Adipose tissue communicates with other organs
Maxim Rousseau, Polit.<url>, based on the materials of Science: Fat tissue can ‘talk’ to other organs, paving way for possible treatments for diabetes, obesity
A new study has revealed that adipose tissue in the body can interact with other organs using small molecules that control the activity of genes in other parts of the body. This new communication pathway in the body shows that fat plays a greater role in regulating metabolism than previously thought. Also, the discovery may provide new treatment options for diseases such as obesity and diabetes.
Previously, scientists already knew that adipocytes – adipose tissue cells – secrete a number of hormones, for example, resistin, adiponectin and leptin. But now new information carriers have been identified – microRNA molecules. In the body, microRNA participates in the regulation of genes using the mechanism of so-called RNA interference. microRNA molecules travel between cells in exosomes, small formations of cytoplasm that have a membrane. When the exosome reaches its target, the microRNA gets into the right cell and the work of the genes in this cell is corrected.
Diabetes specialist Thomas Tomou from Harvard Medical School and his colleagues decided to clarify the functions of microRNAs in adipose tissue. To do this, they created a special line of genetically modified laboratory mice that were deprived of the necessary enzyme for the production of microRNAs. As it turned out, these mice had less adipose tissue and were not able to process glucose as efficiently as normal mice.
By transplanting fat from ordinary mice into these mice, the scientists restored the level of microRNA in their blood. At the same time, the transplantation of brown fat also allowed to normalize the breakdown of glucose in their body, but when transplanting white fat, this did not happen. Recall that usually in the body white fat is used for energy storage, and brown, so named because of the abundance of mitochondria in cells, is used for thermoregulation.
In a previous study of mice whose function of microRNA formation in adipose tissue was impaired, it turned out that their heart, liver and other organs were also affected, although genetic modification should not have affected them directly. Therefore, Tomou and his colleagues hypothesized that adipose tissue influences organs through microRNA molecules.
To test this, they prepared two groups of mice. In one of them, brown adipose tissue cells could produce human microRNA molecules. In another, molecules were produced in liver cells that serve as a target for this microRNA, bound to a fluorescent protein so that they could be easily detected. After the exosomes with microRNA of the mice of the first group were introduced to the second group, the number of fluorescent molecules in their liver fell. This means that adipose tissue, releasing microRNAs into the blood, is able to influence gene expression in the liver. The effect of this microRNA on the Fgf21 gene (fibroblast growth factor 21 gene) important for metabolism in liver cells was also found.
"This finding will not only provide insight into new communication pathways in tissues, but also pathways that can be altered in diseases," says one of the authors of the paper, Ronald Kahn (C. Ronald Kahn) from Harvard University. If researchers can figure out how exosomes orient themselves when heading to certain types of cells, they will be able to use this type of transport in the future to deliver drugs and other therapies to cells. But it is not yet clear what exactly serves as a "molecular address" for them to find their target.
Article by Thomou et al. Adipose-derived circulating miRNAs regulate gene expression in other tissues published in Nature – VM.
Portal "Eternal youth" http://vechnayamolodost.ru
17.02.2017