The MECP2 gene, located at Xq28, encodes methyl-CpG-binding protein 2 (MeCP2), which is frequently mutated (up to 90%) in Rett syndrome (RTT). RTT is a progressive neurodevelopmental disorder, which affects primarily girls during early childhood and it is one of the most common causes of mental retardation in females. R270X is one of the most frequent recurrent MECP2 mutations among RTT cohorts. The R270X mutation resides within the TRD-NLS (Transcription Repression Domain-Nuclear Localization Signal) region of MeCP2 and causes a more severe clinical phenotype with increased mortality as compared to other mutations. To evaluate the functional role of the R270X mutation, we generated a transgenic mouse model expressing MeCP2270_EGFP (human mutation equivalent) by BAC recombineering. The expression pattern of MeCP2270_EGFP was similar to that of endogenous MeCP2. Strikingly, MeCP2270_EGFP localizes in the nucleus, contrary to the conjecture that R270X could cause disruption of the NLS. In primary hippocampal cells, we show that MeCP2270_EGFP was expressed in astrocytes by colocalization with the astrocyte-specific marker glial fibrillary acidic protein. Our data showing expression of MeCP2270_EGFP in transgenic mice astrocytes further reinforce the recent findings concerning the expression of MeCP2 in the glial cells.

Keywords:
MeCP2, R270X mutation, Rett syndrome, Transgenic mice
1.
Adams VH, McBryant SJ, Wade PA, Woodcock CL, Hansen JC: Intrinsic disorder and autonomous domain function in the multifunctional nuclear protein, MeCP2. J Biol Chem 282:15057–15064 (2007).
2.
Amir RE, Van den Veyver IB, Wan M, Tran CQ, Francke U, et al: Rett syndrome is caused by mutations in X-linked MECP2, encoding methyl-CpG binding protein 2. Nat Genet 23:185–188 (1999).
3.
Ballas N, Lioy DT, Grunseich C, Mandel G: Non-cell autonomous influence of MeCP2 deficient glia on neuronal dendritic morphology. Nat Neurosci 12:311–317 (2009).
4.
Bebbington A, Anderson A, Ravine D, Fyfe S, Pineda M, et al: Investigating genotype-phenotype relationships in Rett syndrome using an international data set. Neurology 70:868–875 (2008).
5.
Ben-Shachar S, Chahrour M, Thaller C, Shaw CA, Zoghbi HY: Mouse models of MeCP2 disorders share gene expression changes in the cerebellum and hypothalamus. Hum Mol Genet 18:2431–2442 (2009).
6.
Chahrour M, Zoghbi HY: The story of Rett syndrome: from clinic to neurobiology. Neuron 56:422–437 (2007).
7.
Chahrour M, Jung SY, Shaw C, Zhou X, Wong ST: MeCP2, a key contributor to neurological disease, activates and represses transcription. Science 320:1224–1229 (2008).
8.
Chen RZ, Akbarian S, Tudor M, Jaenisch R: Deficiency of methyl-CpG binding protein-2 in CNS neurons results in a Rett-like phenotype in mice. Nat Genet 27:327–331 (2001).
9.
Collins AL, Levenson JM, Vilaythong AP, Richman R, Armstrong DL, et al: Mild overexpression of MeCP2 causes a progressive neurological disorder in mice. Hum Mol Genet 13:2679–2689 (2004).
10.
Colvin L, Leonard H, de Klerk N, Davis M, Weaving L, et al: Refining the phenotype of common mutations in Rett syndrome. J Med Genet 41:25–30 (2004).
11.
D’Esposito M, Quaderi NA, Ciccodicola A, Bruni P, Esposito T, et al: Isolation, physical mapping, and Northern analysis of the X-linked human gene encoding methyl CpG-binding protein, MECP2. Mamm Genome 7:533–553 (1996).
12.
Dietrich MO, Mantese CE, Anjos GD, Souza DO, Farina M: Motor impairment induced by oral exposure to methylmercury in adult mice. Environ Toxicol Pharm 19:169–175 (2005).
13.
Dragich J, Houwink-Manville I, Schanen C: Rett syndrome: A surprising result of mutation in MECP2. Hum Mol Genet 9:2365–2375 (2000).
