Cortactin Associates with the Cell-Cell Junction Protein ZO-1 in both Drosophila and Mouse*
- From the Neurogenetics Research Project, Mitsubishi Kasei Institute of Life Sciences, Minamiooya 11, Machida-shi, Tokyo 194-8511, Japan
Abstract
Cortactin is an actin filament-binding protein localizing at cortical regions of cells and a prominent substrate for Src family protein-tyrosine kinases in response to multiple extracellular stimuli. Human cortactin has been identified as a protein product of a putative oncogene, EMS1. In this report, we describe the identification of a Drosophila homolog of cortactin as a molecule that interacts with Drosophila ZO-1 using yeast two-hybrid screening. Drosophila cortactin is a 559-amino acid protein highly expressed in embryos, larvae, and pupae but relatively underexpressed in adult flies. Deletion and substitution mutant analyses revealed that the SH3 domain of Drosophilacortactin binds to a PXXP motif in the proline-rich domain of Drosophila ZO-1. Colocalization of these proteins at cell-cell junction sites was evident under a confocal laser-scanning microscope. In vivo association was confirmed by coimmunoprecipitation of cortactin and ZO-1 from Drosophilaembryo lysates. We also demonstrate an association for each of the murine homologs by immunoprecipitation analyses of mouse tissue lysates. Our previous work has demonstrated the involvement of ZO-1 in a signaling pathway that regulates expression of the emcgene in Drosophila. The potential roles of the cortactin·ZO-1 complex in cell adhesion and cell signaling are discussed.
Footnotes
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↵* This study was supported in part by grants from the Human Frontier Science Program Organization.The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
The nucleotide sequence(s) reported in this paper has been submitted to the GenBank™/EMBL Data Bank with accession number(s) AB009998.
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↵‡ Present address: National Institute of Radiological Sciences, Anagawa 4-9-1, Inage-ku, Chiba-shi, Chiba 263-8555, Japan.
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↵§ To whom correspondence should be addressed. Tel.: 81-427-24-6220; Fax: 81-427-24-6314; E-mail: shin{at}libra.ls.m-kagaku.co.jp.
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↵2 S. Togashi, M. Takahisa, and R. Ueda, unpublished results.
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↵3 T. Katsube, M. Takahisa, R. Ueda, N. Hashimoto, M. Kobayashi, and S. Togashi, unpublished results.
- Abbreviations:
- MAGUKs
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membrane-associated guanylate kinase homologs
- GUK
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guanylate kinase
- DZO-1
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Drosophila ZO-1
- emc
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extramacrochaetae
- DCortactin
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Drosophila cortactin
- GST
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glutathioneS-transferase
- PAGE
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polyacrylamide gel electrophoresis
- kb
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kilobase(s).
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- Received June 3, 1998.
- Revision received August 10, 1998.
- The American Society for Biochemistry and Molecular Biology, Inc.
