Universities

| Duke University | Loma Linda University | Northwestern University | University of Chicago | University of California Davis |

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Northwestern University
University of Chicago
University of California Davis
Effects of Low Dose Irradiation on NF-κB Signaling Networks and Mitochondria
Principal Investigator: Dr. Gayle Woloschak

DOE Low Dose Research Program Projects

1. Low dose-low dose rate irradiation leads to long term changes in numbers of mitochondria and mitochondrial genomes - Principal Investigator: Gayle Woloschak, Professor, Department of Radiation Oncology, Northwestern University, Chicago, IL, USA
2. NF-κB-mediated pro-survival network in low dose radiation-induced adaptive protection - Principal Investigator: Jian Jian Li, Professor, Department of Radiation Oncology, University of California Davis, Davis, CA, USA
3. NF-κB in the thiol-induced adaptive response - Principal Investigator: David Grdina, Professor, Department of Radiation Oncology, University of Chicago, Chicago, IL, USA

Program Summary
The overarching hypotheses of the program projects are that 1) Mitochondria are a key cellular organelle responsible for coping with radiation stress. 2) Adaptive low dose radiation treatments, which lead to protection from radiation stress of the challenge dose of radiation, fortify mitochondrial stability and increase mitochondrial biogenesis. 3) NF-κB protein complexes play a pivotal role in these events.

Project 1 will use an archive of tissues from thousands of irradiated mice with the corresponding database to investigate the effects of low dose and low dose rate radiation exposure on long-term mitochondrial enrichment of cells and disease prevention associated with this enrichment.

Hypothesis: The adaptive response of organisms to low dose irradiation stems from an increase in mitochondrial biogenesis; chronic exposure to low dose radiation leads to an extended/permanent increase in the number of mitochondria with higher content of mitochondrial genomes, which prevents oxidative damage to tissues causing disease aversion or amelioration.

Aims: Statistical analyses of the tissue archive database and investigations of mitochondrial DNA content of hundreds of archived tissues from animals exposed to chronic low dose radiation, sometimes lifelong and sometimes shorter.

Project 2 will investigate the role of NF-κB in the pro-survival network triggered by low dose irradiation using cultured cells and mice.

Hypothesis: Mitochondria are the target organelle for NF-κB-mediated adaptive radioprotection.

Aims: To investigate NF-ΚB prosurvival network in mouse and human cells in culture and in mouse skin tissue treated with 10cGy x-ray/5Gy γ-ray sequence, and determine whether pre-exposure to low dose radiation reduces skin tumor incidence of mouse using established papilloma formation model.

Project 3 will interrogate the involvement of NF-κB in thiol induced pro-survival behavior of cells in mice and cells in culture.

Hypothesis: Mitochondria are the target organelle for the thiol-induced adaptive response and that the mechanism of this adaptive response is mediated by NF-κB.

Aims: To investigate the effects of the thiol-induced adaptive response on mitochondrial structure and changes in the levels of mitochondrial signaling molecules; to use co-cultures of wild-type cells and cells with a perturbed NF-κB pathways; and to perform animal studies in conjunction with the thiol-induced adaptive response in mitochondria.

These projects are interconnected in several different ways with respect to the research design:

• The findings of Project 1 will be used to direct selection of doses and dose rates for additional investigations of Projects 2 and 3
• Projects 2 and 3 will supply Project 1 with the non-archival tissues for testing of the abundance of mitochondria/mitochondrial genomes after different treatments
• Projects 1 and 3 will supply Project 2 with archived tissues or fresh tissues to be tested for MnSOD, cyclins D1 and B1 and 14-3-3s by immunohistochemistry
• Project 3 will determine mitochondrial protein influx and kinetics of MnSOD, cyclins and 14-3-3 in samples provided by Project 2
• Project 1 will supply statistical analysis tools for the entire project.

