Imprinted expression in genetically defined cell-types in cerebral cortex

In mammalian genomes a subset of genes is regulated by genomic imprinting resulting in silencing of one parental allele. Imprinting is essential for cerebral cortex development but prevalence and functional impact in individual cells is unclear. Here we determined allelic expression in cortical cell types and established a quantitative platform to interrogate imprinting in single cells. We created cells with uniparental disomy (UPD) containing either two copies of the maternal or paternal chromosome hence imprinted genes will be twofold overexpressed or not expressed. By genetic labeling of UPD we determined cellular phenotypes and transcriptional responses to deregulated imprinted gene expression at unprecedented single cell resolution. We discovered an unexpected degree of cell type specificity and a novel function of imprinting in the regulation of cortical astrocyte survival. More generally our results suggest functional relevance of imprinted gene expression in glial astrocyte lineage and thus for generating cortical cell type diversity.