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Mechanisms of enhancer regulation in leukemia

白血病增强子调控机制

基本信息

批准号：
10321638
负责人：
Iannis Aifantis
金额：
$ 49.24万
依托单位：
NEW YORK UNIVERSITY SCHOOL OF MEDICINE
依托单位国家：
美国
项目类别：
财政年份：
2019
资助国家：
美国
起止时间：
2019-01-01 至 2023-12-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/10321638
关键词：
3-Dimensional Address Adult Animal Model Architecture B-Lymphocytes Binding Biological Biology Blood Cell Line Cell Lineage Cell model Cells Cervical Chromosomes Chronic Lymphocytic Leukemia Clustered Regularly Interspaced Short Palindromic Repeats Colon Carcinoma Complex DNA Polymerase II DNA-Directed RNA Polymerase Data Development Disease Endometrial Enhancers Ensure Epigenetic Process FBXW7 gene Gene Expression Generations Genes Genetic Genetic Transcription Genomics Growth Head Hematopoietic Hematopoietic Neoplasms Hematopoietic stem cells Human In Vitro Laboratories Lead Lesion Light Lung Macromolecular Complexes Malignant - descriptor Malignant Neoplasms Maps Mature B-Lymphocyte Mediating Mediator of activation protein Molecular Mus Mutagenesis Mutate Mutation Patients Pharmacology Phosphotransferases Proteins Publishing Recurrence Regulation Role Sampling Scientist Solid Solid Neoplasm Somatic Mutation Specialist Study models Tail Techniques Testing Transgenic Mice Translating Tumor Suppressor Proteins Western World adult leukemia base cell transformation chromosome conformation capture chronic lymphocytic leukemia cell flexibility gain of function genomic locus hematopoietic stem cell differentiation in vivo insight large cell Diffuse non-Hodgkin&apos s lymphoma leukemia member microdeletion mouse model multidisciplinary mutant new therapeutic target novel pre-clinical programs promoter protein expression recruit small molecule stem cell function stem cell survival tool transcription factor transcriptome tumor tumorigenesis ubiquitin ligase unpublished works

项目摘要

ABSTRACT Transcription factors require coactivators to communicate with the general transcription machinery and, thereby, ensure that biological inputs are translated into specific gene-expression programs. The Mediator complex is such a coactivator and acts as a ‘molecular bridge’ between transcription factor at enhancers and RNA polymerase II (Pol II) at promoters. It is a large macromolecular complex further arranged in four modules that confer high flexibility: the head, the middle, the tail and the kinase module. The member of the kinase module Mediator 12 (MED12) has been found frequently mutated in both solid (endometrial, lung, cervical, colon carcinomas) and blood (DLBCL, CLL, ALL, AML) cancers. However, the underlying mechanisms of MED12 mutations and its role in disease initiation and progression remain elusive. We have recently focused on the function of the kinase module and specifically MED12 in hematopoietic stem cell (HSC) differentiation and transformation. We found that MED12 protein expression is controlled post-translationally by the ubiquitin ligase FBXW7, a frequently mutated tumor suppressor. We also found that MED12 is an essential regulator of HSC function, as in vivo deletion of MED12 compromises HSC survival and leads to mouse lethality. Together with essential hematopoietic transcription factors, MED12 co-occupies HSC-specific enhancers. MED12 depletion destabilizes P300 binding thus leading to rapid enhancer “inactivation”, and loss of expression of key HSC-specific genes. These data suggest that MED12 expression and function can be altered due to multiple mechanisms, including somatic mutations targeting the gene itself or its regulators (FBXW7), and that this aberrant function can lead to malignant transformation. This proposal aims to shed light on the molecular mechanisms altered upon deregulation of a crucial regulator of enhancer activity, such as MED12. While it has been suggested that MED12 mutations confer a “gain-of-function”, no mechanistic studies have been performed up to date. To address this key question, we are studying chronic lymphocytic leukemia (CLL), the most common adult leukemia in the western world. To dissect how disruption of Mediator function contributes to this heterogeneous and complex disease, we use a combination of: a) transcriptional/epigenetic characterization of human patient samples harboring MED12 mutations, b) CRISPR-modified and ES targeted transgenic mouse models to investigate the ability of MED12 lesions to initiate and maintain disease, and, c) in vitro transcriptome, epigenetic and 3D-chromosome topology in CRISPR-modified cell lines with MED12 mutations. Defining the mechanisms by which Mediator and enhancer regulation contribute to malignant transformation will be beneficial for the development of novel therapies targeting blood malignancies and solid tumors. The recent identification of small molecules targeting Mediator pharmacologically suggests that such therapies are within reach.

摘要