title: Activation of the redox sensor Pap1 by hydrogen peroxide requires modulation of the intracellular oxidant concentration.
abstract: The transcription factor Pap1 and the MAP kinase Sty1 are key regulators of hydrogen peroxide-induced responses in Schizosaccharomyces pombe. Pap1 can be activated quickly at low, but not high, hydrogen peroxide concentrations. The MAP kinase Sty1 has been reported to participate in Pap1 activation by the oxidant. Here, we provide biochemical and genetic evidence for the in vivo formation of a hydrogen peroxide-induced disulphide bond in Pap1, which precedes the rapid and reversible nuclear accumulation of the transcription factor. We show that activation of the Sty1 cascade before the oxidative insult, or overexpression of the Sty1-regulated genes ctt1 (encoding catalase) or gpx1 (encoding glutathione peroxidase), can accelerate Pap1 entry even at high doses of hydrogen peroxide. In fact, the lack of Sty1 impedes Pap1 nuclear localization, but only at high doses of the oxidant. We propose that, whereas low doses of hydrogen peroxide lead directly to Pap1 oxidation-activation, high concentrations of the oxidant initially activate the Sty1 pathway, with the consequent increase in scavenging enzymes, which in turn helps to decompose the excess of hydrogen peroxide and achieve an appropriate concentration for the subsequent activation of Pap1. Our results also suggest that activation of Sty1 at high doses of hydrogen peroxide may also be required to trigger other antioxidant activities such as those reverting the overoxidation of cysteine residues at the Pap1 pathway.
authors.affiliation: Cell Signalling Unit, Departament de Ciències Experimentals i de la Salut, Universitat Pompeu Fabra, C/Dr Aiguader 80, E-08003 Barcelona, Spain.
authors.forename: Ana P
authors.initials: AP
authors.lastname: Vivancos
authors.forename: Esther A
authors.initials: EA
authors.lastname: Castillo
authors.forename: Nic
authors.initials: N
authors.lastname: Jones
authors.forename: José
authors.initials: J
authors.lastname: Ayté
authors.forename: Elena
authors.initials: E
authors.lastname: Hidalgo
mesh_terms: D021581:Active Transport, Cell Nucleus; D050976:Basic-Leucine Zipper Transcription Factors; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004220:Disulfides / Q000737:chemistry; D004789:Enzyme Activation; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D015966:Gene Expression Regulation, Fungal; D005979:Glutathione Peroxidase / Q000235:genetics / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000378:metabolism*; D020935:MAP Kinase Signaling System / Q000502:physiology; D008298:Maleates / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D016877:Oxidants / Q000378:metabolism*; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D000073718:Pancreatitis-Associated Proteins; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D012568:Schizosaccharomyces / Q000166:cytology / Q000235:genetics / Q000378:metabolism*; D029702:Schizosaccharomyces pombe Proteins / Q000378:metabolism
chemical_list: D050976:Basic-Leucine Zipper Transcription Factors; D004268:DNA-Binding Proteins; D004220:Disulfides; D005656:Fungal Proteins; D008298:Maleates; D016877:Oxidants; D000073718:Pancreatitis-Associated Proteins; C105096:Pap1 protein, S pombe; C000612141:REG3A protein, human; D011993:Recombinant Fusion Proteins; D029702:Schizosaccharomyces pombe Proteins; D006861:Hydrogen Peroxide; D005979:Glutathione Peroxidase; D020928:Mitogen-Activated Protein Kinases; C095409:sty1 protein, S pombe; C014476:diethyl maleate