ИСТИНА

Recently renin-angiotensin system (RAS) was shown to be involved in the regulation of fat mass. However, mechanisms underlying the effect of RAS on adipogenesis, in particular on adipogenic differentiation of adipose-derived mesenchymal stem cells (ADSCs) remains poorly understood. Previously, we found the expression of angiotensin receptors (AGTRs) on human ADSCs. This study was aimed on functional characterization of cells expressing AGTR1. ADSCs were isolated from subcutaneous fat tissue of healthy young donors (n=5) and analyzed at the next day after isolation as well as upon culturing up to 5 passages. mRNAs encoding AGTR1 and 2 in ADSC were analyzed using real-time PCR. Activity of AGTR1 was analyzed by the ability of its specific agonist to activate Ca2+ mobilization in single cells using Fluo-8 probe. Subpopulations of ADSCs expressing AGTR1 were evaluated by flow cytometry and purified using FACS. ADSC phenotype characterized by flow cytometry was CD90+/CD73+/CD105+/CD45-/CD31- for all samples and these cells were capable of adipogenic and osteogenic differentiation. We found that these cells contained mRNAs of AGTR1 and AGTR2. Total population of ADSCs contained 2.2 ± 1.06 % of cells expressing AGTR1. Moreover, the proportion of cells carrying this receptor does not change during passages, but at 5th passage we also identified additional population of ADSCs with high expression of AGTR1 (AGTR1bright). ADSC functional analysis with Fluo-8 Ca2+ indicator and specific antagonist showed that activation of AGTR1 on ADSCs induces Ca2+ mobilization. Motility and proliferation of ADSC expressing AGTR1 were 1.3 and 2.5 times lower comparing to AGTR1-negative population. Evaluation of the differentiation potential revealed that AGTR1-expressing subpopulation differentiated into adipocytes more rapidly, which may indicate that these cells are committed to adipose differentiation. Taken together, our data indicate that human ADSCs contain a small subpopulation of cells expressing AGTR1. These are committed to adipogenic differentiation, which might be a target for RAS regulation of adiposity. This study was supported by RSF grant 14-15-00439.