A Ligand-Induced Extracellular Cleavage Regulates γ-Secretase-like Proteolytic Activation of Notch1

• Published in: Molecular cell 2000-02, Vol.5 (2), p.197-206
• Main Authors: Mumm, Jeffrey S, Schroeter, Eric H, Saxena, Meera T, Griesemer, Adam, Tian, Xiaolin, Pan, D.J, Ray, William J, Kopan, Raphael
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Amyloid Precursor Protein Secretases; Conserved Sequence; Cysteine - genetics; Disintegrins - metabolism; Drosophila Proteins; Endopeptidases - metabolism; g-secretase; Ligands; Membrane Proteins - genetics; Membrane Proteins - metabolism; Metalloendopeptidases - metabolism; Mutation; NEXT protein; NICD protein; Notch1 protein; Peptide Fragments - genetics; Peptide Fragments - metabolism; Presenilin-1; Protein Processing, Post-Translational; Receptor, Notch1; Receptors, Cell Surface - genetics; Receptors, Cell Surface - metabolism; Signal Transduction; Transcription Factors
• ISSN: 1097-2765; 1097-4164
• DOI: 10.1016/S1097-2765(00)80416-5

γ-secretase-like proteolysis at site 3 (S3), within the transmembrane domain, releases the N otch i ntra c ellular d omain (NICD) and activates CSL-mediated Notch signaling. S3 processing occurs only in response to ligand binding; however, the molecular basis of this regulation is unknown. Here we demonstrate that ligand binding facilitates cleavage at a novel site (S2), within the extracellular juxtamembrane region, which serves to release ectodomain repression of NICD production. Cleavage at S2 generates a transient intermediate peptide termed NEXT ( N otch ex tracellular t runcation). NEXT accumulates when NICD production is blocked by point mutations or γ-secretase inhibitors or by loss of presenilin 1, and inhibition of NEXT eliminates NICD production. Our data demonstrate that S2 cleavage is a ligand-regulated step in the proteolytic cascade leading to Notch activation.