Bloom's syndrome is a rare autosomal recessive genetic disorder characterized by chromosomal aberrations, genetic instability, and cancer predisposition, all of which may be the result of abnormal signal transduction during DNA damage recognition. Here, we show that BLM is an intermediate responder to stalled DNA replication forks. BLM colocalized and physically interacted with the DNA damage response proteins 53BP1 and H2AX. Although BLM facilitated physical interaction between p53 and 53BP1, 53BP1 was required for efficient accumulation of both BLM and p53 at the sites of stalled replication. The accumulation of BLM/53BP1 foci and the physical interaction between them was independent of γ-H2AX. The active Chk1 kinase was essential for both the accurate focal colocalization of 53BP1 with BLM and the consequent stabilization of BLM. Once the ATR/Chk1- and 53BP1-mediated signal from replicational stress is received, BLM functions in multiple downstream repair processes, thereby fulfilling its role as a caretaker tumor suppressor.
Functional interaction between BLM helicase and 53BP1 in a Chk1-mediated pathway during S-phase arrest
Abbreviations used in this paper: AS, antisense; BS, Bloom's syndrome; DSB, double-strand break; HR, homologous recombination; HU, hydroxyurea; IR, ionizing radiation; KD, kinase defective; KO, knockout; MEF, murine embryo fibroblast; NCS, neocarzinostatin; NHEJ, non-homologous end joining; NHF, normal human fibroblast; SCE, sister chromatid exchange; WT, wild-type.
Sagar Sengupta, Ana I. Robles, Steven P. Linke, Natasha I. Sinogeeva, Ran Zhang, Remy Pedeux, Irene M. Ward, Arkady Celeste, André Nussenzweig, Junjie Chen, Thanos D. Halazonetis, Curtis C. Harris; Functional interaction between BLM helicase and 53BP1 in a Chk1-mediated pathway during S-phase arrest . J Cell Biol 13 September 2004; 166 (6): 801–813. doi: https://doi.org/10.1083/jcb.200405128
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