RESUMEN
A microarray analysis of an animal model with experimental sepsis induced by caecal ligation and puncture revealed that the level of microRNA195 (miR195) was upregulated. However, to the best of our knowledge, the role of miR195 in sepsis remains unknown. The present study investigated the effect of miR195 on apoptosis in sepsis and investigated the underlying mechanism. The level of miR195 was measured in human intestinal epithelial cells following exposure to lipopolysaccharide (LPS). Cell viability and apoptosis were detected using Cell Counting kit8 and flow cytometry assays. The expression levels of apoptosisassociated proteins were determined using western blot analysis. In addition, a dualluciferase reporter assay was employed to verify the association between miR195 and sirtuin 1 (SIRT1). Furthermore, the SIRT1 inhibitor EX527 was applied to further confirm the regulatory network of miR195/SIRT1 in LPSinduced apoptosis. It was demonstrated that LPS significantly inhibited cell viability and promoted cell apoptosis in NCM460 cells in a dosedependent manner. In addition, miR195 was significantly upregulated following LPS treatment. The present results revealed that silencing miR195 prevented apoptosis and alleviated cell injury in LPSinduced NCM460 cells. Further investigation demonstrated that miR195 bound directly to and negatively regulated SIRT1. Inhibition of SIRT1 reversed the protective effects of miR195silencing on the apoptosis and viability of NCM460 cells. Furthermore, silencing miR195 prevented endoplasmic reticulum (ER) stressinduced apoptosis via a downregulation of SIRT1 and its downstream effectors, including activating transcription factor 4, C/EBP homologous protein, glucoseregulated protein 78 and growth arrest and DNAdamage protein 34, as well as the phosphorylation of eukaryotic translation initiation factor 2A. In conclusion, the present study revealed a novel mechanism by which miR195 regulates SIRT1mediated downstream effectors in ER stressinduced apoptosis in sepsis.