title: Oxidative stress-induced degradation of thioredoxin-1 and apoptosis is inhibited by thioredoxin-1-actin interaction in endothelial cells.
abstract: OBJECTIVE
  Thioredoxin-1 (Trx-1), one important antioxidative enzyme in endothelial cells, is required for apoptosis inhibition. Apoptosis induction is dependent on cytoskeletal changes, which depend on actin rearrangements. Therefore, we wanted to elucidate whether a physical interaction exists between Trx-1 and actin and what the functional consequences are.
  
  
  RESULTS
  Combined immunoprecipitation/mass spectrometry identified actin as a new binding partner for Trx-1. A separate pool of Trx-1 forms a complex with apoptosis signaling kinase 1. Actin is required for stress fiber formation; thus, the interaction of actin with Trx-1 might interfere with this process. Stress fiber formation, which is directly linked to the phosphorylation of focal adhesion kinase (FAK), occurs as early as 1 hour after H(2)O(2) treatment. It is inhibited by Trx-1 overexpression, treatment with exogenous Trx-1, or inhibition of FAK. Prolonged incubation with H(2)O(2) induced stress fiber formation, reduced Trx-1 protein levels, and increased apoptosis. All these processes were inhibited by preincubation with the FAK inhibitor PF573228. On the contrary, incubation with PF573228 1 hour after H(2)O(2) treatment did not block stress fiber formation, degradation of Trx-1, or apoptosis.
  
  
  CONCLUSIONS
  These data demonstrate that the actin-Trx-1 complex protects Trx-1 from degradation and, thus, endothelial cells from apoptosis. Reciprocally, Trx-1 prevents stress fiber formation.
authors.affiliation: Molecular Cell and Aging Research, IUF-Leibniz Institute for Environmental Medicine at the University of Duesseldorf, Auf'm Hennekamp 50, 40225 Duesseldorf, Germany. juhae001@uni-duesseldorf.de.
authors.forename: Tim-Christian
authors.initials: TC
authors.lastname: Zschauer
authors.forename: Kerstin
authors.initials: K
authors.lastname: Kunze
authors.forename: Sascha
authors.initials: S
authors.lastname: Jakob
authors.forename: Judith
authors.initials: J
authors.lastname: Haendeler
authors.forename: Joachim
authors.initials: J
authors.lastname: Altschmied
mesh_terms: D000199:Actins / Q000378:metabolism*; D017209:Apoptosis / Q000187:drug effects; D002478:Cells, Cultured; D042783:Endothelial Cells / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D051417:Focal Adhesion Kinase 1 / Q000037:antagonists & inhibitors / Q000378:metabolism; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D047468:Immunoprecipitation; D048848:MAP Kinase Kinase Kinase 5 / Q000378:metabolism; D013058:Mass Spectrometry; D016877:Oxidants / Q000494:pharmacology; D018384:Oxidative Stress / Q000187:drug effects; D010766:Phosphorylation; D011485:Protein Binding; D025941:Protein Interaction Mapping; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D015363:Quinolones / Q000494:pharmacology; D022502:Stress Fibers / Q000378:metabolism; D013450:Sulfones / Q000494:pharmacology; D013879:Thioredoxins / Q000235:genetics / Q000378:metabolism*; D014162:Transfection
chemical_list: C521108:6-(4-(3-(methylsulfonyl)benzylamino)-5-(trifluoromethyl)pyrimidin-2-ylamino)-3,4-dihydroquinolin-2(1H)-one; D000199:Actins; D016877:Oxidants; D047428:Protein Kinase Inhibitors; D015363:Quinolones; D013450:Sulfones; C491203:TXN protein, human; D013879:Thioredoxins; D006861:Hydrogen Peroxide; D051417:Focal Adhesion Kinase 1; C496050:PTK2 protein, human; D048848:MAP Kinase Kinase Kinase 5; C482858:MAP3K5 protein, human