RNA-binding protein quaking (Qk) promotes switching from neurogenesis to gliogenesis of neural stem cells during brain development [P7 cortex]

During mammalian brain development, neural stem cells (NSCs) initially produce only neurons and subsequently shift to glial production, while it is still unknown what regulates this drastic fate change. Here we discovered RNA-binding protein (RBP) of quaking (Qk) is selectively expressed in NSCs and is essential for switching from neurogenesis to gliogenesis. Using CNS-specific KO mice for Qk, we found that gliogenesis, but not neurogenesis, was specifically disrupted in Qk-/- brains. In glial differentiating condition, Qk-/- NSCs failed to enter gliogenesis but caused ectopic neurogenic gene expression. Pathway analysis of Qk-/- NSCs identified endocytosis as the regulatory functional cluster of Qk which has been shown to facilitate extra-cellular signaling receptors replacement and promote NSC differentiation. Mechanistically, Qk regulates endocytosis pathway genes through stabilizing their mRNAs via Qk binding sequences in 3'UTR. These results uncovered the cell fate determination mechanism of NSCs through mRNA regulation. Overall design: We analyzed mRNA expression in cerebral cortices from 3 control & 3 Qk-/- P7 mouse brains