Deficiency of methyl-CpG binding protein-2 in CNS neurons results in a Rett-like phenotype in mice.
Mecp2 is an X-linked gene encoding a nuclear protein that binds specifically to methylated DNA (ref. 1) and functions as a general transcriptional repressor by associating with chromatin-remodeling complexes. Mecp2 is expressed at high levels in the postnatal brain, indicating that methylation-dependent regulation of gene expression may have a crucial role in the mammalian central nervous system. Consistent with this notion is the recent demonstration that MECP2 mutations cause Rett syndrome (RTT, MIM 312750), a childhood neurological disorder that represents one of the most common causes of mental retardation in females. Here we show that Mecp2-deficient mice exhibit phenotypes that resemble some of the symptoms of RTT patients. Mecp2-null mice were normal until 5 weeks of age, when they began to develop disease, leading to death between 6 and 12 weeks. Mutant brains showed substantial reduction in both weight and neuronal cell size, but no obvious structural defects or signs of neurodegeneration. Brain-specific deletion of Mecp2 at embryonic day (E) 12 resulted in a phenotype identical to that of the null mutation, indicating that the phenotype is caused by Mecp2 deficiency in the CNS rather than in peripheral tissues. Deletion of Mecp2 in postnatal CNS neurons led to a similar neuronal phenotype, although at a later age. Our results indicate that the role of Mecp2 is not restricted to the immature brain, but becomes critical in mature neurons. Mecp2 deficiency in these neurons is sufficient to cause neuronal dysfunction with symptomatic manifestation similar to Rett syndrome.
The Whitehead Institute for Biomedical Research, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA.
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Chen
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Akbarian
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Tudor
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Jaenisch
D000818:Animals; D002454:Cell Differentiation; D048429:Cell Size; D002490:Central Nervous System / Q000378:metabolism / Q000473:pathology; D002868:Chromosomal Proteins, Non-Histone; D018899:CpG Islands; D004268:DNA-Binding Proteins / Q000172:deficiency* / Q000235:genetics*; D004195:Disease Models, Animal; D005260:Female; D006801:Humans; D008297:Male; D051783:Methyl-CpG-Binding Protein 2; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D009474:Neurons / Q000378:metabolism / Q000473:pathology; D010641:Phenotype; D012097:Repressor Proteins; D015518:Rett Syndrome / Q000235:genetics* / Q000378:metabolism / Q000473:pathology
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