title: A transgenic Xenopus laevis reporter model to study lymphangiogenesis.
abstract: The importance of the blood- and lymph vessels in the transport of essential fluids, gases, macromolecules and cells in vertebrates warrants optimal insight into the regulatory mechanisms underlying their development. Mouse and zebrafish models of lymphatic development are instrumental for gene discovery and gene characterization but are challenging for certain aspects, e.g. no direct accessibility of embryonic stages, or non-straightforward visualization of early lymphatic sprouting, respectively. We previously demonstrated that the Xenopus tadpole is a valuable model to study the processes of lymphatic development. However, a fluorescent Xenopus reporter directly visualizing the lymph vessels was lacking. Here, we created transgenic Tg(Flk1:eGFP) Xenopus laevis reporter lines expressing green fluorescent protein (GFP) in blood- and lymph vessels driven by the Flk1 (VEGFR-2) promoter. We also established a high-resolution fluorescent dye labeling technique selectively and persistently visualizing lymphatic endothelial cells, even in conditions of impaired lymph vessel formation or drainage function upon silencing of lymphangiogenic factors. Next, we applied the model to dynamically document blood and lymphatic sprouting and patterning of the initially avascular tadpole fin. Furthermore, quantifiable models of spontaneous or induced lymphatic sprouting into the tadpole fin were developed for dynamic analysis of loss-of-function and gain-of-function phenotypes using pharmacologic or genetic manipulation. Together with angiography and lymphangiography to assess functionality, Tg(Flk1:eGFP) reporter tadpoles readily allowed detailed lymphatic phenotyping of live tadpoles by fluorescence microscopy. The Tg(Flk1:eGFP) tadpoles represent a versatile model for functional lymph/angiogenomics and drug screening.
authors.affiliation: Laboratory of Angiogenesis and Neurovascular link, Vesalius Research Center , VIB, 3000 Leuven , Belgium ; Laboratory of Angiogenesis and Neurovascular link, Vesalius Research Center , KU Leuven, 3000 Leuven , Belgium.
authors.forename: Annelii
authors.initials: A
authors.lastname: Ny
authors.forename: Wouter
authors.initials: W
authors.lastname: Vandevelde
authors.forename: Philipp
authors.initials: P
authors.lastname: Hohensinner
authors.forename: Manu
authors.initials: M
authors.lastname: Beerens
authors.forename: Ilse
authors.initials: I
authors.lastname: Geudens
authors.forename: Antonio
authors.initials: A
authors.lastname: Diez-Juan
authors.forename: Katleen
authors.initials: K
authors.lastname: Brepoels
authors.forename: Stéphane
authors.initials: S
authors.lastname: Plaisance
authors.forename: Paul A
authors.initials: PA
authors.lastname: Krieg
authors.forename: Tobias
authors.initials: T
authors.lastname: Langenberg
authors.forename: Stefan
authors.initials: S
authors.lastname: Vinckier
authors.forename: Aernout
authors.initials: A
authors.lastname: Luttun
authors.forename: Peter
authors.initials: P
authors.lastname: Carmeliet
authors.forename: Mieke
authors.initials: M
authors.lastname: Dewerchin
keywords: Imaging; Lymphangiogenesis; Xenopus