FORTIFY - From Molecular Physiology to Biophysics of the Glymphatic System: a Regulatory Role for Aquaporin-4

每天从大脑中清除废物的过程是沿着血管周围空间进行的。在睡眠期间，流经这种“淋巴系统”的液体流量增加，其损害导致各种中枢神经系统(CNS)紊乱。淋巴交换由水通道水通道4(AQP4)支持，并被认为是由动脉搏动性和中枢神经系统流体动力学驱动的，这些流体在一天中都会发生变化。然而，星形胶质细胞跨膜水流量、脑血管机械生物学和睡眠之间的机制联系尚不清楚。Fortify项目将定义这些联系，并揭示它们是如何控制淋巴功能的。我将研究我的新概念，即动态的AQP4亚细胞重新定位是脑水稳态的主要调节因素。我假设，从睡眠到醒来的机械生物学因素的变化通过动态调节星形胶质细胞表面AQP4的丰度来调节淋巴流量。这反过来又控制了星形胶质细胞末端足部之间的间隙大小，从而控制了血管周围屏障的孔洞。使用独特的“芯片上的胶质血管接口”将允许测量末端足部的形态、AQP4丰度和示踪剂动力学，以响应特定的生物物理输入。活体双光子成像将证实我在活体大脑中的发现。对淀粉样蛋白-β清除受损的啮齿动物模型的纵向研究将建立星形细胞AQP4定位调节和中枢神经系统废物清除障碍之间的机制联系。我独特的复合筛选将识别AQP4本地化的调节剂，这些调节剂有可能成为未来治疗认知衰退的疗法。总体而言，Fortify将通过连接分子和宏观控制机制来创建对淋巴调节的整体理解。它的实验结果将定义动态的AQP4亚细胞重新定位如何调节一生中健康的脑废物清除，并将建立治疗神经退行性变的新途径。

The daily clearance of waste products from the brain occurs along perivascular spaces. Fluid flow through this "glymphatic system" is elevated during sleep and its impairment leads to diverse central nervous system (CNS) disorders. Glymphatic exchange is supported by the water channel, aquaporin-4 (AQP4), and is thought to be driven by arterial pulsatility and CNS fluid dynamics that vary throughout the day. However, mechanistic linkages between astroglial transmembrane water flow, cerebrovascular mechanobiology and sleep are unclear. The FORTIFY project will define these linkages and reveal how they control glymphatic function. I will investigate my novel concept that dynamic AQP4 subcellular relocalisation is a master regulator of brain water homeostasis. I hypothesise that sleep-to-wake changes in mechanobiological factors regulate glymphatic flux through the dynamic regulation of AQP4 abundance at the astrocyte cell surface. This in turn controls the gap size between astrocyte endfeet and hence the porosity of the perivascular barrier. Use of a unique "gliovascular interface-on-a-chip" will allow measurement of endfoot morphology, AQP4 abundance and tracer kinetics in response to defined biophysical inputs. In vivo 2-photon imaging will confirm my findings in the living brain. Longitudinal studies in rodent models of impaired amyloid-beta clearance will establish mechanistic links between the regulation of astrocytic AQP4 localisation and dysfunctional CNS waste clearance. My unique compound screens will identify modulators of AQP4 localisation that have potential as future therapeutics to treat cognitive decline. Overall, FORTIFY will create a holistic understanding of glymphatic regulation by bridging molecular and macroscopic control mechanisms. Its experimental outcomes will define how dynamic AQP4 subcellular relocalisation regulates healthy brain waste clearance across the lifespan and will establish novel routes to treat neurodegeneration.