GSE97208
PRDM15 mutation prevents forebrain development through an Otx2 pathway
Acquiring correct brain anatomy and function requires extensive morphogenesis and patterning, which is regulated by a complex gradient of transcription factors. Members of the PR domain containing (PRDM) chromatin-modulating family of transcriptional regulators function in neuronal specification and brain patterning. Little is known about the function of PRDM15, even though it is predicted to have a role in the development of the central nervous system, and lies in the Down syndrome trisomy region of HSA21 and MMU16. Here, we show that PRDM15 is required for forebrain development and repression of hindbrain gene expression. The phenotype of Prdm15 mutants mimics that of Otx2 loss. Using RNA sequencing, we found that a PRDM15 dependent molecular pathway, which includes many homeodomain factors that pattern the forebrain, including OTX2 and PAX6, is disrupted in Prdm15 mutants. Consistent with the role of OTX2 as a master regulator of forebrain development, which represses rostral expansion of the hindbrain to maintain the brain rostro-caudal axis, conditionally inactivating PRDM15 in the forebrain also truncates the forebrain and disrupts the brain rostro-caudal axis. PRDM15 co-expresses with OTX2 in cells of the primordial anterior forebrain, a region where OTX2 is known to function, and PRDM15 binds to the Otx2 promoter, suggesting it may directly impact Otx2 expression. These findings place PRDM15 in the forebrain transcriptional hierarchy for the first time, revealing that PRDM15 is a candidate for pathogenesis in Down syndrome or other neurodevelopmental disorders. Overall design: Six samples were analyzed, including replicates of two for wildtype (Prdm15tm1a+/+), Heterozygote (Prdm15tm1a+/-), and Mutant (Prdm15tm1a-/-)