Tiny fateful RNA

Micro-RNA is a special class of regulatory RNA just 19-22 nucleotides in length. Such micro-RNAs are the products of operation of short genes that do not encode proteins. Micro-RNA was found both in plants and in animals. Scientists assume that mammals have hundreds or, possibly, thousands of various sequences of micro-RNAs in their genome. Specialists are unable to give a more precise figure yet but they have already performed certain research that gives grounds to believe that micro-RNAs may participate in the pathogenesis of mental diseases.

Micro-RNAs are common in brain cells, and some of these molecules are mostly found just there. Experiments on Danio rerio, Caenorhabditis elegans and rats give evidence that normal development of the nervous system is impossible without micro-RNAs. Composition of micro-RNA in the neural tissue changes depending on the stage of the nervous system’s embryonal development.

Human brain diseases related to impairment of consciousness, intellect, mood and memory can be subdivided into two groups. They are diseases of nervous system’s development such as mental deficiency, autism, schizophrenia, and the group of neurodegenerative diseases (involving disintegration of nerve cells), for example, senile dementia and Parkinson’s disease.

Using computer algorithms, scientists demonstrated that potential micro-RNA targets include genes related to the nervous system’s development, developmental lagging, contact formation between neurons, and Alzheimer’s disease. However, the list of target genes depends on the computer program used to prepare the forecast, and its accuracy can only be verified experimentally.

Preliminary research conducted by Evgeny Rogaev and his colleagues demonstrated that such verification is feasible. Advanced research methods allow finding and identifying tiny micro-RNAs in the brain tissues of the deceased normal and mentally sick people and comparing them. A lot of mental diseases are, undoubtedly, inherited, but when comparing the sequences of genes that encode proteins, the scientists do not find significant differences between normal and sick people. Evgeny Rogaev believes that they should look for differences in the regulation of operation of genes encoding proteins rather than in their sequences. It is highly possible that micro-RNAs are exactly such regulators which define nervous system’s development and functioning.