Frazer, SarahSarahFrazerPrados, JulienJulienPradosNiquille, MathieuMathieuNiquilleCadilhac, ChristelleChristelleCadilhacMarkopoulos, FoivosFoivosMarkopoulosGomez Teijeiro, LuciaLuciaGomez TeijeiroTomasello, UgoUgoTomaselloTelley, LudovicLudovicTelleyHoltmaat, AnthonyAnthonyHoltmaatJabaudon, DenisDenisJabaudonDayer, AlexandreAlexandreDayer2024-11-192024-11-1920172041-172310.24451/arbor.22051https://doi.org/10.24451/arbor.2205110.1038/ncomms14219https://arbor.bfh.ch/handle/arbor/38559Cortical GABAergic interneurons constitute a highly diverse population of inhibitory neurons that are key regulators of cortical microcircuit function. An important and heterogeneous group of cortical interneurons specifically expresses the serotonin receptor 3A (5-HT3AR) but how this diversity emerges during development is poorly understood. Here we use single-cell transcriptomics to identify gene expression patterns operating in Htr3a-GFP+ interneurons during early steps of cortical circuit assembly. We identify three main molecular types of Htr3a-GFP+ interneurons, each displaying distinct developmental dynamics of gene expression. The transcription factor Meis2 is specifically enriched in a type of Htr3a-GFP+ interneurons largely confined to the cortical white matter. These MEIS2-expressing interneurons appear to originate from a restricted region located at the embryonic pallial–subpallial boundary. Overall, this study identifies MEIS2 as a subclass-specific marker for 5-HT3AR-containing interstitial interneurons and demonstrates that the transcriptional and anatomical parcellation of cortical interneurons is developmentally coupled.enQ1QPR1article