Reversible oxidative modification: a key mechanism of Na+-K+ pump regulation.
Angiotensin II (Ang II) inhibits the cardiac sarcolemmal Na(+)-K(+) pump via protein kinase (PK)C-dependent activation of NADPH oxidase. We examined whether this is mediated by oxidative modification of the pump subunits. We detected glutathionylation of beta(1), but not alpha(1), subunits in rabbit ventricular myocytes at baseline. beta(1) Subunit glutathionylation was increased by peroxynitrite (ONOO(-)), paraquat, or activation of NADPH oxidase by Ang II. Increased glutathionylation was associated with decreased alpha(1)/beta(1) subunit coimmunoprecipitation. Glutathionylation was reversed after addition of superoxide dismutase. Glutaredoxin 1, which catalyzes deglutathionylation, coimmunoprecipitated with beta(1) subunit and, when included in patch pipette solutions, abolished paraquat-induced inhibition of myocyte Na(+)-K(+) pump current (I(p)). Cysteine (Cys46) of the beta(1) subunit was the likely candidate for glutathionylation. We expressed Na(+)-K(+) pump alpha(1) subunits with wild-type or Cys46-mutated beta(1) subunits in Xenopus oocytes. ONOO(-) induced glutathionylation of beta(1) subunit and a decrease in Na(+)-K(+) pump turnover number. This was eliminated by mutation of Cys46. ONOO(-) also induced glutathionylation of the Na(+)-K(+) ATPase beta(1) subunit from pig kidney. This was associated with a approximately 2-fold decrease in the rate-limiting E(2)-->E(1) conformational change of the pump, as determined by RH421 fluorescence. We propose that kinase-dependent regulation of the Na(+)-K(+) pump occurs via glutathionylation of its beta(1) subunit at Cys46. These findings have implications for pathophysiological conditions characterized by neurohormonal dysregulation, myocardial oxidative stress and raised myocyte Na(+) levels.
Figtree
Gemma A
GA
Department of Cardiology, Royal North Shore Hospital, University of Sydney, St Leonards NSW 2065, Australia.
Liu
Chia-Chi
CC
Bibert
Stephanie
S
Hamilton
Elisha J
EJ
Garcia
Alvaro
A
White
Caroline N
CN
Chia
Karin K M
KK
Cornelius
Flemming
F
Geering
Kaethi
K
Rasmussen
Helge H
HH
D000251:Adenosine Triphosphatases / Q000378:metabolism; D000804:Angiotensin II / Q000378:metabolism; D000818:Animals; D027682:Cation Transport Proteins / Q000378:metabolism; D015816:Cell Adhesion Molecules, Neuronal / Q000378:metabolism; D003545:Cysteine; D054477:Glutaredoxins / Q000378:metabolism; D005978:Glutathione / Q000378:metabolism*; D006801:Humans; D007668:Kidney / Q000187:drug effects / Q000201:enzymology*; D007700:Kinetics; D008297:Male; D009154:Mutation; D032383:Myocytes, Cardiac / Q000187:drug effects / Q000201:enzymology*; D019255:NADPH Oxidases / Q000378:metabolism; D009865:Oocytes; D010084:Oxidation-Reduction; D010269:Paraquat / Q000494:pharmacology; D030421:Peroxynitrous Acid / Q000378:metabolism; D011487:Protein Conformation; D011493:Protein Kinase C / Q000378:metabolism; D011499:Protein Processing, Post-Translational; D011817:Rabbits; D012756:Sheep; D015398:Signal Transduction; D000254:Sodium-Potassium-Exchanging ATPase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D013329:Structure-Activity Relationship; D013482:Superoxide Dismutase / Q000378:metabolism; D013552:Swine; D014982:Xenopus laevis
C503551:ATP1B1 protein, human; C504190:ATP1B2 protein, human; C519304:ATP1B3 protein, human; D027682:Cation Transport Proteins; D015816:Cell Adhesion Molecules, Neuronal; D054477:Glutaredoxins; D000804:Angiotensin II; D030421:Peroxynitrous Acid; D013482:Superoxide Dismutase; D019255:NADPH Oxidases; D011493:Protein Kinase C; C499076:ATP1A1 protein, human; D000251:Adenosine Triphosphatases; D000254:Sodium-Potassium-Exchanging ATPase; D005978:Glutathione; D003545:Cysteine; D010269:Paraquat