Roles of angiopoietins in kidney development and disease

J Am Soc Nephrol. 2009 Feb;20(2):239-44. doi: 10.1681/ASN.2008020243. Epub 2008 Sep 17.

Abstract

Angiopoietins are a family of growth factors, the best studied being angiopoietin 1 (Ang-1), which binds to and tyrosine-phosphorylates endothelial Tie-2, causing enhanced survival and cell-cell stabilization. Ang-2 and Tie-1 downregulate Ang-1-induced Tie-2 signaling, and angiopoietin actions are further modified by vascular endothelial growth factor A and integrins. Metanephric capillaries express Tie genes, whereas metanephric mesenchyme, maturing tubules, and mature podocytes express Ang-1. Ang-1 null embryos begin to form blood vessels, but subsequent vascular remodeling fails, and analyses of chimeric wild-type/Tie null mutant embryos show that Tie genes are needed for renal endothelial survival. Ang-2 is transiently expressed in renal arterial smooth muscle and mesangial cells, and tubules around adult vasa rectae express Ang-2. Ang-2 null mice have increased pericytes around kidney cortical peritubular capillaries, perhaps an indirect consequence of upregulated Tie-2 signaling. Ang-1 therapies attenuate peritubular capillary loss in adult models of tubulointerstitial disease, although, in one study, this was accompanied by enhanced inflammation and fibrosis. Podocyte-directed Ang-2 transgenic overexpression causes glomerular endothelial apoptosis, downregulated nephrin expression, and increased albuminuria, and glomerular Ang-2 is upregulated in hyperglycemic and immune-mediated glomerulopathies. Thus, angiopoietins affect podocyte as well as glomerular endothelial biology, and imbalanced angiopoietin signaling contributes to glomerular pathobiology.

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Angiopoietin-2 / genetics
  • Angiopoietin-2 / metabolism
  • Angiopoietins / physiology*
  • Animals
  • Apoptosis
  • Cell Survival
  • Gene Expression Regulation*
  • Humans
  • Kidney / metabolism*
  • Kidney Diseases / metabolism*
  • Kidney Glomerulus / metabolism
  • Mice
  • Models, Biological
  • Signal Transduction
  • Transgenes

Substances

  • Angiopoietin-2
  • Angiopoietins