microarray analysis workflow
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.