24.10.2014 change 24.10.2014

MicroRNAs - midgets that change the way our cells work

Source: Fotolia Source: Fotolia

Little travellers wander in our body: microRNA molecules that alter the genetic information coming out of the cell nucleus. It is believed that they regulate the ex.pression of approximately half of human genes and affect virtually every cellular pathway. They are capable of inducing tumour development, and sometimes can make an adult cell... become a stem cell again.

Dr. Aleksandra Bielawska-Pohl from the Institute of Immunology and Experimental Therapy PAS in Wrocław spoke in an interview with PAP about studies of microRNAs, tiny molecules with huge potential.

"MicroRNAs are tiny molecules that are such silent travellers - they may inhibit something, or lead to the silencing of reactions, pathways ..." - Bielawska-Pohl said in an interview with PAP. The importance of these molecules comes from the fact that more than 30 percent human genes are controlled by microRNAs. The researcher explained that this allows microRNAs to alter the functioning of the cells, and sometimes even the body, without changing our genome.

MicroRNAs have important functions in the regulation of expression of the mRNA (messenger RNA), which is responsible for protein synthesis in the cell. MicroRNA binds to complementary mRNA sequences and mostly inhibits of target mRNA expression, which results in the inhibition of protein synthesis.

"In different species - animals and plants - a total of more than 2 thousand different microRNAs have already been identified" - said Bielawska-Pohl. She explained that each species has its own microRNAs. These molecules may also mediate communication between cells.

However, research has shown that not only our own microRNAs are present in human bodies, but also microRNAs from organisms that we consume. "For example, rice microRNAs have been found in the blood of the Chinese, and in the blood of people who like to eat beef you can find cow microRNAs" - said the biologist.

She explained that alien microRNAs penetrate into our blood and cells and affect the functioning of the body. For example, rice microRNA may negatively affect how cells get rid of cholesterol. However, not everything is known about the effect of microRNAs of other species on our body.

Other studies indicate the relationship between the presence of specific microRNAs produced in the body and the development of cancer. "Recent studies indicate that microRNAs can play an important role in the diagnosis and treatment of cancer. Blood of women with breast cancer has high levels of certain five microRNAs. When a young person has a sudden increase of these microRNAs in the bloodstream, it means that something begins to happen and in a few - several years it may lead to the development of cancer" - said the biologist.

Te effects of microRNA are not always adverse. There are, in fact, microRNAs that may inhibit tumour growth. Dr. Bielawska-Pohl spoke about the latest research, which showed that the increased expression of specific microRNAs was associated with long-term improvement in survival of patients with melanoma (skin cancer).

Recent studies also revealed the unusual nature of these molecules. They showed that with certain microRNA molecules, adult cell can be reprogrammed into ... stem cell. It had been known before that stem cells could be obtained by introducing the set of three genes into an adult cell. "Now it turns out that it is enough to increase the expression of certain microRNAs and the cell "reverts" to the stem cell stage. We no longer need to interfere with its genome, just "add" certain microRNAs and voila! We couldn’t believe it when we found out about these studies" - said the scientist.

Dr. Bielawska-Pohl noted that intensive research on microRNAs is carried out in laboratories around the world, because there are still many question marks. "We continue to look for opportunities to use these microRNAs to treat a variety of diseases, by learning the mechanisms of their regulation and action" - noted the researcher.

PAP - Science and Scholarship in Poland, Ludwika Tomala

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