Temporal control of progenitor competence shapes maturation in GABAergic neuron development in mice.

Diverse types of GABAergic projection neuron and interneurons of the telencephalon derive from progenitors in a ventral germinal zone called the ganglionic eminence. Using single-cell transcriptomics, chromatin accessibility profiling, lineage tracing, birthdating, transplantation across developmental stages and perturbation sequencing in mouse embryos, we investigated how progenitor competence influences the maturation and differentiation of these neurons. We found that the temporal progression of neurogenesis shapes maturation competence in ganglionic eminence progenitors, influencing how their progeny progress toward mature states. By contrast, differentiation competence-defined as the ability of progenitors to produce diverse transcriptomic identities-was maintained throughout neurogenesis. Chromatin remodeling, together with a regulatory module composed of the transcription factor NFIB and its target genes, influenced maturation competence in late-born neurons. These findings reveal how transcriptional programs and chromatin accessibility govern neuronal maturation and the diversification of GABAergic neuron subtypes during neurodevelopment.