Regulation of human and pig renal Na(+),K (+)-ATPase activity by tyrosine phosphorylation of their alpha(1)-subunits.
Modulation of the physiologically influential Na(+),K(+)-ATPase is a complex process involving a wide variety of factors. To determine the possible effects of the protein tyrosine phosphatase (PTP) inhibitors dephostatin and Et-3,4-dephostatin on human and pig, renal cells and enzymatic extracts, we treated our samples (15 min-24 h) with those PTP inhibitors (0-100 microM). PTP inhibitors were found to possess a concentration-dependent inhibition of Na(+),K(+)-ATPase activity in both human and pig samples. The inhibition was similarly demonstrated on all cellular, microsomal fraction and purified Na(+),K(+)-ATPase levels. Despite rigorous activity recovery attempts, the PTP inhibitors' effects were sustained on Na(+),K(+)-ATPase activity. Western blotting experiments revealed the expression of both alpha(1)- and beta(1)-subunits in both human and pig tissues. alpha(1)-Subunits possessed higher tyrosine phosphorylation levels with higher concentrations of PTP inhibitors. Meanwhile, serine/threonine residues of both alpha(1)- and beta(1)-subunits demonstrated diminished phosphorylation levels upon dephostatin treatment. Accordingly, we provide evidence that Na(+),K(+)-ATPase can be regulated through tyrosine phosphorylation of primarily their alpha(1)-subunits, using PTP inhibitors.
Department of Oral and Maxillofacial Surgery, Hokkaido University Graduate School of Dental Medicine, Sapporo, Japan. wbeialy@den.hokudai.ac.jp
Waleed
W
El-Beialy
Nadia
N
Galal
Yoshiaki
Y
Deyama
Yoshitaka
Y
Yoshimura
Kuniaki
K
Suzuki
Kanchu
K
Tei
Yasunori
Y
Totsuka
D000818:Animals; D015153:Blotting, Western; D002395:Catecholamines / Q000494:pharmacology; D045744:Cell Line, Tumor; D005434:Flow Cytometry; D006801:Humans; D006873:Hydroquinones / Q000494:pharmacology; D007668:Kidney / Q000201:enzymology*; D009603:Nitroso Compounds / Q000494:pharmacology; D010766:Phosphorylation / Q000187:drug effects; D021122:Protein Subunits / Q000378:metabolism*; D017027:Protein Tyrosine Phosphatases / Q000037:antagonists & inhibitors; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*; D013552:Swine; D014443:Tyrosine / Q000378:metabolism*
C432919:4-(ethyl)(nitroso)amino-3,4-benzenediol; D002395:Catecholamines; D006873:Hydroquinones; D009603:Nitroso Compounds; D021122:Protein Subunits; C084037:dephostatin; D014443:Tyrosine; D017027:Protein Tyrosine Phosphatases; D000254:Sodium-Potassium-Exchanging ATPase