Somatic Gain of KRAS Function in the Endothelium Is Sufficient to Cause Vascular Malformations That Require MEK but Not PI3K Signaling
Somatic Gain of KRAS Function in the Endothelium Is Sufficient to Cause Vascular Malformations That Require MEK but Not PI3K Signaling
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DOI：
10.1161/circresaha.119.316500
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发表时间：
2020-08-28
影响因子：
20.1
通讯作者：
Wythe, Joshua D.
中科院分区：
文献类型：
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作者：
Fish, Jason E.;Flores-Suarez, Carlos Perfecto;Wythe, Joshua D.
基本原理：我们先前在大多数人散发性脑动静脉畸形的内皮细胞中发现了KRAS（Kirsten大鼠肉瘤病毒癌基因同源物）基因的体细胞激活突变;这种疾病的特征是动脉和静脉之间的直接连接。然而，这种遗传异常是否足以形成病变，以及活跃的KRAS信号如何促成动静脉畸形，仍然是未知的。目的：建立小鼠和斑马鱼内皮细胞中体细胞KRAS功能获得的第一个体内模型，以直接观察体内细胞水平上组成性KRAS活性的表型结果，并测试动静脉畸形的潜在治疗干预。方法和结果：使用出生后和成年小鼠，以及胚胎斑马鱼，我们证明，内皮特异性功能的Kras（G12 D或G12 V）突变增益足以诱导脑动静脉畸形。活跃的KRAS信号传导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，我们发现这些病变与内皮生长动力学改变或缺乏适当的动静脉特性无关，但似乎具有旺盛的血管生成信号。最后，我们证明了斑马鱼的KRAS依赖性动静脉畸形是难以抑制的下游效应PI 3 K，而是需要主动MEK（丝裂原活化蛋白激酶激酶1）信号。结论：我们证明，即使在未受伤的成人血管系统中，内皮细胞中活跃的KRAS表达也足以治疗脑动静脉畸形。此外，KRAS依赖性病变在斑马鱼中是可逆的这一发现表明，MEK抑制可能代表了动静脉畸形患者有希望的治疗方法。
Rationale: We previously identified somatic activating mutations in theKRAS(Kirsten rat sarcoma viral oncogene homologue) 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. Objective: 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. Methods and Results: Using both postnatal and adult mice, as well as embryonic zebrafish, we demonstrate that endothelial-specific gain of function mutations inKras(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. Conclusions: 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.