STARGAZING: HOW ARE ASTROCYTES MADE? ROLE OF ZEB1 IN TRANSCRIPTIONAL REGULATION OF ASTROCYTE SPECIFICATION ACROSS DEVELOPMENT AND ADULTHOOD

Astrocytes are integral to neural function, yet the transcription factors regulating their specification, maturation and maintenance remain under-characterised. Conditional knockout of Zinc-finger E-box binding homeobox 1 (Zeb1) in neural progenitor cells of the adult hippocampus impaired de novo astrocyte generation, driving fate commitment towards the neurogenic fate. This placed Zeb1 as a potential candidate in the transcriptional regulation of astrogliogenesis. While Zeb1 is expressed in all adult astrocytes, its specific targets and functional roles are unknown. Whether these roles are globally homogenous or regionally specified to suit the microcircuitry are also not known. Combining bulk RNA-Sequencing and morphometric reconstruction, we investigated Zeb1 function in an inducible, astrocyte-specific knockout mouse model (GLAST::CreER^T2, Rosa26-tdTomato, Zeb1 ^flox/flox).
Transcriptomic profiling of FACS-purified astrocytes across five brain regions revealed significant differential gene expression in the cortex, hippocampus, and striatum, suggesting Zeb1 exerts context-dependent regulatory control. Long-term morphological assessment (8 weeks to 6 months post-induction) demonstrated that Zeb1 deletion reduces astrocytic density in the cortex and thalamus. Furthermore, knockout astrocytes exhibited a progressive, "shrunken" phenotype with significantly diminished arborisation and breached tiling.
These findings identify Zeb1 as a potential critical regulator of astrocyte structural integrity and heterogeneity. Uncovering these region-specific pathways holds potential to provide a crucial foundation for understanding the selective vulnerability of neural circuits in pathology.