Office of Biological and Environmental Research
DOE Lowdose Radiation Program Workshop IV
Abstract
Title:Microarray transcription profiles for adaptive response in human lymphoblastoid
cells identify molecular linkages between DNA damage and signal transduction
Authors: MA Coleman1, F Marchetti1, D Nelson1, LE Peterson2, E Yin1, and AJ Wyrobek1.
Institutions: 1Biology and Biotechnology Research Program. Lawrence Livermore National Laboratory, Livermore, CA. 94551; 2Departments of Medicine, Molecular and Human Genetics, and Urology, Baylor College of Medicine, Houston, TX 77030.
Previous studies have shown that a low dose of ionizing radiation (IR) can induce
protection from a subsequent high dose of IR, but the responsible genes and pathways are not well understood. We applied gene transcript profiling in combination with micronucleus assays to elucidate the molecular pathways underlying the cytogenetic radioadaptive response in human lymphoblastoid (HLB) cell lines. HLB cells received a priming dose of 5 cGy followed 6 hr later by a challenging dose of 200 cGy or the challenging dose only. Two HLB cell lines that demonstrated reproducible radioadaptation by the micronucleus assay were compared to a HLB cell line that reproducibly did not adapt using Affymetrix U95A oligonucleotide microarray chips representing ~22,000 genes. RNAs were isolated 4 hours after the challenging doses in experiments that simultaneously tested for adaptation and non-adaptation. Statistical analysis with a false discovery rate of <0.1 and a significance value of >0.05 identified 166 genes among the three cell lines with significant differences in transcription levels after exposure to fractionated dose (5 and 200 cGy) versus 200 cGy only. Also, cluster analysis identified consistent differential responses between the two adapting cell lines and the non-adapting cell line. Genes associated with adaptive response by cluster analysis include ATM, JUND, c-MYC as well as SP100, M phase phosphoprotein, INF2AR and a member of the HSP70 family. A global view of radioadaption using Gene Ontology Maps suggests that radioadaptation may be linked to modulated expression of genes associated with signal transduction, inflammation, and stress response. Interestingly, genes involved in protein synthesis were found to be highly induced within all three HLB cell lines in response to the low-dose followed by the high dose. These data suggest a relationship between pathways involved in signal transduction and DNA damage sensing and repair. Further studies are needed to investigate the time course of gene expression profiles after the priming dose but before the challenging dose to identify and gain insights into the cellular functions and pathways of genes that may predispose a cell to radioadaptation.
This work was performed under the auspices of the U.S. Department of Energy by the University of California, Lawrence Livermore National Laboratory under Contract No. W-7405-Eng-48 with funding from the DOE Low Dose Radiation Research Program
