Notchl's oncogenic activity in T cell progenitors appears to represent an exaggeration of its normal functions during T cell development. We will use new ChlP-Seq and bioinformatic technologies to delineate the interaction of Notchl with the genomes of normal murine and human thymocytes. By correlating these interactions with chromatin marks and gene expression, we will gain a global view of how Notchl regulates T cell development, and by comparing these interactions with those of Notchl in murine and human T-ALLs, we will further gain a deep understanding of key similarities and differences between normal and malignant thymocytes. A second key aspect of Notchl interaction with normal and malignant thymocytes is regulation of gene expression through sequence-paired binding sites (SPSs) for the transcription factor CSL that permit Notchl dimerization. Mutants that disrupt dimeric Notch complexes cannot induce T-ALL, show defects in T cell development, and lose the ability to upregulate key target genes such as Myc and pTa. These complementary lines of investigation will be pursued through two aims:
Aim 1; To determine how Notchl regulates T cell development. We will combine ChlP-Seq with computational approaches to identify Notch1/CSL binding sites genome-wide, characterize the specific response elements that control transcription of key Notch target genes, identify both novel Notchl target genes, and elucidate mechanisms used by Notch to regulate p-selection and other stages of T cell development. In addition, the epigenetic landscapes of normal stages of T cell development will be compared to T-ALL cells.
Aim 2 : To determine the role of dimeric Notch signaling complexes in T-ALL. We will identify and validate dimerization-dependent Notch targets and determine the in vivo importance of dimerization-dependent Notch signaling during T cell development. Together, these studies will provide a comprehensive molecular and genomic understanding of how Notch regulates T cell development and T cell transformation, and in doing so provide new opportunities to rationally target the Notch pathway in T-ALL and other diseases.

Public Health Relevance

Notchl is a key regulator of T cell development and an important, potentially targetable oncogene in leukemia. We propose to comprehensively determine how Notchl regulates the genomes of normal and malignant thymocytes. The molecular details of how this occurs are expected to provide new ways to target Notchl in leukemia and to manipulate the development of normal T lymphocytes.

Agency
National Institute of Health (NIH)
Type
Research Program Projects (P01)
Project #
5P01CA119070-08
Application #
8701031
Study Section
Special Emphasis Panel (ZCA1)
Project Start
Project End
Budget Start
Budget End
Support Year
8
Fiscal Year
2014
Total Cost
Indirect Cost
Name
Brigham and Women's Hospital
Department
Type
DUNS #
City
Boston
State
MA
Country
United States
Zip Code
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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