title: Phosphorylation of rat kidney Na-K pump at Ser938 is required for rapid angiotensin II-dependent stimulation of activity and trafficking in proximal tubule cells.
abstract: How angiotensin (ANG) II acutely stimulates the Na-K pump in proximal tubules is only partially understood, limiting insight into how ANG II increases blood pressure. First, we tested whether ANG II increases the number of pumps in plasma membranes of native rat proximal tubules under conditions of rapid activation. We found that exposure to 100 pM ANG II for 2 min, which was previously shown to increase affinity of the Na-K pump for Na and stimulate activity threefold, increased the amount of the Na-K pump in plasma membranes of native tubules by 33%. Second, we tested whether previously observed increases in phosphorylation of the Na-K pump at Ser(938) were part of the stimulatory mechanism. These experiments were carried out in opossum kidney cells, cultured proximal tubules stably coexpressing the ANG type 1 (AT1) receptor, and either wild-type or a S938A mutant of rat kidney Na-K pump under conditions found by others to stimulate activity. We found that 10 min of incubation in 10 pM ANG II stimulated activity of wild-type pumps from 2.3 to 3.5 nmol K · mg protein(-1) · min(-1) and increased the amount of the pump in the plasma membrane by 80% but had no effect on cells expressing the S938A mutant. We conclude that acute stimulation of Na-K pump activity in native rat proximal tubules includes increased trafficking to the plasma membrane and that phosphorylation at Ser(938) is part of the mechanism by which ANG II directly stimulates activity and trafficking of the rat kidney Na-K pump in opossum kidney cells.
authors.affiliation: Department of Physiology, School of Medicine, Wayne State University, Detroit, Michigan;
authors.forename: Katherine J
authors.initials: KJ
authors.lastname: Massey
authors.affiliation: Department of Pharmacology, School of Medicine, Wayne State University, Detroit, Michigan;
authors.forename: Quanwen
authors.initials: Q
authors.lastname: Li
authors.affiliation: Department of Physiology, School of Medicine, Wayne State University, Detroit, Michigan; Department of Internal Medicine, School of Medicine, Wayne State University, Detroit, Michigan; John D. Dingell Veterans Affairs Medical Center, Detroit, Michigan.
authors.forename: Noreen F
authors.initials: NF
authors.lastname: Rossi
authors.affiliation: Cell Signaling Technology, Danvers, Massachusetts; and.
authors.forename: Susan M
authors.initials: SM
authors.lastname: Keezer
authors.affiliation: Department of Pharmacology, School of Medicine, Wayne State University, Detroit, Michigan;
authors.forename: Raymond R
authors.initials: RR
authors.lastname: Mattingly
authors.affiliation: Department of Physiology, School of Medicine, Wayne State University, Detroit, Michigan; dyingst@med.wayne.edu.
authors.forename: Douglas R
authors.initials: DR
authors.lastname: Yingst
mesh_terms: D000804:Angiotensin II / Q000494:pharmacology*; D000818:Animals; D002460:Cell Line; D002462:Cell Membrane / Q000187:drug effects* / Q000201:enzymology; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D004789:Enzyme Activation; D007687:Kidney Tubules, Proximal / Q000187:drug effects* / Q000201:enzymology; D008297:Male; D009154:Mutation; D009893:Opossums; D010766:Phosphorylation; D011493:Protein Kinase C / Q000378:metabolism; D021381:Protein Transport; D017207:Rats, Sprague-Dawley; D044140:Receptor, Angiotensin, Type 1 / Q000819:agonists / Q000235:genetics / Q000378:metabolism; D012694:Serine; D000254:Sodium-Potassium-Exchanging ATPase / Q000235:genetics / Q000378:metabolism*; D013997:Time Factors; D014162:Transfection; D015854:Up-Regulation
chemical_list: D044140:Receptor, Angiotensin, Type 1; D000804:Angiotensin II; D012694:Serine; D017868:Cyclic AMP-Dependent Protein Kinases; D011493:Protein Kinase C; C499075:Atp1a1 protein, rat; D000254:Sodium-Potassium-Exchanging ATPase
keywords: Na-K-ATPase; protein kinase A; protein kinase C