Toxicity of overexpressed MeCP2 is independent of HDAC3 activity

Martha V. Koerner, Laura Fitzpatrick, Jim Selfridge, Jacky Guy, Dina De Sousa, Rebekah Tillotson, Alastair Kerr, Zheng Sun, Mitchell A. Lazar, Matthew J. Lyst, Adrian Bird

Research output: Contribution to journalArticlepeer-review

Abstract

Duplication of the X-linked MECP2 gene causes a severe neurological syndrome whose molecular basis is poorly understood. To determine the contribution of known functional domains to overexpression toxicity, we engineered a mouse model that expresses wild-type or mutated MeCP2 from the Mapt (Tau) locus in addition to the endogenous protein. Animals that expressed approximately four times the wild-type level of MeCP2 failed to survive to weaning. Strikingly, a single amino acid substitution that prevents MeCP2 from binding to the TBL1X(R1) subunit of nuclear receptor corepressor 1/2 (NCoR1/2) complexes, when expressed at equivalent high levels, was phenotypically indistinguishable from wild type, suggesting that excessive corepressor recruitment underlies toxicity. In contrast, mutations affecting the DNA-binding domain were toxic when overexpressed. As the NCoR1/2 corepressors are thought to act through histone deacetylation by histone deacetylase 3 (HDAC3), we asked whether mutations in NCoR1 and NCoR2 that drastically reduced their ability to activate this enzyme would relieve the MeCP2 overexpression phenotype. Surprisingly, severity was unaffected, indicating that the catalytic activity of HDAC3 is not the mediator of toxicity. Our findings shed light on the molecular mechanisms underlying MECP2 duplication syndrome and call for a re-evaluation of the precise biological role played by corepressor recruitment.
Original languageEnglish
Pages (from-to)1514-1524
Number of pages11
JournalGenes & Development
Volume32
Issue number23-24
Early online date21 Nov 2018
DOIs
Publication statusPublished - 1 Dec 2018

Keywords

  • histone deacetylase 3
  • MeCP2
  • NCoR

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