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A novel mechanism of ataxia telangiectasia mutated mediated regulation of chromatin remodeling in hypoxic conditions

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Show simple item record Likhatcheva, Maria Gieling, Roben G. Brown, James A.L. Demopoulos, Constantinos A. Williams, Kaye J. 2021-11-18T14:47:02Z 2021-11-18T14:47:02Z 2021
dc.description peer-reviewed en_US
dc.description.abstract The effects of genotoxic stress can be mediated by activation of the Ataxia Telangiectasia Mutated (ATM) kinase, under both DNA damage-dependent (including ionizing radiation), and independent (including hypoxic stress) conditions. ATM activation is complex, and primarily mediated by the lysine acetyltransferase Tip60. Epigenetic changes can regulate this Tip60-dependent activation of ATM, requiring the interaction of Tip60 with tri-methylated histone 3 lysine 9 (H3K9me3). Under hypoxic stress, the role of Tip60 in DNA damage-independent ATM activation is unknown. However, epigenetic changes dependent on the methyltransferase Suv39H1, which generates H3K9me3, have been implicated. Our results demonstrate severe hypoxic stress (0.1% oxygen) caused ATM auto-phosphorylation and activation (pS1981), H3K9me3, and elevated both Suv39H1 and Tip60 protein levels in FTC133 and HCT116 cell lines. Exploring the mechanism of ATM activation under these hypoxic conditions, siRNA mediated Suv39H1 depletion prevented H3K9me3 induction, and Tip60 inhibition (by TH1834) blocked ATM auto-phosphorylation. While MDM2 (Mouse double minute 2) can target Suv39H1 for degradation, it can be blocked by sirtuin-1 (Sirt1). Under severe hypoxia MDM2 protein levels were unchanged, and Sirt1 levels depleted. SiRNA-mediated depletion of MDM2 revealed MDM2 dependent regulation of Suv39H1 protein stability under these conditions. We describe a novel molecular circuit regulating the heterochromatic state (H3K9me3 positive) under severe hypoxic conditions, showing that severe hypoxia-induced ATM activation maintains H3K9me3 levels by downregulating MDM2 and preventing MDM2-mediated degradation of Suv39H1. This novel mechanism is a potential anti-cancer therapeutic opportunity, which if exploited could target the hypoxic tumor cells known to drive both tumor progression and treatment resistance. en_US
dc.language.iso eng en_US
dc.publisher Frontiers Media en_US
dc.relation.ispartofseries Frontiers in Cell and Developmental Biology;9, article 720194
dc.rights This Document is Protected by copyright and was first published by Frontiers. All rights reserved. it is reproduced with permission en_US
dc.subject Ataxia Telangiectasia Mutated (ATM) en_US
dc.subject hypoxia en_US
dc.subject SUV39H1 en_US
dc.subject Tip60 en_US
dc.subject MDM2 en_US
dc.title A novel mechanism of ataxia telangiectasia mutated mediated regulation of chromatin remodeling in hypoxic conditions en_US
dc.type info:eu-repo/semantics/article en_US
dc.type.supercollection all_ul_research en_US
dc.type.supercollection ul_published_reviewed en_US
dc.identifier.doi 10.3389/fcell.2021.720194
dc.contributor.sponsor Consejo Nacional de Ciencia y Tecnologia en_US
dc.relation.projectid 226081/381343 en_US
dc.rights.accessrights info:eu-repo/semantics/openAccess en_US

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