The long non-coding RNA MALAT1 is increased in renal ischemia-reperfusion injury and inhibits hypoxia-induced inflammation

Background: To investigate the expression of long non-coding RNA metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) in renal ischemia-reperfusion injury and explore its role in acute kidney injury. Methods: 18 mice were randomly divided into a sham operation group (Sham) and an ischemiareperfusion group (IR) in which animals were sacrificed at 6 h or 12 h after surgery. The kidneys were harvested to measure the expression of MALAT1 mRNA. HK2 cells were treated with cobalt chloride (CoCl2) to mimic hypoxia or transfected with siRNA to knockdown MALAT1 before CoCl2 treatment. After that, MALAT1 was analyzed by RT-PCR (reverse transcription-polymerase chain reaction). HIF-1a (hypoxia-inducible factor-1 alpha) and NF-kappa B (nuclear factor-kappa B) was measured by Western blot. The concentrations of IL-6 (interleukin-6) and TNF-a (tumor necrosis factor- alpha) in the media were detected by ELISA (enzyme-linked immunosorbent assay). Results: The expression of MALAT1 in the IR (6 h/12 h) group was significantly higher than that in the sham group. In HK2 cells, MALAT1 was significantly increased at 1 h, 3 h, and 6 h after CoCl2 treatment but had reduced to the basal level at 12 h and 24 h. Knockdown of MALAT1 by siRNA significantly up-regulated the expression of HIF-1a and NF-kappa B proteins in CoCl2-treated HK2 cells. In addition, the concentrations of IL-6 and TNF-a were increased by MALAT1 siRNA transfection in CoCl2-treated HK2 cells. Conclusion: The expression of MALAT1 is increased in renal ischemia-reperfusion injury. It is likely that MALAT1 inhibits the hypoxia-induced inflammatory response through the NF-kappa B pathway.