title: C-peptide stimulates Na+, K+-ATPase via activation of ERK1/2 MAP kinases in human renal tubular cells.
abstract: Proinsulin-connecting peptide (C-peptide) exerts physiological effects partially via stimulation of Na(+), K(+)-ATPase. We determined the molecular mechanism by which C-peptide stimulates Na(+), K(+)-ATPase in primary human renal tubular cells (HRTCs). Incubation of the cells with 5 nM human C-peptide at 37 degrees C for 10 min stimulated (86)Rb(+) uptake by 40% (p<0.01). The carboxy-terminal pentapeptide was found to elicit 57% of the activity of the intact molecule. In parallel with ouabain-sensitive (86)Rb(+) uptake, C-peptide increased alpha subunit phosphorylation and basolateral membrane (BLM) abundance of the Na(+), K(+)-ATPase alpha(1) and beta(1) subunits. The increase in BLM abundance of the Na(+), K(+)-ATPase alpha(1) and beta(1) subunits was accompanied by depletion of alpha(1) and beta(1) subunits from the endosomal compartments. C-peptide action on Na(+), K(+)-ATPase was ERK1/2-dependent in HRTCs. C-peptide-stimulated Na(+), K(+)-ATPase activation, phosphorylation of alpha(1)-subunit and translocation of alpha(1) and beta(1) subunits to the BLM were abolished by a MEK1/2 inhibitor (20 muM PD98059). C-peptide stimulation of (86)Rb(+) uptake was also abolished by preincubation of HRTCs with an inhibitor of PKC (1 muM GF109203X). C-peptide stimulated phosphorylation of human Na(+), K(+)-ATPase alpha subunit on Thr-Pro amino acid motifs, which form specific ERK substrates. In conclusion, C-peptide stimulates sodium pump activity via ERK1/2-induced phosphorylation of Thr residues on the alpha subunit of Na(+), K(+)-ATPase.
authors.affiliation: Section of Clinical Physiology, Department of Surgical Sciences, Karolinska Institutet, 17177 Stockholm, Sweden.
authors.forename: Z
authors.initials: Z
authors.lastname: Zhong
authors.forename: O
authors.initials: O
authors.lastname: Kotova
authors.forename: A
authors.initials: A
authors.lastname: Davidescu
authors.forename: I
authors.initials: I
authors.lastname: Ehrén
authors.forename: K
authors.initials: K
authors.lastname: Ekberg
authors.forename: H
authors.initials: H
authors.lastname: Jörnvall
authors.forename: J
authors.initials: J
authors.lastname: Wahren
authors.forename: A V
authors.initials: AV
authors.lastname: Chibalin
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002096:C-Peptide / Q000494:pharmacology*; D002478:Cells, Cultured; D004789:Enzyme Activation / Q000187:drug effects; D005419:Flavonoids / Q000494:pharmacology; D006801:Humans; D007684:Kidney Tubules / Q000187:drug effects* / Q000201:enzymology*; D008566:Membranes / Q000187:drug effects / Q000378:metabolism; D019950:Mitogen-Activated Protein Kinase 1 / Q000037:antagonists & inhibitors / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3 / Q000037:antagonists & inhibitors / Q000378:metabolism*; D008969:Molecular Sequence Data; D010042:Ouabain / Q000494:pharmacology; D010766:Phosphorylation; D021122:Protein Subunits / Q000737:chemistry / Q000378:metabolism; D051381:Rats; D012414:Rubidium Radioisotopes; D016415:Sequence Alignment; D000254:Sodium-Potassium-Exchanging ATPase / Q000737:chemistry / Q000378:metabolism*
chemical_list: D002096:C-Peptide; D005419:Flavonoids; D021122:Protein Subunits; D012414:Rubidium Radioisotopes; D010042:Ouabain; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D000254:Sodium-Potassium-Exchanging ATPase; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one