Cholesterol inhibits M-type K+ channels via protein kinase C-dependent phosphorylation in sympathetic neurons.
M-type (KCNQ) potassium channels play an important role in regulating the action potential firing in neurons. Here, we investigated the effect of cholesterol on M current in superior cervical ganglion (SCG) sympathetic neurons, using the patch clamp technique. M current was inhibited in a dose-dependent manner by cholesterol loading with a methyl-beta-cyclodextrin-cholesterol complex. This effect was prevented when membrane cholesterol level was restored by including empty methyl-beta-cyclodextrin in the pipette solution. Dialysis of cells with AMP-PNP instead of ATP prevented cholesterol action on M currents. Protein kinase C (PKC) inhibitor, calphostin C, abolished cholesterol-induced inhibition whereas the PKC activator, PDBu, mimicked the inhibition of M currents by cholesterol. The in vitro kinase assay showed that KCNQ2 subunits of M channel can be phosphorylated by PKC. A KCNQ2 mutant that is defective in phosphorylation by PKC failed to show current inhibition not only by PDBu but also by cholesterol. These results indicate that cholesterol-induced inhibition of M currents is mediated by PKC phosphorylation. The inhibition of M currents by PDBu and cholesterol was completely blocked by PIP(2) loading, indicating that the decrease in PIP(2)-channel interaction underlies M channel inhibition by PKC-mediated phosphorylation. We conclude that cholesterol specifically regulates M currents in SCG neurons via PKC activation.
Lee
Seul-Yi
SY
Department of Physiology, Sungkyunkwan University School of Medicine, Suwon 440-746, Korea.
Choi
Hyun-Kyung
HK
Kim
Seong-Tae
ST
Chung
Sungkwon
S
Park
Myoung Kyu
MK
Cho
Jung-Hwa
JH
Ho
Won-Kyung
WK
Cho
Hana
H
D000200:Action Potentials; D000255:Adenosine Triphosphate / Q000494:pharmacology; D000266:Adenylyl Imidodiphosphate / Q000494:pharmacology; D000818:Animals; D002478:Cells, Cultured; D002784:Cholesterol / Q000494:pharmacology*; D004594:Electrophysiology; D006801:Humans; D015640:Ion Channel Gating; D051658:KCNQ2 Potassium Channel / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D007668:Kidney / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D009474:Neurons / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D018408:Patch-Clamp Techniques; D010766:Phosphorylation / Q000187:drug effects; D011493:Protein Kinase C / Q000378:metabolism*; D051381:Rats; D017783:Superior Cervical Ganglion / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D047392:beta-Cyclodextrins / Q000494:pharmacology
D051658:KCNQ2 Potassium Channel; D047392:beta-Cyclodextrins; C108732:methyl-beta-cyclodextrin; D000266:Adenylyl Imidodiphosphate; D000255:Adenosine Triphosphate; D002784:Cholesterol; D011493:Protein Kinase C