Oxidative stress-induced mitophagy is suppressed by the miR-106b-93-25 cluster in a protective manner

Cheng Zhang,Chunliu Zhou,Zixin Deng,Meijia Gu,Jincao Chen,Dongxu Jiang,Pengqing Nie,Lianrong Wang,Shi Chen,Yue Hu,Suling Duan,Yunfu Wang

doi:10.1038/s41419-021-03484-3

Abstract

Increased reactive oxygen species levels in the mitochondrial matrix can induce Parkin-dependent mitophagy, which selectively degrades dysfunctional mitochondria via the autolysosome pathway. Phosphorylated mitofusin-2 (MFN2), a receptor of parkin RBR E3 ubiquitin-protein ligase (Parkin), interacts with Parkin to promote the ubiquitination of mitochondrial proteins; meanwhile, the mitophagy receptors Optineurin (OPTN) and nuclear dot protein 52 (NDP52) are recruited to damaged mitochondria to promote mitophagy. However, previous studies have not investigated changes in the levels of OPTN, MFN2, and NDP52 during Parkin-mediated mitophagy. Here, we show that mild and sustained hydrogen peroxide (H2O2) stimulation induces Parkin-dependent mitophagy accompanied by downregulation of the mitophagy-associated proteins OPTN, NDP52, and MFN2. We further demonstrate that H2O2 promotes the expression of the miR-106b-93-25 cluster and that miR-106b and miR-93 synergistically inhibit the translation of OPTN, NDP52, and MFN2 by targeting their 3’ untranslated regions. We further reveal that compromised phosphorylation of MYC proto-oncogene protein (c-Myc) at threonine 58 (T58) (producing an unstable form of c-Myc) caused by reduced nuclear glycogen synthase kinase-3 beta (GSK3β) levels contributes to the promotion of miR-106b-93-25 cluster expression upon H2O2 induction. Furthermore, miR-106b-mediated and miR-93-mediated inhibition of mitophagy-associated proteins (OPTN, MFN2, and NDP52) restrains cell death by controlling excessive mitophagy. Our data suggest that microRNAs (miRNAs) targeting mitophagy-associated proteins maintain cell survival, which is a novel mechanism of mitophagy control. Thus, our findings provide mechanistic insight into how miRNA-mediated regulation alters the biological process of mitophagy.

Highlights

Impaired mitochondria can be discriminated from normal mitochondria and cleared by the autophagosomelysosome pathway[1]
We investigated the occurrence of mitophagy and the effects of mitophagy induced by mild and sustained Reactive oxygen species (ROS) exposure on mitochondrial morphology and function
In EGFP-Parkin-transfected cells, the number of individual and network mitochondria decreased in a timedependent manner, and the mean network size was reduced; these results showed that mitochondria aggregated after 12–18 h of H2O2 stimulation (Fig. 1B, C)

Summary

Introduction

Impaired mitochondria can be discriminated from normal mitochondria and cleared by the autophagosomelysosome pathway[1]. One common mechanism for mitophagy involves the PTEN-induced kinase 1 (PINK1)/ parkin RBR E3 ubiquitin-protein ligase (Parkin) pathway. PINK1 is stabilized and MFN2 recruits Parkin, which links to polyubiquitin, to dysfunctional mitochondria[2]. Optineurin (OPTN) and nuclear dot protein 52. (NDP52) interact with polyubiquitin chains through ubiquitin-binding domains, and the microtubuleassociated protein 1 light chain 3 (LC3)-interacting regions (LIRs) of OPTN and NDP52 recruit LC3 along with autolysosomes to clear damaged mitochondria[3,4,5]. Numerous reports have suggested that disordered mitochondrial dynamics, disruption of mitochondrial function, and mutations in mitophagy receptors/adapters contribute to neurodegenerative diseases[6,7,8].

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