General Microarray Analysis Workflow
Our studies to date have laid the groundwork for applied gene expression biodosimetry, focusing on signature development for whole-body high dose rate external photon exposure. Other types of radiation exposures, including partial-body exposure, internal emitters, low dose rate, and neutron exposure, will also impact triage needs and may produce distinct responses, or variations in the dosimetric signatures already identified. As estimates of dose provide only a general idea of the radiation injury expected across a population, it will also be important to develop signatures that may provide a more accurate prediction of radiation injury response and outcome on an individual basis. Project 2 uses a functional genomics approach to develop refined gene expression signatures of radiation exposure and dose addressing these two main themes: first, the impact of different radiation modalities (partial-body exposure, internal emitters, low dose rate, and neutron exposure), and second, prediction of individual radiation sensitivity.
Microarray analyses are applied to human and murine samples to build upon the predictive signatures we have already developed and to better adapt them for use in realistic radiation exposure scenarios. Mouse models are also used to investigate the mechanistic underpinnings of the gene expression signatures that predict radiation dose and sensitivity.
Our initial studies have used an ex vivo irradiation protocol in which blood is drawn from healthy donors, placed into culture, and then irradiated outside the body to mimic radiation exposure to a person. The blood was incubated for a range of times, and then RNA was purified, labeled, and hybridized to whole genome microarrays. This approach allows initial exploration of time and dose-dependent responses. Major findings from this approach include:
Our current studies focus on:
- Further refinement of our understanding of the effects of dose rate and the internal emitter 137Cs.
- Investigation of the gene-specific IND-neutron RBE and its impact on mixed neutron + photon exposures.
- Development of a humanized mouse approach to enable more informative in vivo studies.
- The impact of chronic inflammation or impaired inflammatory response on transcriptomic signatures of radiation exposure.