title: MiR-155 is Involved in Renal Ischemia-Reperfusion Injury via Direct Targeting of FoxO3a and Regulating Renal Tubular Cell Pyroptosis.
abstract: OBJECTIVE
  Ischemia/reperfusion injury (IRI) plays a crucial role in renal transplantation and can cause renal failure associated with pyroptosis, a pro-inflammatory-induced programmed cell death. Small endogenous non-coding RNAs have been shown to be involved in renal ischemia/reperfusion injury. This study was performed to investigate which miRNAs regulate pyroptosis in response to renal ischemia/reperfusion injury and determine the mechanism underlying this regulation.
  
  
  METHODS
  An in vivo rat model of renal IRI was established, and the serum and kidneys were harvested 24 h after reperfusion to assess renal function and histological changes. For the in vitro study, the cultured human renal proximal tubular cell line HK-2 was subjected to 24 h of hypoxia (5% CO2, 1% O2, and 94% N2) followed by 12 h of reoxygenation (5% CO2, 21% O2, and 74% N2). The mRNA expression levels were analyzed by real-time PCR, and the protein expression levels were analyzed using Western blot, immunofluorescence staining and enzyme-linked immunosorbent assay (ELISA). Bioinformatics analyses were applied to predict miR-155 targets, which were then confirmed by a luciferase reporter assay.
  
  
  RESULTS
  We found that the levels of pyroptosis-related proteins, including caspase-1, caspase-11, IL-1β and IL-18, were significantly increased after renal ischemia/reperfusion injury. Similarly, hypoxia-reoxygenation injury (HRI) also induced pyroptosis in HK2 cells. Furthermore, our study revealed that miR-155 expression was substantially increased in the renal tissues of IRI rats and in HRI HK2 cells. Up-regulation of miR-155 promoted HK2 cell pyroptosis in HRI; conversely, knockdown of miR-155 attenuated this process. To understand the signaling mechanisms underlying the pro-pyroptotic activity of miR-155, we found that exogenous expression of miR-155 up-regulated the expression of caspase-1 as well as the pro-inflammatory cytokines IL-1β and IL-18. Moreover, miR-155 directly repressed FoxO3a expression and its downstream protein apoptosis repressor with caspase recruitment domain (ARC).
  
  
  CONCLUSIONS
  Our study proposes a new signaling pathway of miR-155/FoxO3a/ARC leading to renal pyroptosis under ischemia/reperfusion injury conditions.
authors.affiliation: Transplantation Center of Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China.
authors.forename: Haoyu
authors.initials: H
authors.lastname: Wu
authors.forename: Tao
authors.initials: T
authors.lastname: Huang
authors.forename: Liang
authors.initials: L
authors.lastname: Ying
authors.forename: Conghui
authors.initials: C
authors.lastname: Han
authors.forename: Dawei
authors.initials: D
authors.lastname: Li
authors.forename: Yao
authors.initials: Y
authors.lastname: Xu
authors.forename: Ming
authors.initials: M
authors.lastname: Zhang
authors.forename: Shan
authors.initials: S
authors.lastname: Mou
authors.forename: Zhen
authors.initials: Z
authors.lastname: Dong
mesh_terms: D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D003598:Cytoskeletal Proteins / Q000378:metabolism; D015536:Down-Regulation / Q000235:genetics; D000071316:Forkhead Box Protein O3 / Q000378:metabolism*; D006801:Humans; D007249:Inflammation / Q000235:genetics / Q000473:pathology; D007684:Kidney Tubules / Q000098:blood supply* / Q000378:metabolism / Q000473:pathology*; D008297:Male; D035683:MicroRNAs / Q000235:genetics / Q000378:metabolism*; D008954:Models, Biological; D009419:Nerve Tissue Proteins / Q000378:metabolism; D000069292:Pyroptosis / Q000235:genetics*; D017207:Rats, Sprague-Dawley; D015427:Reperfusion Injury / Q000235:genetics* / Q000473:pathology; D015854:Up-Regulation / Q000235:genetics
chemical_list: D003598:Cytoskeletal Proteins; C499517:FOXO3 protein, human; C499515:FOXO3 protein, rat; D000071316:Forkhead Box Protein O3; C524942:MIRN155 microRNA, human; C580597:MIRN155 microRNA, rat; D035683:MicroRNAs; D009419:Nerve Tissue Proteins; C092069:activity regulated cytoskeletal-associated protein