The role of Methyl-CpG Binding Protein 2 in Rett Syndrome Jessica Connor

Rett Syndrome is a neurodevelopmental disorder Hypotonia – loss of muscle tone Apraxia —inability to perform motor functions loss of use hands repetitive hand movements diminished eye contact gait abnormalities lack of speech development Other Symptoms autism like behaviors toe walking sleep problems cognitive disabilities seizures breathing problems teeth grinding difficulty chewing

Rett syndrome is caused by mutations in the MECP2 gene Bird, A. Biochem. Soc. Trans. (2008) 36, 575–583

MECP2 GO Terms Suggest Function Biological Process Negative regulation of transcription from RNA polymerase II promoter Cellular Component Mitochondrion Nucleolus Nucleus *Also noted in Uniprot Molecular Function DNA binding Double stranded methylated DNA binding Protein binding Transcription corepressor activity

MECP2 Mouse GO Terms Shed More Light on Role in Rett Syndrome Behavior adult locamotory behavior response to hypoxia social behavior Neurological brain development cerebellum development dendrite development long term synaptic potentiation negative regulation of neuron apoptosis neurite development neuromuscular process controlling posture neuron differentiation neuron maturation synaptic transmission synaptogenesis Transcription negative regulation of transcription, DNA dependent positive regulation of transcription, DNA dependent regulation of transcription Epigenetics chromatin silencing genetic imprinting histone acetylation histone methylation regulation of gene expression, epigenetic Other catecholamine secretion (hormone controlling fight or flight response) respiratory gaseous exchange

The MECP2 gene encodes the MECP2 protein SMART Protein Data Bank

MECP2 homologs are found in other mammals Phylogeny.fr

MECP2 domains are well conserved in homologs Homo sapiens………… Pan troglodytes…………… Canis lupus familiaris ……. Bos taurus………………… Rattus norvegicus………… Mus musculus…………….. Danio rerio………………… SMART

The MECP2 protein represses transcription of methylated genes

MECP2 interacts with proteins that form the histone deacetylase complex and other transcription factors

Pan troglodytes Mus musculus Danio rerio Sin3A

Gene Therapy Experiments Developed mouse model with silenced MECP2 that can be activated with injections of Tamoxifen Mice initially had Rett Syndrome phenotype After MECP2 was activated, symptoms disappeared Rett syndrome symptoms are not irreversible Not a direct therapeutic approach

Future Directions Determine which genes are abnormally expressed in Rett Syndrome –Gel shift to determine which genes bind to MECP2. Use microarray to look at expression changes in these genes in the presence and absence of MECP2 –Mass Spec analysis of brain tissue in MECP2 null mice vs. WT mice