MDC1 collaborates with TopBP1 in DNA replication checkpoint control.

Department of Experimental Radiation Oncology, University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA.
Human TopBP1 is a major player in the control of the DNA replication checkpoint. In this study, we identified MDC1, a key checkpoint protein involved in the cellular response to DNA double-strand breaks, as a TopBP1-associated protein. The specific TopBP1-MDC1 interaction is mediated by the fifth BRCT domain of TopBP1 and the Ser-Asp-Thr (SDT) repeats of MDC1. In addition, we demonstrated that TopBP1 accumulation at stalled replication forks is promoted by the H2AX/MDC1 signaling cascade. Moreover, MDC1 is important for ATR-dependent Chk1 activation in response to replication stress. Collectively, our data suggest that MDC1 facilitates several important steps in both cellular DNA damage response and the DNA replication checkpoint.
Mesh Terms:
Carrier Proteins, Cell Line, Tumor, DNA Breaks, Double-Stranded, DNA Repair, DNA Replication, DNA-Binding Proteins, Histones, Humans, Nuclear Proteins, Protein Kinases, Signal Transduction, Trans-Activators
J. Cell Biol. Apr. 18, 2011; 193(2);267-73 [PUBMED:21482717]
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