Mental retardation, altered facial characteristics, and heart problems are all problems suffered by children affected by Costello syndrome, a genetic disease that is being studied by researchers in Milan at the Italian Foundation for Cancer Research (FIRC) Institute of molecular oncology (IFOM) using the zebrafish as a model.
The cause of the disease – explained the scientists in the January issue of ‘Disease Models & Mechanisms’ monthly magazine – is a mutation of the Ras gene, the same alteration observed in 20pct of tumors. One out of every five cases of cancer and the rare genetic disease have a common thread.
The credit for the discovery also goes to the zebrafish, an important animal among the most popular in laboratories worldwide, since it is versatile, transparent, and mainly, genetically similar to humans. The mutation of the Ras gene responsible for the Costello syndrome – according to a study supported by the Italian Association for Cancer Research (AIRC) – is manifested in the patient’s germ cells.
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Children born with this malformation have a mutation in their DNA, which transmits characteristics that are similar to cancer cells to all of the cells in their body, without causing tumors. In other words, it is as if the people with the disease were ‘healthy tumor carriers’. Inside of an adult cell, underlined the authors, coordinated by Marina Mione, in a note, the same alternations can have three different consequences: the cell goes into apoptosis (programmed cell death), senescence (it deactivates, and no longer reproduces) or results in a neoplasm.
In Costello syndrome in particular, the Ras mutation induces cells to prematurely age (senescence), but only in brain and heart stem cells. The zebrafish has shown to be a fundamental model for research on the disease, whereas other models closer to man have failed, pointed out the researchers. Now they hope to “pinpoint possible cures that reduce senescence in brain and heart stem cells in people who have Costello syndrome,” specified Mione.
Together with other genetic diseases (neurofibromatosis, Noonan syndrome, and cardio-facio-cutaneous syndrome), all characterized by an increase in the activity which signals the Ras gene, the Costello disease is diagnosed in a reduced, but growing number of cases. “This,” continued the young researcher, “opens the door to new fronts in cancer research. Understanding how a developing organism defends itself from mutations through signaling the Ras gene through senescence would allow scientists to develop new treatments against tumors, which would use the same mechanism to block their proliferation,” concluded Mione.
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Zebrafish in motor neurone clue
Cells that control speech, walking and breathing have been found in tiny fish, offering hope of new treatments for motor neurone disease.
Edinburgh University experts found zebrafish produce motor neurones when repairing damage to their spinal cords.
Now they are trying to find drugs which can stimulate the regeneration process in zebrafish.
The discovery could help patients with motor neurone disease, where motor neurone cells die and are not replaced.
The disease, which is currently incurable, causes paralysis and severe breathing difficulties and is ultimately fatal.
Brain messages
Dr Catherina Becker, of Edinburgh University’s centre for neuroregeneration, said: “Understanding how zebrafish can regenerate large numbers of motor neurones after damage to the spinal cord and how these motor neurones are produced by natural stem cells could help in finding treatments for motor neurone disease.
“This could take the form of improving methods of generating motor neurones in the laboratory that could be transplanted or finding drugs which could help patients renew their motor neurone supply.”
The tropical zebrafish, which are transparent and around 3 cm long, produce the motor neurones from progenitor cells, found in the spinal cord, that develop into other types of cells.
As well as looking at stimulating the production of motor neurones, scientists are working on ways to ensure that these cells are able to function by sending messages from the brain to the spine and then on to muscles.
The research could also have implications for treating spinal cord injuries following accidents.
from http://news.bbc.co.uk/2/hi/uk_news/england/manchester/8024427.stm