MeCP2 deficiency in Rett syndrome causes epigenetic aberrations at the PWS/AS imprinting center that affects UBE3A expression.
Rett syndrome (RS) is a severe and progressive neurodevelopmental disorder caused by heterozygous mutations in the X-linked methyl CpG binding protein 2 (MeCP2) gene. MeCP2 is a nuclear protein that binds specifically to methylated DNA and functions as a general transcription repressor in the context of chromatin remodeling complexes. RS shares clinical features with those of Angelman syndrome (AS), an imprinting neurodevelopmental disorder. In AS patients, the maternally expressed copy of UBE3A that codes for the ubiquitin protein ligase 3A (E6-AP) is repressed. The similar phenotype of these two syndromes led us to hypothesize that part of the RS phenotype is due to MeCP2-associated silencing of UBE3A. Indeed, UBE3A mRNA and protein are shown here to be significantly reduced in human and mouse MECP2 deficient brains. This reduced UBE3A level was associated with biallelic production of the UBE3A antisense RNA. In addition, MeCP2 deficiency resulted in elevated histone H3 acetylation and H3(K4) methylation and reduced H3(K9) methylation at the PWS/AS imprinting center, with no effect on DNA methylation or SNRPN expression. We conclude, therefore, that MeCP2 deficiency causes epigenetic aberrations at the PWS imprinting center. These changes in histone modifications result in loss of imprinting of the UBE3A antisense gene in the brain, increase in UBE3A antisense RNA level and, consequently reduction in UBE3A production.
Makedonski
Kirill
K
Department of Cellular Biochemistry and Human Genetics, The Hebrew University--Hadassah Medical School, Jerusalem, Israel 91120.
Abuhatzira
Liron
L
Kaufman
Yotam
Y
Razin
Aharon
A
Shemer
Ruth
R
D017204:Angelman Syndrome / Q000235:genetics / Q000378:metabolism; D000818:Animals; D001921:Brain / Q000378:metabolism; D002868:Chromosomal Proteins, Non-Histone / Q000172:deficiency* / Q000235:genetics; D004268:DNA-Binding Proteins / Q000172:deficiency* / Q000235:genetics; D044127:Epigenesis, Genetic; D018392:Genomic Imprinting; D006801:Humans; D051783:Methyl-CpG-Binding Protein 2; D051379:Mice; D011218:Prader-Willi Syndrome / Q000235:genetics / Q000378:metabolism; D011401:Promoter Regions, Genetic; D012097:Repressor Proteins / Q000235:genetics; D015518:Rett Syndrome / Q000235:genetics / Q000378:metabolism*; D044767:Ubiquitin-Protein Ligases / Q000096:biosynthesis / Q000235:genetics*
D002868:Chromosomal Proteins, Non-Histone; D004268:DNA-Binding Proteins; C497392:MECP2 protein, human; C497393:Mecp2 protein, mouse; D051783:Methyl-CpG-Binding Protein 2; D012097:Repressor Proteins; C471639:UBE3A protein, human; D044767:Ubiquitin-Protein Ligases