miR-195 promotes LPS-mediated intestinal epithelial cell apoptosis via targeting SIRT1/eIF2a

A microarray analysis of an animal model with experimental sepsis induced by caecal ligation and puncture revealed that the level of microRNA-195 (miR-195) was upregulated. However, to the best of our knowledge, the role of miR-195 in sepsis remains unknown. The present study investigated the effect of miR-195 on apoptosis in sepsis and investigated the underlying mechanism. The level of miR-195 was measured in human intestinal epithelial cells following exposure to lipopolysaccharide (LPS). Cell viability and apoptosis were detected using Cell Counting kit-8 and flow cytometry assays. The expression levels of apoptosis-associated proteins were determined using western blot analysis. In addition, a dual-luciferase reporter assay was employed to verify the association between miR-195 and sirtuin 1 (SIRT1). Furthermore, the SIRT1 inhibitor EX527 was applied to further confirm the regulatory network of miR-195/SIRT1 in LPS-induced apoptosis. It was demonstrated that LPS significantly inhibited cell viability and promoted cell apoptosis in NCM460 cells in a dose-dependent manner. In addition, miR-195 was significantly upregulated following LPS treatment. The present results revealed that silencing miR-195 prevented apoptosis and alleviated cell injury in LPS-induced NCM460 cells. Further investigation demonstrated that miR-195 bound directly to and negatively regulated SIRT1. Inhibition of SIRT1 reversed the protective effects of miR-195-silencing on the apoptosis and viability of NCM460 cells. Furthermore, silencing miR-195 prevented endoplasmic reticulum (ER) stress-induced apoptosis via a downregulation of SIRT1 and its downstream effectors, including activating transcription factor 4, C/EBP homologous protein, glucose-regulated protein 78 and growth arrest and DNA-damage protein 34, as well as the phosphorylation of eukaryotic translation initiation factor 2A. In conclusion, the present study revealed a novel mechanism by which miR-195 regulates SIRT1-mediated downstream effectors in ER stress-induced apoptosis in sepsis.