2009 |
Kurdistani, Siavash |
DP2Activity Code Description: To support highly innovative research projects by new investigators in all areas of biomedical and behavioral research. |
A Blueprint For Oncogenic Epigenetic Reprogramming @ University of California Los Angeles
DESCRIPTION (Provided by the applicant) Abstract: While cancer is a genetic disease, the cancerous cellular state is associated with multiple epigenetic alterations including aberrant DNA methylation and histone modification patterns. A significant challenge in cancer biology is to elucidate the precise order of epigenetic alterations during tumor initiation and progression and their contributions to the transformed phenotype. To meet this challenge, one requires a model of cellular transformation that is temporally traceable from a normal to a malignant state. Cancer cell lines are not necessarily good models as they have already accumulated hundreds to thousands of genetic and epigenetic alterations. Here I propose to study the oncogenic transformation of normal human cells by viral oncoproteins as a model to determine the precise epigenetic reprogramming events occurring along the path of neoplastic transformation. Viral oncoproteins such as the Adenovirus small e1a or Papilloma virus E7 have been extraordinarily useful in delineating the central molecular players that regulate cell proliferation such as the retinoblastoma (RB) and p53 tumor suppressors. Our work has recently elucidated a defined global epigenetic reprogramming by one viral oncoprotein, e1a, that forces normal cells to escape quiescence-a hallmark of cancer. Importantly, e1a directly implements a precise and coordinated mechanism of regulation of thousands of host cell genes leading to cellular transformation by interacting and rearranging specific epigenetic modifiers across the whole genome in a time-dependent manner. This provides a powerful model that is amenable to time-series measurements with phenotypically defined endpoints, enabling one to delineate the successive order of epigenetic alterations that contribute to oncogenic transformation. By understanding how e1a orchestrates a specific sequence of epigenetic alterations for cellular transformation, we should learn greatly about the functions and mechanisms of fundamental epigenetic processes in normal biology and human disease, especially cancer. Public Health Relevance: Cancer cells depend on multiple alterations in various molecular pathways to overcome normal defense mechanisms against uncontrolled cell replication. However, how these changes cooperate in time to transform a normal cell to a cancerous one is not very well understood. Certain viruses encode proteins, such as the Adenovirus e1a, that can force a normal cell to overcome its defense mechanism and to replicate-a hallmark of cancer-so that more viral progenies are produced. Because viruses use the cell's own machinery, they have been extraordinarily revealing about processes that must be altered for cancer to arise. We have discovered that the e1a protein displays a highly coordinated program of binding to different sets of host genes at different times after infection. Through such temporally-ordered pattern of binding, the e1a protein rearranges a specific set of gene regulatory enzymes so as to promote cell growth and replication and to repress antiviral responses and molecular pathways that would normally stop the cell from dividing. This is akin to rearranging the furniture in the host's house to serve the guest's sinister purposes. This proposal aims to use e1a-mediated cellular transformation to generate a blueprint for the successive order of events that must occur in a precise manner for cancer to develop. This work may provide fundamental insights into the initial molecular events that lead to cancer development, enabling us to design better therapeutics and/or develop diagnostic and prognostic assays that may aid in personalization of therapy.
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0.915 |
2013 — 2017 |
Kurdistani, Siavash |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
Dynamics of Histone Acetylation in Cancer Cell Physiology @ University of California Los Angeles
DESCRIPTION (provided by applicant): Our laboratory has discovered that cancer tissues with lower global levels of histone acetylation display significantly increased rate of tumor recurrence or cancer-related mortality, findings that have been validated independently by multiple other laboratories. However, the function of global changes in histone acetylation in normal biology and how it might contribute to the cancer phenotype have been completely unknown. We present evidence that global histone acetylation and deacetylation is coupled to the co-transport of acetate and protons in and out of the cell, effectively making chromatin a regulator of intracellular proton load, and hence, of intracellular pH (pHi). In acidic conditions, histones are globally deacetylated and the resulting acetate molecules are co-transported with protons out of the cell through the monocarboxylate transporters (MCTs), thereby decreasing the intracellular proton load. At alkaline pH, histones are globally acetylated, serving to store acetate molecules and resisting further increases in pHi. Deacetylation of histones at low pH requires continuous histone deacetylase (HDAC) activity and is not due to compromised HAT activity. Inhibition of HDACs or MCTs to decrease acetate availability or export, respectively, lowers pHi and particularly compromises pHi maintenance in acidic microenvironments. Thus histone acetylation functions as a rheostat to regulate pHi. Our data suggest a novel mechanism of action for HDAC inhibitors and raise the possibility that cancer tissues displaying low levels o histone acetylation may be secreting acetate and protons to maintain an alkaline pHi relative to the extracellular environment-a hallmark of rapidly dividing cells. In this application, we aim to determine how global changes in histone acetylation in response to pH map to specific regions of the genome and the consequences for gene expression. We will determine the mechanism of pH- induced histone deacetylation and identify the main MCTs that transport the acetate molecules that are released from chromatin by HDACs. We will also determine how global changes in histone acetylation in response to pH affect the tumorigenic properties of cancer cells. Finally, we will relate the expression of MCTs, localization of HDACs and global histone acetylation levels in fully-annotated primary cancer tissues to determine the clinical relevance of our findings. Our work will add a novel dimension to the functions chromatin and histone acetylation serve for the cell.
