Down-regulation of LncRNA CRNDE aggravates kidney injury via increasing MiR-181a-5p in sepsis

Long non-coding RNA (lncRNA) colorectal neoplasia differentially expressed (CRNDE) is reported to be linked to inflammation and cell apoptosis. However its role in sepsis induced kidney injury remains unclear. This study aims to explore the possible mechanism of CRNDE in kidney injury induced by sepsis. In vivo urine-derived sepsis (US) rat model and in vitro LPS-induced HK-2 and HEK293 cells were established. Kidney function was measured in rats from different groups. Relative levels of tumor necrosis factor-alpha (TNF-alpha) and interleukin-1 beta(IL-1 beta) in kidney tissue were detected via Enzyme-linked immune sorbent assay (ELISA). Then we up- or down-regulated CRNDE and miRNA-181a-5p expression in the cells. The biological influence of CRNDE and miR-181a-5p on cells was studied using CCK-8 assay and Annexin V assay. Interaction between CRNDE and miR-181a-5p was determined by bioinformatics analysis, RT-PCR, and dual luciferase reporter assay. Peroxisome proliferator-activated receptor-alpha (PPAR alpha) and cell apoptosis related molecules were detected by western blot. We demonstrated that CRNDE was markedly down-regulated while miR-181a-5p was significantly up-regulated in sepsis models. CRNDE interacted with miR-181a-5p, and negatively regulated its expression level. CRNDE knockdown in rats increased the urea nitrogen and serum creatinine in plasma. Knockdown of CRNDE or transfection of miR-181a5p significantly inhibited proliferation and promoted apoptosis of HK-2 and HEK293 cells, while overexpression of CRNDE and transfection of miR-181a-5p inhibitors had opposite effects. For mechanism, miR-181a-5p directly targeted the 3' untranslated region of PPAR alpha, and depressed its protein level, and PPAR alpha was regulated indirectly by CRNDE. We concluded that CRNDE protected renal cell from sepsis-induced injury via miR-181a-5p/PPAR alpha pathway.