Notch proteins are the receptors in a highly conserved signal transduction system used to communicate information between cells that contact each other. The overarching goal of this Project is to elucidate the mechanism by which canonical ligands expressed on signal-sending cells activate Notch receptors on signal-receiving cells. Specifically, we propose two complementary sets of studies that will decipher two of the critical events that are required for ligand-induced Notch signaling:
Aim 1. To determine how Mind bomb induces ligand-dependent Notch signaling We will exploit the modular nature of mib and our expertise in structural and biochemical methods to determine the molecular logic underlying Mind bomb function. Our top priorities will be i) to determine the structural basis for ligand-tail binding, and ii) to determine how the different Mib domains cooperate to transfer ubiquitin onto these tails.
Aim 2. To determine how ligand stimulation induces metalloprotease cleavage of Notch receptors One leading model for ligand-dependent activation of Notch posits that the endocytosis of bound ligand exerts a mechanical force on the receptor, releasing autoinhibitory interactions that protect the metalloprotease cleavage site. These studies will combine powerful single-molecule approaches and cellbased assays to evaluate the feasibility of the mechanical force model of Notch signal induction. Distinguishing between a mechanotransduction model and alternatives, such as allosteric

Public Health Relevance

Ligand-dependent Notch signaling is important in many cancer-related processes, including tumor cell grovi/th/survival, angiogenesis, and the host immune response. Surprisingly little is known about the molecular details of how Notch ligands activate Notch receptors. This project will perform studies that fill this gap in current knowledge, and in doing so elucidate key aspects of Notch receptor activation that are likely to produce insights leading to new ways to target Notch in various human diseases, including cancer.

National Institute of Health (NIH)
National Cancer Institute (NCI)
Research Program Projects (P01)
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Special Emphasis Panel (ZCA1-RPRB-J (J1))
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Brigham and Women's Hospital
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Yashiro-Ohtani, Yumi; Wang, Hongfang; Zang, Chongzhi et al. (2014) Long-range enhancer activity determines Myc sensitivity to Notch inhibitors in T cell leukemia. Proc Natl Acad Sci U S A 111:E4946-53
Arnett, Kelly L; Blacklow, Stephen C (2014) Analyzing the nuclear complexes of Notch signaling by electrophoretic mobility shift assay. Methods Mol Biol 1187:231-45
Wang, Hongfang; Zang, Chongzhi; Taing, Len et al. (2014) NOTCH1-RBPJ complexes drive target gene expression through dynamic interactions with superenhancers. Proc Natl Acad Sci U S A 111:705-10
Dail, Monique; Wong, Jason; Lawrence, Jessica et al. (2014) Loss of oncogenic Notch1 with resistance to a PI3K inhibitor in T-cell leukaemia. Nature 513:512-6
Gerhardt, Dawson M; Pajcini, Kostandin V; D'altri, Teresa et al. (2014) The Notch1 transcriptional activation domain is required for development and reveals a novel role for Notch1 signaling in fetal hematopoietic stem cells. Genes Dev 28:576-93
Stoeck, Alexander; Lejnine, Serguei; Truong, Andrew et al. (2014) Discovery of biomarkers predictive of GSI response in triple-negative breast cancer and adenoid cystic carcinoma. Cancer Discov 4:1154-67
Tiyanont, Kittichoat; Wales, Thomas E; Siebel, Christian W et al. (2013) Insights into Notch3 activation and inhibition mediated by antibodies directed against its negative regulatory region. J Mol Biol 425:3192-204
Andrawes, Marie Blanke; Xu, Xiang; Liu, Hong et al. (2013) Intrinsic selectivity of Notch 1 for Delta-like 4 over Delta-like 1. J Biol Chem 288:25477-89
Chiang, Mark Y; Shestova, Olga; Xu, Lanwei et al. (2013) Divergent effects of supraphysiologic Notch signals on leukemia stem cells and hematopoietic stem cells. Blood 121:905-17
Blacklow, Stephen C (2013) Refining a Jagged edge. Structure 21:2100-1

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