Description
Parental imprinting is a form of epigenetic regulation that results in parent-of-origin differential gene expression. To study Prader-Willi syndrome (PWS), a developmental imprinting disorder, we generated patient-derived induced pluripotent stem cells (iPSCs) harboring distinct deletions in the affected region on chromosome 15. Studying PWS-iPSCs and human parthenogenetic iPSCs unexpectedly revealed substantial upregulation of virtually all maternally expressed genes (MEGs) in the imprinted DLK1-DIO3 locus on chromosome 14. Subsequently, we identified IPW, a long noncoding RNA in the critical region of the PWS locus, as a regulator of the DLK1-DIO3 region, as its over-expression in PWS and parthenogenetic iPSCs results in downregulation of the MEGs in this locus. We further show that gene expression changes in the DLK1-DIO3 region coincide with chromatin modifications, rather than DNA methylation levels. Our results suggest that a subset of PWS phenotypes may arise from dysregulation of an imprinted locus distinct from the PWS region.