Haigh Jody J, Morelli Paula I, Gerhardt Holger, Haigh Katharina, Tsien John, Damert Annette, Miquerol Lucile, Muhlner Ulrich, Klein Rudiger, Ferrara Napoleone, Wagner Erwin F, Betsholtz Christer, Nagy Andras
Mount Sinai Hospital, Samuel Lunenfeld Research Institute, Toronto, Canada.
Dev Biol. 2003 Oct 15;262(2):225-41. doi: 10.1016/s0012-1606(03)00356-7.
To determine the function of VEGF-A in nervous system development, we have utilized the Nestin promoter-driven Cre recombinase transgene, in conjunction with a conditional and hypomorphic VEGF-A allele, to lower VEGF-A activity in neural progenitor cells. Mice with intermediate levels of VEGF-A activity showed decreased blood vessel branching and density in the cortex and retina, resulting in a thinner retina and aberrant structural organization of the cortex. Severe reductions in VEGF-A led to decreases in vascularity and subsequent hypoxia, resulting in the specific degeneration of the cerebral cortex and neonatal lethality. Decreased neuronal proliferation and hypoxia was evident at E11.5, leading to increased neuronal apoptosis in the cortex by E15.5. In order to address whether the observed changes in the structural organization of the nervous system were due to a direct and autocrine role of VEGF-A on the neural population, we conditionally inactivated the main VEGF-A receptor, Flk1, specifically in neuronal lineages, by using the Nestin Cre transgene. The normality of these mice ruled out the possibility that VEGF-A/Flk1 signaling has a significant autocrine role in CNS development. VEGF-A dosage is therefore a critical parameter regulating the density of the vascular plexus in the developing CNS that is in turn a key determinant in the development and architectural organization of the nervous system.
为了确定血管内皮生长因子A（VEGF-A）在神经系统发育中的功能，我们利用巢蛋白启动子驱动的Cre重组酶转基因，结合一个条件性低表达的VEGF-A等位基因，来降低神经祖细胞中VEGF-A的活性。VEGF-A活性处于中等水平的小鼠，其大脑皮质和视网膜中的血管分支和密度降低，导致视网膜变薄以及大脑皮质结构组织异常。VEGF-A的严重减少导致血管形成减少及随后的缺氧，进而导致大脑皮质特异性退化和新生小鼠死亡。在胚胎第11.5天（E11.5）时，神经元增殖减少和缺氧明显，到E15.5时导致大脑皮质中神经元凋亡增加。为了探究观察到的神经系统结构组织变化是否归因于VEGF-A对神经细胞群的直接自分泌作用，我们通过使用巢蛋白Cre转基因，在神经元谱系中特异性地条件性失活主要的VEGF-A受体Flk1。这些小鼠的正常状态排除了VEGF-A/Flk1信号在中枢神经系统发育中具有显著自分泌作用的可能性。因此，VEGF-A剂量是调节发育中的中枢神经系统血管丛密度的关键参数，而血管丛密度又是神经系统发育和结构组织的关键决定因素。
