PI3 kinase inhibition improves vascular malformations in mouse models of hereditary haemorrhagic telangiectasia

Nat Commun. 2016 Nov 29;7:13650. doi: 10.1038/ncomms13650.


Activin receptor-like kinase 1 (ALK1) is an endothelial serine-threonine kinase receptor for bone morphogenetic proteins (BMPs) 9 and 10. Inactivating mutations in the ALK1 gene cause hereditary haemorrhagic telangiectasia type 2 (HHT2), a disabling disease characterized by excessive angiogenesis with arteriovenous malformations (AVMs). Here we show that inducible, endothelial-specific homozygous Alk1 inactivation and BMP9/10 ligand blockade both lead to AVM formation in postnatal retinal vessels and internal organs including the gastrointestinal (GI) tract in mice. VEGF and PI3K/AKT signalling are increased on Alk1 deletion and BMP9/10 ligand blockade. Genetic deletion of the signal-transducing Vegfr2 receptor prevents excessive angiogenesis but does not fully revert AVM formation. In contrast, pharmacological PI3K inhibition efficiently prevents AVM formation and reverts established AVMs. Thus, Alk1 deletion leads to increased endothelial PI3K pathway activation that may be a novel target for the treatment of vascular lesions in HHT2.

Publication types

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

MeSH terms

  • Activin Receptors, Type I / metabolism
  • Activin Receptors, Type II
  • Animals
  • Bone Morphogenetic Proteins / metabolism
  • Disease Models, Animal
  • Gene Deletion
  • Human Umbilical Vein Endothelial Cells / metabolism
  • Humans
  • Mice
  • Models, Biological
  • Neovascularization, Pathologic / drug therapy
  • Phosphatidylinositol 3-Kinases / metabolism
  • Phosphoinositide-3 Kinase Inhibitors*
  • Protein Kinase Inhibitors / pharmacology
  • Protein Kinase Inhibitors / therapeutic use
  • Retina / pathology
  • Signal Transduction / drug effects
  • Telangiectasia, Hereditary Hemorrhagic / complications*
  • Vascular Endothelial Growth Factor Receptor-2 / metabolism
  • Vascular Malformations / complications*
  • Vascular Malformations / enzymology*


  • Bone Morphogenetic Proteins
  • Phosphoinositide-3 Kinase Inhibitors
  • Protein Kinase Inhibitors
  • Vascular Endothelial Growth Factor Receptor-2
  • Activin Receptors, Type I
  • Activin Receptors, Type II
  • Acvrl1 protein, mouse