Expression of angiopoietin-1, angiopoietin-2, and tie receptors after middle cerebral artery occlusion in the rat

Am J Pathol. 2000 Nov;157(5):1473-83. doi: 10.1016/S0002-9440(10)64786-4.

Abstract

Vascular endothelial growth factor (VEGF), a key regulator of vasculogenesis and embryonic angiogenesis, was recently found to be up-regulated in an animal model of stroke. Unlike VEGF, angiopoietin (Ang)-1 and -2, their receptor tie-2, and the associated receptor tie-1 exert their functions at later stages of vascular development, i.e., during vascular remodeling and maturation. To assess the role of the angiopoietin/tie family in ischemia-triggered angiogenesis we analyzed their temporal and spatial expression pattern after middle cerebral artery occlusion (MCAO) using in situ hybridization and immunohistochemistry. Ang-1 mRNA was constitutively expressed in a subset of glial and neuronal cells with no apparent change in expression after MCAO. Ang-2 mRNA was up-regulated 6 hours after MCAO and was mainly observed in endothelial cell (EC) cord tips in the peri-infarct and infarct area. Up-regulation of both Ang-2 and VEGF coincided with EC proliferation. Interestingly, EC proliferation was preceded by a transient period of EC apoptosis, correlating with a change in VEGF/Ang-2 balance. Our observation of specific stages of vascular regression and growth after MCAO are in agreement with recent findings suggesting a dual role of Ang-2 in blood vessel formation, depending on the availability of VEGF.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Angiopoietin-1
  • Angiopoietin-2
  • Animals
  • Apoptosis
  • Arterial Occlusive Diseases / metabolism*
  • Arterial Occlusive Diseases / physiopathology
  • Blood Vessels / physiopathology
  • Cell Division
  • Cerebral Arteries*
  • Endothelium, Vascular / pathology
  • Endothelium, Vascular / physiopathology
  • Immunohistochemistry
  • In Situ Hybridization
  • Male
  • Membrane Glycoproteins / genetics
  • Membrane Glycoproteins / metabolism*
  • Proteins / genetics
  • Proteins / metabolism*
  • RNA, Messenger / metabolism
  • Rats
  • Rats, Inbred F344
  • Receptor Protein-Tyrosine Kinases / genetics
  • Receptor Protein-Tyrosine Kinases / metabolism*
  • Receptor, TIE-1
  • Receptor, TIE-2
  • Receptors, Cell Surface / genetics
  • Receptors, Cell Surface / metabolism*
  • Receptors, TIE

Substances

  • Angiopoietin-1
  • Angiopoietin-2
  • Angpt1 protein, rat
  • Membrane Glycoproteins
  • Proteins
  • RNA, Messenger
  • Receptors, Cell Surface
  • Receptor Protein-Tyrosine Kinases
  • Receptor, TIE-1
  • Receptor, TIE-2
  • Receptors, TIE