Endothelin antagonism prevents early EGFR transactivation but not increased matrix metalloproteinase activity in diabetes

Am J Physiol Regul Integr Comp Physiol. 2006 Feb;290(2):R435-41. doi: 10.1152/ajpregu.00300.2005. Epub 2005 Oct 20.

Abstract

Although past studies have demonstrated decreased renal matrix metalloproteinase (MMP) activity in type 1 diabetes and in mesangial cells grown under high glucose conditions, renal MMP expression and activity in type 2 diabetes and the regulation of MMPs by profibrotic factors involved in diabetic renal complications such as endothelin-1 (ET-1) remained unknown. The renal expression and activity of MMPs in type 2 diabetic Goto-Kakizaki (GK) rats treated with vehicle or ET(A) receptor selective antagonist ABT-627 for 4 wk were assessed by gelatin zymography, fluorogenic gelatinase assay, and immunoblotting. In addition, expression and phosphorylation of epidermal growth factor receptor (EGFR) and connective tissue growth factor were evaluated by immunoblotting. Renal sections stained with Masson trichrome were used to investigate kidney structure. MMP-2 activity and protein levels were significantly increased in both cortical and medullary regions in the GK rats. Membrane-bound MMP (MT1-MMP), MMP-9, and fibronectin levels were also increased, and ABT-627 treatment did not have an effect on MMP activity and expression. Histological analysis of kidneys did not reveal any structural changes. Phosphorylation of EGFR was significantly increased in the diabetic animals, and ABT-627 treatment prevented this increase, suggesting ET-1-mediated transactivation of EGFR. These results suggest that there is early upregulation of renal MMPs in the absence of any kidney damage. Although the ET(A) receptor subtype is not involved in the early activation of MMPs in type 2 diabetes, ET-1 contributes to transactivation of growth-promoting and profibrotic EGFR.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Atrasentan
  • Blood Glucose / metabolism
  • Diabetes Mellitus, Type 2 / enzymology
  • Diabetes Mellitus, Type 2 / metabolism*
  • Endothelins / antagonists & inhibitors*
  • Endothelins / metabolism
  • ErbB Receptors / genetics*
  • Fibronectins / metabolism
  • Gene Expression Regulation, Enzymologic*
  • Kidney / enzymology
  • Male
  • Matrix Metalloproteinase 2 / metabolism*
  • Matrix Metalloproteinase 9 / metabolism*
  • Phosphorylation
  • Pyrrolidines / pharmacology
  • Rats
  • Rats, Inbred Strains
  • Transcriptional Activation*

Substances

  • Blood Glucose
  • Endothelins
  • Fibronectins
  • Pyrrolidines
  • Egfr protein, rat
  • ErbB Receptors
  • Matrix Metalloproteinase 2
  • Matrix Metalloproteinase 9
  • Atrasentan