title: Myeloperoxidase inactivates TIMP-1 by oxidizing its N-terminal cysteine residue: an oxidative mechanism for regulating proteolysis during inflammation.
abstract: An imbalance between the proteolytic activity of matrix metalloproteinases (MMPs) and the activity of tissue inhibitors of metalloproteinases (TIMPs) is implicated in tissue injury during inflammation. The N-terminal cysteine of TIMP-1 plays a key role in the inhibitory activity of the protein because it coordinates the essential catalytic Zn2+ of the MMP, preventing the metal ion from functioning. An important mechanism for controlling the interaction of TIMPs with MMPs might involve hypochlorous acid (HOCl), a potent oxidant produced by the myeloperoxidase (MPO) system of phagocytes. Here, we show that HOCl generated by the MPO-H2O2-chloride system inactivates TIMP-1 by oxidizing its N-terminal cysteine. The product is a novel 2-oxo acid. Liquid chromatography-mass spectrometry and tandem mass spectrometry analyses demonstrated that methionine and N-terminal cysteine residues were rapidly oxidized by MPO-derived HOCl but only oxidation of the N-terminal cysteine of TIMP-1 correlated well with loss of inhibitory activity. Importantly, we detected the signature 2-oxo-acid N-terminal peptide in tryptic digests of bronchoalveolar lavage fluid from patients with acute respiratory distress syndrome, demonstrating that TIMP-1 oxidation occurs in vivo. Loss of the N-terminal amino group and disulfide structure are crucial for preventing TIMP-1 from inhibiting MMPs. Our findings suggest that pericellular production of HOCl by phagocytes is a pathogenic mechanism for impairing TIMP-1 activity during inflammation.
authors.affiliation: Department of Medicine, University of Washington, Fred Hutchinson Cancer Research Center, Seattle, Washington 98195, USA.
authors.forename: Yi
authors.initials: Y
authors.lastname: Wang
authors.forename: Henry
authors.initials: H
authors.lastname: Rosen
authors.forename: David K
authors.initials: DK
authors.lastname: Madtes
authors.forename: Baohai
authors.initials: B
authors.lastname: Shao
authors.forename: Thomas R
authors.initials: TR
authors.lastname: Martin
authors.forename: Jay W
authors.initials: JW
authors.lastname: Heinecke
authors.forename: Xiaoyun
authors.initials: X
authors.lastname: Fu
mesh_terms: D000595:Amino Acid Sequence; D006801:Humans; D006997:Hypochlorous Acid / Q000378:metabolism; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction; D009195:Peroxidase / Q000378:metabolism*; D010586:Phagocytes / Q000378:metabolism; D012128:Respiratory Distress Syndrome / Q000378:metabolism*; D053719:Tandem Mass Spectrometry; D019715:Tissue Inhibitor of Metalloproteinase-1 / Q000737:chemistry* / Q000378:metabolism*
chemical_list: D019715:Tissue Inhibitor of Metalloproteinase-1; D006997:Hypochlorous Acid; D009195:Peroxidase