title: Mitochondrial dysfunction induces SESN2 gene expression through Activating Transcription Factor 4.
abstract: We found that inhibitors of mitochondrial respiratory chain complexes III (myxothiazol) and I (piericidin A) in some epithelial carcinoma cell lines induce transcription of the p53-responsive SESN2 gene that plays an important role in stress response and homeostatic regulation. However, the effect did not depend on p53 because i) there was no induction of p53 after the treatment with piericidin A; ii) after the treatment with myxothiazol the peak of SESN2 gene upregulation occurred as early as 5h, before the onset of p53 activation (13h); iii) a supplementation with uridine that abolishes the p53 activation in response to myxothiazol did not abrogate the induction of SESN2 transcripts; iv) in the p53 negative HCT116 p53 -/- cells SESN2 transcription could be also induced by myxothiazol. In response to the respiratory chain inhibitors we observed an induction of ATF4, the key transcription factor of the integrated stress response (ISR). We found that the induction of SESN2 transcripts could be prevented by the ISR inhibitory small molecule ISRIB. Also, by inhibiting or overexpressing ATF4 with specific shRNA or ATF4-expressing constructs, respectively, we have confirmed the role of ATF4 in the SESN2 gene upregulation induced by mitochondrial dysfunction. At a distance of 228 bp upstream from the SESN2 transcription start site we found a candidate sequence for the ATF4 binding site and confirmed its requirement for the induction of SESN2 in luciferase reporter experiments. We suggest that the upregulation of SESN2 by mitochondrial dysfunction provides a homeostatic feedback that attenuates biosynthetic processes during temporal losses of energy supply from mitochondria thereby assisting better adaptation and viability of cells in hostile environments.
authors.affiliation: a Department of Bioengineering and Bioinformatics , Lomonosov Moscow State University , Moscow , Russia.|b Engelhardt Institute of Molecular Biology, Russian Academy of Sciences , Moscow , Russia.
authors.forename: Alisa A
authors.initials: AA
authors.lastname: Garaeva
authors.affiliation: c Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University , Moscow , Russia.
authors.forename: Irina E
authors.initials: IE
authors.lastname: Kovaleva
authors.affiliation: b Engelhardt Institute of Molecular Biology, Russian Academy of Sciences , Moscow , Russia.
authors.forename: Peter M
authors.initials: PM
authors.lastname: Chumakov
authors.affiliation: a Department of Bioengineering and Bioinformatics , Lomonosov Moscow State University , Moscow , Russia.|c Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University , Moscow , Russia.
authors.forename: Alexandra G
authors.initials: AG
authors.lastname: Evstafieva
mesh_terms: D051701:Activating Transcription Factor 4 / Q000096:biosynthesis* / Q000235:genetics; D005786:Gene Expression Regulation; D045325:HCT116 Cells; D006367:HeLa Cells; D006801:Humans; D008928:Mitochondria / Q000235:genetics / Q000378:metabolism*; D009687:Nuclear Proteins / Q000096:biosynthesis* / Q000235:genetics; D015533:Transcriptional Activation / Q000502:physiology; D015854:Up-Regulation / Q000502:physiology; D000084622:Sestrins
chemical_list: D051701:Activating Transcription Factor 4; D009687:Nuclear Proteins; C497109:ATF4 protein, human; C465398:SESN2 protein, human; D000084622:Sestrins
keywords: ATF4-binding site; ISRIB; SESN2 promoter; Sestrin 2; integrated stress response; mitochondrial respiratory chain complex III; transcription factor ATF4; tumor suppressor p53