RESUMO
Hepatic fibrosis and its end-stage cirrhosis have increased worldwide, and, despite all the efforts, no successful therapy is available. More recently, the heptapeptide angiotensin-(1-7) [ang-(1-7)] was reported to be able to modulate liver fibrosis and even steatosis; however, the molecular bases of these effects are not clear. In this study, we investigated the overexpression of the microRNA-1254 in the human hepatic stellate cell line LX-2, based on the effect of the heptapeptide in such cells, previously, demonstrated by our research group. In addition, this miRNA was chosen based on the identification of putative binding site of this small molecule in the mRNA sequences of different molecular connectors of the AKT/ PI3K pathway, which is modulated by the heptapeptide and connects to the control of several cellular mechanisms, including proliferation, survival, migration, and even liver fibrogenesis. The results revealed an innovative function of the miR-1254 in controlling SMAD3 and pro-fibrosing elements as well as the wound healing response in LX-2, attenuating the scaring repair of the injured tissue. The combined findings provide useful information for future studies on the controlling of hepatic fibrogenesis.
Assuntos
Cirrose Hepática/genética , Cirrose Hepática/patologia , MicroRNAs/metabolismo , Proteína Smad3/metabolismo , Cicatrização , Sequência de Bases , Linhagem Celular , Humanos , MicroRNAs/genética , Transcrição GênicaRESUMO
The development of new therapeutic strategies to control or reverse hepatic fibrosis requires thorough knowledge about its molecular and cellular basis. It is known that the heptapeptide angiotensin-(1-7) [ang-(1-7)] can reduce hepatic fibrosis and steatosis in vivo; therefore, it is important to uncover the mechanisms regulating its activity and cellular model of investigation. Ang-(1-7) is a peptide of the renin-angiotensin system (RAS), and here we investigated its modulatory effect on the expression pattern of microRNAs (miRNAs) in hepatic stellate cells (HSCs) LX-2, which transdifferentiate into fibrogenic and proliferative cells. We compared the miRNA profiles between quiesced, activated and ang-(1-7)-treated activated HSCs to identify miRNAs that may regulate their transdifferentiation. Thirteen miRNAs were pointed, and cellular and molecular analyses identified miRNA-1914-5p as a molecule that contributes to the effects of ang-(1-7) on lipid metabolism and on the pro-fibrotic environment control. In our cellular model, we also analyzed the regulators of fatty acid metabolism. Specifically, miRNA-1914-5p regulates the expression of malonyl-CoA decarboxylase (MLYCD) and phosphatidic acid phosphohydrolase (PAP or Lipin-1). Additionally, Lipin-1 was closely correlated with mRNA expression of peroxisome proliferator-activated receptors (PPAR)-α and -γ, which also contribute to lipid homeostasis and to the reduction of TGF-ß1 expression. These findings provide a novel link between RAS and lipid metabolism in controlling HSCs activation.