Molecular and functional characterization of a new potassium conductance in mouse ventricular fibroblasts
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- 作者：Najate Benamer ; Hamid Moha Ou Maati ; Sophie Demolombe ; Anne Cantereau ; Adriana Delwail ; Patrick Bois ; Jocelyn Bescond ; Jean-Franç ; ois Faivre
- 关键词：SUR2/Kir6.1 ; K-channel ; Cardiac fibroblasts ; IL-6 ; Sphingosine-1-phosphate
- 刊名：Journal of Molecular and Cellular Cardiology
- 出版年：2009
- 出版时间：April 2009
- 年：2009
- 卷：46
- 期：4
- 页码：508-517
- 全文大小：1110 K
文摘
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.