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Nuclear p53-mediated repression of autophagy involves PINK1 transcriptional down-regulation.

ABSTRACT: p53 is a transcription factor that is implicated in the control of both apoptotic and autophagic cell death. This tumor suppressor elicits both pro-autophagic and anti-autophagic phenotypes depending of its intracellular localization. The ability of p53 to repress autophagy has been exclusively associated to its cytoplasmic localization. Here, we show that transcriptional activity of p53 also contributes to autophagy down-regulation. Thus, nuclear p53 controls PINK1, a key protein involved in the control of mitophagy, by repressing its promoter activity, protein and mRNA levels, ex-vivo and in vivo. We establish that deletion of an identified p53 responsive element on PINK1 promoter impacts p53-mediated PINK1 transcriptional repression and we demonstrate a p53-PINK1 physical interaction by chromatin immunoprecipitation. Accordingly, we show that only nuclear p53 accounts for its ability to repress PINK1 gene transcription. Further, we demonstrate ex-vivo and in vivo that p53 invalidation in human cells increases LC3 maturation as well as optineurin and NDP52 autophagy receptors expression and down-regulates TIM23, TOM20 and HSP60 mitophagy markers. Importantly, this phenotype is mimicked by TP53 invalidation in mice brain. Finally, by combining pharmacological and genetic approaches, we show that the p53-mediated negative regulation of autophagy is PINK1-dependent. Thus pifithrin-?-mediated blockade of p53 transcriptional activity enhances LC3 maturation and reduces p62, TIM23, TOM20 and HSP60 protein levels. This pifithrin-?-associated pro-mitophagy phenotype is fully abolished by PINK1 depletion. This data unravels a novel pathway by which nuclear p53 can repress autophagy/mitophagy that could underlie important dysfunctions in both neurodegenerative and cancer diseases.

SUBMITTER: Goiran T

PROVIDER: S-EPMC5943347 | biostudies-literature | 2018 May

REPOSITORIES: biostudies-literature

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Nuclear p53-mediated repression of autophagy involves PINK1 transcriptional down-regulation.

Goiran Thomas T Duplan Eric E Rouland Lila L El Manaa Wejdane W Lauritzen Inger I Dunys Julie J You Han H Checler Frédéric F Alves da Costa Cristine C

Cell death and differentiation 20180119 5

p53 is a transcription factor that is implicated in the control of both apoptotic and autophagic cell death. This tumor suppressor elicits both pro-autophagic and anti-autophagic phenotypes depending of its intracellular localization. The ability of p53 to repress autophagy has been exclusively associated to its cytoplasmic localization. Here, we show that transcriptional activity of p53 also contributes to autophagy down-regulation. Thus, nuclear p53 controls PINK1, a key protein involved in th ...[more]

PMID: 29352272

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Project description:Little is known about the protective role of inflammatory processes in modulating lipid metabolism in infection. Here we report an intimate link between the innate immune response to infection and regulation of the sterol metabolic network characterized by down-regulation of sterol biosynthesis by an interferon regulatory loop mechanism. In time-series experiments profiling genome-wide lipid-associated gene expression of macrophages, we show a selective and coordinated negative regulation of the complete sterol pathway upon viral infection or cytokine treatment with IFNγ or β but not TNF, IL1β, or IL6. Quantitative analysis at the protein level of selected sterol metabolic enzymes upon infection shows a similar level of suppression. Experimental testing of sterol metabolite levels using lipidomic-based measurements shows a reduction in metabolic output. On the basis of pharmacologic and RNAi inhibition of the sterol pathway we show augmented protection against viral infection, and in combination with metabolite rescue experiments, we identify the requirement of the mevalonate-isoprenoid branch of the sterol metabolic network in the protective response upon statin or IFNβ treatment. Conditioned media experiments from infected cells support an involvement of secreted type 1 interferon(s) to be sufficient for reducing the sterol pathway upon infection. Moreover, we show that infection of primary macrophages containing a genetic knockout of the major type I interferon, IFNβ, leads to only a partial suppression of the sterol pathway, while genetic knockout of the receptor for all type I interferon family members, ifnar1, or associated signaling component, tyk2, completely abolishes the reduction of the sterol biosynthetic activity upon infection. Levels of the proteolytically cleaved nuclear forms of SREBP2, a key transcriptional regulator of sterol biosynthesis, are reduced upon infection and IFNβ treatment at both the protein and de novo transcription level. The reduction in srebf2 gene transcription upon infection and IFN treatment is also found to be strictly dependent on ifnar1. Altogether these results show that type 1 IFN signaling is both necessary and sufficient for reducing the sterol metabolic network activity upon infection, thereby linking the regulation of the sterol pathway with interferon anti-viral defense responses. These findings bring a new link between sterol metabolism and interferon antiviral response and support the idea of using host metabolic modifiers of innate immunity as a potential antiviral strategy.

Project description:BackgroundEukaryotic cells have developed surveillance mechanisms to prevent the expression of aberrant transcripts. An early surveillance checkpoint acts at the transcription site and prevents the release of mRNAs that carry processing defects. The exosome subunit Rrp6 is required for this checkpoint in Saccharomyces cerevisiae, but it is not known whether Rrp6 also plays a role in mRNA surveillance in higher eukaryotes.Methodology/principal findingsWe have developed an in vivo system to study nuclear mRNA surveillance in Drosophila melanogaster. We have produced S2 cells that express a human beta-globin gene with mutated splice sites in intron 2 (mut beta-globin). The transcripts encoded by the mut beta-globin gene are normally spliced at intron 1 but retain intron 2. The levels of the mut beta-globin transcripts are much lower than those of wild type (wt) ss-globin mRNAs transcribed from the same promoter. We have compared the expression of the mut and wt beta-globin genes to investigate the mechanisms that down-regulate the production of defective mRNAs. Both wt and mut beta-globin transcripts are processed at the 3', but the mut beta-globin transcripts are less efficiently cleaved than the wt transcripts. Moreover, the mut beta-globin transcripts are less efficiently released from the transcription site, as shown by FISH, and this defect is restored by depletion of Rrp6 by RNAi. Furthermore, transcription of the mut beta-globin gene is significantly impaired as revealed by ChIP experiments that measure the association of the RNA polymerase II with the transcribed genes. We have also shown that the mut beta-globin gene shows reduced levels of H3K4me3.Conclusions/significanceOur results show that there are at least two surveillance responses that operate cotranscriptionally in insect cells and probably in all metazoans. One response requires Rrp6 and results in the inefficient release of defective mRNAs from the transcription site. The other response acts at the transcription level and reduces the synthesis of the defective transcripts through a mechanism that involves histone modifications.

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Nuclear p53-mediated repression of autophagy involves PINK1 transcriptional down-regulation.

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Nuclear p53-mediated repression of autophagy involves PINK1 transcriptional down-regulation.

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