SAFB regulates hippocampal stem cell fate by targeting Drosha to destabilize Nfib mRNA

Neural stem cell regulation is essential for the formation of the central nervous system and homeostatic neurogenesis in the adult mammalian brain. The RNAseIII Drosha, a key component of the miRNA microprocessor, plays a central role in regulating NSC maintenance partially through a miRNA-independent mechanism. Drosha controls mRNA expression levels by targeting and cleaving evolutionary conserved stem-loop hairpins located in the mRNAs of stem cell-related transcription factors. However, it is unknown how the Drosha-mediated endonucleolytic cleavage of mRNA is regulated. Here, we identify novel Drosha and NFIB interactors in hippocampal NSCs by in vitro pull-down assays followed by Mass Spectrometry. We unravel the RNA binding proteins implicated in Drosha-mediated regulation of neurogenesis and we find Scaffold Attachment Factor B1 to play a novel and essential role in NFIB mRNA regulation during neural stem cell differentiation.