Regional und subregional heterogeneity of astrocytes as determinants for viscoelastic tissue properties, neuronal function, and aging

近年来，星形胶质细胞揭示了越来越多的多样性和个体特征，但这些异质表型在多大程度上有助于特定功能，特别是在生命和认知的各个阶段对神经元活动的微调，这在很大程度上是未知的。在本提案中，我们的目标是通过使用最近开发的BONCAT， FUNCAT和GINCAT技术对共培养，急性切片和活转基因小鼠中的星形胶质细胞进行细胞类型选择性蛋白质组学分析，扩展我们之前在星形胶质细胞分子，细胞和区域异质性研究方面的工作。我们将讨论星形胶质细胞异质性对不同年龄小鼠突触可塑性的影响，以及在模拟衰老大脑的特定培养系统中，特别强调星形胶质细胞的蛋白质翻译调节和机械刚度特性的调节。此外，我们将研究星形胶质蛋白合成的调节以及依赖于机械敏感调节的蛋白质周转，作为可能促进衰老大脑变化的一个候选。为此，我们将使用机械敏感阳离子通道（MSC）的激动剂和抑制剂，特别关注蛋白质合成的空间组织，以及与星形胶质细胞异质性相关的星形胶质微域的蛋白质周转和局部稳定性。最后，我们将讨论已知的脑功能恢复剂对星形胶质细胞的影响及其在海马中的异质性。最终，这项工作将有助于理解认知功能的基础，特别是认知功能的下降。

In the recent years, astrocytes unravel more and more diverse and individual characteristics but in how far these heterogeneous phenotypes contribute to specific functions and particularly to a fine-tuning of neuronal activity throughout all stages of life and cognition is largely unknown.In this proposal, we aim to extend our previous work on the investigation of molecular, cellular and regional astroglial heterogeneity by performing cell type-selective proteomic profiling of astrocytes in cocultures, acute slices and in living transgenic mice using the recently developed techniques BONCAT, FUNCAT and GINCAT. We will address the consequences of astroglial heterogeneity for synaptic plasticity at different ages in mice as well as in selected culture systems mimicking the aging brain with a special emphasis on protein translation regulation and modulation of mechanical stiffness properties by astrocytes. Furthermore, we will investigate regulation of astroglial protein synthesis as well as protein turnover depending on mechanosensitive modulation, being one candidate that might promote changes in the aging brain. For this we will use agonists and inhibitors of mechanosensitive cation channels (MSC) with a special focus on the spatial organization of protein synthesis, as well as protein turnover and local stability in astroglial microdomains with regards to astrocytic heterogeneity. Finally, we will address the effect of known rejuvenators of brain function on astrocytes and their heterogeneity in the hippocampus. Ultimately, this work shall help to understand the underpinnings of cognitive function in general as well as cognitive decline in particular.