Delta-induced Notch Signaling Mediated by RBP-J Inhibits MyoD Expression and Myogenesis*
- From the Department of Medical Chemistry, Kyoto University Faculty of Medicine, Yoshida Sakyo-ku, Kyoto 606-8501, Japan and the‡Department of Pharmacology, School of Medicine, University of California San Diego, La Jolla, California 92093-0636
Abstract
Signaling induced by interaction between the receptor Notch and its ligand Delta plays an important role in cell fate determination in vertebrates as well as invertebrates. Vertebrate Notch signaling has been investigated using its constitutively active form, i.e. the truncated intracellular region which is believed to mimic Notch-Delta signaling by interaction with a DNA-binding protein RBP-J. However, the molecular mechanism for Notch signaling triggered by ligand binding, which leads to inhibition of differentiation, is not clear. We have established a myeloma cell line expressing mouse Delta1 on its cell surface which can block muscle differentiation by co-culture with C2C12 muscle progenitor cells. We showed that Delta-induced Notch signaling stimulated transcriptional activation of RBP-J binding motif, containing promoters including the HES1 promoter. Furthermore, ligand-induced Notch signaling up-regulated HES1 mRNA expression within 1 h and subsequently reduced expression of MyoD mRNA. Since cycloheximide treatment did not inhibit induction of HES1 mRNA, the HES1 promoter appears to be a primary target of activated Notch. In addition, a transcriptionally active form of RBP-J, i.e. VP16-RBP-J, inhibited muscle differentiation of C2C12 cells by blocking the expression of MyoD protein. These results suggest that HES1 induction by the Delta1/Notch signaling is mediated by RBP-J and blocks myogenic differentiation of C2C12 cells by subsequent inhibition of MyoD expression.
Footnotes
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↵* This work was supported by grants-in-aid for COE Research from the Ministry of Education, Science, Sports and Culture of Japan.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.
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↵§ To whom correspondence should be addressed. Tel.: 81-75-753-4371; Fax: 81-75-753-4388; E-mail: honjo{at}mfour.med.kyoto-u.ac.jp.
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↵2 K. Kuroda, H. Katou, H. Kurooka, and T. Honjo, unpublished data.
- Abbreviations:
- EGF
-
fibroblast growth factor
- RAM
-
RBP-J associating molecule
- Su(H)
-
Suppresser of Hairless
- DSL
-
Delta-Serrate-Lag-2
- PCR
-
polymerase chain reaction
- RT
-
reverse transcriptase
- MNE-Rg
-
mouse Notch1 EGF-recombinant globulin
- Tp1
-
terminal protein 1
- TRITC
-
tetramethylrhodamine B isothiocyanate
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- Received June 29, 1998.
- Revision received October 5, 1998.
- The American Society for Biochemistry and Molecular Biology, Inc.
