Mafb and c-Maf Have Prenatal Compensatory and Postnatal Antagonistic Roles in Cortical Interneuron Fate and Function

Mafb and c-Maf transcription factor (TF) expression is enriched in medial ganglionic eminence (MGE) lineages, beginning in late-secondary progenitors and continuing into mature parvalbumin (PV+) and somatostatin (SST+) interneurons. However, the functions of Maf TFs in MGE development remain to be elucidated. Herein, Mafb and c-Maf were conditionally deleted, alone and together, in the MGE and its lineages. Analyses of Maf mutant mice revealed redundant functions of Mafb and c-Maf in secondary MGE progenitors, where they repress the generation of SST+ cortical and hippocampal interneurons. By contrast, Mafb and c-Maf have distinct roles in postnatal cortical interneuron (CIN) morphological maturation, synaptogenesis, and cortical circuit integration. Thus, Mafb and c-Maf have redundant and opposing functions at different steps in CIN development.