title: Constitutively active endothelial Notch4 causes lung arteriovenous shunts in mice.
abstract: Lung arteriovenous (AV) shunts or malformations cause significant morbidity and mortality in several distinct clinical syndromes. For most patients with lung AV shunts, there is still no optimal treatment. The underlying molecular and cellular etiology for lung AV shunts remains elusive, and currently described animal models have insufficiently addressed this problem. Using a tetracycline-repressible system, we expressed constitutively active Notch4 (Notch4*) specifically in the endothelium of adult mice. More than 90% of mice developed lung hemorrhages and respiratory insufficiency and died by 6-7 wk after gene expression began. Vascular casting and fluorescent microsphere analysis showed evidence of lung AV shunts in affected mice. Cessation of Notch4* expression reversed these pathophysiological effects. Assessment of the vascular morphology revealed enlarged, tortuous vessels in the lungs that resembled arteriovenous malformations. By using whole lung organ culture, we demonstrated the effects of constitutively active Notch4 on the lung vasculature to be a primary lung phenomenon. Together, our results indicate the importance of Notch signaling in maintaining the lung vasculature and offer a new, reliable model with which to study the pathobiology of lung arteriovenous shunts and malformations.
authors.affiliation: Laboratory for Accelerated Vascular Research, Division of Vascular Surgery, San Francisco, CA 94143-0507, USA. douglas.miniati@ucsfmedctr.org
authors.forename: Doug
authors.initials: D
authors.lastname: Miniati
authors.forename: Eric B
authors.initials: EB
authors.lastname: Jelin
authors.forename: Jennifer
authors.initials: J
authors.lastname: Ng
authors.forename: Jianfeng
authors.initials: J
authors.lastname: Wu
authors.forename: Timothy R
authors.initials: TR
authors.lastname: Carlson
authors.forename: Xiaoqing
authors.initials: X
authors.lastname: Wu
authors.forename: Mark R
authors.initials: MR
authors.lastname: Looney
authors.forename: Rong A
authors.initials: RA
authors.lastname: Wang
mesh_terms: D000818:Animals; D001165:Arteriovenous Malformations / Q000378:metabolism* / Q000473:pathology; D004622:Embryo, Mammalian / Q000033:anatomy & histology; D004730:Endothelium, Vascular / Q000378:metabolism*; D006801:Humans; D008168:Lung / Q000098:blood supply* / Q000196:embryology / Q000378:metabolism* / Q000473:pathology; D051379:Mice; D023421:Models, Animal; D009154:Mutation; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism*; D000074562:Receptor, Notch4; D051880:Receptors, Notch / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology; D046509:Tissue Culture Techniques
chemical_list: D011518:Proto-Oncogene Proteins; D000074562:Receptor, Notch4; D051880:Receptors, Notch; C073572:Notch4 protein, mouse