 = 24 microM), benzamil (IC50 = 2 microM), and ethylisopropyl amiloride (IC50 = 49 microM). These properties are clearly different from those obtained after expression of the previously cloned members of this family, including ENaC and the human alphaENaC-like subunit, deltaNaC. Interestingly, the pharmacology of dGNaC1 is not very different from that found for the Na+ channel characterized in rabbit preimplantation embryos. We postulate that this channel may participate in gametogenesis and early embryonic development in Drosophila.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amiloride / analogs & derivatives
  • Amiloride / metabolism
  • Amiloride / pharmacology
  • Amino Acid Sequence
  • Animals
  • Caenorhabditis elegans
  • Cations / metabolism
  • Drosophila Proteins
  • Drosophila melanogaster
  • Embryo, Nonmammalian / physiology
  • Epithelial Sodium Channels
  • Female
  • Helix, Snails
  • Humans
  • Male
  • Membrane Potentials / physiology
  • Molecular Sequence Data
  • Multigene Family
  • Oocytes / physiology
  • Rabbits
  • Recombinant Proteins / biosynthesis
  • Recombinant Proteins / chemistry
  • Sequence Alignment
  • Sequence Homology, Amino Acid
  • Sex Characteristics
  • Sodium / metabolism
  • Sodium Channels / biosynthesis*
  • Sodium Channels / chemistry
  • Sodium Channels / genetics
  • Sodium Channels / physiology*
  • Sperm-Ovum Interactions
  • Testis / metabolism*
  • Xenopus laevis

Substances

  • Cations
  • Drosophila Proteins
  • Epithelial Sodium Channels
  • Recombinant Proteins
  • Sodium Channels
  • rpk protein, Drosophila
  • benzamil
  • Amiloride
  • Sodium
  • ethylisopropylamiloride

Associated data

  • GENBANK/Y16240