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Enhancement of Notch receptor maturation and signaling sensitivity by Cripto-1
Correspondence to Kazuhide Watanabe: kazuhidew{at}yahoo.com; or David S. Salomon: salomond{at}mail.nih.gov
Nodal and Notch signaling pathways play essential roles in vertebrate development. Through a yeast two-hybrid screening, we identified Notch3 as a candidate binding partner of the Nodal coreceptor Cripto-1. Coimmunoprecipitation analysis confirmed the binding of Cripto-1 with all four mammalian Notch receptors. Deletion analyses revealed that the binding of Cripto-1 and Notch1 is mediated by the Cripto-1/FRL-1/Cryptic domain of Cripto-1 and the C-terminal region of epidermal growth factor–like repeats of Notch1. Binding of Cripto-1 to Notch1 occurred mainly in the endoplasmic reticulum–Golgi network. Cripto-1 expression resulted in the recruitment of Notch1 protein into lipid raft microdomains and enhancement of the furin-like protein convertase-mediated proteolytic maturation of Notch1 (S1 cleavage). Enhanced S1 cleavage resulted in the sensitization to ligand-induced activation of Notch signaling. In addition, knockdown of Cripto-1 expression in human and mouse embryonal carcinoma cells desensitized the ligand-induced Notch signaling activation. These results suggest a novel role of Cripto-1 in facilitating the posttranslational maturation of Notch receptors.
Abbreviations used in this paper: BFA, brefeldin A; CFC, Cripto-1/FRL-1/Cryptic; EC, embryonal carcinoma; ECD, extracellular domain; FL, full length; GAPDH, glyceraldehyde 3-phosphate dehydrogenase; ICD, intracellular domain; IP, immunoprecipitation; PE, phycoerythrin; SA, streptavidin; WT, wild type; Y2H, yeast two-hybrid.
© 2009 The Rockefeller University Press
This article is distributed under the terms of an Attribution–Noncommercial–Share Alike–No Mirror Sites license for the first six months after the publication date (see http://www.jcb.org/misc/terms.shtml). After six months it is available under a Creative Commons License (Attribution–Noncommercial–Share Alike 3.0 Unported license, as described at http://creativecommons.org/licenses/by-nc-sa/3.0/).
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