Selective inhibition of JNK mitochondrial location is protective against seawater inhalation‑induced ALI/ARDS.

Liyan Bo,Yanyan Li,Wei Liu,Congcong Li,Faguang Jin

doi:10.3892/mmr.2021.12154

Abstract

Localization of phosphorylated (p)-JNK to the mitochondria can lead to functional mitochondrial disorder, resulting in a decrease in energy supply and membrane potential, as well as an increase in reactive oxygen species production and apoptosis. JNK is involved in the occurrence of acute lung injury (ALI), and activation of the JNK pathway is one of the crucial factors resulting in injury. The aim of the present study was to investigate whether the JNK-mitochondria (mitoJNK) location participated in the occurrence of ALI and acute respiratory distress syndrome (ALI/ARDS). The present study examined the activation of the JNK pathway, the content of JNK located on the mitochondria and the treatment effects of a cell-permeable peptide Tat-SabKIM1, which can selectively inhibit the location of JNK on mitochondria. The expression levels of proteins were detected by western blot analysis. Lung injuries were evaluated by histological examination, wet-to-dry weight ratios, and H2O2 and malondialdehyde concentrations in the lung tissues. Lung cells apoptosis was evaluated using TUNEL assay. The results demonstrated that JNK was phosphorylated and activated during seawater inhalation-induced ALI/ARDS, not only in the routine JNK pathway but also in the mitoJNK pathway. It was also found that Tat-SabKIM1 could specifically inhibit JNK localization to mitochondria and the activation of mitoJNK signaling. Furthermore, Tat-SabKIM1 could inhibit Bcl-2-regulated autophagy and mitochondria-mediated apoptosis. In conclusion, mitoJNK localization disrupted the normal physiological functions of the mitochondria during ALI/ARDS, and selective inhibition of JNK and mitochondrial SH3BP5 (also known as Sab) binding with Tat-SabKIM1 can block deterioration from ALI/ARDS.

Highlights

JNK belongs to the family of MAPKs and encompasses three encoded genes, JNK1, JNK2 and JNK3 [1]
Tracheal injection of Tat‐SabKIM1 10 min before modelling significantly decreased the phosphorylation level of JNK in mitochondria (Fig. 2A and B) and total JNK expression in mitochondria when compared with the seawater inhalation group (Fig. 2A and C); it did not influence the ratio of p‐JNK/JNK when compared with the seawater inhalation group (Fig. 2D). p‐JNK expression in the cytosol/nucleus was elevated in both the seawater inhalation group and Tat‐SabKIM1 pre‐treatment group compared with that in the control group (Fig. 2E and F)
These results indicated that Tat‐SabKIM1 could inhibit JNK localization to the mitochondria and the activation of mitoJNK signaling, without any impact on the ratio of p‐JNK/JNK or the cytosolic/nuclear JNK activation

Summary

Introduction

JNK belongs to the family of MAPKs and encompasses three encoded genes, JNK1, JNK2 and JNK3 [1]. As a response to a specific stimulation, MAPKs [such as MAPK kinase (MKK) 4 and MKK7] activate JNK via phosphorylation [4], and subsequently, regulate the phosphorylation and activity of several downstream factors, such as activating transcription factor‐2 [5], ETS transcription factor [6] and nuclear factor of activated T‐cells [7]. Among these factors, c‐jun/activator protein‐1 (AP‐1) has been clearly elucidated with respect to the JNK regulatory pathway. The localization of p‐JNK to mitochondria can lead to its functional disorder, resulting in a decrease in the energy supply and membrane potential, as well as an increase in reac‐ tive oxygen species (ROS) production and the occurrence of apoptosis [8,9,12]

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Conclusion