Endothelial expression of constitutively active Notch4 elicits reversible arteriovenous malformations in adult mice.
Direct communication between arteries and veins without intervening capillary beds is the primary pathology of arteriovenous malformations (AVMs). Although Notch signaling is implicated in embryonic arteriovenous (AV) differentiation, its function in the adult mammalian vasculature has not been established due to the embryonic lethality that often occurs in both gain- and loss-of-function mutants. We expressed a constitutively active Notch4, int3, in the adult mouse endothelium by using the tetracycline-repressible system to suppress int3 during embryogenesis. int3 caused profound blood vessel enlargement and AV shunting, which are hallmarks of AVM, and led to lethality within weeks of its expression. Vessel enlargement, a manifestation of AVM, occurred in an apparently tissue-specific fashion; the liver, uterus, and skin were affected. int3-mediated vascular defects were accompanied by arterialization, including ectopic venous expression of ephrinB2, increased smooth muscle cells, and up-regulation of endogenous Notch signaling. Remarkably, the defective vessels and illness were reversed upon repression of int3 expression. Finally, endothelial expression of a constitutively active Notch1 induced similar hepatic vascular lesions. Our results provide gain-of-function evidence that Notch signaling in the adult endothelium is sufficient to render arterial characteristics and lead to AVMs.
Pacific Vascular Research Laboratory, Division of Vascular Surgery, Department of Surgery and Department of Anatomy, University of California-San Francisco, San Francisco, CA 94143, USA.
Timothy R
TR
Carlson
Yibing
Y
Yan
Xiaoqing
X
Wu
Michael T
MT
Lam
Gale L
GL
Tang
Levi J
LJ
Beverly
Louis M
LM
Messina
Anthony J
AJ
Capobianco
Zena
Z
Werb
Rong
R
Wang
D000818:Animals; D001165:Arteriovenous Malformations / Q000150:complications / Q000235:genetics* / Q000473:pathology; D006332:Cardiomegaly / Q000209:etiology*; D004452:Echocardiography; D004730:Endothelium, Vascular / Q000378:metabolism*; D036388:Ephrin-B2 / Q000378:metabolism; D005260:Female; D005453:Fluorescence; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation / Q000235:genetics*; D008099:Liver / Q000098:blood supply / Q000473:pathology; D051379:Mice; D008863:Microspheres; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism*; D000074562:Receptor, Notch4; D011956:Receptors, Cell Surface / Q000235:genetics / Q000378:metabolism*; D051880:Receptors, Notch; D015398:Signal Transduction / Q000235:genetics*; D012867:Skin / Q000098:blood supply / Q000473:pathology; D013752:Tetracycline; D014599:Uterus / Q000098:blood supply / Q000473:pathology
D036388:Ephrin-B2; D011518:Proto-Oncogene Proteins; D000074562:Receptor, Notch4; D011956:Receptors, Cell Surface; D051880:Receptors, Notch; C073572:Notch4 protein, mouse; D013752:Tetracycline