Protein arginine methylation in the control of neural stem cell “stemness” and differentiation (360G-Wellcome-201941_Z_16_Z)

During development cortical neuroepithelial stem cells (NSCs) generate all the neurons and glia of the central nervous system in a precise spatiotemporal manner. Aberrations of this process are linked to neurological diseases, e.g., autism, schizophrenia, mental retardation. The molecular mechanisms controlling NSCs’ transition from "stemness" to differentiation remain elusive. We recently identified a novel regulatory complex, comprised of PRDM4 protein and the protein arginine methyltransferase 5 (PRMT5), whose activity maintains NSC "stemness" in vitro. We hypothesise that PRDM4/PRMT5-mediated protein arginine methylation (R-Me) is necessary to maintain NSC "stemness". To explore this hypothesis, we generated mice with the cortical NSC-specific deletion of PRDM4 (PRDM4fl/fl;Emx1-Cre) and analysed proteome-wide changes in R-Me of these mice. We propose to test our hypothesis by investigating the biological outcomes of the observed reduction in R-Me and validating the strongest candidate of the proteomic screen, KSRP protein, biochemically. We will: 1) characterise differentiation profiles of NSCs from the mutant mice, 2) biochemically characterise PRDM4:PRMT5-mediated KSRP-R-Me in vivo, using PRDM4fl/fl:Emx1-Cre and control tissue, and in vitro. Achieving these goals will validate a novel mechanism of NSC "stemness" control, mediated by protein R-Me, providing the basis for further investigations into its role in NSC reprogramming and neurological diseases.