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Abstract
In mammals, there are four NOTCH receptors and five Delta-Jagged-type ligands regulating many aspects of embryonic development and adult tissue homeostasis. NOTCH proteins are type I transmembrane receptors that interact with ligands on adjacent cells and are activated by regulated intramembrane proteolysis (RIP). The activation mechanism of NOTCH1 receptors upon ligand binding is well understood and requires cleavage by ADAM10 metalloproteases prior to intramembranous cleavage by γ-secretase. How the other human NOTCH receptor homologues are activated upon ligand binding is not known. Here, we dissect the proteolytic activation mechanism of the NOTCH2 and NOTCH3 receptors. We show that NOTCH2 and NOTCH3 signaling can be triggered by both Delta-Jagged-type ligands and requires ADAM10 and presenilin-1 or -2. Importantly, we did not find any role for the highly related ADAM17/TACE (tumor necrosis factor alpha-converting enzyme) protease in ligand-induced NOTCH2 or NOTCH3 signaling. These results demonstrate that canonical ligand-induced proteolysis of the NOTCH1, -2, and -3 receptors strictly depends on consecutive cleavage of these receptors by ADAM10 and the presenilin-containing γ-secretase complex, leading to transcriptional activation.
SUPPLEMENTAL MATERIAL
Supplemental material for this article may be found at http://dx.doi.org/10.1128/MCB.00206-14.
ACKNOWLEDGMENTS
We kindly thank T. Wang (The University of Manchester, Manchester, United Kingdom) for providing the NOTCH3 cDNA and I. Prudovsky (Center for Molecular Medicine, Maine Medical Center Research Institute, ME) for providing the NOTCH2 cDNA. We thank H. Kawamoto (RIKEN Research Center for Allergy and Immunology, Yokohama, Japan) for providing TSt-4/Dll4 ligand-expressing cells.
This work is supported by the Deutsche Forschungsgemeinschaft (DFG grant SFB877) (to P.S.) and by the European Research Council under the European Community Seventh Framework Program (FP7/2007-2013)/ERC grant 208259 (to M.V.).