NOTCH1 extracellular juxtamembrane expansion mutations in T-ALL

Blood. 2008 Aug 1;112(3):733-40. doi: 10.1182/blood-2007-12-130096. Epub 2008 Apr 14.


Heterodimerization domain (HD) mutations in NOTCH1 induce ligand-independent activation of the receptor and contribute to the pathogenesis of one-third of human T-cell lymphoblastic leukemias (T-ALLs). Here we report a novel class of activating mutations in NOTCH1 leading to aberrant activation of NOTCH1 signaling in T-cell lymphoblasts. These so-called juxtamembrane expansion (JME) alleles consist of internal duplication insertions in the vicinity of exon 28 of the NOTCH1 gene encoding the extracellular juxtamembrane region of the receptor. Notably, structure-function analysis of leukemia-derived and synthetic JME mutants demonstrated that the aberrant activation of NOTCH1 signaling is dependent on the number of residues introduced in the extracellular juxtamembrane region of the receptor and not on the specific amino acid sequence of these insertions. JME NOTCH1 mutants are effectively blocked by gamma-secretase inhibitors and require an intact metalloprotease cleavage site for activation. Overall, these results show a novel mechanism of NOTCH1 activation in T-ALL and provide further insight on the mechanisms that control the activation of NOTCH1 signaling.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amyloid Precursor Protein Secretases / physiology
  • Base Sequence
  • Cell Line
  • Cell Membrane
  • DNA Mutational Analysis
  • Extracellular Space
  • Humans
  • Jurkat Cells
  • Leukemia-Lymphoma, Adult T-Cell / etiology
  • Leukemia-Lymphoma, Adult T-Cell / genetics*
  • Mutation*
  • Receptor, Notch1 / genetics*
  • Receptor, Notch1 / metabolism
  • Tandem Repeat Sequences*
  • Transfection


  • Receptor, Notch1
  • Amyloid Precursor Protein Secretases