microRNAs play an important role in the formation of the heart muscle
Scientists at the Gladstone Institute of Cardiovascular Diseases and the University of California, working under the leadership of Dr. Deepak Srivastava, for the first time established how miRNAs affect the differentiation of pluripotent embryonic stem cells into heart muscle cells.
The authors demonstrated that two types of microRNAs, miR-1 and miR-133, associated with the development of muscle tissue, not only stimulate the formation of heart muscle tissue, but also effectively suppress the activity of genes whose functioning leads to the differentiation of embryonic stem cells into cells of other types, for example, neurons or osteocytes.
Differentiation of embryonic stem cells into various cells of the adult body is a very complex process involving many factors. Apparently, microRNAs play the role of rheostats in this process, providing fine regulation of the levels of important proteins in the cell. Scientists have described more than 450 human miRNAs. It is believed that each of these molecules regulates the synthesis of tens or even hundreds of proteins that can determine the direction of cellular differentiation.
While many miRNAs specific to embryonic stem cells have already been identified, the role of individual molecules of this class in cell differentiation has so far been completely unclear. The authors showed for the first time that miRNAs can control the choice of the direction of differentiation by pluripotent stem cells, in this case, into heart muscle cells.
They found that miR-1 and miR-133 are active in the early stages of heart formation. At this stage of embryonic development, part of the embryo's cells forms the mesoderm – one of the three main germ leaves. In experiments, the activity of miR-1 or miR-133 stimulated the work of genes that ensure the formation of the mesoderm, and at the same time suppressed the activity of genes necessary for the formation of two other germ leaves – ectoderm and endoderm. For example, MIR-1 reduced the expression of a specific delta-like factor-1 (Delta-like 1), the removal of which from embryonic cells by other methods also triggered their transformation into cardiomyocytes.
According to the authors, the data obtained shed light on the subtle mechanisms of regulation of the genes involved in the formation of heart cells, and a detailed understanding of this complex system in the future will allow the development of methods for the treatment and prevention of heart diseases in children and adults.
Portal "Eternal youth" www.vechnayamolodost.ru based on the materials of ScienceDaily
11.03.2008