Identification of potential radiation-responsive biomarkers based on human orthologous genes with possible roles in DNA repair pathways by comparison between Arabidopsis thaliana and homo sapiens.

Rapid and reliable ionization radiation (IR) exposure estimation has become increasingly important in environment due to the urgent requirement of medical evaluation and treatment in the event of nuclear accident emergency. Human DNA repair genes can be identified as important candidate biomarkers to assess IR exposure, while how to find the enough sensitive and specific biomarkers in the DNA repair networks is still challenged and not fully determined. The conserved features of DNA repair pathways may facilitate interdisciplinary studies that cross the traditional boundaries between animal and plant biology, with the aim of identifying undiscovered human DNA repair genes for potential radiation-responsive biomarkers. In this work, an in silico method of homologous comparison was performed to identify the human orthologues of A. thaliana DNA repair genes, and thereby to explore the sensitive and specific human radiation-responsive genes to evaluate the IR exposure levels. The results showed that a total of 16 putative candidate genes were involved in the human DNA repair pathways of homologous recombination (HR) and non-homologous end joining (NHEJ), and most of them were confirmed by previous experiments. Additionally, we analyzed the gene expression patterns of these 16 candidate genes in several human transcript microarray datasets with different IR treatments. The results indicated that most of the gene expression levels for these candidate genes were significantly changed under different radiation treatments. Based on these results, we integrated these putative human DNA repair genes into the DNA repair pathways to propose new insights of the HR and NHEJ pathways, which can also provide the potential targets for the development of radiation biomarkers. Notably, two putative DNA repair genes, named ERCC1 and ESCO2, were identified and were considered to be the sensitive and specific biomarkers in response to γ-ray exposures.