Objective: Although an increasing number of reports suggest that physiological concentrations of C-peptide protect against the development of diabetic nephropathy, possibly through the modulation of Na-K pump activity, the intracellular pathways controlled by C-peptide are still unrecognized. C-peptide and vasopressin share similar intracellular effects including the activation of calcium influx and endothelial nitric oxide synthase. Both hormones stimulate also the activity of Na-K pump activity. Whether the activity of C-peptide is mediated by the recently identified vasopressin-activated calcium-mobilizing receptor (VACM-1) has never been previously investigated. Design and methods: To clarify this issue, we evaluated the effect of C-peptide on VACM-1 RNA (measured by semiquantitative RT-PCR) and protein expression (measured by immunoblotting) in human skin fibroblasts (where a specific binding of C-peptide was demonstrated) and in human mesangial cells, the cellular target of diabetic nephropathy. Results: C-peptide-induced activation of VACM-1 was demonstrated in fibroblasts from six healthy individuals (0.51(plus or minus)0.1 vs 1.48(plus or minus) 0.4, arbitrary units(plus or minus)S.E., P = 0.025). This finding was paralleled by an increased VACM-1 protein expression (5.64(plus or minus)1.0 vs 8.47(plus or minus)1.2, arbitrary units(plus or minus)S.E., P = 0.043). Similar results were confirmed in three independent cultures of human mesangial cells. VACM-1 activation in fibroblasts was insensitive to phosphatidylinositol-3-kinase inhibitor LY294002, but was inhibited by pertussis toxin, suggesting that activation of VACM-1 could be mediated by a G protein-coupled receptor. Conclusions: This study demonstrates for the first time that C-peptide activates VACM-1, possibly through a G protein-coupled receptor. Further studies are needed to clarify whether VACM-1 is involved in the protective effect of C-peptide against the development of diabetic nephropathy.
|Titolo:||C-peptide increases the expression of vasopressin-activated calcium-mobilizing receptor gene through a G protein-dependent pathway|
|Autori interni:||LUZI, LIVIO (Penultimo)|
|Parole Chiave:||article ; calcium transport ; concentration (parameters) ; controlled study ; diabetic nephropathy ; gene expression ; human cell ; human ; immunoblotting ; mesangium cell ; modulation ; nucleotide sequence ; pathogenesis ; priority journal ; protein binding ; quantitative analysis ; renal protection ; reverse transcription polymerase chain reaction ; sensitivity analysis ; skin fibroblast ; target cell ; 2 morpholino 8 phenylchromone ; C peptide ; G protein coupled receptor ; RNA ; adenosine triphosphatase (potassium sodium) ; calcium ion ; endothelial nitric oxide synthase ; pertussis toxin ; unclassified drug ; vasopressin activated calcium mobilizing receptor ; vasopressin receptor ; vasopressin|
|Settore Scientifico Disciplinare:||Settore BIO/09 - Fisiologia|
|Data di pubblicazione:||gen-2005|
|Digital Object Identifier (DOI):||10.1530/eje.1.01823|
|Appare nelle tipologie:||01 - Articolo su periodico|