ABSTRACT
DNA repair is essential in maintaining genome integrity and defects in different steps of the process have been linked to cancer and aging. It is a long lasting question how DNA repair is spatially and temporarily organized in the highly compartmentalized nucleus and whether the diverse nuclear compartments regulate differently the efficiency of repair. Increasing evidence suggest the involvement of nuclear pore complexes in repair of double-strand breaks (DSBs) in yeast. Here, we show that the human nucleoporin 153 (NUP153) has a role in repair of DSBs and in the activation of DNA damage checkpoints. We explore the mechanism of action of NUP153 and we propose its potential as a novel therapeutic target in cancers.
Subject(s)
DNA Breaks, Double-Stranded , DNA Repair/physiology , Nuclear Pore Complex Proteins/metabolism , Antibiotics, Antineoplastic/pharmacology , Bleomycin/pharmacology , Cell Line , Cell Nucleus/metabolism , Cell Survival/genetics , DNA Breaks, Double-Stranded/drug effects , DNA End-Joining Repair , Homologous Recombination , Humans , Intracellular Signaling Peptides and Proteins/metabolism , Nuclear Pore Complex Proteins/genetics , Protein Transport , RNA Interference/drug effects , Tumor Suppressor p53-Binding Protein 1ABSTRACT
We used intrachromosomal substrates to directly monitor the effect of the cell cycle on the efficiency and the accuracy of nonhomologous end joining (NHEJ) in mammalian cells. We show that both KU and KU-independent (KU-alt) pathways are efficient when maintaining cells in G1/S, in G2/M or during dynamic progression through S phase. In addition, the accuracy of NHEJ is barely altered when the cells are blocked in G1/S or in G2/M. However, progression through S phase increases the frequency of deletions, which is a hallmark of the KU-alt pathway. Moreover, we show that the intermediates that are generated by the KU-dependent end joining of non-fully complementary ends, and which contain mismatches, nicks or gap intermediates, are less accurately processed when the cells progress through S phase. In conclusion, both KU and KU-alt processes are active throughout the cell cycle, but the repair is more error prone during S phase, both by increasing the mutagenic KU-alt pathway and decreasing the accuracy of the repair of the intermediates generated by the KU-dependent pathway.
