Rett syndrome mutation MeCP2 T158A disrupts DNA binding, protein stability and ERP responses

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Abstract

Mutations in the MECP2 gene cause the autism spectrum disorder Rett syndrome (RTT). One of the most common MeCP2 mutations associated with RTT occurs at threonine 158, converting it to methionine (T158M) or alanine (T158A). To understand the role of T158 mutations in the pathogenesis of RTT, we generated knockin mice that recapitulate the MeCP2 T158A mutation. We found a causal role for T158A mutation in the development of RTT-like phenotypes, including developmental regression, motor dysfunction, and learning and memory deficits. These phenotypes resemble those present in Mecp2 null mice and manifest through a reduction in MeCP2 binding to methylated DNA and a decrease in MeCP2 protein stability. The age-dependent development of event-related neuronal responses was disrupted by MeCP2 mutation, suggesting that impaired neuronal circuitry underlies the pathogenesis of RTT and that assessment of event-related potentials (ERPs) may serve as a biomarker for RTT and treatment evaluation.

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Figure 1: Generation and phenotypic characterization of Mecp2T158A/y mice.
Figure 2: Behavioral characterization of Mecp2T158A/y mice.
Figure 3: Decreased MeCP2 protein stability in Mecp2T158A/y mice.
Figure 4: Reduced MeCP2 binding to methylated DNA in Mecp2T158A/y mice.
Figure 5: Disruption of MeCP2 methyl-DNA binding leads to deregulation of gene expression.
Figure 6: EEG and ERP recordings in Mecp2T158A/y mice.
Figure 7: Decreased event-related power and PLF in Mecp2T158A/y mice.
Figure 8: Age-dependent increase in event-related power and PLF is absent in Mecp2T158A/y mice.

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Acknowledgements

This work is dedicated to the memory of Dr. Tom Kadesch, an inspirational colleague and mentor. We thank A. West, D. Epstein and members of the Zhou laboratory for critical readings of the manuscript, and the Intellectual and Developmental Disability Research Center Gene Manipulation Core (P30 HD18655) at the Children's Hospital Boston for generation of knockin mice (M. Thompson, Y. Zhou and H. Ye). This work was supported by grants from the US National Institutes of Health (R00 NS058391 and P30 HD026979), the Philadelphia Foundation and International Rett Syndrome Foundation to Z.Z. D.G. acknowledges the generous support of the Alavi-Dabiri Postdoctoral Fellowship. Z.Z. is a Pew Scholar in Biomedical Science.

Author information

D.G. designed and performed the EEG and ERP studies, analyzed protein stability, and was involved in most aspects of the project, except for the generation of the mice. M. Allen and I.-T.J.W. characterized mouse phenotypes. L.Z. analyzed protein expression and interaction. M. Amorim analyzed DNA binding and gene expression. A.-R.S.R. and C.O. provided technical assistance. S.C. assisted with targeting construct. L.H. assisted with the generation of T158 antibody. A.M.-B. and J.A.B. helped design and interpret behavioral tests. G.C.C. and S.J.S. helped design and interpret the EEG and ERP studies. Z.Z. generated the knockin mice with supervision from M.E.G., designed the experiments and supervised the project. D.G. and Z.Z. wrote the paper.

Correspondence to Zhaolan Zhou.

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The authors declare no competing financial interests.

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Supplementary Text and Figures

Supplementary Figures 1–15 (PDF 5838 kb)

Supplementary Video 1

Motor deficits in Mecp2T158A/y mice. Example video shows locomotor deficits in male Mecp2+/y (starts at bottom left), Mecp2T158A/y (starts at top right) and Mecp2–/y mice (starts at top left) at 11 weeks of age. Both Mecp2T158A/y and Mecp2–/y mice show decreased locomotor activity and aberrant gait with splaying of hind limbs upon movement. (MOV 11659 kb)

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