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0.915 |
2013 — 2014 |
Kurdistani, Siavash Portera-Cailliau, Carlos (co-PI) [⬀] |
T32Activity Code Description: To enable institutions to make National Research Service Awards to individuals selected by them for predoctoral and postdoctoral research training in specified shortage areas. |
Medical Scientist Training Program @ University of California Los Angeles
DESCRIPTION (provided by applicant): The mission of the UCLA-Caltech MSTP is to promote the education of outstanding physician-scientists. To fulfill this mission, our current goals are to 1) recruit exceptionally bright and accomplished students who exhibit an unusual degree of passion for scientific knowledge and a life-long commitment to research and leadership, 2) help guide admitted students toward outstanding training environments that encourage individual thinking and provide students with the tools needed to develop into accomplished physician-scientists, 3) provide a comprehensive support system to meet the trainees' needs and 4) play an increasingly prominent role in guiding the career development of undergraduate students from under-represented ethnic groups and disadvantaged backgrounds. To accomplish these goals as effectively as possible, the UCLA-Caltech MSTP is run by two equal Co-Directors, three Associate Directors, and a strong administrative team, all of whom are deeply committed to the Program. The Program is structured for an average of eight years of study. An integrated, problem-based medical school curriculum is particularly well suited for MSTP students, due to increased time for independent exploration and increased emphasis on research advances that contributed to current knowledge of disease etiology, diagnosis, and treatment. For their Ph.D. research, students choose mentors from a wide array of science and engineering Ph.D. Programs. The MSTP's commitment to excellence was perhaps most apparent when UCLA and Caltech entered into an affiliation agreement fifteen years ago. This affiliation, which provides an opportunity for two students per year to perform their thesis research at Caltech, not only has increased the number of outstanding mentors available to students, but also appears to have increased the Program's visibility and recruitment success. Substantial institutional support from the David Geffen School of Medicine at UCLA and from Caltech has permitted an increase in the size of the MSTP, with 97 students currently enrolled in the program. The MSTP derives great benefit from recent dramatic improvements in physical facilities at both UCLA and Caltech, from the financial health of the universities, and from the recruitment of a large number of outstanding new faculty members to UCLA and Caltech.
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0.915 |
2021 |
Kurdistani, Siavash |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
Understanding the Function of Histone H3 as An Oxidoreductase Enzyme @ University of California Los Angeles
PROJECT SUMMARY This application proposes to investigate the newly discovered function of histone H3 as an oxidoreductase enzyme, catalyzing the reduction of cupric (Cu+2) ions to the biousable cuprous (Cu+1) form. The eukaryotic histone H3-H4 tetramer contains a putative Cu2+ binding site at the interface of the apposing H3 proteins with unknown function. The coincident emergence of eukaryotes with global oxygenation, which challenged cellular copper utilization, raised the possibility that histones may function in cellular copper homeostasis. We have extensive evidence that histones are required for efficient use of copper inside cells, which depend on availability of copper ions in their reduced, +1 oxidation state. It is the Cu+1 ions that are trafficked intracellularly by protein chaperones to destination target proteins. We show that the H3-H4 tetramer, assembled from recombinant histones, binds Cu2+ and catalyzes its reduction to Cu1+ in vitro. Loss- and gain-of-function mutations of the putative active site residues correspondingly altered copper binding and the enzymatic activity, as well as intracellular Cu1+ levels and copper-dependent activities such as mitochondrial respiration and superoxide dismutase 1 (Sod1) function in S. cerevisiae. Our data have uncovered a function of the histone H3-H4 tetramer with little precedence in literature, revealing that the eukaryotic genome is wrapped around an enzyme. We now propose to develop a mechanistic understanding of this new function of histones and how it is regulated and linked to cellular copper homeostasis. In Aim 1, we seek to understand the mechanism of catalysis by determining the structure of copper-bound H3-H4 tetramer and the contributions of the residues in and around the active site. In Aim 2, we will discern how the enzyme activity is regulated, especially through post-translational modifications of histones and certain histone variants. The enzymatic activity of histones indicates that there must be a previously undiscovered biological network that shuttles Cu2+ to histones and then distributes the reaction product (Cu1+) to different parts of the cell for use by proteins in the nucleus, cytoplasm and mitochondria. In Aim 3, we plan to systematically identify the protein effectors involved in this novel copper biological network in yeast by utilizing a high-throughput CRISPR-interference (CRISPRi) technology. We aim to identify the genes and pathways that integrate the enzymatic activity of histones with other cellular functions. Our proposal will begin to build the scientific foundation for understanding chromatin structure and function as an enzyme and its impact on eukaryotic biology with instructive consequences for the evolution of the eukaryotic cell as well as a range of human pathologies such as cancer and neurodegeneration in which copper homeostasis is altered.
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0.915 |