title: Integrity of intracellular domain of Notch ligand is indispensable for cleavage required for release of the Notch2 intracellular domain.
abstract: The biological activity of the soluble form of the Notch ligand (sNL) and requirement of the intracellular domain (ICD) of the Notch ligand have been debated. Here we show that soluble Delta1 (sD1) activates Notch2 (N2), but much more weakly than full-length Delta1 (fD1). Furthermore, tracing the N2 molecule after sD1 stimulation revealed that sD1 has a defect in the cleavage releasing ICD of N2 (intracellular cleavage), although it triggers cleavage in the extracellular domain of N2. This represents the molecular basis of the lower activity of sD1 and suggests the presence of an unknown mechanism regulating activation of the intracellular cleavage. The fact that Delta1 lacking its ICD (D1Delta(ICD)) exhibits the phenotype similar to that exhibited by sD1 indicates that the ICD of D1 (D1(ICD)) is involved in such an as yet unknown mechanism. Furthermore, the findings that D1Delta(ICD) acts in a dominant-negative fashion against fD1 and that the signal-transducing activity of sD1 is enhanced by antibody-mediated cross-linking suggest that the multi merization of Delta1 mediated by D1(ICD) may be required for activation of the N2 intracellular cleavage.
authors.affiliation: Department of Hematology and Oncology, Graduate School of Medicine, University of Tokyo, Tokyo, Japan.
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Shimizu
authors.forename: Shigeru
authors.initials: S
authors.lastname: Chiba
authors.forename: Toshiki
authors.initials: T
authors.lastname: Saito
authors.forename: Tokiharu
authors.initials: T
authors.lastname: Takahashi
authors.forename: Keiki
authors.initials: K
authors.lastname: Kumano
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Hamada
authors.forename: Hisamaru
authors.initials: H
authors.lastname: Hirai
mesh_terms: D000818:Animals; D002460:Cell Line; D003432:Cross-Linking Reagents; D019281:Dimerization; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics* / Q000502:physiology; D051379:Mice; D011485:Protein Binding; D051883:Receptor, Notch2; D011956:Receptors, Cell Surface / Q000235:genetics* / Q000502:physiology; D051880:Receptors, Notch; D015398:Signal Transduction
chemical_list: D003432:Cross-Linking Reagents; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; C497764:NOTCH2 protein, human; C497765:Notch2 protein, mouse; D051883:Receptor, Notch2; D011956:Receptors, Cell Surface; D051880:Receptors, Notch; C064045:delta protein