Functional interaction between SEL-10, an F-box protein, and the nuclear form of activated Notch1 receptor.
The Notch signaling pathway is essential in many cell fate decisions in invertebrates as well as in vertebrates. After ligand binding, a two-step proteolytic cleavage releases the intracellular part of the receptor which translocates to the nucleus and acts as a transcriptional activator. Although Notch-induced transcription of genes has been reported extensively, its endogenous nuclear form has been seldom visualized. We report that the nuclear intracellular domain of Notch1 is stabilized by proteasome inhibitors and is a substrate for polyubiquitination in vitro. SEL-10, an F-box protein of the Cdc4 family, was isolated in a genetic screen for Lin12/Notch-negative regulators in Caenorhabditis elegans. We isolated human and murine counterparts of SEL-10 and investigated the role of a dominant-negative form of this protein, deleted of the F-box, on Notch1 stability and activity. This molecule could stabilize intracellular Notch1 and enhance its transcriptional activity but had no effect on inactive membrane-anchored forms of the receptor. We then demonstrated that SEL-10 specifically interacts with nuclear forms of Notch1 and that this interaction requires a phosphorylation event. Taken together, these data suggest that SEL-10 is involved in shutting off Notch signaling by ubiquitin-proteasome-mediated degradation of the active transcriptional factor after a nuclear phosphorylation event.
Gupta-Rossi
N
N
Unité de Biologie Moléculaire de l'Expression Génique, FRE 2364, CNRS, Institut Pasteur, 25 rue du Dr Roux, 75724 Paris Cedex 15, France.
Le Bail
O
O
Gonen
H
H
Brou
C
C
Logeat
F
F
Six
E
E
Ciechanover
A
A
Israël
A
A
D000595:Amino Acid Sequence; D000818:Animals; D029742:Caenorhabditis elegans Proteins; D018797:Cell Cycle Proteins / Q000235:genetics / Q000502:physiology*; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism*; D003546:Cysteine Endopeptidases / Q000502:physiology; D015801:Helminth Proteins / Q000235:genetics / Q000502:physiology*; D006801:Humans; D008565:Membrane Proteins / Q000378:metabolism*; D051379:Mice; D008969:Molecular Sequence Data; D009097:Multienzyme Complexes / Q000502:physiology; D010766:Phosphorylation; D046988:Proteasome Endopeptidase Complex; D051881:Receptor, Notch1; D011956:Receptors, Cell Surface; D014157:Transcription Factors; D015533:Transcriptional Activation; D014452:Ubiquitins / Q000378:metabolism
D029742:Caenorhabditis elegans Proteins; D018797:Cell Cycle Proteins; D015801:Helminth Proteins; D008565:Membrane Proteins; D009097:Multienzyme Complexes; C497761:NOTCH1 protein, human; C497762:Notch1 protein, mouse; D051881:Receptor, Notch1; D011956:Receptors, Cell Surface; C109554:SEL-10 protein, C elegans; D014157:Transcription Factors; D014452:Ubiquitins; D003546:Cysteine Endopeptidases; D046988:Proteasome Endopeptidase Complex