title: T3 increases Na-K-ATPase activity via a MAPK/ERK1/2-dependent pathway in rat adult alveolar epithelial cells.
abstract: Thyroid hormone (T3) increases Na-K-ATPase activity in rat adult alveolar type II cells via a PI3K-dependent pathway. In these cells, dopamine and beta-adrenergic agonists can stimulate Na-K-ATPase activity through either PI3K or MAPK pathways. We assessed the role of the MAPK pathway in the stimulation of Na-K-ATPase by T3. In the adult rat alveolar type II-like cell line MP48, T3 enhanced MAPK/ERK1/2 activity in a dose-dependent manner. Increased ERK1/2 phosphorylation was observed within 5 min, peaked at 20 min, and then decreased. Two MEK1/2 inhibitors, U0126 and PD-98059, each abolished the T3-induced increase in the quantity of Na-K-ATPase alpha(1)-subunit plasma membrane protein and Na-K-ATPase activity. T3 also increased the phosphorylation of MAPK/p38; however, SB-203580, a specific inhibitor of MAPK/p38 activity, did not prevent the T3-induced Na-K-ATPase activity. SP-600125, a specific inhibitor of the MAPK/JNK pathway, also did not block the T3-induced Na-K-ATPase activity. Phorbol 12-myristate 13-acetate (PMA) significantly increased ERK1/2 phosphorylation and Na-K-ATPase activity. The PMA-induced Na-K-ATPase activity was inhibited by U0126. These data indicate that activation of MAPK-ERK1/2 was required for the T3-induced increase in Na-K-ATPase activity in addition to the requirement for the PI3K pathway.
authors.affiliation: Department of Medicine, Medical School, University of Minnesota, Minneapolis, MN 55455, USA.
authors.forename: Jianxun
authors.initials: J
authors.lastname: Lei
authors.forename: Cary N
authors.initials: CN
authors.lastname: Mariash
authors.forename: Maneesh
authors.initials: M
authors.lastname: Bhargava
authors.forename: Elizabeth V
authors.initials: EV
authors.lastname: Wattenberg
authors.forename: David H
authors.initials: DH
authors.lastname: Ingbar
mesh_terms: D000818:Animals; D018929:Cell Culture Techniques; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism*; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D011480:Protease Inhibitors / Q000494:pharmacology; D011650:Pulmonary Alveoli / Q000166:cytology / Q000201:enzymology / Q000502:physiology*; D051381:Rats; D020545:Respiratory Mucosa / Q000166:cytology / Q000187:drug effects / Q000201:enzymology / Q000502:physiology*; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*; D014284:Triiodothyronine / Q000494:pharmacology*
chemical_list: D011480:Protease Inhibitors; D014284:Triiodothyronine; D048049:Extracellular Signal-Regulated MAP Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D000254:Sodium-Potassium-Exchanging ATPase