title: A transgene-assisted genetic screen identifies essential regulators of vascular development in vertebrate embryos.
abstract: Formation of a functional vasculature during mammalian development is essential for embryonic survival. In addition, imbalance in blood vessel growth contributes to the pathogenesis of numerous disorders. Most of our understanding of vascular development and blood vessel growth comes from investigating the Vegf signaling pathway as well as the recent observation that molecules involved in axon guidance also regulate vascular patterning. In order to take an unbiased, yet focused, approach to identify novel genes regulating vascular development, we performed a three-step ENU mutagenesis screen in zebrafish. We first screened live embryos visually, evaluating blood flow in the main trunk vessels, which form by vasculogenesis, and the intersomitic vessels, which form by angiogenesis. Embryos that displayed reduced or absent circulation were fixed and stained for endogenous alkaline phosphatase activity to reveal blood vessel morphology. All putative mutants were then crossed into the Tg(flk1:EGFP)(s843) transgenic background to facilitate detailed examination of endothelial cells in live and fixed embryos. We screened 4015 genomes and identified 30 mutations affecting various aspects of vascular development. Specifically, we identified 3 genes (or loci) that regulate the specification and/or differentiation of endothelial cells, 8 genes that regulate vascular tube and lumen formation, 8 genes that regulate vascular patterning, and 11 genes that regulate vascular remodeling, integrity and maintenance. Only 4 of these genes had previously been associated with vascular development in zebrafish illustrating the value of this focused screen. The analysis of the newly defined loci should lead to a greater understanding of vascular development and possibly provide new drug targets to treat the numerous pathologies associated with dysregulated blood vessel growth.
authors.affiliation: Department of Biochemistry and Biophysics, Genetics and Human Genetics, and Cardiovascular Research Institute, University of California San Francisco, CA 94158, USA. suk-won_jin@med.unc.edu
authors.forename: Suk-Won
authors.initials: SW
authors.lastname: Jin
authors.forename: Wiebke
authors.initials: W
authors.lastname: Herzog
authors.forename: Massimo M
authors.initials: MM
authors.lastname: Santoro
authors.forename: Tracy S
authors.initials: TS
authors.lastname: Mitchell
authors.forename: Julie
authors.initials: J
authors.lastname: Frantsve
authors.forename: Benno
authors.initials: B
authors.lastname: Jungblut
authors.forename: Dimitris
authors.initials: D
authors.lastname: Beis
authors.forename: Ian C
authors.initials: IC
authors.lastname: Scott
authors.forename: Leonard A
authors.initials: LA
authors.lastname: D'Amico
authors.forename: Elke A
authors.initials: EA
authors.lastname: Ober
authors.forename: Heather
authors.initials: H
authors.lastname: Verkade
authors.forename: Holly A
authors.initials: HA
authors.lastname: Field
authors.forename: Neil C
authors.initials: NC
authors.lastname: Chi
authors.forename: Ann M
authors.initials: AM
authors.lastname: Wehman
authors.forename: Herwig
authors.initials: H
authors.lastname: Baier
authors.forename: Didier Y R
authors.initials: DY
authors.lastname: Stainier
mesh_terms: D000818:Animals; D001808:Blood Vessels / Q000196:embryology / Q000254:growth & development*; D004625:Embryo, Nonmammalian; D042783:Endothelial Cells / Q000166:cytology; D023281:Genomics / Q000379:methods*; D016296:Mutagenesis; D009154:Mutation; D018919:Neovascularization, Physiologic; D019076:Transgenes; D014714:Vertebrates; D015027:Zebrafish