title: An unexpected function of the Prader-Willi syndrome imprinting center in maternal imprinting in mice.
abstract: Genomic imprinting is a phenomenon that some genes are expressed differentially according to the parent of origin. Prader-Willi syndrome (PWS) and Angelman syndrome (AS) are neurobehavioral disorders caused by deficiency of imprinted gene expression from paternal and maternal chromosome 15q11-q13, respectively. Imprinted genes at the PWS/AS domain are regulated through a bipartite imprinting center, the PWS-IC and AS-IC. The PWS-IC activates paternal-specific gene expression and is responsible for the paternal imprint, whereas the AS-IC functions in the maternal imprint by allele-specific repression of the PWS-IC to prevent the paternal imprinting program. Although mouse chromosome 7C has a conserved PWS/AS imprinted domain, the mouse equivalent of the human AS-IC element has not yet been identified. Here, we suggest another dimension that the PWS-IC also functions in maternal imprinting by negatively regulating the paternally expressed imprinted genes in mice, in contrast to its known function as a positive regulator for paternal-specific gene expression. Using a mouse model carrying a 4.8-kb deletion at the PWS-IC, we demonstrated that maternal transmission of the PWS-IC deletion resulted in a maternal imprinting defect with activation of the paternally expressed imprinted genes and decreased expression of the maternally expressed imprinted gene on the maternal chromosome, accompanied by alteration of the maternal epigenotype toward a paternal state spread over the PWS/AS domain. The functional significance of this acquired paternal pattern of gene expression was demonstrated by the ability to complement PWS phenotypes by maternal inheritance of the PWS-IC deletion, which is in stark contrast to paternal inheritance of the PWS-IC deletion that resulted in the PWS phenotypes. Importantly, low levels of expression of the paternally expressed imprinted genes are sufficient to rescue postnatal lethality and growth retardation in two PWS mouse models. These findings open the opportunity for a novel approach to the treatment of PWS.
authors.affiliation: Department of Biochemistry and Molecular Biology, George Washington University, Washington, District of Columbia, United States of America. bcmmxw@gwumc.edu
authors.forename: Mei-Yi
authors.initials: MY
authors.lastname: Wu
authors.forename: Ming
authors.initials: M
authors.lastname: Jiang
authors.forename: Xiaodong
authors.initials: X
authors.lastname: Zhai
authors.forename: Arthur L
authors.initials: AL
authors.lastname: Beaudet
authors.forename: Ray-Chang
authors.initials: RC
authors.lastname: Wu
mesh_terms: D000818:Animals; D015153:Blotting, Western; D047369:Chromatin Immunoprecipitation; D002874:Chromosome Mapping; D033481:Chromosomes, Mammalian / Q000235:genetics; D004195:Disease Models, Animal; D005260:Female; D018392:Genomic Imprinting / Q000235:genetics*; D006130:Growth Disorders / Q000209:etiology; D006801:Humans; D047468:Immunoprecipitation; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009154:Mutation / Q000235:genetics; D010641:Phenotype; D011218:Prader-Willi Syndrome / Q000235:genetics*; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D017384:Sequence Deletion; D044767:Ubiquitin-Protein Ligases / Q000235:genetics*; D055517:snRNP Core Proteins / Q000235:genetics*
chemical_list: D012333:RNA, Messenger; D055517:snRNP Core Proteins; C502429:Ube3a protein, mouse; D044767:Ubiquitin-Protein Ligases