BubR1 is involved in regulation of DNA damage responses.
Defective mitotic spindles or an impaired spindle-kinetochore interaction activates the spindle checkpoint. We have previously shown that BubR1 haplo-insufficiency results in enhanced genomic instability and tumorigenesis in mice. Here we report that BubR1 deficiency also leads to a compromised response to DNA damage. Following treatment with doxorubicin, BubR1(+/-) murine fibroblast cells (MEF) were defective in undergoing G(2)/M arrest. Thus, whereas in the presence of DNA damage BubR1(+/+) MEF cells remained arrested in mitosis, BubR1(+/-) MEFs rapidly exited from mitosis and divided. The impaired mitotic arrest of BubR1(+/-) MEFs was associated with low levels of phospho-histone H2AX, p53, and p21 after DNA damage caused by treatment with both doxorubicin and ultraviolet light (UV). The impaired expression of p53 and p21 was also confirmed in human cell lines with BubR1 knockdown via RNA interference. Affinity pull-down coupled with mass spectrometry identified Poly(ADP-ribose) polymerase 1 (PARP-1) as one of the proteins interacting with BubR1. Reciprocal co-immunoprecipitation analysis confirmed the physical interaction between BubR1 and PARP-1. Our further study revealed that the ability of retaining intact PARP-1 or its cleavage product p89 was compromised in BubR1(+/-) MEFs upon treatment with doxorubicin or UV. Given that PARP-1 mediates DNA damage responses and regulates the activity of p53, our studies suggest that there exists a cross-talk between the spindle checkpoint and the DNA damage checkpoint and that BubR1 may play an important role in mediating the cross-talk.
Fang
Y
Y
Division of Molecular Carcinogenesis, New York Medical College, Valhalla, NY 10595, USA.
Liu
T
T
Wang
X
X
Yang
Y-M
YM
Deng
H
H
Kunicki
J
J
Traganos
F
F
Darzynkiewicz
Z
Z
Lu
L
L
Dai
W
W
D000818:Animals; D000903:Antibiotics, Antineoplastic / Q000633:toxicity; D015153:Blotting, Western; D018797:Cell Cycle Proteins; D002460:Cell Line; D004249:DNA Damage / Q000502:physiology*; D004260:DNA Repair / Q000502:physiology*; D004317:Doxorubicin / Q000633:toxicity; D005347:Fibroblasts / Q000187:drug effects; D005434:Flow Cytometry; D005455:Fluorescent Antibody Technique; D006367:HeLa Cells; D006657:Histones / Q000378:metabolism; D006801:Humans; D047468:Immunoprecipitation; D013058:Mass Spectrometry; D051379:Mice; D008938:Mitosis / Q000187:drug effects / Q000502:physiology*; D008969:Molecular Sequence Data; D000071137:Poly (ADP-Ribose) Polymerase-1; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases; D034622:RNA Interference; D015398:Signal Transduction / Q000502:physiology; D014162:Transfection; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism; D020741:rho GTP-Binding Proteins / Q000378:metabolism
D000903:Antibiotics, Antineoplastic; D018797:Cell Cycle Proteins; D004317:Doxorubicin; D006657:Histones; D000071137:Poly (ADP-Ribose) Polymerase-1; D011065:Poly(ADP-ribose) Polymerases; D011494:Protein Kinases; D017346:Protein Serine-Threonine Kinases; D016159:Tumor Suppressor Protein p53; D020741:rho GTP-Binding Proteins; C584278:Bub1b protein, mouse; C499320:PARP1 protein, human; C584277:BUB1 protein, human; C090464:Bub1 spindle checkpoint protein; C475961:gamma-H2AX protein, mouse