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

J. Biol. Chem., Vol. 283, Issue 20, 13638-13651, May 16, 2008

This Article Full Text Full Text (PDF) Supplemental Data All Versions of this Article: 283/20/13638    most recent M802027200v1 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 Stahl, M. Articles by Stanley, P. Search for Related Content PubMed PubMed Citation Articles by Stahl, M. Articles by Stanley, P. Social Bookmarking                      What's this?

Roles of Pofut1 and O-Fucose in Mammalian Notch Signaling^*

From the Department of Cell Biology, Albert Einstein College of Medicine, New York, New York 10461

Mammalian Notch receptors contain 29–36 epidermal growth factor (EGF)-like repeats that may be modified by protein O-fucosyltransferase 1 (Pofut1), an essential component of the canonical Notch signaling pathway. The Drosophila orthologue Ofut1 is proposed to function as both a chaperone required for stable cell surface expression of Notch and a protein O-fucosyltransferase. Here we investigate these dual roles of Pofut1 in relation to endogenous Notch receptors of Chinese hamster ovary and murine embryonic stem (ES) cells. We show that fucosylation-deficient Lec13 Chinese hamster ovary cells have wild type levels of Pofut1 and cell surface Notch receptors. Nevertheless, they have reduced binding of Notch ligands and low levels of Delta1- and Jagged1-induced Notch signaling. Exogenous fucose but not galactose rescues both ligand binding and Notch signaling. Murine ES cells lacking Pofut1 also have wild type levels of cell surface Notch receptors. However, Pofut1^–/– ES cells do not bind Notch ligands or exhibit Notch signaling. Although overexpression of fucosyltransferase-defective Pofut1 R245A in Pofut1^–/– cells partially rescues ligand binding and Notch signaling, this effect is not specific. The same rescue is achieved by an unrelated, inactive, endoplasmic reticulum glucosidase. Therefore, mammalian Notch receptors require Pofut1 for the generation of optimally functional Notch receptors, but, in contrast to Drosophila, Pofut1 is not required for stable cell surface expression of Notch. Importantly, we also show that, under certain circumstances, mammalian Notch receptors are capable of signaling in the absence of Pofut1 and O-fucose.

Received for publication, October 7, 2007 , and in revised form, March 13, 2008.

^* This work was supported, in whole or in part, by National Institutes of Health Grant CA 95022 (to P. S.). This work was also supported by Albert Einstein Cancer Center Grant PO1 13330. 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–S5.

¹ Supported in part by Medical Scientist Training Program Grant T32 GM07288.

² Both authors contributed equally to this work.

³ Supported by the Naito Foundation, Japan. Present address: Dept. of Molecular Medicine, School of Pharmaceutical Sciences, University of Shizuoka, Shizuoka 422-8526, Japan.

⁴ Present address: Beijing Institute of Radiation Medicine, 27 Taiping Rd., Beijing 100850, China.

⁵ Current Address: Dept. Medicine, Division of Nephrology, Mt. Sinai School of Medicine, New York, NY 10029, USA.

⁶ Supported by The Osaka Medical Research Foundation for Incurable Diseases, Japan, and The Uehara Memorial Foundation, Japan.

⁷ To whom correspondence should be addressed: Dept. of Cell Biology, Albert Einstein College of Medicine, 1300 Morris Park Ave., Bronx, NY 10461. Tel.: 718-430-3346; Fax: 718-430-8574; E-mail: stanley{at}aecom.yu.edu.

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

This article has been cited by other articles:

				A.-C. Tien, A. Rajan, and H. J. Bellen A Notch updated J. Cell Biol., March 9, 2009; 184(5): 621 - 629. [Abstract] [Full Text] [PDF]