Angiotensin II stimulates alpha3(IV) collagen production in mouse podocytes via TGF-beta and VEGF signalling: implications for diabetic glomerulopathy.
Nephrol Dial Transplant
; 20(7): 1320-8, 2005 Jul.
Article
en En
| MEDLINE
| ID: mdl-15840669
ABSTRACT
BACKGROUND:
The podocyte is bathed in an angiotensin II (AngII)-rich ultrafiltrate, but the impact of AngII on podocyte pathobiology is not well known. Because podocytes play a direct role in the glomerular basement membrane (GBM) thickening of diabetes, the alpha3(IV) collagen chain was examined. Podocyte expression of alpha3(IV) collagen may involve the transforming growth factor-beta (TGF-beta) and vascular endothelial growth factor (VEGF) systems.METHODS:
Cultured mouse podocytes were treated with various doses of AngII for selected periods of time, with or without inhibitors of TGF-beta and VEGF signalling, SB-431542 and SU5416, respectively. TGF-beta1 and VEGF were assayed by enzyme-linked immunosorbent assay (ELISA); alpha3(IV) collagen, TGF-beta type II receptor and phospho-Smad2 were assayed by immunoblotting.RESULTS:
AngII >or=10(-10) M was found to stimulate the production of alpha3(IV) collagen significantly in as short a time as 3 h. The expression of alpha3(IV) collagen was influenced by the TGF-beta system, but AngII did not increase the podocyte's production of TGF-beta1 ligand; rather, it increased the expression of the TGF-beta type II receptor and activated the TGF-beta signalling system through Smad2. Despite the TGF-beta receptor upregulation, synergy between AngII and TGF-beta1 to boost alpha3(IV) collagen production was not observed. However, blockade of TGF-beta signalling with SB-431542 prevented AngII from stimulating alpha3(IV) collagen production. Podocyte expression of alpha3(IV) collagen was also increased by the autocrine activity of VEGF. Podocytes were stimulated to secrete VEGF by 10(-10) M or higher AngII after 48 h. Blockade of the endogenous VEGF activity by SU5416 prevented AngII-stimulated alpha3(IV) collagen production.CONCLUSIONS:
AngII stimulates the podocyte to produce alpha3(IV) collagen protein via mechanisms involving TGF-beta and VEGF signalling. Alterations in alpha3(IV) collagen production may contribute to GBM thickening and perhaps proteinuria in diabetes.
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Colección:
01-internacional
Banco de datos:
MEDLINE
Asunto principal:
Autoantígenos
/
Vasoconstrictores
/
Angiotensina II
/
Colágeno Tipo IV
/
Células Epiteliales
/
Glomérulos Renales
Límite:
Animals
Idioma:
En
Revista:
Nephrol Dial Transplant
Asunto de la revista:
NEFROLOGIA
/
TRANSPLANTE
Año:
2005
Tipo del documento:
Article
País de afiliación:
Estados Unidos