Contract Period: 2009-2014

Research staff

Jeffrey S. Murley, Ph.D.
Louis Philipson, M.D. Ph. D
Tatjana Paunesku, Ph.D.
Fred Rademaker, Ph. D.

Websites:
Beagle Dog Archives
Grdina Lab Website
Janus Mouse Archive
Li Lab Website
Woloschak Lab Website

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Duke University
Epigenomic Targets of Low-LET Radiation: Metastable Epialleles and Imprinted Genes - Duke University, Durham, NC, USA
Principal Investigator: Dr. Randy L. Jirtle

Program Summary
We seek to determine the effects of low dose radiation on the epigenome by examining methylation and histone modification changes in metastable epialleles and imprinted genes. We are using the Agouti Viable Yellow (Avy) mouse model to determine if low LET radiation can alter the establishment of methylation and histone marks at the Avy allele. These mice have been shown to be sensitive biomarkers for early developmental exposures that alter the epigenome. We have also identified imprinted genes that are particularly susceptible to developmental exposures due to apparent haploidy resulting from parent of origin expression. This expression pattern is governed by epigenetic modifications in imprint regulatory regions. We have located a number of imprinted regulatory regions in both the mouse and human genomes and will be analyzing the effects of ionizing radiation on epigenetic modifications in these regions. These studies will further elucidate the effects of radiation on the epigenome and, ultimately, on human disease.

Contract Period: 2005-2013

Research staff
Yui Li, PhD
Autumn Bernal, PhD Candidate
Dale Huang, BS
Website: geneimprint

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Loma Linda University
Th Cell Gene Expression and Function in Response to Low Dose and Acute Radiation - Loma Linda University, Loma Linda, CA, USA
Principal Investigator: Dr. Daila S. Gridley

Program Summary
We are identifying specific mechanisms affected by low dose, low-LET radiation in CD4+ T lymphocytes and determining whether the induced changes affect their response to an acute irradiation event such as photons, protons, and simulated solar flare protons (sSPE). An sSPE delivery system is fully operational for rodent exposure; several successful experiments with mice have already been completed.

CD4+ T helper and other cells from total-body irradiated mice are being assessed for cytokine gene expression patterns and ability to secrete these potent molecules after activation. Many of these cytokines are critical in defense against infectious agents and destruction of neoplastic cells, whereas some are implicated in radiation-induced pathologies such as fibrosis, cancer, and cataracts.

Hypothesis: Whole-body exposure to low dose, low-LET radiation will significantly ameliorate the effects of acute radiation. More specifically, we propose that: a) Th cell hypo-responsiveness following acute exposure will be a result of defective TCR/CD3 signaling; b) The protective effect of low dose exposure will include up-regulation of IFN-gamma; and c) The efficacy of low dose-induced protection will be dependent upon the quality of acute radiation.

The data should contribute significantly to our long-term goal of elucidating molecular mechanisms in CD4+ T cells that are induced by low dose, low-LET radiation and that may also influence response to subsequent acute exposure. Samples of spleen, thymus, liver, lungs, skin and other tissues have been archived and studies (partly funded through other sources) are being evaluated in cancer-related and other assays in this animal model that is prone to radiation-induced T cell lymphoma.

Previous Research (2005-2007) Mechanisms of Low Dose Radiation-induced T Helper Cell Function

The focus of this research was on T lymphocytes that secrete cytokines and thus control actions and interactions of many other cell types and on mechanisms altered by exposure to photons (gamma-rays) and protons. This study compared, for the first time, low-dose/low-dose rate effects of photons and protons, on the response of T cells, as well as other cell types with which they communicate. The overall hypothesis was that whole-body exposure to low-dose/low-dose-rate gamma rays will alter CD4+ T helper cell function. We further proposed that exposure to low-dose/low-dose-rate proton radiation will induce a different pattern of gene expression and functional changes compared to photons. Most of the generated data supported our hypotheses and has already been published.

Newsletter: A publication of Loma Linda University Medical Center

Contract Period: 2007-2010