Astrocyte allocation during brain development is controlled by Tcf4-mediated fate restriction
Astrocytes within specific brain regions contribute uniquely to regional circuits for higher-order brain function through interactions with local neurons. The regional diversification of astrocytes is dictated by their embryonic origin, yet the mechanisms governing their regional allocation remain unknown. Here we show that allocation of astrocytes to specific brain regions requires the transcription factor 4 (Tcf4) mediated fate restriction during brain development. Loss of Tcf4 in ventral telencephalic neural progenitors alters the fate of oligodendrocyte precursors to transient intermediate astrocyte precursor cells, resulting in mislocated astrocytes in the dorsal neocortex. These ectopic astrocytes originated from the ventral telencephalon engage with neurons and acquire features reminiscent of local neocortical astrocytes. Furthermore, Tcf4 functions as a suppressor of astrocyte fate during differentiation of oligodendrocyte precursors, thereby restricting the fate to oligodendrocyte lineage. Our study reveals that fate restriction governs regional astrocyte allocation, contributing to astrocyte diversification across brain regions. Overall design: For all expresiments, cells from the Nkx2.1 lineage in the neocortex from control and Tcf4 cKO mice  were collected by FACS sorting. After cell variablity checking,  single cell sequencing library were prepared using 10x Genomics Chromium Single Cell 3`v3 assays, or ATACseq and cut and tag were performed.