NOTCH1 missense alleles associated with left ventricular outflow tract defects exhibit impaired receptor processing and defective EMT.
Notch signaling is essential for proper cardiac development. We recently identified missense variants in the NOTCH1 receptor in patients with diverse left ventricular outflow tract (LVOT) malformations (NOTCH1(G661S) and NOTCH1(A683T)) that reduce ligand-induced Notch signaling. Here, we examine the molecular mechanisms that contribute to reduced signaling and perturbed development. We find that NOTCH1(A683T) exhibits reduced S1 cleavage due to impaired trafficking through the endoplasmic reticulum (ER). This observation is consistent with improper localization of the variant receptor to the ER and decreased presentation at the cell surface. In contrast, the nearby mutation NOTCH1(G661S) exhibits reduced cell-surface presentation in the absence of overt folding or trafficking defects. To examine the implications of these variants in disease pathogenesis, we investigated their effect on epithelial-to-mesenchymal transition (EMT), a critical process for development of the outflow tract. We find that these LVOT-associated NOTCH1 alleles can contribute to defective EMT in endothelial cell lines through impaired induction of Snail and Hes family members. These data represent the first description of a molecular mechanism underlying NOTCH1 mutations in individuals with LVOT malformations, and have important implications regarding the functional contribution of these alleles to a complex set of developmental defects.
Riley
Maurisa F
MF
Department of Molecular Genetics, Ohio State University, Columbus, OH, USA.
McBride
Kim L
KL
Cole
Susan E
SE
D000199:Actins / Q000378:metabolism; D000818:Animals; D015153:Blotting, Western; D002135:Calcium-Binding Proteins / Q000378:metabolism; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D018920:Coculture Techniques; D004721:Endoplasmic Reticulum / Q000378:metabolism; D058750:Epithelial-Mesenchymal Transition / Q000235:genetics / Q000502:physiology; D005455:Fluorescent Antibody Technique; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D009130:Muscle, Smooth / Q000737:chemistry; D020125:Mutation, Missense; D041681:NIH 3T3 Cells; D051381:Rats; D051881:Receptor, Notch1 / Q000235:genetics* / Q000378:metabolism; D000072099:Serrate-Jagged Proteins; D015398:Signal Transduction / Q000235:genetics* / Q000502:physiology; D014162:Transfection; D014694:Ventricular Outflow Obstruction / Q000235:genetics / Q000503:physiopathology
D000199:Actins; D002135:Calcium-Binding Proteins; D036341:Intercellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D051881:Receptor, Notch1; D000072099:Serrate-Jagged Proteins