Regulation of the voltage-gated K(+) channels KCNQ2/3 and KCNQ3/5 by ubiquitination. Novel role for Nedd4-2.
The muscarine-sensitive K(+) current (M-current) stabilizes the resting membrane potential in neurons, thus limiting neuronal excitability. The M-current is mediated by heteromeric channels consisting of KCNQ3 subunits in association with either KCNQ2 or KCNQ5 subunits. The role of KCNQ2/3/5 in the regulation of neuronal excitability is well established; however, little is known about the mechanisms that regulate the cell surface expression of these channels. Ubiquitination by the Nedd4/Nedd4-2 ubiquitin ligases is known to regulate a number of membrane ion channels and transporters. In this study, we investigated whether Nedd4/Nedd4-2 could regulate KCNQ2/3/5 channels. We found that the amplitude of the K(+) currents mediated by KCNQ2/3 and KCNQ3/5 were reduced by Nedd4-2 (but not Nedd4) in a Xenopus oocyte expression system. Deletion experiments showed that the C-terminal region of the KCNQ3 subunit is required for the Nedd4-2-mediated regulation of the heteromeric channels. Glutathione S-transferase fusion pulldowns and co-immunoprecipitations demonstrated a direct interaction between KCNQ2/3 and Nedd4-2. Furthermore, Nedd4-2 could ubiquitinate KCNQ2/3 in transfected cells. Taken together, these data suggest that Nedd4-2 is potentially an important regulator of M-current activity in the nervous system.
Ekberg
Jenny
J
School of Biomedical Sciences, University of Queensland, Brisbane, Queensland 4072, Australia.
Schuetz
Friderike
F
Boase
Natasha A
NA
Conroy
Sarah-Jane
SJ
Manning
Jantina
J
Kumar
Sharad
S
Poronnik
Philip
P
Adams
David J
DJ
D020816:Amino Acid Motifs; D000818:Animals; D015536:Down-Regulation; D056827:Endosomal Sorting Complexes Required for Transport; D005786:Gene Expression Regulation; D006801:Humans; D051656:KCNQ Potassium Channels / Q000502:physiology*; D051658:KCNQ2 Potassium Channel / Q000502:physiology*; D051659:KCNQ3 Potassium Channel / Q000502:physiology*; D008564:Membrane Potentials; D000075702:Nedd4 Ubiquitin Protein Ligases; D009865:Oocytes / Q000378:metabolism; D011485:Protein Binding; D051381:Rats; D025801:Ubiquitin / Q000737:chemistry; D044767:Ubiquitin-Protein Ligases / Q000502:physiology*; D029867:Xenopus Proteins; D014982:Xenopus laevis
D056827:Endosomal Sorting Complexes Required for Transport; D051656:KCNQ Potassium Channels; D051658:KCNQ2 Potassium Channel; D051659:KCNQ3 Potassium Channel; C496915:Kcnq2 protein, rat; C496918:Kcnq3 protein, rat; C501028:Kcnq5 protein, rat; D025801:Ubiquitin; D029867:Xenopus Proteins; C000618479:NEDD4L protein, rat; D000075702:Nedd4 Ubiquitin Protein Ligases; C000618482:Nedd4 protein, Xenopus; C000618483:Nedd4 protein, human; C000618484:Nedd4 protein, rat; C000618485:Nedd4L protein, human; C000618460:nedd4l protein, Xenopus; D044767:Ubiquitin-Protein Ligases