Basic Science and Pathogenesis.

Area of Science:

• Neuroscience
• Genomics
• Molecular Biology

Background:

• Single-nucleus RNA sequencing (snRNA-seq) has improved understanding of astrocyte heterogeneity.
• Variability in study designs complicates the interpretation of astrocyte heterogeneity, obscuring true biological differences from technical variations.
• Astrocyte subpopulations, their regional distribution, and disease responses remain poorly understood.

Purpose of the Study:

• To uniformly analyze human snRNA-seq datasets to resolve astrocyte heterogeneity across brain regions and neurodegenerative diseases (NDs).
• To identify conserved astrocyte subpopulations and their molecular characteristics.
• To elucidate common molecular mechanisms and potential therapeutic targets in NDs.

Main Methods:

• Uniform analysis of eight human snRNA-seq datasets from seven brain regions and six NDs.
• Comparison of astrocyte heterogeneity, transcriptional regulation, and disease-associated transcriptomic changes.
• Functional validation of identified astrocyte-specific genes (PBX1, SOX2) in primary astrocytes and model organisms.

Main Results:

• Identification of three conserved astrocyte subpopulations (Ast-0, Ast-1, Ast-2) across datasets.
• Ast-1 showed enrichment for amyloid-beta binding and ND-related pathways, suggesting a specific role in neurodegeneration.
• Coordinated differential gene expression (DEGs) and dysregulation of Wnt and endolysosomal pathways across all NDs and brain regions, indicating common pathogenic mechanisms.
• Identification of known and novel disease risk genes through DEG frequency analysis.
• Functional validation confirmed astrocyte-specific roles for PBX1 and SOX2.

Conclusions:

• Astrocyte-specific molecular changes are shared across multiple NDs and brain regions.
• These conserved changes illuminate common pathogenic mechanisms underlying various dementias.
• The identified molecular signatures and pathways offer potential novel therapeutic targets for NDs.