Lysosome mediated Kir2.1 breakdown directly influences inward rectifier current density.
The inward rectifier current generated by Kir2.1 ion channel proteins is primarily responsible for the stable resting membrane potential in various excitable cell types, like neurons and myocytes. Tight regulation of Kir2.1 functioning prevents premature action potential formation and ensures optimal repolarization times. While Kir2.1 forward trafficking has been addressed in a number of studies, its degradation pathways are thus far unknown. Using three different lysosomal inhibitors, NH(4)Cl, chloroquine and leupeptin, we now demonstrate involvement of the lysosomal degradation pathway in Kir2.1 breakdown. Upon application of the inhibitors, increased steady state protein levels are detectable within few hours coinciding with intracellular granular Kir2.1 accumulation. Treatment for 24h with either chloroquine or leupeptin results in increased plasmamembrane originating inward rectifier current densities, while current-voltage characteristics remain unaltered. We conclude that the lysosomal degradation pathway contributes to Kir2.1 mediated inward rectifier current regulation.
Jansen
John A
JA
Department of Medical Physiology, Division Heart & Lungs, University Medical Center Utrecht, Yalelaan 50, 3584 CM Utrecht, The Netherlands.
de Boer
Teun P
TP
Wolswinkel
Rianne
R
van Veen
Toon A B
TA
Vos
Marc A
MA
van Rijen
Harold V M
HV
van der Heyden
Marcel A G
MA
D000643:Ammonium Chloride / Q000494:pharmacology; D000818:Animals; D002478:Cells, Cultured; D002738:Chloroquine / Q000494:pharmacology; D005455:Fluorescent Antibody Technique; D006801:Humans; D007424:Intracellular Fluid / Q000187:drug effects / Q000378:metabolism; D007976:Leupeptins / Q000494:pharmacology; D008247:Lysosomes / Q000187:drug effects / Q000378:metabolism*; D051379:Mice; D018408:Patch-Clamp Techniques; D024661:Potassium Channels, Inwardly Rectifying / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D013997:Time Factors
C489457:KCNJ2 protein, human; D007976:Leupeptins; D024661:Potassium Channels, Inwardly Rectifying; D000643:Ammonium Chloride; D002738:Chloroquine; C032854:leupeptin