The NALCN ion channel is activated by M3 muscarinic receptors in a pancreatic beta-cell line.
A previously uncharacterized putative ion channel, NALCN (sodium leak channel, non-selective), has been recently shown to be responsible for the tetrodotoxin (TTX)-resistant sodium leak current implicated in the regulation of neuronal excitability. Here, we show that NALCN encodes a current that is activated by M3 muscarinic receptors (M3R) in a pancreatic beta-cell line. This current is primarily permeant to sodium ions, independent of intracellular calcium stores and G proteins but dependent on Src activation, and resistant to TTX. The current is recapitulated by co-expression of NALCN and M3R in human embryonic kidney-293 cells and in Xenopus oocytes. We also show that NALCN and M3R belong to the same protein complex, involving the intracellular I-II loop of NALCN and the intracellular i3 loop of M3R. Taken together, our data show the molecular basis of a muscarinic-activated inward sodium current that is independent of G-protein activation, and provide new insights into the properties of NALCN channels.
Swayne
Leigh Anne
LA
Institut de Génomique Fonctionnelle, Centre National de la Recherche Scientifique, Unité Mixte de Recherche 5203, Montpellier, France.
Mezghrani
Alexandre
A
Varrault
Annie
A
Chemin
Jean
J
Bertrand
Gyslaine
G
Dalle
Stephane
S
Bourinet
Emmanuel
E
Lory
Philippe
P
Miller
Richard J
RJ
Nargeot
Joel
J
Monteil
Arnaud
A
D015153:Blotting, Western; D002460:Cell Line; D004594:Electrophysiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D050417:Insulin-Secreting Cells / Q000187:drug effects / Q000378:metabolism*; D007473:Ion Channels / Q000235:genetics / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D011720:Pyrazoles / Q000494:pharmacology; D011743:Pyrimidines / Q000494:pharmacology; D034622:RNA Interference; D034741:RNA, Small Interfering; D043587:Receptor, Muscarinic M3 / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction
C108123:4-amino-5-(4-methylphenyl)-7-(tert-butyl)pyrazolo(3,4-d)pyrimidine; D004791:Enzyme Inhibitors; D007473:Ion Channels; D011720:Pyrazoles; D011743:Pyrimidines; D034741:RNA, Small Interfering; D043587:Receptor, Muscarinic M3