Mutations in MeCP2, a methyl-CpG-binding protein that functions as a regulator of gene expression, are a major cause of Rett Syndrome (RTT), an X-linked progressive autism spectrum disorder that is among the most common causes of profound cognitive impairment in girls and women. While the selective inactivation of MeCP2 in neurons has been suggested to be sufficient to confer a Rett-like phenotype in mice, the specific mechanisms by which the loss of MeCP2 function in postimitotic neurons contributes to RTT phenotypes remain unclear. We have identified serine 421 (S421) on MeCP2 as a site of neuronal activity-dependent phosphorylation that is induced selectively in the brain in response to physiological stimuli. Significantly, we have found that S421 phosphorylation controls the ability of MeCP2 to regulate dendritic patterning, spine morphogenesis, and the activity-dependent induction of Bdnf transcription in both cultured neurons and slice preparations. To further explore the role of this regulatory mechanism in neural development in vivo, we have generated a knock-in mouse in which S421 of MeCP2 is mutated to an alanine residue (S421A KI), preventing the phosphorylation of MeCP2 at this site. Intriguingly, whereas the abrogation of MeCP2 S421 phosphorylation in vivo does not result in the motor and survival phenotypes seen with complete loss of MeCP2 expression, our preliminary studies have revealed a deficit in cortical inhibitory synaptic development in these S421A KI mice, suggesting that activity-dependent phosphorylation may be involved in a specific subset of MeCP2 functions relevant to the synaptic and cognitive defects observed in RTT. To begin to test this hypothesis and determine the extent to which MeCP2 functions as a general regulator of neuronal activity- dependent gene expression, we propose the following specific aims: (1) to investigate the contribution of MeCP2 S421 phosphorylation to experience-dependent synaptic development in vivo;(2) to assess the role of MeCP2 S421 phosphorylation in the regulation of activity-dependent neuronal gene expression;and (3) to characterize additional sites of activity-dependent MeCP2 phosphorylation. It is our hope that the proposed experiments will provide a better understanding of MeCP2 function, give insight into the mechanisms of activity-dependent gene expression, and provide new opportunities for the development of therapeutic strategies to alleviate RTT pathology.

Public Health Relevance

Project Narrative: Rett Syndrome is a progressive autistic disorder that is among the most common causes of profound cognitive impairment in girls and women. In an effort to gain insight into the underlying molecular basis of the disorder, the proposed study will seek to explore the hypothesis that this autistic disorder reflects a defect in the dynamic regulation of genes in the central nervous system.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
3R01NS048276-06S1
Application #
8092154
Study Section
Neurodifferentiation, Plasticity, and Regeneration Study Section (NDPR)
Program Officer
Mamounas, Laura
Project Start
2004-03-01
Project End
2015-03-31
Budget Start
2010-04-01
Budget End
2011-03-31
Support Year
6
Fiscal Year
2010
Total Cost
$77,123
Indirect Cost
Name
Harvard University
Department
Biology
Type
Schools of Medicine
DUNS #
047006379
City
Boston
State
MA
Country
United States
Zip Code
02115
Renthal, William; Boxer, Lisa D; Hrvatin, Sinisa et al. (2018) Characterization of human mosaic Rett syndrome brain tissue by single-nucleus RNA sequencing. Nat Neurosci 21:1670-1679
Vierbuchen, Thomas; Ling, Emi; Cowley, Christopher J et al. (2017) AP-1 Transcription Factors and the BAF Complex Mediate Signal-Dependent Enhancer Selection. Mol Cell 68:1067-1082.e12
Stroud, Hume; Su, Susan C; Hrvatin, Sinisa et al. (2017) Early-Life Gene Expression in Neurons Modulates Lasting Epigenetic States. Cell 171:1151-1164.e16
Kinde, Benyam; Wu, Dennis Y; Greenberg, Michael E et al. (2016) DNA methylation in the gene body influences MeCP2-mediated gene repression. Proc Natl Acad Sci U S A 113:15114-15119
Kinde, Benyam; Gabel, Harrison W; Gilbert, Caitlin S et al. (2015) Reading the unique DNA methylation landscape of the brain: Non-CpG methylation, hydroxymethylation, and MeCP2. Proc Natl Acad Sci U S A 112:6800-6
Gabel, Harrison W; Kinde, Benyam; Stroud, Hume et al. (2015) Disruption of DNA-methylation-dependent long gene repression in Rett syndrome. Nature 522:89-93
Spiegel, Ivo; Mardinly, Alan R; Gabel, Harrison W et al. (2014) Npas4 regulates excitatory-inhibitory balance within neural circuits through cell-type-specific gene programs. Cell 157:1216-29
Ebert, Daniel H; Gabel, Harrison W; Robinson, Nathaniel D et al. (2013) Activity-dependent phosphorylation of MeCP2 threonine 308 regulates interaction with NCoR. Nature 499:341-5
Yu, Timothy W; Chahrour, Maria H; Coulter, Michael E et al. (2013) Using whole-exome sequencing to identify inherited causes of autism. Neuron 77:259-73
Lyst, Matthew J; Ekiert, Robert; Ebert, Daniel H et al. (2013) Rett syndrome mutations abolish the interaction of MeCP2 with the NCoR/SMRT co-repressor. Nat Neurosci 16:898-902

Showing the most recent 10 out of 24 publications