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