MiR-181d-5p Targets KLF6 to Improve Ischemia/Reperfusion-Induced AKI Through Effects on Renal Function, Apoptosis, and Inflammation.

Yue Zhang,Chen Guan,Chengyu Yang,Jie Dai,Yan Xu,Long Zhao,Li Zhen,Lin Wang,Bin Zhou,Chenyu Li,Wei Jiang

doi:10.3389/fphys.2020.00510

Abstract

Renal tubular epithelial cell (RTEC) death and renal interstitial inflammation are the most crucial pathophysiological changes in acute kidney ischemia/reperfusion injury (IRI). The microRNA (miR)-181d family plays diverse roles in cell proliferation, apoptosis and inflammation, but its renal target and potential role in IRI are unknown. Here, we showed that the expression of miR-181d-5p decreased and Krueppel-like factor 6 (KLF6) increased in a renal cell (HK-2) model of hypoxia/reoxygenation (H/R) injury and a mouse model of renal IRI. They were mainly distributed in the renal tubules. After renal IRI, miR-181d-5p overexpression significantly inhibited inflammatory mediators, reduced apoptosis and further improved renal function. KLF6 exacerbated RTEC damage and acted as a NF-κB co-activator to aggravate the renal IRI inflammatory response. Mechanistically, KLF6 was predicted as a new potential target gene of miR-181d-5p through bioinformatic analysis and luciferase reporter assay verification. After overexpressing miR-181d-5p and inhibiting KLF6, the role of miR-181d-5p was weakened on the renal damage improvement. In conclusion, miR-181d-5p upregulation produced protective antiapoptotic and anti-inflammatory effects against IRI in kidneys in vivo and H/R injury in HK-2 cells in vitro, and these effects were achieved by targeted inhibition of KLF6. Thus, our results provide novel insights into the molecular mechanisms associated with IRI and a potential novel therapeutic target.

Highlights

Ischemia/reperfusion injury (IRI) is the outcome of an inflammatory process and tubular cell death triggered by a transient reduction in or cessation of blood flow followed by reperfusion (Lameire et al, 2005)
Renal ischemia/reperfusion injury (IRI) was induced in mice via bilateral renal artery occlusion for 45 min and reperfusion for the indicated time. quantitative real-time PCR (qRT-PCR) showed that miR-181d-5p levels increased gradually in the IRI group, peaking at 9 h but declining at 24 h compared with those in the normal control and sham groups (Figure 1C)
The in situ hybridization assay results revealed that miR-181d5p staining was distributed mainly in renal tubular epithelial cells (RTECs) in the renal cortex (Figure 1B)

Summary

Introduction

Ischemia/reperfusion injury (IRI) is the outcome of an inflammatory process and tubular cell death triggered by a transient reduction in or cessation of blood flow followed by reperfusion (Lameire et al, 2005). Numerous studies have investigated the molecular and cellular mechanisms of renal IRI, suggesting the occurrence of various pathophysiological changes, including tubular epithelial cell injury, microvascular dysfunction, and inflammation, which show dramatic contributions to overall renal. The microRNA (miR)-181 family plays diverse roles in regulating key aspects of cellular growth, development, and activation. Accumulating evidence supports an important role for the miR-181 family in inflammation via the control of critical signaling pathways, such as downstream NF-κB signaling (Sun et al, 2012; Cao et al, 2017), and targets relevant to immune cell homeostasis (Xue et al, 2011; Seeger et al, 2013). A recent study showed that miR-181d activated the NF-κB pathway and promoted the expression of the proinflammatory cytokines TNFα and IL-12. Whether miR-181d plays an important role in the regulation of renal IRI is unknown

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