Fish Jason E, Flores Suarez Carlos Perfecto, Boudreau Emilie, Herman Alexander M, Gutierrez Manuel Cantu, Gustafson Dakota, DiStefano Peter V, Cui Meng, Chen Zhiqi, De Ruiz Karen Berman, Schexnayder Taylor S, Ward Christopher S, Radovanovic Ivan, Wythe Joshua D
From the Toronto General Hospital Research Institute (J.E.F., E.B., D.G., P.V.D., Z.C.), University Health Network, Canada.
Peter Munk Cardiac Centre (J.E.F.), University Health Network, Canada.
Circ Res. 2020 Aug 28;127(6):727-743. doi: 10.1161/CIRCRESAHA.119.316500. Epub 2020 Jun 17.
We previously identified somatic activating mutations in the () gene in the endothelium of the majority of human sporadic brain arteriovenous malformations; a disorder characterized by direct connections between arteries and veins. However, whether this genetic abnormality alone is sufficient for lesion formation, as well as how active KRAS signaling contributes to arteriovenous malformations, remains unknown.
To establish the first in vivo models of somatic KRAS gain of function in the endothelium in both mice and zebrafish to directly observe the phenotypic consequences of constitutive KRAS activity at a cellular level in vivo, and to test potential therapeutic interventions for arteriovenous malformations.
Using both postnatal and adult mice, as well as embryonic zebrafish, we demonstrate that endothelial-specific gain of function mutations in (G12D or G12V) are sufficient to induce brain arteriovenous malformations. Active KRAS signaling leads to altered endothelial cell morphogenesis and increased cell size, ectopic sprouting, expanded vessel lumen diameter, and direct connections between arteries and veins. Furthermore, we show that these lesions are not associated with altered endothelial growth dynamics or a lack of proper arteriovenous identity but instead seem to feature exuberant angiogenic signaling. Finally, we demonstrate that KRAS-dependent arteriovenous malformations in zebrafish are refractory to inhibition of the downstream effector PI3K but instead require active MEK (mitogen-activated protein kinase kinase 1) signaling.
We demonstrate that active KRAS expression in the endothelium is sufficient for brain arteriovenous malformations, even in the setting of uninjured adult vasculature. Furthermore, the finding that KRAS-dependent lesions are reversible in zebrafish suggests that MEK inhibition may represent a promising therapeutic treatment for arteriovenous malformation patients. Graphical Abstract: A graphical abstract is available for this article.
我们之前在大多数人类散发性脑动静脉畸形的内皮细胞中鉴定出了（）基因的体细胞激活突变；脑动静脉畸形是一种以动脉和静脉直接相连为特征的疾病。然而，仅这种基因异常是否足以形成病变，以及活跃的KRAS信号如何导致动静脉畸形，仍不清楚。
在小鼠和斑马鱼中建立内皮细胞中体细胞KRAS功能获得的首个体内模型，以在体内细胞水平直接观察组成型KRAS活性的表型后果，并测试动静脉畸形的潜在治疗干预措施。
使用新生和成年小鼠以及胚胎斑马鱼，我们证明（G12D或G12V）在内皮细胞中的功能获得性突变足以诱导脑动静脉畸形。活跃的KRAS信号导致内皮细胞形态发生改变和细胞大小增加、异位发芽、血管腔直径扩大以及动脉和静脉之间的直接连接。此外，我们表明这些病变与内皮细胞生长动力学改变或动静脉特征缺失无关，而是似乎具有旺盛的血管生成信号。最后，我们证明斑马鱼中KRAS依赖性动静脉畸形对下游效应物PI3K的抑制具有抗性，但需要活跃的MEK（丝裂原活化蛋白激酶激酶1）信号。
我们证明内皮细胞中活跃的KRAS表达足以导致脑动静脉畸形，即使在未受损的成年脉管系统中也是如此。此外，KRAS依赖性病变在斑马鱼中可逆的发现表明，MEK抑制可能是动静脉畸形患者一种有前景的治疗方法。图形摘要：本文有图形摘要。
