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
Stein, Sarah J; Mack, Ethan A; Rome, Kelly S et al. (2016) Trib2 Suppresses Tumor Initiation in Notch-Driven T-ALL. PLoS One 11:e0155408
Bernasconi-Elias, P; Hu, T; Jenkins, D et al. (2016) Characterization of activating mutations of NOTCH3 in T-cell acute lymphoblastic leukemia and anti-leukemic activity of NOTCH3 inhibitory antibodies. Oncogene 35:6077-6086
Chiang, Mark Y; Wang, Qing; Gormley, Anna C et al. (2016) High selective pressure for Notch1 mutations that induce Myc in T-cell acute lymphoblastic leukemia. Blood 128:2229-2240
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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

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