ANALYSIS OF IONIZING RADIATION-INDUCED DNA DAMAGE AND REPAIR IN THREE-DIMENSIONAL HUMAN SKIN MODEL SYSTEM.
This study by researchers in the Columbia University College of Physicians and Surgeons Center for Radiological Research demonstrated that MatTek’s EpiDerm in vitro 3-D human skin tissue equivalent and EpiDermFT full-thickness in vitro 3-D human skin tissue equivalent can be used to study the damaging effects to DNA of ionizing radiation exposure. Knowledge of cellular responses in tissue microenvironment is crucial for the accurate prediction of human health risks following chronic or acute exposure to ionizing radiation (IR). With this objective, researchers investigated the radio responses for the first time in three-dimensional (3D) artificial human skin tissue microenvironment after gamma rays radiation. IR-induced DNA damage/repair response was assessed by immunological analysis of well-known DNA double strand break (DSB) repair proteins, i.e. 53BP1 and phosphorylated ataxia telangiectasia mutatedser1981 (ATMser1981). Efficient 53BP1 and phosphorylated ATM foci formation was observed in human EpiDerm tissue constructs after low and high doses of gamma rays. Interestingly, EpiDerm tissue constructs displayed less 53BP1 and ATM foci number at all radiation doses (0.1, 1, 2.5 and 5 Gy) than that observed for 2D human fibroblasts. DSB repair efficiency judged by the disappearance of 53BP1 foci declined with increasing doses of gamma rays and tissue constructs irradiated with 2.5 and 5 Gy of gammma rays displayed 53BP1 foci persisting up to 72 h of analysis. Pretreatment of EpiDerm tissue constructs with LY294002, [an inhibitor of phosphatidylinositol-3 kinase and PI-3 kinase like kinases (PIKK)] completely abolished IR-induced 53BP1 foci formation and increased the apoptotic death. This observation indicates the importance of PIKK signalling pathway for efficient radiation responses in intact tissue constructs. In summary, researchers successfully demonstrated the feasibility of monitoring the DNA damage response in human skin tissue microenvironment. In this system, 53BP1 can be used as a useful marker for monitoring the DSB repair efficiency.
53 binding protein 1 (53BP1), 53BP1, Ataxia telangiectasia mutated (ATM), Confocal laser scanning microscope, DNA damage, DNA double strand break (DSB) induction and repair proteins, DNA repair, DNA–dependent protein kinase (DNA-PK), EpiDerm, EpiDerm-FT, EpiDermFT, Ionizing radiation, Low LET radiation, PI-3 kinase like kinases (PIKK), Phosphatidylinositol-3 kinase like kinases, TUNEL assay
Gamma rays, Ionizing radiation, LY294002 An inhibitor of phosphatidylinositol-3 kinase, PI-3 kinase inhibitor
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