Neumaier, T. ; Swenson, J.* ; Pham, C.* ; Polyzos, A.* ; Lo, A.T.* ; Yang, P.* ; Dyball, J.* ; Asaithamby, A.* ; Chen, D.J.* ; Bissell, M.J.* ; Thalhammer, S. ; Costes, S.V.*
     
    
        
         Evidence for formation of DNA repair centers and dose-response nonlinearity in human cells.
        Evidence for formation of DNA repair centers and dose-response nonlinearity in human cells.
     
    
        
    
    
        
        Proc. Natl. Acad. Sci. U.S.A. 109, 443-448 (2012)
    
    
    
      
      
	
	    The concept of DNA "repair centers" and the meaning of radiation-induced foci (RIF) in human cells have remained controversial. RIFs are characterized by the local recruitment of DNA damage sensing proteins such as p53 binding protein (53BP1). Here, we provide strong evidence for the existence of repair centers. We used live imaging and mathematical fitting of RIF kinetics to show that RIF induction rate increases with increasing radiation dose, whereas the rate at which RIFs disappear decreases. We show that multiple DNA double-strand breaks (DSBs) 1 to 2 μm apart can rapidly cluster into repair centers. Correcting mathematically for the dose dependence of induction/resolution rates, we observe an absolute RIF yield that is surprisingly much smaller at higher doses: 15 RIF/Gy after 2 Gy exposure compared to approximately 64 RIF/Gy after 0.1 Gy. Cumulative RIF counts from time lapse of 53BP1-GFP in human breast cells confirmed these results. The standard model currently in use applies a linear scale, extrapolating cancer risk from high doses to low doses of ionizing radiation. However, our discovery of DSB clustering over such large distances casts considerable doubts on the general assumption that risk to ionizing radiation is proportional to dose, and instead provides a mechanism that could more accurately address risk dose dependency of ionizing radiation.
	
	
	    
	
       
      
	
	    
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        Publication type
        Article: Journal article
    
 
    
        Document type
        Scientific Article
    
 
    
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        Keywords
        DOUBLE-STRAND BREAKS; HISTONE H2AX PHOSPHORYLATION; HEAT-LABILE SITES; LOW-LET RADIATION; CHROMOSOME-ABERRATIONS; MAMMALIAN-CELLS; GAMMA-H2AX FOCI; PARTICLE TRACKS; X-RAYS; IRRADIATION
    
 
    
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        Language
        english
    
 
    
        Publication Year
        2012
    
 
    
        Prepublished in Year
        2011
    
 
    
        HGF-reported in Year
        2011
    
 
    
    
        ISSN (print) / ISBN
        0027-8424
    
 
    
        e-ISSN
        1091-6490
    
 
    
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	    Volume: 109,  
	    Issue: 2,  
	    Pages: 443-448 
	    Article Number: ,  
	    Supplement: ,  
	
    
 
    
        
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            National Academy of Sciences
        
 
        
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        Reviewing status
        Peer reviewed
    
 
     
    
        POF-Topic(s)
        30504 - Mechanisms of Genetic and Environmental Influences on Health and Disease
    
 
    
        Research field(s)
        Radiation Sciences
    
 
    
        PSP Element(s)
        G-501100-006
    
 
    
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        Erfassungsdatum
        2011-12-31