On blood vessels. Identification and Validation of Therapeutic Targets for Vascular Disease

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1 Identification and Valition of Therapeutic Targets for Vascular Disease UCSF LAVR Rong Wang, Ph. D. Director Laboratory for Accelerated Vascular Research Associate Professor Department of Surgery University of California San Francisco Endothelial Signaling Regulating Arterial Venous Specification Embryonic development: the dorsal aorta (DA) and cardinal vein (CV) Disease pathogenesis: arteriovenous malformation (AVM) On blood vessels Ancient Greek physician Galen proposed blood does not circulate but is locally generated 1628 William Harvey discovered the heart: arteries carry blood away and veins return blood back to the heart 1661 Marcello Malphighi identified capillaries as the smallest vessels that close the circulation 1

2 Chick Vasculature Arterial venous hierarchy is essential for vascular function Drawing by Malphighi (1661) Harvey and Rosenthal, Heart Development, 1999 Notch Pathway Genes are Expressed in Arteries but not Veins Notch, a Universal Arbiter of Cell Fate Decision Ligand Dll4-lacZ Adult Brain Bendito et al., Gene Expression Patterns

3 Notch Signaling Promotes Arterial Differentiation Signaling Cell CV DA Jagged1, Jagged2, Dll1,Dll3,Dll4 Notch1, Notch2, Notch3, Notch4 Constitutively Active Notch4* (int3) Notch1* (N1ICD) HDAc RBPJ CoR Nucleus MAML HAc RBPJ HDAc CoR Hes & Hey Receiving Cell CV DA CV DA 3

4 Morphogenesis of the Dorsal Aorta and Cardinal Vein - the first artery-vein pair in the body Ventral Lateral Lateral p- Constitutively Active Notch4 Leads to Enlarged Aortae and Diminished Cardinal Veins 6ss 11ss 20ss Kim YH et al., Development, Kim and Wang, Development, 2008, 135: Notch4* Increases the Size of the DA At the Expense of the CV Notch4* Does Not Affect Proliferation or Total Number of Endothelial Cells Salvador Guevara Gallardo, Tyson Kim, and Rong Wang Kim and Wang, Development, 2008, 135:

5 Dorsal Aorta is Reduced while the Cardinal Vein Primordium is Enlarged in Notch -/- Mice Notch Determines Arterial Differentiation Thereby Balancing the Allocation of Endothelial Cells between the DA and CV Notch1 -/- Wild-type Kim and Wang, Development, 2008, 135: EC ephrinb2 + EphB4 + ephrinb2 + /EphB4 + ephrinb2 - Kim YH et al., Development, Notch Allocates the Ratio of Arterial vs. Venous Endothelial Cells Temporal and Spatial Effect of Notch4* Notch4* embryo Birth Adult ON: Notch Phenotype: embryonic AVM in Brain AVM: Liver, Uterus, AV coordination Skin but not Bran Publication: Development 08 PNAS 08 PNAS 2005 Kim and Wang, Development, 2008, 135:

6 Brain Arterial Venous Malformation (BAVMs) Six million people (young) harbor BAVM Significant contributions to stroke half of the hemorrhagic stroke in children 2% of all stokes Current surgical treatment has limited benefit ongoing trial to test surgery against natural course Little is known about the pathogenesis no animal model Hallmarks of BAVMs Operational definition of BAVM Arteriovenous shunting Enlarged blood vessels Hemorrhage Symptoms of stroke Ataxia Enlarged and Tangled Vessels in the Mutant Brian Arterio-venous Malformations (BAVMs) Contains Enlarged and Tangled Vessels Friedlander, NEJM

7 Hemorrhage and Necrosis in the Mutant Notch4* Leads to Brain AV Shunting 400µm 400µm Arteriovenous Connections are Larger than Capillaries Illness and Ataxia Are Reversed by Repression of Notch4* Brain Lung P20 P23 (3 ys Notch4* repression ) Bright field FITC Carotid Injection of 15µm FITC-beads 7

8 Summary The luminal sizes of the growing artery and vein are reciprocally balanced Notch dictates this balance. Increase in Notch signaling promotes and sustains arterial venous malformation Notch activation is up-regulated in human Brain AVM patients A robust and faithful animal model for BAVM progression and regression In-lab Construction of a Two-Photon Microscope Patrick Murphy PhD student Tyson Kim MD/PhD student Thanks Yuankai Lin, PhD Henrik Lindskog, PhD Weiya Jiang, PhD Olivera Marjanovic, PhD Tayoshi Watanabe, PhD Salvador Guevara Gallardo, MD Eric Jelin, MD Doug Miniati, MD Patrick Murphy, PhD Student Tyson Kim, MD/PhD Bioengineering Student Yeni Chen, UC Berkeley undergrad Gloria Lu, UC Berkeley undergrad David Yiu Lab Helper Yung Hae Kim, Ph. D Huiqing Hu, MS UCSF LAVR Mike Conte, MD Joe Rapp, MD Lin Reilly, MD Chris Owen, MD Darren Schneider, MD Tim Chuter, MD Christin Munkittrick, PhD Research Manager Caltech David Anderson, Ph.D. The Jackson Lab Tom Gridley NIH AHA Fountion for Accelerated Vascular Research UCSF HHMI Start-Up Fund 8