Project 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. Gene expression analysis was performed on a total of 4 human cell lines, including 3 Prader-Willi Syndrome indcued pluripotent stem cell lines - derived from 3 affected individuals and one of their parental fibroblast cell line.
Project description:Rhythmic oscillations of physiological processes depend on integrating the circadian clock and diurnal environment. DNA methylation is epigenetically responsive to daily rhythms, as a subset of CpG dinucleotides in brain exhibit diurnal rhythmic methylation. A major genetic effect on rhythmic methylation was identified in a mouse Snord116 deletion model of the imprinted disorder Prader-Willi syndrome (PWS). > 23,000 diurnally rhythmic CpGs were identified in wild-type cortex, with nearly all lost or phase-shifted in PWS. Circadian dysregulation of a second imprinted Snord cluster at the Temple/Kagami-Ogata syndrome locus was observed at the level of methylation, transcription, and chromatin, providing mechanistic evidence of cross-talk. Genes identified by diurnal epigenetic changes in PWS mice overlapped rhythmic and PWS-specific genes in human brain and were enriched for PWS-relevant phenotypes and pathways. These results support the proposed evolutionary relationship between imprinting and sleep, and suggest possible chronotherapy in the treatment of PWS and related disorders.
Project description:Prader-Willi syndrome (PWS) is a multigenic disorder caused by the loss of seven contiguous paternally expressed genes. Mouse models with inactivation of all PWS genes display 100% lethality within the first postnatal week and have not helped understand the postnatal pathophysiology of this syndrome. Knockout (KO) models for each candidate gene were also generated, but they lack the functional interactions and possible compensatory functions between PWS-related genes. Here, we generated a novel double KO mouse model to explore the effect of a combined deletion of Magel2 and Necdin.
Project 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.
Project description:Prader-Willi syndrome (PWS) is a genetic disorder caused by deficiency of imprinted gene expression from the paternal chromosome 15q11-15q13 and clinically characterized by neonatal hypotonia, short stature, cognitive impairment, hypogonadism, hyperphagia, morbid obesity and diabetes. Previous clinical studies suggest that a defect in energy metabolism may be involved in the pathogenesis of PWS. Assessment of enzyme activities of mitochondrial oxidative phosphorylation (OXPHOS) complexes in the brain, heart, liver and muscle were assessed. We used microarrays to detail the global programme of gene expression underlyingthe PWS and identified distinct classes of disregulated genes during this process. Skeletal (quadriceps) muscle Vastus Lateralis and whole brain samples from the mutant mice and their wild-type age-matched littermates were analyzed by microarray technology using the Mouse Genome 430 2.0 arrays (Affymetrix).
Project description:Prader-Willi syndrome (PWS) is a genetic disorder caused by deficiency of imprinted gene expression from the paternal chromosome 15q11-15q13 and clinically characterized by neonatal hypotonia, short stature, cognitive impairment, hypogonadism, hyperphagia, morbid obesity and diabetes. Previous clinical studies suggest that a defect in energy metabolism may be involved in the pathogenesis of PWS. Assessment of enzyme activities of mitochondrial oxidative phosphorylation (OXPHOS) complexes in the brain, heart, liver and muscle were assessed. We used microarrays to detail the global programme of gene expression underlyingthe PWS and identified distinct classes of disregulated genes during this process.
Project description:We performed gene expression microarray analysis of the hypothalamic response to starvation in neonatal wild-type mice, and in Snord116del mice that are a mouse model for PWS. This study is motivated by the neonatal feeding problems observed in several genetic diseases including Prader-Willi syndrome (PWS). Later in life, individuals with PWS develop hyperphagia and obesity due to lack of appetite control. We hypothesize that failure to thrive in infancy and later-onset hyperphagia may be related and could be due to a defect in the hypothalamus. In this study, we performed gene expression microarray analysis of the hypothalamic response to starvation in neonatal wild-type mice, and in Snord116del mice that are a mouse model for PWS. The neonatal starvation response was dramatically different from that reported in adult rodents. Genes that are affected by adult starvation are not changed in the hypothalamus of 5 day-old pups that were starved for 6 hrs. Unlike in adult rodents, expression levels of Nanos2 and Pdk4 were increased, and those of Pgpep1, Ndph, Brms1l, Mett10d, and Snx1 were decreased after fasting. In addition, we compared hypothalamic gene expression profiles at days 5 and 13 to document developmental changes. Notably, the gene expression profiles of Snord116del deletion mice and wild-type littermates were very similar at both postnatal days 5 and 13, and after starvation. We compared hypothalamic RNA between Snord116del mice with wild type (C57BL/6J) littermates at P5 and P13, with or without fasting treatment. We are particularly interested in the following comparisons: Comparison 1: wild type vs. PWS deletion in P5 non-starved mice; Comparison 2: wild type vs. PWS deletion in P5 fasting mice; Comparison 3: non-starved vs. fasting in P5 wild type mice; Comparison 4: non-starved vs. fasting in P5 PWS deletion mice; Comparison 5: wild type vs. PWD deletion in P13 non-starved mice; Comparison 6: P5 wild type vs. P13 wild type mice;
Project description:Transcriptional analysis of brain tissue from people with molecularly defined causes of obesity may highlight novel disease mechanisms and therapeutic targets. Prader-Willi syndrome (PWS) is a genetic obesity syndrome characterised by severe hyperphagia. We performed RNA sequencing of the hypothalamus from 4 individuals with PWS and 4 age-matched controls.
