microRNA against stroke: the elbow is close…
microRNA protecting the brain from the effects of stroke has been discovered
NanoNewsNet based on Johns Hopkins University materials –
Double Duty: Immune System Regulator Found to Protect Brain from Effects of StrokeAccording to Johns Hopkins University scientists, the molecule, known for its ability to exert a regulatory effect on white blood cells, has another property: it is involved in protecting brain cells from the harmful effects of stroke.
This molecule, microRNA-223, affects how brain cells react to the temporary cessation of blood flow caused by a stroke and, therefore, largely determine the likelihood of irreparable harm to them.
RNAs are known primarily as intermediaries that transmit genetic information encoded in DNA, and then help, on the basis of this information, to build the proteins necessary for the cell. But ten years ago, scientists discovered a completely different class of RNA – small mobile fragments of genetic material that do not encode proteins, but regulate protein synthesis. The regulation of protein synthesis by microRNAs is based on their ability to bind to the matrix RNA molecules carrying genetic information, and thus interfere with the delivery of these messages.
"Compared to most ways of "turning off" genes, this one is particularly fast," explains the head of the study Valina Dawson, PhD, professor at the Institute for Cell Engineering at Johns Hopkins University School of Medicine.
Reasonably reasoning that this speed, along with other properties, can make microRNA molecules a good target for therapeutic drugs, Professor Dawson and her colleagues began to search for microRNAs that regulate the reaction of brain cells to oxygen starvation.
Scientists were looking for proteins whose levels rise in a stressed cell, and then studied how the synthesis of these proteins is regulated. For many of them, microRNA-223 played a certain role.
As it turned out, most of the regulated microRNA-223 proteins are involved in the detection and reaction to glutamate, a chemical signal used by the brain in intercellular communication. Stroke or injury, along with a number of other diseases such as autism and Alzheimer's disease, can lead to a dangerous excess of glutamate in the brain. Since microRNA-223 is involved in the regulation of the synthesis of such a large number of different proteins, and also affects glutamate receptors, which are also involved in many different processes, the area of influence of this molecule turned out to be much wider than expected.
Scheme of formation and functioning of microRNA molecules regulating protein synthesis (jonlieffmd.com )"Before this experiment, we had no idea that one microRNA could regulate such a number of proteins," notes the first author of the study, Dr. Maged M. Harraz.
"Our goal was to find a small molecule with very specific effects in the brain that could be the target of future stroke treatments," Professor Dawson comments on the results of the study. "What we have discovered is a molecule involved in the immune response, which affects the brain in complex ways. This raises a number of interesting questions about what and how microRNA-223 does, but any therapeutic use of it remains a big question."
In her opinion, based on the data obtained, it can be assumed that in the near future microRNA-223 will not be able to become a therapeutic target, unless scientists understand how to avoid undesirable side effects.
The study was funded by the US National Institutes of Health and published in the Proceedings of the National Academy of Sciences (Harraz et al., microRNA-223 is neuroprotective by targeting glutamate receptors).
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