Мolecular and genetic mechanisms of rat skeletal muscle satellite cells transdifferentiation to cardiomyocyte-like ones

摘要

Satellite cells are myogenic stem cells responsible for growth, repair, and maintenance of skeletal muscles at all stages of ontogenesis. Isolated satellite cells in vitro represent a c onvenient model for an analysis of cellular and molecular mechanisms governing proliferation, differentiation, and apoptosis. It was shown that satellite cells under in vitro conditions are able to differentiate into osteogenic, adipogenic and chodrogenic cells. However it is not clear so far whether these cells can transform into cardiomyoc ytes. The answer for this question is important not only for understanding of fundamental aspects of satellite cell phenot ype changes but also for the development of the approaches necessary for therapy of cardiac dystrophy. It is well known that Gata, Nkx, Tbx, Ptx, connexins and cadherins play an essential role in regulation of the initial stages of cardiomyogenesis. We studied on the expression of genes encoding transcriptional factors Nkx2.5, Gata4 and membrane proteins connexin-43 (Cx-43), N-cadherin (N-Ca) in the process of satellite cells transdifferentiation into cardiomyoc ytes in vitro. In rat development satellite cells have specificities of differentiation. Because of this we used both: fetal (E20-21) and adult (3 month) rats as a source of cells. In 7-day-old satellite cell culture obtained from f etal rat we revealed low Gata4 expression. Then its level gradually raised throughout the process of transdifferentiation. Whereas in satellite cell culture obtained from adult skeletal muscle Gata4 transcripts could be found only on the 14thday of cultivation. Expression of Nkx2.5 was detected exclusively in fetal satellite cell culture and from the 14thday of transdifferentiation. As to a number of Gata4-possitive cells some of them appeared in 7-day-old satellite cell culture from fetal muscles and in 14-day-old satellite cell from adult ones. The majority of cells were Gata4-positive by the 28thday of transdifferentiation in both cases. Expression of Cx-43 and N-C a followed since the 7th(fetal satellite cell culture) and the 14th(adult satellite cell culture) days of transdifferentiation. Cx-43 and N-Ca-positive cells were identified in 14-, 21-, 28-days-old satellite cell cultures obtained from both, fetal and adult rat skeletal muscle. It is necessary to note also that expression of heart specific L-type Ca2*-channel (Cacna1c) was revealed only in the course of fetal satellite cell conversion. In sum our observations suggest that in satellite cells isolated from fetal skeletal muscle the molecular program of cardiomyogenic differentiation is initiated in vitro leading to formation of cardiomyoc yte specific cell contacts. This study was supported by the Presidium program of RAS .A biological variety. Gene pool dynamics