The essentialome of imprinting genes in early embryonic development reveals therapeutic targets of imrpinting disorders

Imprinted genes are expressed in uniparental fashion and their transcription is controlled by differentially methylated regions. Genomic imprinting regulates early human development and is involved in multiple disorders such as Angelman-syndrome, Beckwith-Wiedemann-Syndrome, Prader-Willi-syndrome, and Russel-Silver-syndrome. Previous works from our lab discovered that human embryonic stem cells (ESCs) that contain either only paternal epigenome (androgenetic ESCs) or only maternal epigenome (parthenogenetic ESCs) have unbalanced contribution to the different organs, and the maternal epigenome is essential for the proper development of the brain. We have recently established a genome-wide screening in human pluripotent stem cells, defining the essentialome of undifferentiated cells and their differentiated progenies. To uncover the role of imprinting in early human development we set out to determine the essentialome of imprinted genes. Our analysis demonstrated that none of the maternal imprinted genes are essential for the maintenance of pluripotency or for the differentiation of the germ layers, but there are several imprinted genes that are essential for neuron development. Using CRISPR-Cas9 technology, we created mutant ESCs for three of these imprinted genes, which are also involved in Angelman syndrome and Beckwith-Wiedemann syndrome. Neuronal differentiation of single and double mutants showed lower capacity of neurogenesis and suggested the involvement of cytokines in their regulation. These results clarify the effect of maternal genes in neuronal development and in neural imprinting disorders and should assist us in identifying novel therapeutic agents.