Pericyte-neuronal crosstalk in health and Alzheimer's Disease

摘要 神经功能和大脑连接需要一个高度协调的神经血管单位(NVU)。神经元和 血管细胞并不仅仅位于相邻的位置；它们通过不同的 信令模块。周细胞是内皮的血管壁细胞，是NVU功能的重要整合细胞， 包括维持血脑屏障(BBB)和血管的完整性，调节血液流动和组织 氧合，调节神经炎症，支持神经元健康。发生周细胞损伤和丢失 常见于中枢神经系统疾病，包括阿尔茨海默病和痴呆症。我们目前的知识暗示了一个 周细胞对神经元功能的关键作用，这需要对周细胞-神经元进行彻底的研究 健康，特别是阿尔茨海默病患者不同神经元功能的通讯。 利用新的三维共培养系统和新的转基因模型，我们发现周细胞可以直接调节 神经发生和神经元功能，这可以归因于周细胞衍生的胰岛素样生长因子2。 IGF2是一种多肽类激素，在调节代谢功能和发育过程中具有多种作用。 携带IGF2突变的人和缺乏IGF2的小鼠表现出强烈的生长缺陷和神经异常 发展。IGF2在大脑中局部产生；然而，大脑IGF2在神经发生和 中枢神经系统疾病中的神经元功能障碍知之甚少。我们的初步研究还表明 IGF2通过激活非规范的IGF2R-GαI-PLC途径介导周细胞-神经元通讯 增强神经元功能，以及刺激规范的PI3K/Akt途径，以促进神经发生或 抑制Tau-磷酸化。在这里，我们建议研究周细胞和细胞之间的功能串扰。 并检测IGF2介导的旁分泌信号对神经发生的影响。 发育(AIM1)，成年神经元成熟和功能(AIM2)，以及AD样发病机制 (AIM3)。遵循严谨和可重复性指南，我们计划：i)探索周细胞-神经元串扰 使用3D共培养系统；ii)通过操纵基因表达来精确定位受体介导的信号传递 和关键激酶活性；iii)确定周细胞特异性IGF2在神经发生和神经元中的作用 在新的周细胞消融和Igf2条件性基因敲除小鼠模型中的功能；iv)检测IGF2- 用复杂的行为学测试和免疫细胞化学方法研究小鼠阿尔茨海默病发病过程中的周细胞-神经元串扰 组织学分析。 我们希望产生第一个证据，证明周细胞-神经元功能对健康和健康的大脑功能有影响 疾病，并在分子水平上明确IGF2介导的周细胞神经元的这种信号转导机制 相声。这一结果可能为研究IGF系统和脑内神经血管相互作用提供新的见解。 缩小代谢性疾病与阿尔茨海默病等中枢神经退行性疾病之间的重要差距。

SUMMARY Neuronal functions and brain connectivity require a highly coordinated neurovascular unit (NVU). Neurons and vascular cells are not just adjacently located; they communicate with each other vigorously via different signaling modules. Pericytes are vascular mural cells of the endothelium and vital integrators of NVU functions, including maintaining the blood-brain barrier (BBB) and vascular integrity, regulating blood flow and tissue oxygenation, modulating neuroinflammation and supporting neuronal health. Pericyte injury and loss occur commonly in CNS diseases including Alzheimer’s disease and dementia. Our current knowledge implicates a critical role of pericytes for neuronal functions, which calls for a thorough investigation of pericyte–neuronal communication for different neuronal functions in health and particularly in Alzheimer’s disease. Using new 3D co-culture systems and novel transgenic models, we found that pericytes can directly regulate neurogenesis and neuronal functions, which can be attributed to pericyte-derived insulin-like growth factor 2. IGF2 is a peptide hormone with multiple roles in regulating metabolic functions and developmental processes. Human with IGF2 mutation and mice lacking IGF2 exhibited strong growth defects with abnormal neural development. IGF2 is produced locally in the brain; however, the roles of brain IGF2 in neurogenesis and neuronal dysfunction in CNS diseases are poorly understood. Our preliminary studies additionally indicated that IGF2 mediates pericyte-neuronal communication by activating a noncanonical IGF2R-Gαi-PLC pathway to enhance neuronal functions, as well as stimulating a canonical PI3K/Akt pathway to promote neurogenesis or suppressing Tau-phosphorylation. Here, we propose to study the functional crosstalk between pericytes and neurons, and examine the influence of IGF2-mediated paracrine signaling on neurogenesis during development (AIM1), on neuronal maturation and functions in adult (AIM2), and on AD-like pathogenesis (AIM3). Follow the Rigor and Reproducibility guidelines, we plan to: i) explore pericyte–neuronal crosstalk using 3D co-culture systems; ii) pinpoint the receptor mediated signaling by manipulating gene expressions and key kinase activities; iii) to determine the role of pericyte-specific IGF2 on neurogenesis and neuronal functions in new pericyte ablation and Igf2 conditional knockout mouse models; iv) examine the role of IGF2- mediated pericyte–neuronal crosstalk during AD-like pathogenies in mice using complex behavioral tests and histological analysis. We hope to generate first evidence of functional pericyte-neuron crosstalk for brain function in health and diseases, and pinpoint the mechanism of this signaling at molecular level for IGF2-mediated pericyte-neuron crosstalk. The outcomes may provide new insights to the IGF system and neurovascular interaction in brain, and close an important gap between metabolic diseases and CNS neurodegenerative diseases such as AD.