title: Increasing extracellular H2O2 produces a bi-phasic response in intracellular H2O2, with peroxiredoxin hyperoxidation only triggered once the cellular H2O2-buffering capacity is overwhelmed.
abstract: Reactive oxygen species, such as H2O2, can damage cells but also promote fundamental processes, including growth, differentiation and migration. The mechanisms allowing cells to differentially respond to toxic or signaling H2O2 levels are poorly defined. Here we reveal that increasing external H2O2 produces a bi-phasic response in intracellular H2O2. Peroxiredoxins (Prx) are abundant peroxidases which protect against genome instability, ageing and cancer. We have developed a dynamic model simulating in vivo changes in Prx oxidation. Remarkably, we show that the thioredoxin peroxidase activity of Prx does not provide any significant protection against external rises in H2O2. Instead, our model and experimental data are consistent with low levels of extracellular H2O2 being efficiently buffered by other thioredoxin-dependent activities, including H2O2-reactive cysteines in the thiol-proteome. We show that when extracellular H2O2 levels overwhelm this buffering capacity, the consequent rise in intracellular H2O2 triggers hyperoxidation of Prx to thioredoxin-resistant, peroxidase-inactive form/s. Accordingly, Prx hyperoxidation signals that H2O2 defenses are breached, diverting thioredoxin to repair damage.
authors.affiliation: Institute for Cell and Molecular Biosciences, Newcastle University, Framlington Place, Newcastle upon Tyne NE2 4HH, UK.
authors.forename: Lewis Elwood
authors.initials: LE
authors.lastname: Tomalin
authors.affiliation: Institute for Cell and Molecular Biosciences, Newcastle University, Framlington Place, Newcastle upon Tyne NE2 4HH, UK.
authors.forename: Alison Michelle
authors.initials: AM
authors.lastname: Day
authors.affiliation: Institute for Cell and Molecular Biosciences, Newcastle University, Framlington Place, Newcastle upon Tyne NE2 4HH, UK.
authors.forename: Zoe Elizabeth
authors.initials: ZE
authors.lastname: Underwood
authors.affiliation: Bioinformatics Support Unit, Newcastle University, Framlington Place, Newcastle upon Tyne NE2 4HH, UK.
authors.forename: Graham Robert
authors.initials: GR
authors.lastname: Smith
authors.affiliation: Institute for Cell and Molecular Biosciences, Newcastle University, Framlington Place, Newcastle upon Tyne NE2 4HH, UK.
authors.forename: Piero
authors.initials: P
authors.lastname: Dalle Pezze
authors.affiliation: University College London, Department of Genetics, Evolution & Environment and Institute of Healthy Ageing, Gower Street - Darwin Building, London WC1E 6BT, UK.
authors.forename: Charalampos
authors.initials: C
authors.lastname: Rallis
authors.affiliation: Institute for Cell and Molecular Biosciences, Newcastle University, Framlington Place, Newcastle upon Tyne NE2 4HH, UK.
authors.forename: Waseema
authors.initials: W
authors.lastname: Patel
authors.affiliation: Department of Chemistry, The University of Chicago, Chicago, IL 60637, USA.
authors.forename: Bryan Craig
authors.initials: BC
authors.lastname: Dickinson
authors.affiliation: University College London, Department of Genetics, Evolution & Environment and Institute of Healthy Ageing, Gower Street - Darwin Building, London WC1E 6BT, UK.
authors.forename: Jürg
authors.initials: J
authors.lastname: Bähler
authors.affiliation: Howard Hughes Medical Institute and Departments of Chemistry and Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA.
authors.forename: Thomas Francis
authors.initials: TF
authors.lastname: Brewer
authors.affiliation: Howard Hughes Medical Institute and Departments of Chemistry and Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA.
authors.forename: Christopher Joh-Leung
authors.initials: CJ
authors.lastname: Chang
authors.affiliation: Institute for Cell and Molecular Biosciences, Newcastle University, Framlington Place, Newcastle upon Tyne NE2 4HH, UK. Electronic address: daryl.shanley@ncl.ac.uk.
authors.forename: Daryl Pierson
authors.initials: DP
authors.lastname: Shanley
authors.affiliation: Institute for Cell and Molecular Biosciences, Newcastle University, Framlington Place, Newcastle upon Tyne NE2 4HH, UK. Electronic address: e.a.veal@ncl.ac.uk.
authors.forename: Elizabeth Ann
authors.initials: EA
authors.lastname: Veal
mesh_terms: D003593:Cytoplasm / Q000737:chemistry / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000737:chemistry* / Q000378:metabolism; D008956:Models, Chemical; D010084:Oxidation-Reduction; D054464:Peroxiredoxins / Q000737:chemistry* / Q000235:genetics; D017382:Reactive Oxygen Species / Q000737:chemistry / Q000378:metabolism; D015398:Signal Transduction; D013879:Thioredoxins / Q000737:chemistry* / Q000378:metabolism
chemical_list: D017382:Reactive Oxygen Species; D013879:Thioredoxins; D006861:Hydrogen Peroxide; D054464:Peroxiredoxins
keywords: Computational model; Hydrogen peroxide; Oxidation; Peroxiredoxin; Signaling; Thiol; Thioredoxin