Abnormal lncRNA CCAT1/microRNA-155/SIRT1 axis promoted inflammatory response and apoptosis of tubular epithelial cells in LPS caused acute kidney injury

Backgrounds: Acute kidney injury (AKI) is characterized by excessive inflammatory response and apoptosis in tubular epithelial cells. Recent studies suggested that long non-coding RNAs colon cancer-associated transcript-1 (CCAT-1) and microRNA-155 (miR-155) might regulate cell death and inflammation. We aimed to explore the role of CCAT-1/miRNA-155 axis in the AKI. Methods: LPS was applied to establish in vitro and in vivo models of AKI using HK2 cells and pcDNA-CCAT1 transgenic mice, respectively. Gene overexpression or knockdown were performed through plasmids transfecfion. Apoptosis were determined by qRT-PCR, western blotting (Fas, FasL, Caspase-3), AnnexinV/PI staining and TUNEL assay. Cytokines were assessed by ELISA. Interaction of CCAT1/miR-155 and miR-155/SIRT1 were detected by dual-luciferase reporter assay. RNA immunoprecipitation (RIP) was also performed to determine CCAT1/miR-155 interaction. Pathological changes of AKI were evaluated using H&E staining, blood urine nitrogen (BUN) and serum creatinine (Cr) detection kits. The degree of renal fibrosis was determined by Masson trichrome stain. Results: LPS administration reduced CCAT1 and SIRT1 expression, but increased miR-155 levels in tubular epithelial cells in vitro. Luciferase assay demonstrated that miR-155 might bind to and regulate CCAT1 and SIRT1. RIP further confirmed the direct interaction of CCAT1 and miR-155. Restoration of CCAT1 attenuated LPS induced inflammation and apoptosis through sequestering miR-155. The anti-inflammation and pro-survival effects of CCAT1 overexpression and miR-155 inhibition were abolished by SIRT1 knockdown, as indicated by the expression of cytokine and apoptotic markers, as well as H&E, BUN and Cr detection. Dysregulated CCAT1/miR-155/SIRT1 pathway regulated disease progression in a murine model of LPS-induced AKI, and NF-kappa B pathway involved in. Conclusion: CCAT1 restoration sequestered miR-155, leading to upregulation of SIRT1 and alleviated LPS induced renal tubular epithelial cell damage in vitro and in vivo.