A ligand-induced extracellular cleavage regulates gamma-secretase-like proteolytic activation of Notch1.
Gamma-secretase-like proteolysis at site 3 (S3), within the transmembrane domain, releases the Notch intracellular domain (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 (Notch extracellular truncation). NEXT accumulates when NICD production is blocked by point mutations or gamma-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.
Mumm
J S
JS
Division of Biology and Biomedical Sciences, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
Schroeter
E H
EH
Saxena
M T
MT
Griesemer
A
A
Tian
X
X
Pan
D J
DJ
Ray
W J
WJ
Kopan
R
R
D000595:Amino Acid Sequence; D053829:Amyloid Precursor Protein Secretases; D017124:Conserved Sequence; D003545:Cysteine / Q000235:genetics; D019483:Disintegrins / Q000378:metabolism; D029721:Drosophila Proteins; D010450:Endopeptidases / Q000378:metabolism*; D008024:Ligands; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D008666:Metalloendopeptidases / Q000378:metabolism; D009154:Mutation; D010446:Peptide Fragments / Q000235:genetics / Q000378:metabolism*; D053764:Presenilin-1; D011499:Protein Processing, Post-Translational; D051881:Receptor, Notch1; D011956:Receptors, Cell Surface / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D014157:Transcription Factors
D019483:Disintegrins; D029721:Drosophila Proteins; D008024:Ligands; D008565:Membrane Proteins; D010446:Peptide Fragments; D053764:Presenilin-1; D051881:Receptor, Notch1; D011956:Receptors, Cell Surface; D014157:Transcription Factors; D053829:Amyloid Precursor Protein Secretases; D010450:Endopeptidases; C100953:KUZ protein, Drosophila; D008666:Metalloendopeptidases; D003545:Cysteine