APE1/Ref-1 promotes the effect of angiotensin II on Ca2+ -activated K+ channel in human endothelial cells via suppression of NADPH oxidase.
The effects of angiotensin II (Ang II) on whole-cell large conductance Ca(2+)-activated K(+) (BK(Ca)) currents was investigated in control and Apurinic/apyrimidinic endonuclease1/redox factor 1 (APE1/Ref-1)-overexpressing human umbilical vein endothelial cells (HUVECs). Ang II blocked the BK(Ca) current in a dose-dependent fashion, and this inhibition was greater in APE1/Ref-1-overexpressing HUVECs than in control HUVECs (half-inhibition values of 102.81+/-9.54 nM and 11.34+/-0.39 nM in control and APE1/Ref-1-overexpressing HUVECs, respectively). Pretreatment with the NADPH oxidase inhibitor diphenyleneiodonium (DPI) or knock down of NADPH oxidase (p22 phox) using siRNA increased the inhibitory effect of Ang II on the BK(Ca) currents, similar to the effect of APE1/Ref-1 overexpression. In addition, application of Ang II increased the superoxide and hydrogen peroxide levels in the control HUVECs but not in APE1/Ref-1-overexpressing HUVECs. Furthermore, direct application of hydrogen peroxide increased BK(Ca) channel activity. Finally, the inhibitory effect of Ang II on the BK(Ca) current was blocked by an antagonist of the Ang II type 1 (AT(1)) receptor in both control and APE1/Ref-1-overexpressing HUVECs. From these results, we conclude that the inhibitory effect of Ang II on BK(Ca) channel function is NADPH oxidase-dependent and may be promoted by APE1/Ref-1.
Park
Won Sun
WS
National Research Laboratory for Mitochondrial Signaling Laboratory, FIRST Mitochondria Research Group, Department of Physiology and Biophysics, College of Medicine, Medical Research Center, Inje University, Busan, Korea.
Ko
Eun A
EA
Jung
In Duk
ID
Son
Youn Kyoung
YK
Kim
Hyoung Kyu
HK
Kim
Nari
N
Park
So Youn
SY
Hong
Ki Whan
KW
Park
Yeong-Min
YM
Choi
Tae-Hoon
TH
Han
Jin
J
D000256:Adenoviridae / Q000235:genetics; D000804:Angiotensin II / Q000494:pharmacology*; D015153:Blotting, Western; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D042783:Endothelial Cells / Q000187:drug effects / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005822:Genetic Vectors; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism; D007473:Ion Channels / Q000187:drug effects / Q000378:metabolism; D018613:Microscopy, Confocal; D032389:Myocytes, Smooth Muscle / Q000187:drug effects / Q000378:metabolism; D019255:NADPH Oxidases / Q000037:antagonists & inhibitors*; D018408:Patch-Clamp Techniques; D024681:Potassium Channels, Calcium-Activated / Q000037:antagonists & inhibitors*; D034622:RNA Interference; D013481:Superoxides / Q000378:metabolism
D004791:Enzyme Inhibitors; D007473:Ion Channels; D024681:Potassium Channels, Calcium-Activated; D013481:Superoxides; D000804:Angiotensin II; D006861:Hydrogen Peroxide; D019255:NADPH Oxidases; C085108:APEX1 protein, human; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase