title: Differential Molecular Stress Responses to Low Compared to High Doses of Ionizing Radiation in Normal Human Fibroblasts.
abstract: Understanding the mechanisms producing low dose ionizing radiation specific biological effects represents one of the major challenges of radiation biology. Although experimental evidence does suggest that various molecular stress response pathways may be involved in the production of low dose effects, much of the detail of those mechanisms remains elusive. We hypothesized that the regulation of various stress response pathways upon irradiation may differ from one another in complex dose-response manners, causing the specific and subtle low dose radiation effects. In the present study, the transcription level of 22 genes involved in stress responses were analyzed using RT-qPCR in normal human fibroblasts exposed to a range of gamma-doses from 1 to 200 cGy. Using the alkali comet assay, we also measured the level of DNA damages in dose-response and time-course experiments. We found non-linear dose responses for the repair of DNA damage after exposure to gamma-radiation. Alterations in gene expression were also not linear with dose for several of the genes examined and did not follow a single pattern. Rather, several patterns could be seen. Our results suggest a complex interplay of various stress response pathways triggered by low radiation doses, with various low dose thresholds for different genes.
authors.affiliation: Institute of Biology, Komi Science Center of Russian Academy of Sciences, Syktyvkar, Russia. 28 Kommunisticheskaya st., 167982.
authors.forename: Ilya O
authors.initials: IO
authors.lastname: Velegzhaninov
authors.affiliation: Institute of Biology, Komi Science Center of Russian Academy of Sciences, Syktyvkar, Russia. 28 Kommunisticheskaya st., 167982.
authors.forename: Dmitry M
authors.initials: DM
authors.lastname: Shadrin
authors.affiliation: Institute of Biology, Komi Science Center of Russian Academy of Sciences, Syktyvkar, Russia. 28 Kommunisticheskaya st., 167982.
authors.forename: Yana I
authors.initials: YI
authors.lastname: Pylina
authors.affiliation: Syktyvkar State University, Syktyvkar, Russia. 55 Octyabrskiy ave., 167001.
authors.forename: Anastasia V
authors.initials: AV
authors.lastname: Ermakova
authors.affiliation: Institute of Biology, Komi Science Center of Russian Academy of Sciences, Syktyvkar, Russia. 28 Kommunisticheskaya st., 167982.
authors.forename: Olga A
authors.initials: OA
authors.lastname: Shostal
authors.affiliation: Institute of Biology, Komi Science Center of Russian Academy of Sciences, Syktyvkar, Russia. 28 Kommunisticheskaya st., 167982.
authors.forename: Elena S
authors.initials: ES
authors.lastname: Belykh
authors.affiliation: Institute of Biology, Komi Science Center of Russian Academy of Sciences, Syktyvkar, Russia. 28 Kommunisticheskaya st., 167982 ; Syktyvkar State University, Syktyvkar, Russia. 55 Octyabrskiy ave., 167001.
authors.forename: Anna V
authors.initials: AV
authors.lastname: Kaneva
authors.affiliation: Institute of Biology, Komi Science Center of Russian Academy of Sciences, Syktyvkar, Russia. 28 Kommunisticheskaya st., 167982.
authors.forename: Olga V
authors.initials: OV
authors.lastname: Ermakova
authors.affiliation: Canadian Nuclear Laboratories, 1 Plant Rd, Chalk River, K0J1P0, Ontario, Canada.
authors.forename: Dmitry Y
authors.initials: DY
authors.lastname: Klokov
keywords: DNA repair; dose response; gene expression; human fibroblasts; ionizing radiation; low doses