CORTICAL ASTROCYTES FORM FUNCTIONAL SUBPOPULATIONS DEFINED BY INTRINSIC SIGNALING CASCADES IN WILD TYPE AND ALZHEIMER’S DISEASE MICE

Astrocytes play critical roles in brain homeostasis and in Alzheimer’s disease (AD), yet the mechanisms underlying astrocyte heterogeneity remain poorly understood. The aim of this study was to determine whether intrinsic signaling cascades define distinct astrocyte subpopulations in the cortex and to assess their functional relevance in AD. We developed astrocyte-specific fluorescent reporter systems to monitor activation of the JAK2-STAT3 and NF-kB pathways in the prefrontal cortex of wild-type (WT) and APP/PS1dE9 mice. Three astrocyte subpopulations were identified based on selective activation of NF-kB, STAT3, or both pathways. These subpopulations were present in both WT and AD mice and were not influenced by amyloid plaque proximity, indicating that they represent intrinsic cortical astrocyte states rather than pathology-induced phenotypes. Morphological analysis, transcriptomic profiling, and biochemical[CE1] [ED2] characterization revealed distinct molecular signatures and functional properties across subpopulations. To investigate their functional impact, STAT3 or NF-kB signaling was selectively inhibited in astrocytes using pathway-specific lentiviral vectors in the prefrontal cortex of APP/PS1dE9 and WT mice. Selective modulation of each subpopulation differentially affected anxiety-like behavior, social preference, and social memory in APP/PS1dE9 mice only. In conclusion, our findings demonstrate that astrocyte heterogeneity is established by specific intrinsic signaling pathways and that distinct astrocyte subpopulations exhibit specialized morphological, molecular, and functional profiles, with non-redundant contributions to behavioral alterations in AD.