14.
Dragich JM, Kim YH, Arnold AP, Schanen NC: Differential distribution of the MeCP2 splice variants in the postnatal mouse brain. Comp Neurol 501:526–542 (2007).
15.
Georgel PT, Horowitz-Scherer RA, Adkins N, Woodcock CL, Wade PA, et al: Chromatin compaction by human MeCP2. Assembly of novel secondary chromatin structures in the absence of DNA methylation. J Biol Chem 278:32181–32188 (2003).
16.
Guy J, Hendrich B, Holmes M, Martin JE, Bird A: A mouse Mecp2-null mutation causes neurological symptoms that mimic Rett syndrome. Nat Genet 27:322–326 (2001).
17.
Hagberg B, Aicardi J, Dias K, Ramos O: A progressive syndrome of autism, dementia, ataxia, and loss of purposeful hand use in girls: Rett’s syndrome: report of 35 cases. Ann Neurol 14:471–479 (1983).
18.
Horton P, Nakai K: Better prediction of protein cellular localization sites with the k nearest neighbors classifier. Proc Int Conf Intell Syst Mol Biol 5:147–152 (1997).
19.
Huppke P, Held M, Hanefeld F, Engel W, Laccone F: Influence of mutation type and location on phenotype in 123 patients with Rett syndrome. Neuropediatrics 33:63–68 (2002).
20.
Jian L, Archer HL, Ravine D, Kerr A, de Klerk N, et al: p.R270X MECP2 mutation and mortality in Rett syndrome. Eur J Hum Genet 13:1235–1238 (2005).
21.
Kishi N, Macklis JD: MECP2 is progressively expressed in post-migratory neurons and is involved in neuronal maturation rather than cell fate decisions. Mol Cell Neurosci 27:306–321 (2004).
22.
Kriaucionis S, Bird A: The major form of MeCP2 has a novel N-terminus generated by alternative splicing. Nucleic Acids Res 32:1818–1823 (2004).
23.
Laccone F, Huppke P, Hanefeld F, Meins M: Mutation spectrum in patients with Rett syndrome in the German population: Evidence of hot spot regions. Hum Mutat 17:183–190 (2001).
24.
Maezawa I, Swanberg S, Harvey D, LaSalle JM, Jin LW: Rett syndrome astrocytes are abnormal and spread MeCP2 deficiency through gap junctions. J Neurosci 29:5051–5061 (2009).
25.
Meehan RR, Lewis JD, Bird AP: Characterization of MeCP2, a vertebrate DNA binding protein with affinity for methylated DNA. Nucleic Acids Res 20:5085–5092 (1992).
26.
Nan X, Meehan RR, Bird A: Dissection of the methyl-CpG binding domain from the chromosomal protein MeCP2. Nucleic Acids Res 21:4886–4892 (1993).
27.
Ng HH, Bird A: DNA methylation and chromatin modification. Curr Opin Genet Dev 9:158–163 (1999).
28.
Orford M, Nefedov M, Vadolas J, Zaibak F, Williamson R, et al: Engineering EGFP reporter constructs into a 200-kb human beta-globin BAC clone using GET recombination. Nucleic Acids Res 28:E84 (2000).
29.
Razin A: CpG methylation, chromatin structure and gene silencing – a three-way connection. EMBO J 17:4905–4908 (1998).
30.
Rett A: On an unusual brain atrophy syndrome in hyperammonemia in childhood. Wien Med Wochenschr116:723–726 (1966).
31.
Shahbazian MD, Antalffy B, Armstrong DL, Zoghbi HY: Insight into Rett syndrome: MeCP2 levels display tissue- and cell-specific differences and correlate with neuronal maturation. Hum Mol Genet 11:115–124 (2002).
32.
Trevathan E, Moser HW: Diagnostic criteria for Rett syndrome. Ann Neurol 23:425–428 (1988).
33.
Young JI, Hong EP, Castle JC, Crespo-Barreto J, Bowman AB, et al: Regulation of RNA splicing by the methylation-dependent transcriptional repressor methyl-CpG binding protein 2. Proc Natl Acad Sci USA 102:17551–17558 (2005).
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