Roles of Superoxide Radical Anion in Signal Transduction Mediated by Reversible Regulation of Protein-tyrosine Phosphatase 1B

• Published in: The Journal of biological chemistry Vol. 274; no. 49; pp. 34543 - 34546
• Main Authors: Barrett, W C, DeGnore, J P, Keng, Y F, Zhang, Z Y, Yim, M B, Chock, P B
• Format: Journal Article
• Language: English
• Published: United States American Society for Biochemistry and Molecular Biology 03.12.1999
• Subjects: Anions - metabolism; Carrier Proteins - metabolism; Catalase - pharmacology; Chromatography, Liquid; Enzyme Activation - drug effects; Enzyme Activation - physiology; Humans; Hydrogen Peroxide - metabolism; Kinetics; Mass Spectrometry; Membrane Proteins - metabolism; Oxidation-Reduction; Protein Tyrosine Phosphatase, Non-Receptor Type 1; Protein Tyrosine Phosphatases; Reactive Oxygen Species - metabolism; Signal Transduction; Superoxides - metabolism; Time Factors; Tumor Cells, Cultured; Xanthine - pharmacology
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.274.49.34543

Growth factors induce intracellular production of reactive oxygen species in non-phagocytic cells and elevation of their phosphorylated protein tyrosine level. The latter can be achieved by activating protein-tyrosine kinases and/or inactivating protein-tyrosine phosphatases (PTPs). A highly abundant PTP, PTP-1B, is known to be inactivated by oxidation of its catalytic site Cys-215. We show that O·̄ 2 is kinetically more efficient and chemically more specific oxidant than H 2 O 2 for inactivating PTP-1B. The second-order rate constant for the O·̄ 2 - and H 2 O 2 -mediated inactivation is 334 ± 45 m −1 s −1 and 42.8 ± 3.8 m −1 s −1 , respectively. PTP-1B oxidized by H 2 O 2 exhibits significantly more oxidized methionine residues and shows a lower degree of reversibility. The initial oxidative product, the Cys-215 sulfenic derivative, can easily be oxidized further to its irreversible sulfinic and sulfonic derivatives. This step is prevented by glutathionylation of the sulfenic derivative to form a S -glutathionylated PTP-1B, which can be reactivated by dithiothreitol or thioltransferase. Thus, a signal transduction mechanism mediated by the O·̄ 2 and the participation of glutathione is proposed for the regulation of PTP-1B. This mechanism is supported by the in vivo demonstration that glutathionylated PTP-1B at Cys-215 is formed in A431 cells when they were treated with epidermal growth factor.