Pannexin-1 regulates cellular identity and excitability in the developing cortex

Abstract Mutations in genes encoding a range of ion-conducting proteins disrupt development of the cerebral cortex in humans, often causing polymicrogyria (PMG); yet how ion conduction guides the development of cortical architecture is not clear. Here, we describe three individuals with brain malformations including PMG and microcephaly in whom de novo, missense mutations were identified in PANX1 – encoding an ATP and ion conducting channel. We show that these PMG-associated PANX1 mutations (p.D14H, p.M37R, and p.N338T) disrupt normal glycosylation and confer gain-of-function with respect to ATP release and channel conductance. In vivo modeling of mutant PANX1 in cortical progenitor cells demonstrated disrupted cell migration and excess cell death in both mice and ferret models. In vitro modeling of the p.N338T allele in human induced pluripotent stem cell (hiPSC)-derived neurons further revealed changes in neuronal morphology and increased excitability, and dysregulation of key transcription factors critical for neurogenesis and cell fate. In addition, p.N338T iPSC-derived neural progenitor cells displayed increased PANX1 activation. Our results show that normal PANX1 function contributes to cortical structure through regulation of ion conductance and ATP release and provides insight into how these processes influence corticogenesis and cytoarchitecture more broadly. Significance Statement The purpose of ionic flux in human cortical histogenesis remains poorly examined. The recent identification of mutations in the gene encoding the ATP-releasing ion channel Pannexin 1 (PANX1) associated with polymicrogyria (PMG) provides a window for investigating processes of brain development regulated by ion and metabolite flux. In this study, we apply a combination of in vitro and in vivo approaches to both establish the pathogenicity of PANX1 -associated PMG mutations and elaborate how perturbations in PANX1 disrupt cortical architecture. Our findings not only provide insight into the pathogenesis of PMG, but also further establish that conductive membrane properties of cortical progenitors influence neuronal identity and migration during neurogenesis.