Molecular and functional characterization of a new potassium conductance in mouse ventricular fibroblasts.
The present work is aimed at identifying and characterizing, at a molecular and functional level, new ionic conductances potentially involved in the excitation-secretion coupling and proliferation of cardiac ventricular fibroblasts. Among potassium channel transcripts which were screened by high-throughput real-time PCR, SUR2 and Kir6.1 mRNAs were found to be the most abundant in ventricular fibroblasts. The corresponding proteins were not detected by western blot following 5 days of cell culture, but had appeared at 7 days, increasing with extended cell culture duration as the fibroblasts differentiated into myofibroblasts. Using the inside-out configuration of the patch-clamp technique, single potassium channels could be recorded. These had properties similar to those reported for SUR2/Kir6.1 channels, i.e. activation by pinacidil, inhibition by glibenclamide and activation by intracellular UDP. As already reported for this molecular signature, they were insensitive to intracellular ATP. In the whole-cell configuration, these channels have been shown to be responsible for a glibenclamide-sensitive macroscopic potassium current which can be activated not only by pinacidil, but also by nanomolar concentrations of the sphingolipid sphingosine-1-phosphate (S1P). The activation of this current resulted in an increase in cell proliferation and a decrease in IL-6 secretion, suggesting it has a functional role in situations where S1P increases. Overall, this work demonstrates for the first time that SUR2/Kir6.1 channels represent a significant potassium conductance in ventricular fibroblasts which may be activated in physio-pathological conditions and which may impact on fibroblast proliferation and function.
Benamer
Najate
N
Institut de Physiologie et Biologie Cellulaires, CNRS UMR 6187, Université de Poitiers, France.
Moha Ou Maati
Hamid
H
Demolombe
Sophie
S
Cantereau
Anne
A
Delwail
Adriana
A
Bois
Patrick
P
Bescond
Jocelyn
J
Faivre
Jean-François
JF
D018528:ATP-Binding Cassette Transporters / Q000235:genetics / Q000378:metabolism*; D000199:Actins / Q000378:metabolism; D000818:Animals; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000187:drug effects; D005905:Glyburide / Q000494:pharmacology; D006352:Heart Ventricles / Q000166:cytology* / Q000378:metabolism; D015850:Interleukin-6 / Q000378:metabolism; D015640:Ion Channel Gating / Q000187:drug effects; D054086:KATP Channels; D008246:Lysophospholipids / Q000494:pharmacology; D051379:Mice; D020110:Pinacidil / Q000494:pharmacology; D024661:Potassium Channels, Inwardly Rectifying / Q000235:genetics / Q000378:metabolism*; D021122:Protein Subunits / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011955:Receptors, Drug / Q000235:genetics / Q000378:metabolism*; D013110:Sphingosine / Q000031:analogs & derivatives / Q000494:pharmacology; D064233:Sulfonylurea Receptors
D018528:ATP-Binding Cassette Transporters; D000199:Actins; D015850:Interleukin-6; D054086:KATP Channels; D008246:Lysophospholipids; D024661:Potassium Channels, Inwardly Rectifying; D021122:Protein Subunits; D012333:RNA, Messenger; D011955:Receptors, Drug; D064233:Sulfonylurea Receptors; C092520:uK-ATP-1 potassium channel; C060506:sphingosine 1-phosphate; D020110:Pinacidil; D013110:Sphingosine; D005905:Glyburide