ANO1/TMEM16A regulates process maturation in radial glial cells in the developing brain

Significance

Radial glial cells (RGCs), a type of neural stem cell in the developing brain, not only generate progenitors, newly born neurons and glial cells, but also deliver neurons through its process to the appropriate cortical target layers. Thus, the function of RGCs is crucial for cortex development, in which Cl ⁻ channels are thought to play a role. Here we highlight that Anoctamin 1 (ANO1)/TMEM16A, a Ca ²⁺-activated Cl ⁻ channel, mediates the process extension in RGCs. ANO1-null mice show a decrease in cortical thickness with disorganized cortical layers. Thus, as a Cl ⁻ channel, ANO1 is involved in the process maturation of RGCs and contributes to cortex development.

Abstract

Neural stem cells (NSCs) are primary progenitor cells in the early developmental stage in the brain that initiate a diverse lineage of differentiated neurons and glia. Radial glial cells (RGCs), a type of neural stem cell in the ventricular zone, are essential for nurturing and delivering new immature neurons to the appropriate cortical target layers. Here we report that Anoctamin 1 (ANO1)/TMEM16A, a Ca ²⁺-activated chloride channel, mediates the Ca ²⁺-dependent process extension of RGCs. ANO1 is highly expressed and functionally active in RGCs of the mouse embryonic ventricular zone. Knockdown of ANO1 suppresses RGC process extension and protrusions, whereas ANO1 overexpression stimulates process extension. Among various trophic factors, brain-derived neurotrophic factor (BDNF) activates ANO1, which is required for BDNF-induced process extension in RGCs. More importantly, Ano1-deficient mice exhibited disrupted cortical layers and reduced cortical thickness. We thus conclude that the regulation of RGC process extension by ANO1 contributes to the normal formation of mouse embryonic brain.