A requirement for breast-cancer-associated gene 1 (BRCA1) in the spindle checkpoint.

BRCA1-associated breast cancer exhibits significantly higher levels of chromosomal abnormalities than sporadic breast cancers. However, the molecular mechanisms regarding the roles of BRCA1 in maintaining genome integrity remain elusive. By using a mouse model deficient for Brca1 full-length isoform (Brca1(Delta11/Delta11)), we found that Brca1(Delta11/Delta11) cells displayed decreased expression of a number of genes that are involved in the spindle checkpoint, including Mad2, which is a key component of spindle checkpoint that inhibits anaphase-promoting complex. We showed that Brca1(Delta11/Delta11) cells failed to arrest at metaphase in the presence of nocodazole and underwent apoptosis because of activation of p53. Consistently, reconstitution of Mad2 in Brca1(Delta11/Delta11) cells partially restored the spindle checkpoint and attenuated apoptosis. By using UBR60 cells, which carry tetracycline-regulated expression of BRCA1, we demonstrated that BRCA1 binds to transcription factor OCT-1 and up-regulates the transcription of MAD2. Furthermore, we showed that the induction of BRCA1 to endogenous MAD2 or transfected MAD2 luciferase reporter in UBR60 cells was completely inhibited by acute suppression of BRCA1 by RNA interference. These data reveal a role of BRCA1 in maintaining genome integrity by interplaying with p53 and genes that are involved in the spindle checkpoint and apoptosis.

[1]  C. Deng,et al.  Roles of BRCA1 in DNA damage repair: a link between development and cancer. , 2003, Human molecular genetics.

[2]  T. Crook,et al.  TP53 mutations in familial breast cancer: Functional aspects , 2003, Human mutation.

[3]  K. Sullivan,et al.  Centromeres and Kinetochores From Epigenetics to Mitotic Checkpoint Signaling , 2003, Cell.

[4]  R. Benezra,et al.  Mad2 phosphorylation regulates its association with Mad1 and the APC/C , 2003, The EMBO journal.

[5]  C. Deng,et al.  Normal lymphocyte development and thymic lymphoma formation in Brca1 exon-11-deficient mice , 2003, Oncogene.

[6]  C. Deng,et al.  Senescence, aging, and malignant transformation mediated by p53 in mice lacking the Brca1 full-length isoform. , 2003, Genes & development.

[7]  Hongtao Yu,et al.  Regulation of APC-Cdc20 by the spindle checkpoint. , 2002, Current opinion in cell biology.

[8]  C. Deng,et al.  Mammary tumors in mice conditionally mutant for Brca1 exhibit gross genomic instability and centrosome amplification yet display a recurring distribution of genomic imbalances that is similar to human breast cancer , 2002, Oncogene.

[9]  G. Fang,et al.  Checkpoint protein BubR1 acts synergistically with Mad2 to inhibit anaphase-promoting complex. , 2002, Molecular biology of the cell.

[10]  Ashok R Venkitaraman,et al.  Cancer Susceptibility and the Functions of BRCA1 and BRCA2 , 2002, Cell.

[11]  C. Deng.  Tumor formation in Brca1 conditional mutant mice , 2002, Environmental and Molecular Mutagenesis.

[12]  C. Deng,et al.  Multiple genetic changes are associated with mammary tumorigenesis in Brca1 conditional knockout mice , 2001, Oncogene.

[13]  G. Chan,et al.  Checkpoint inhibition of the APC/C in HeLa cells is mediated by a complex of BUBR1, BUB3, CDC20, and MAD2 , 2001, The Journal of cell biology.

[14]  Hongtao Yu,et al.  Mad2-Independent inhibition of APCCdc20 by the mitotic checkpoint protein BubR1. , 2001, Developmental cell.

[15]  Curtis C. Harris,et al.  Genetic interactions between tumor suppressors Brca1 and p53 in apoptosis, cell cycle and tumorigenesis , 2001, Nature Genetics.

[16]  C. Deng,et al.  Tumorigenesis as a consequence of genetic instability in Brca1 mutant mice. , 2001, Mutation research.

[17]  W. Gerald,et al.  MAD2 haplo-insufficiency causes premature anaphase and chromosome instability in mammalian cells , 2001, Nature.

[18]  J. Shah,et al.  Waiting for Anaphase Mad2 and the Spindle Assembly Checkpoint , 2000, Cell.

[19]  Wen-Hwa Lee,et al.  Lessons learned from BRCA1 and BRCA2 , 2000, Oncogene.

[20]  Myles Brown,et al.  Cofactor Dynamics and Sufficiency in Estrogen Receptor–Regulated Transcription , 2000, Cell.

[21]  C. Deng,et al.  Roles of BRCA1 and its interacting proteins , 2000, BioEssays : news and reviews in molecular, cellular and developmental biology.

[22]  P. Sorger,et al.  Chromosome Missegregation and Apoptosis in Mice Lacking the Mitotic Checkpoint Protein Mad2 , 2000, Cell.

[23]  F. Christians,et al.  Induction of GADD45 and JNK/SAPK-Dependent Apoptosis following Inducible Expression of BRCA1 , 1999, Cell.

[24]  Thomas Ried,et al.  Conditional mutation of Brca1 in mammary epithelial cells results in blunted ductal morphogenesis and tumour formation , 1999, Nature Genetics.

[25]  X. Wang,et al.  Centrosome amplification and a defective G2-M cell cycle checkpoint induce genetic instability in BRCA1 exon 11 isoform-deficient cells. , 1999, Molecular cell.

[26]  A. Murray,et al.  Microinjection of Antibody to Mad2 Protein into Mammalian Cells in Mitosis Induces Premature Anaphase , 1998, The Journal of cell biology.

[27]  C. Deng,et al.  The tumor suppressor SMAD4/DPC4 is essential for epiblast proliferation and mesoderm induction in mice. , 1998, Proceedings of the National Academy of Sciences of the United States of America.

[28]  T. Ouchi,et al.  BRCA1 regulates p53-dependent gene expression. , 1998, Proceedings of the National Academy of Sciences of the United States of America.

[29]  H. Ruffner,et al.  BRCA1 is a cell cycle-regulated nuclear phosphoprotein. , 1997, Proceedings of the National Academy of Sciences of the United States of America.

[30]  Nicklas Rb.  How Cells Get the Right Chromosomes , 1997, Science.

[31]  A. Berchuck,et al.  BRCA1 expression is induced before DNA synthesis in both normal and tumor-derived breast cells. , 1996, Cell growth & differentiation : the molecular biology journal of the American Association for Cancer Research.

[32]  P. Chambon,et al.  Conditional site-specific recombination in mammalian cells using a ligand-dependent chimeric Cre recombinase. , 1995, Proceedings of the National Academy of Sciences of the United States of America.

[33]  J. Trent,et al.  WAF1, a potential mediator of p53 tumor suppression , 1993, Cell.

[34]  S. Elledge,et al.  The p21 Cdk-interacting protein Cip1 is a potent inhibitor of G1 cyclin-dependent kinases , 1993, Cell.