Dual regulation of the ATP-sensitive potassium channel by activation of cGMP-dependent protein kinase.
Adenosine triphosphate (ATP)-sensitive potassium (K(ATP)) channels couple cellular metabolic status to membrane electrical activity. In this study, we performed patch-clamp recordings to investigate how cyclic guanosine monophosphate (cGMP)-dependent protein kinase (PKG) regulates the function of K(ATP) channels, using both transfected human SH-SY5Y neuroblastoma cells and embryonic kidney (HEK) 293 cells. In intact SH-SY5Y cells, the single-channel currents of Kir6.2/sulfonylurea receptor (SUR) 1 channels, a neuronal-type K(ATP) isoform, were enhanced by zaprinast, a cGMP-specific phosphodiesterase inhibitor; this enhancement was abolished by inhibition of PKG, suggesting a stimulatory role of cGMP/PKG signaling in regulating the function of neuronal K(ATP) channels. Similar effects of cGMP accumulation were confirmed in intact HEK293 cells expressing Kir6.2/SUR1 channels. In contrast, direct application of purified PKG suppressed rather than activated Kir6.2/SUR1 channels in excised, inside-out patches, while tetrameric Kir6.2LRKR368/369/370/371AAAA channels expressed without the SUR subunit were not modulated by zaprinast or purified PKG. Lastly, reconstitution of the soluble guanylyl cyclase/cGMP/PKG signaling pathway by generation of nitric oxide led to Kir6.2/SUR1 channel activation in both cell types. Taken together, here, we report novel findings that PKG exerts dual functional regulation of neuronal K(ATP) channels in a SUR subunit-dependent manner, which may provide new means of therapeutic intervention for manipulating neuronal excitability and/or survival.
Chai
Yongping
Y
Department of Physiology and Membrane Biology, University of California, Rm. 4144, Tupper Hall, One Shields Avenue, Davis, CA, 95616, USA.
Lin
Yu-Fung
YF
D000255:Adenosine Triphosphate / Q000378:metabolism*; D000818:Animals; D002227:Carbazoles / Q000378:metabolism; D002460:Cell Line; D017869:Cyclic GMP-Dependent Protein Kinases / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000378:metabolism; D006801:Humans; D054086:KATP Channels / Q000378:metabolism*; D009474:Neurons / Q000166:cytology / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism; D020030:Nitric Oxide Donors / Q000378:metabolism; D009603:Nitroso Compounds / Q000378:metabolism; D018408:Patch-Clamp Techniques; D024661:Potassium Channels, Inwardly Rectifying / Q000378:metabolism; D011688:Purinones / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology; D000099161:Kcnj11 Channel
D000255:Adenosine Triphosphate; D002227:Carbazoles; D017869:Cyclic GMP-Dependent Protein Kinases; D004791:Enzyme Inhibitors; D054086:KATP Channels; D009569:Nitric Oxide; D020030:Nitric Oxide Donors; D009603:Nitroso Compounds; D024661:Potassium Channels, Inwardly Rectifying; D011688:Purinones; D011993:Recombinant Fusion Proteins; D000099161:Kcnj11 Channel; C093285:NOC 18; C073601:KT 5823; C011145:zaprinast