Xenbase Image ID: 82352

Fig. 3. Fli1 and Gata2 regulate Etv6/VEGFA signalling in the DLP to control the establishment of adult haemangioblasts. (A) Expression analysis showing that the expression of Fli1, Gata2 and Flk1 in the DLP (arrows) are not dependent on Etv6/VegfA signalling. (B) Expression analysis showing that the expression of Etv6, VegfA, Scl and Flk1 in the DLP (arrows) are dependent on both Fli1 and Gata2 transcriptional activities and that Gata2 expression is controlled by Fli1. (C) Expression analysis showing that the expression of Etv6 and VegfA in the DLP (arrows) is dependent on VEGFA signalling. (D) Expression analysis in staged embryos shows that Etv6 controls the expression of VegfA in the DLP (arrows) and in the somites (striped staining) but not in the hypochord (arrowheads). Note that VegfA expression in the somites is initially completely dependent on Etv6 but that by stage 24 some recovery is observed. (E) Diagram summarising the genetic cascade regulating Scl expression in the DLP. Relationships between genes are depicted by an arrow from the regulating gene to the regulated genes. This regulatory network shows that, although Fli1 and Gata2 are required for Etv6, VegfA and Scl expression, the establishment of endogenous VEGFA signalling and Scl expression in the DLP can only happen when VEGFA is produced in the somites, that paracrine VEGFA signalling is absolutely required for the initiation of the adult haemangioblast programme. The open circle indicates the interaction between the VEGFA receptor, Flk1, and VEGFA ligand from the somites. The arrow with chevrons indicates that VEGFA activates Scl indirectly, and that an intermediate factor controlled by VEGFA signalling is required. All embryos were hybridised as whole mounts and are shown in lateral view, with anterior to the left and dorsal to the top. All embryos are shown at stage 26, unless otherwise indicated. Numbers of embryos represented by each panel, out of the number analysed, are indicated in the top right corner. Image published in: Ciau-Uitz A et al. (2013) Copyright © 2013. Image reproduced with permission of the publisher and the copyright holder. This is an Open Access article distributed under the terms of the Creative Commons Attribution License. Larger Image Printer Friendly View

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