Downstream molecular mechanisms underlying cerebral cavernous malformation

摘要--项目3 我们小组和其他人最近的研究发现，MEKK3-KLF2/4信号是 CCM复合功能的直接目标，并表明CCM功能的丧失赋予 MEKK3信号增强和KLF2、KLF4升高导致的病变形成 在脑内皮细胞中的表达。出乎意料的是，我们还发现内皮细胞 肠道革兰氏阴性菌脂多糖对TLR4的激活作用 微生物组在激活MEKK3-KLF2/4信号中起中心上游作用 在小鼠和人类中都形成了CCM。这些发现在现在达到了顶峰 被广泛接受的CCM疾病模型，但KLF2通过其下游效应分子 而KLF4驱动病变的形成尚不清楚。我们的初步研究揭示了两个 对推动CCM形成的下游事件的新见解：1)PI3K收益 功能与CCM功能丧失协同作用，推动小鼠和 大多数手术切除的人CCM病变，以及2)周围的ADAMTS卵裂。 血管变态反应驱动小鼠的CCM表型。项目3将定义 在CCM发病过程中PI3K信号转导和多种蛋白分解 新开发的小鼠遗传模型。这些研究将有力地补充那些 在项目1和核心A中，检查了人类CCM病变中的PIK3CA突变和 野生型内皮细胞参与的细胞非自主机制 CCM病变。最重要的是，我们预计这些研究将迅速转化为 通过为使用FDA批准的药物(如PI3K)提供支持 途径抑制剂雷帕霉素治疗CCM病。

SUMMARY – PROJECT 3 Recent studies by our group and others have identified MEKK3-KLF2/4 signaling as the direct target of CCM complex function, and showed that loss of CCM function confers lesion formation through gain of MEKK3 signaling and elevated KLF2 and KLF4 expression in brain endothelial cells. Unexpectedly, we have also found that endothelial TLR4 activation by lipopolysaccharide derived from gram negative bacteria in the gut microbiome plays a central, upstream role in the activation of MEKK3-KLF2/4 signaling and CCM formation in both mice and humans. These findings have culminated in a now widely accepted model of CCM disease, but the downstream effectors by which KLF2 and KLF4 drive lesion formation remain unknown. Our preliminary studies reveal two new insights into the downstream events that drive CCM formation: 1) PI3K gain of function synergizes with CCM loss of function to drive lesion formation in mice and a majority of surgically resected human CCM lesions, and 2) ADAMTS cleavage of peri- vascular versican drives the CCM phenotype in mice. Project 3 will define the roles of PI3K signaling and versican proteolysis during CCM pathogenesis using established and newly developed mouse genetic models. These studies will strongly complement those in Project 1 and Core A that examine the PIK3CA mutations in human CCM lesions and a cell non-autonomous mechanism by which wild-type endothelial cells contribute to CCM lesions. Most importantly, we expect these studies to be rapidly translated to the clinic by providing support for the use of FDA-approved agents such as the PI3K pathway inhibitor rapamycin to treat CCM disease.