HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

J. Biol. Chem., Vol. 282, Issue 46, 33396-33404, November 16, 2007

This Article Full Text Full Text (PDF) Supplemental Data All Versions of this Article: 282/46/33396    most recent M705224200v1 Submit a Letter to Editor Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Iwamoto, N. Articles by Kumagai, Y. Search for Related Content PubMed PubMed Citation Articles by Iwamoto, N. Articles by Kumagai, Y. Social Bookmarking                      What's this?

Chemical Knockdown of Protein-tyrosine Phosphatase 1B by 1,2-Naphthoquinone through Covalent Modification Causes Persistent Transactivation of Epidermal Growth Factor Receptor^*

Noriko Iwamoto, Daigo Sumi, Takeshi Ishii, Koji Uchida^¶, Arthur K. Cho^||, John R. Froines^||, and Yoshito Kumagai^||1

From the Doctoral Programs in Medical Sciences, Graduate School of Comprehensive Human Sciences, University of Tsukuba, 1-1-1 Tennoudai, Tsukuba, Ibaraki 305-8575, Japan, the Department of Food and Nutritional Sciences and Global COE Program, University of Shizuoka, Shizuoka 422-8526, Japan, the ^¶Laboratory of Food and Biodynamics, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan, and the ^||Southern California Particle Center, Institute of the Environment, University of California, Los Angeles, California 90095

1,2-Naphthoquinone (1,2-NQ), an atmospheric contaminant, causes the contraction of guinea pig trachea through the activation of epidermal growth factor receptor (EGFR) by inhibiting protein-tyrosine phosphatases (PTPs). Phosphorylation of EGFR is negatively regulated by PTPs, but details of the mechanism by which 1,2-NQ inhibits PTPs have not been elucidated. Results described in this report demonstrate that 1,2-NQ forms covalent bonds with PTP1B after exposure to human epithelial A431 cells. In this study, a concentration-dependent phosphorylation of EGFR was found to be coupled to the reduction of PTP activity in the cells. The reduction in PTP activity was due to the irreversible modification of PTP1B, and when PTP1B was overexpressed by the cells, the 1,2-NQ-mediated EGFR phosphorylation was suppressed. Studies with purified PTP1B and 1,2-NQ showed that the reduction in enzyme activity was due to a nucleophilic attack by the quinone on the enzyme, to form covalent bonds. Matrix-assisted laser desorption and ionization time-of-flight mass spectrometry analysis and mutation experiments revealed that PTP1B inactivation was primarily due to covalent attachment of the quinone to Cys-121 of the enzyme, with binding to His-25 and Cys-215 as well. Collectively, the results show that covalent attachment of 1,2-NQ to PTP1B is at least partially responsible for the reduction of PTP activity, which leads to prolonged transactivation of EGFR in the cells.

Received for publication, June 26, 2007 , and in revised form, September 10, 2007.

^* This work was supported by the Ministry of Education, Science, Culture and Sports of Japan (Grants-in-Aid 18659167 and 18406003 for scientific research to Y. K.) and by U. S. Environmental Protection Agency-funded Southern California Particle Center Grant RD83241301 (to J. R. F.). The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked "advertisement"in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

The on-line version of this article (available at http://www.jbc.org) contains supplemental Figs. S1–S3.

¹ To whom correspondence should be addressed. Tel.: 81-29-853-3133; Fax: 81-29-853-3133; E-mail: yk-em-tu{at}md.tsukuba.ac.jp.

CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?

This article has been cited by other articles:

				M. Kobayashi, L. Li, N. Iwamoto, Y. Nakajima-Takagi, H. Kaneko, Y. Nakayama, M. Eguchi, Y. Wada, Y. Kumagai, and M. Yamamoto The Antioxidant Defense System Keap1-Nrf2 Comprises a Multiple Sensing Mechanism for Responding to a Wide Range of Chemical Compounds Mol. Cell. Biol., January 15, 2009; 29(2): 493 - 502. [Abstract] [Full Text] [PDF]

				C. Fila, C. Metz, and P. van der Sluijs Juglone Inactivates Cysteine-rich Proteins Required for Progression through Mitosis J. Biol. Chem., August 1, 2008; 283(31): 21714 - 21724. [Abstract] [Full Text] [PDF]