Analysis of a zebrafish VEGF receptor mutant reveals specific disruption of angiogenesis
Analysis of a zebrafish VEGF receptor mutant reveals specific disruption of angiogenesis
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DOI：
10.1016/s0960-9822(02)01044-8
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发表时间：
2002-08-20
期刊：
影响因子：
9.2
通讯作者：
Schulte-Merker, S
中科院分区：
文献类型：
--
作者：
Habeck, H;Odenthal, J;Schulte-Merker, S
血管通过中胚层前体细胞的组装和分化（血管生成）或从预先存在的血管中萌芽（血管生成）形成[1-3]。已知内皮特异性受体酪氨酸激酶及其配体对于这些过程至关重要。小鼠胚胎中血管内皮生长因子 (VEGF) 或其受体 kdr（flk1、VEGFR2）的靶向破坏会导致所有血管严重减少 [4-6]，而 flt1 (VEGFR1) 的完全丧失会导致成血管细胞数量增加和脉管系统紊乱 [7, 8]。在大规模正向遗传筛选中，我们鉴定了两种等位基因斑马鱼突变体，其中血管的萌芽被特异性破坏，而不影响成血管细胞的组装和分化：分子克隆揭示了 flk1 中的无义突变。对flk1突变胚胎中mRNA表达的分析表明，flk1表达严重下调，而参与血管生成或造血的其他基因（scl、gata1和fli1）的表达没有变化。 vegf(121+165) 的过度表达仅在兄弟幼虫中导致额外血管的形成，而在 flk1 突变体中则不然。我们证明 flk1 并不是斑马鱼胚胎中正常血管发生和造血所必需的。然而，flk1 的破坏会损害由萌芽血管生成产生的血管的形成或功能。
Blood vessels form either by the assembly and differentiation of mesodermal precursor cells (vasculogenesis) or by sprouting from preexisting vessels (angiogenesis) [1-3]. Endothelial-specific receptor tyrosine kinases and their ligands are known to be essential for these processes. Targeted disruption of vascular endothelial growth factor (VEGF) or its receptor kdr (flk1, VEGFR2) in mouse embryos results in a severe reduction of all blood vessels [4-6], while the complete loss of flt1 (VEGFR1) leads to an increased number of hemangioblasts and a disorganized vasculature [7, 8]. In a large-scale forward genetic screen, we identified two allelic zebrafish mutants in which the sprouting of blood vessels is specifically disrupted without affecting the assembly and differentiation of angioblasts: Molecular cloning revealed nonsense mutations in flk1. Analysis of mRNA expression in flk1 mutant embryos showed that flk1 expression was severely downregulated, while the expression of other genes (scl, gata1, and fli1) involved in vasculogenesis or hematopoiesis was unchanged. Overexpression of vegf(121+165) led to the formation of additional vessels only in sibling larvae, not in flk1 mutants. We demonstrate that flk1 is not required for proper vasculogenesis and hematopoiesis in zebrafish embryos. However, the disruption of flk1 impairs the formation or function of vessels generated by sprouting angiogenesis.