Department of Surgery, Robert Wood Johnson Medical School-University of Medicine and Dentistry of New Jersey, New Brunswick, 08903-0019, USA.
Arterioscler Thromb Vasc Biol. 2011 Aug;31(8):1861-70. doi: 10.1161/ATVBAHA.111.230144. Epub 2011 Jun 9.
The goal of this study was to determine the role of Cdc42 in embryonic vasculogenesis and the underlying mechanisms.
By using genetically modified mouse embryonic stem (ES) cells, we demonstrate that ablation of the Rho GTPase Cdc42 blocks vascular network assembly during embryoid body (EB) vasculogenesis without affecting endothelial lineage differentiation. Reexpression of Cdc42 in mutant EBs rescues the mutant phenotype, establishing an essential role for Cdc42 in vasculogenesis. Chimeric analysis revealed that the vascular phenotype is caused by inactivation of Cdc42 in endothelial cells rather than surrounding cells. Endothelial cells isolated from Cdc42-null EBs are defective in directional migration and network assembly. In addition, activation of atypical protein kinase Cι (PKCι) is abolished in Cdc42-null endothelial cells, and PKCι ablation phenocopies the vascular abnormalities of the Cdc42-null EBs. Moreover, the inhibitory phosphorylation of glycogen synthase kinase-3β (GSK-3β) at Ser9 depends on Cdc42 and PKCι, and expression of kinase-dead GSK-3β in Cdc42-null EBs promotes the formation of linear endothelial segments without branches. These results suggest that PKCι and GSK-3β are downstream effectors of Cdc42 during vascular morphogenesis.
Cdc42 controls vascular network assembly but not endothelial lineage differentiation by activating PKCι during embryonic vasculogenesis.
本研究旨在确定 Cdc42 在胚胎血管生成中的作用及其潜在机制。
通过使用基因修饰的小鼠胚胎干细胞（ES 细胞），我们证明 Rho GTPase Cdc42 的缺失会阻止类胚体（EB）血管生成过程中的血管网络组装，而不影响内皮谱系分化。在突变型 EB 中重新表达 Cdc42 可挽救突变表型，从而确立了 Cdc42 在血管生成中的重要作用。嵌合体分析表明，血管表型是由于内皮细胞而非周围细胞中 Cdc42 的失活引起的。从 Cdc42 缺失型 EB 中分离出的内皮细胞在定向迁移和网络组装方面存在缺陷。此外，Cdc42 缺失型内皮细胞中异常蛋白激酶 Cι（PKCι）的激活被废除，并且 PKCι 的缺失可模拟 Cdc42 缺失型 EB 的血管异常。此外，糖原合酶激酶-3β（GSK-3β）在 Ser9 的抑制性磷酸化依赖于 Cdc42 和 PKCι，并且在 Cdc42 缺失型 EB 中表达激酶失活型 GSK-3β可促进无分支的线性内皮段的形成。这些结果表明，在胚胎血管生成过程中，PKCι 和 GSK-3β 是 Cdc42 的下游效应物。
Cdc42 通过在胚胎血管生成过程中激活 PKCι 来控制血管网络组装，但不控制内皮谱系分化。
