Presenilin1/gamma-secretase regulate the VEGFA/VEGFR2 brain angiogenesis inhibited by FAD mutants.

摘要 脑血管系统是神经元生存和功能的中心，最近的证据表明 血管脑异常参与了脑血管病的发生和神经病理生理过程。 阿尔茨海默病(AD)等神经退行性疾病。血管生成，新血液的产生 来自现有血管系统的血管，在整个成年生活中对维持脑血液循环和 用于毒性损伤的修复机制，如缺血和缺氧。血管生成受生长控制 因子包括血管内皮细胞生长因子(VEGFs)。通过与它们的受体(VEGFRs)结合， 血管内皮生长因子调节新血管的形成，维持组织和器官的血液供应。突变体 蛋白Presenilin1(PS1)引起家族性AD(FAD)，构成了一个AD样发病机制的系统 可以研究神经退行性变。PS1的一个正常功能是作为一种蛋白酶，称为γ-分泌酶，它 处理I型膜受体。 在这里，我们提出了PS1/γ-分泌酶系统处理VEGFR2的证据，已知VEGFR2在其中起关键作用 在调节血管系统中的作用，包括脑血管系统。关键的血管生成功能 血管内皮细胞生长因子受体2的二聚化、内化及其下游血管生成信号 (ECS)。我们还发现，抑制γ-分泌酶活性可以减少VEGFA诱导的二聚化 VEGFR2及VEGFR2介导的原代皮质内皮细胞的血管生成功能 萌发、管形成、细胞迁移和血管生成复合体的形成。总而言之，我们的数据表明 γ-分泌酶调节血管内皮生长因子2刺激的血管生成功能。重要的是，我们发现 PS1FAD突变体降低血管内皮生长因子诱导的γ分泌酶的加工和二聚化 VEGFA刺激的血管生成信号和内皮细胞的功能。总而言之，我们的数据表明PS1流行 突变体减弱VEGFA诱导的脑内皮细胞血管生成功能 FAD突变通过降低血管生成功能和组织修复导致神经元功能障碍和死亡 大脑。在这个应用中，我们探索了PS1及其FAD突变体与VEGFR2和VEGFR2的相互作用 探讨这种相互作用在VEGFA诱导和VEGFR2介导的血管生成中的重要性 大脑的信号和功能。我们还利用小鼠模型研究了γ-分泌酶活性调节VEGFA/VEGFR2系统血管生成信号的机制，并测试了PS1的作用 和PS1FAD突变体在VEGFA和缺血刺激的脑血管生成中的作用。我们还探索了 人类FAD和散发性AD脑组织中血管生成功能障碍的特征。

Summary The cerebrovascular system is central to neuronal survival and function and recent evidence suggests that vascular brain abnormalities are involved in the development and neuropathophysiology of neurodegenerative disorders such as Alzheimer disease (AD). Angiogenesis, the generation of new blood vessels from existing vasculature, is crucial throughout adult life for maintaining brain blood circulation and for reparative mechanisms of toxic insults such as ischemia and hypoxia. Angiogenesis is controlled by growth factors including the Vascular Endothelial Growth Factors (VEGFs). By binding to their receptors (VEGFRs), VEGFs regulate formation of new blood vessels and maintain blood supply to tissues and organs. Mutants of the protein Presenilin1 (PS1) cause Familial AD (FAD) constituting a system where mechanisms of AD-like neurodegeneration can be studied. A normal function of PS1 is to act as a protease, called γ-secretase, which processes type I membrane receptors. Here we present evidence that the PS1/γ-secretase system processes VEGFR2 that is known to play crucial roles in the regulation of the vascular system, including the brain vasculature. Critical angiogenic functions of VEGFR2 include its dimerization, internalization and downstream angiogenic signaling of endothelial cells (ECs). We also found that inhibition of the γ-secretase activity decreases the VEGFA-induced dimerization of VEGFR2 and the VEGFR2-mediated angiogenenic functions of primary cortical ECs (pCECs) such as sprouting, tube formation, cell migration and angiogenic complex formation. Together, our data suggest that γ-secretase regulates the VEGFA-stimulated angiogenic functions of VEGFR2. Importantly, we found that PS1 FAD mutants decrease the VEGFA-induced γ-secretase processing and dimerization of VEGFR2 and the VEGFA-stimulated angiogenic signaling and functions of ECs. Together, our data indicate that PS1 FAD mutants attenuate the VEGFA-induced angiogenic functions of brain ECs suggesting a mechanism by which FAD mutants cause neuronal dysfunction and death by decreasing angiogenic functions and tissue repair of the brain. In this application, we explore the interactions of PS1 and its FAD mutants with VEGFR2 and explore the importance of this interaction to the VEGFA-induced and VEGFR2-mediated angiogenenic signaling and functions of the brain. We also use mouse models to examine mechanisms by which γ-secretase activity regulates angiogenic signaling of the VEGFA/VEGFR2 system, and test the roles of PS1 and PS1FAD mutants in the VEGFA- and ischemia-stimulated brain angiogenesis. We also explore signatures of angiogenic dysfunction in human FAD and sporadic AD brain tissue.