Ceramide inhibits the potassium channel Kv1.3 by the formation of membrane platforms.
Previous studies suggested a central role of sphingomyelin- and cholesterol-enriched membrane rafts in the initiation of signaling via many receptors. Here, we investigated the role of membrane rafts for the function of the voltage-gated potassium channel Kv1.3. We demonstrate that Kv1.3 localizes in the cell membrane to pre-existing small, sphingolipid- and cholesterol-enriched membrane rafts. Transformation of these small rafts to large ceramide-enriched membrane platforms was achieved by stimulation of the endogenous acid sphingomyelinase, addition of exogenous sphingomyelinase or treatment of the cells with C(16)-ceramide and resulted in clustering of Kv1.3 within ceramide-enriched membrane platforms and inhibition of the channel's activity. Likewise, disruption of pre-existing small rafts inhibited Kv1.3 activity. This indicates that intact small membrane rafts are required for Kv1.3 activity and an alteration of the lipid environment of rafts inhibits Kv1.3. These data, thus, may suggest a novel concept for the regulation of ion channels by the cell membrane composition.
Bock
Jürgen
J
Department of Molecular Biology, University of Essen, Hufelandstrasse 55, Essen 45122, Germany.
Szabó
Ildikò
I
Gamper
Nikita
N
Adams
Constantin
C
Gulbins
Erich
E
D002518:Ceramides / Q000494:pharmacology*; D004553:Electric Conductivity; D006801:Humans; D019169:Jurkat Cells; D051664:Kv1.3 Potassium Channel; D008055:Lipids / Q000032:analysis; D021962:Membrane Microdomains / Q000737:chemistry / Q000502:physiology*; D008856:Microscopy, Fluorescence; D018408:Patch-Clamp Techniques; D026902:Potassium Channel Blockers / Q000494:pharmacology*; D015221:Potassium Channels / Q000032:analysis / Q000502:physiology*; D024642:Potassium Channels, Voltage-Gated; D013108:Sphingomyelin Phosphodiesterase / Q000494:pharmacology; D019014:fas Receptor / Q000032:analysis
D002518:Ceramides; C496973:KCNA3 protein, human; D051664:Kv1.3 Potassium Channel; D008055:Lipids; D026902:Potassium Channel Blockers; D015221:Potassium Channels; D024642:Potassium Channels, Voltage-Gated; D019014:fas Receptor; C097760:N-palmitoylsphingosine; D013108:Sphingomyelin Phosphodiesterase