Author/Editor | Galuska, Dana; Pirkmajer, Sergej; Barres, Romain; Ekberg, Karin; Wahren, John; Chibalin, Alexander V | |
Title | C-peptide increases Na,K-ATPase expression via PKC- and MAP kinase-dependent activation of transcription factor ZEB in human renal tubular cells | |
Type | članek | |
Source | PLoS One | |
Vol. and No. | Letnik 6, št. 12 | |
Publication year | 2011 | |
Volume | str. e28294 | |
Language | eng | |
Abstract | Background: Replacement of proinsulin C-peptide in type 1 diabetes ameliorates nerve and kidney dysfunction, conditions which are associated with a decrease in Na,K-ATPase activity. We determined the molecular mechanism by which long term exposure to C-peptide stimulates Na,K-ATPase expression and activity in primary human renal tubular cells (HRTC) in control and hyperglycemic conditions. Methodology/pricipal findings: HRTC were cultured from the outer cortex obtained from patients undergoing elective nephrectomy. Ouabain-sensitive rubidium ((86)Rb(+)) uptake and Na,K-ATPase activity were determined. Abundance of Na,K-ATPase was determined by Western blotting in intact cells or isolated basolateral membranes (BLM). DNA binding activity was determined by electrical mobility shift assay (EMSA). Culturing of HRTCs for 5 days with 1 nM, but not 10 nM of human C-peptide leads to increase in Na,K-ATPase alpha(1)-subunit protein expression, accompanied with increase in (86)Rb(+) uptake, both in normal- and hyperglycemic conditions. Na,K-ATPase alpha(1)-subunit expression and Na,K-ATPase activity were reduced in BLM isolated from cells cultured in presence of high glucose. Exposure to1 nM, but not 10 nM of C-peptide increased PKCepsilon phosphorylation as well as phosphorylation and abundance of nuclear ERK1/2 regardless of glucose concentration. Exposure to 1 nM of C-peptide increased DNA binding activity of transcription factor ZEB (AREB6), concomitant with Na,K-ATPase alpha(1)-subunit mRNA expression. Effects of 1 nM C-peptide on Na,K-ATPase alpha(1)-subunit expression and/or ZEB DNA binding activity in HRTC were abolished by incubation with PKC or MEK1/2 inhibitors and ZEB siRNA silencing. Conclusions/significance: Despite activation of ERK1/2 and PKC by hyperglycemia, a distinct pool of PKCs and ERK1/2 is involved in regulation of Na,K-ATPase expression and activity by C-peptide. (Abs. trunc. at 2000 ch.) | |
Descriptors | C-PEPTIDE NA(+)-K(+)-EXCHANGING ATPASE CALMODULIN-DEPENDENT PROTEIN KINASES TRANSCRIPTION FACTORS KIDNEY TUBULES TRANSFECTION OUABAIN RUBIDIUM RADIOISOTOPES HYPERGLYCEMIA CELLS, CULTURED RNA, MESSENGER BLOTTING, WESTERN POLYMERASE CHAIN REACTION ELECTROPHORESIS |