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2019

ANUÁRIO DO HOSPITAL
DONA ESTEFÂNIA

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CROSS TALKING BETWEEN NONCODING DNA AND EPIGENOME IN FRAGILE X SYNDROME

Marta Zegre Amorim1, Simão Teixeira da Rocha2, M. Carmo-Fonseca2

1 – Serviço de Genética Médica, Hospital Dona Estefânia, Centro Hospitalar de Lisboa Central;
2 – Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa.

- Global Summit on Rare diseases & Orphan Drugs, Dubai, Nov 2016
- Oral communications by invitation

Resumo:
In recent years the development of genome-wide technologies allowed us to understand many more disease mechanisms, but mostly, made us realize how much is yet to be unfolded. The “software” of the DNA (epigenetics) makes a huge contribution to amplify the complexity of the human genome. Rare diseases may have an epigenetic origin, either by imprinting, methylation or monogenic epigenetic protein defects, but not much is known about the epigenetic influence in variability of expression and incomplete penetrance. We purpose to study the influence of noncoding DNA mutations in methylation marks, using Fragile X as a model of disease. Fragile X is the most common monogenic cause of developmental delay and it is caused by a repeat triplet expansion of noncoding DNA (>200 CGGs) and subsequent methylation and silencing of the FMR1 gene. In the premutation range (between 55 and 200 CGGs repeats) is also responsible for the FXTAS and FXPOI syndromes. We are developing a strategy involving patient-derived induced pluripotent stem cells (iPSCs) to study non-coding RNAs and epigenetic marks that are differentially expressed in Fragile X cells, at different mutation ranges. We are also using Gapmer antisense oligonucleotides to silence candidate non-coding RNAs, and CRISPR-Cas9-Tet1 fusion proteins to guide direct demethylation at specific sites in the FMR1 locus. By unraveling the cross-talk between genome and epigenome in the FMR1 locus we aim to further elucidate the mechanisms that underlie Fragile-X related disorders symptoms and to design novel therapeutic strategies.

Palavras Chave: Non-coding DNA, epigenetics, Fragile-X, iPSC cells, CRISPR-Cas9