On the left, dark genome’s differences of expression (marked with different colours) between healthy neurons and those affected by Rett syndrome. On the right, a deficit of Mecp2 protein can be observed on the brain affected by Rett syndrome (no black band).
By Bibiana Bonmatí, University of Barcelona Press
A research group led by Manel Esteller, ICREA researcher, professor of Genetics at the University of Barcelona and head of Epigenetics and Cancer Biology Program at Bellvitge Biomedical Research Institute (IDIBELL), has described alterations in long non-coding RNA sequences (lncRNA) in Rett syndrome. These molecules act as supervisor agents responsible for 'switching on' or 'switching off' other genes in our genome that regulate the activity of neurons. The work has been published on the latest issue of the journal RNA Biology.
Rett syndrome is a neurodevelopmental disease; it is the second most common cause of mental retardation in women, after Down syndrome. Clinical symptoms occur between 6 and 18 months after birth; they may include a loss of cognitive, social and motor capacities accompanied by autistic behaviours, such as stereotypic hand movements.
Today, there is not any effective treatment for the disease beyond the control of its symptoms. Rett syndrome is usually due to the presence of a mutation in Mecp2, an epigenetic gene that, as a magnet, regulates the expression of many other cell genes.
Esteller's research group works with a mouse model that faithfully reproduces the characteristics of human Rett syndrome. In the study, researchers compared the expression of long chains of RNA in healthy and diseased animals and found that the presence of mutations in Mecp2 gene causes alterations on the activity of long non-coding RNA (lncRNA), molecules that are part of the so-called dark genome. The function of the dark genome, which represents 95% of human genome, is still unknown.
One of these altered lncRNAs regulates the function of a key neurotransmitter in the nervous system in all vertebrates’ brains, the GABA receptor. "Its alteration may explain the impairment of communication between neurons in girls affected by Rett syndrome", states Esteller. “Besides increasing the knowledge about the disease’s causes, this finding could open the door to new therapeutic strategies that target lncRNA molecules or GABA receptor”, adds the researcher.
The study was supported by the Department of Health of the Government of Catalonia, the Catalan Institution for Research and Advanced Studies (ICREA), the Spanish Health Ministry, the European projects DISCHROM and EPINORC, Jérôme Lejeune Foundation, and the Catalan Association Rett Syndrome.
Further information:
http://www.ub.edu/web/ub/en/menu_eines/noticies/2013/05/012.html
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