miR­195 promotes LPS­mediated intestinal epithelial cell apoptosis via targeting SIRT1/eIF2a.

ABSTRACT

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.