The LIM Domain Protein LMO4 Interacts with the Cofactor CtIP and the Tumor Suppressor BRCA1 and Inhibits BRCA1 Activity*

LMO4 belongs to the LIM-only (LMO) group of transcriptional regulators that appear to function as molecular adaptors for protein-protein interactions. Expression of the LMO4 gene is developmentally regulated in the mammary gland and is up-regulated in primary breast cancers. Using LMO4 in a yeast two-hybrid screen, we have identified the cofactor CtIP as an LMO4-binding protein. Interaction with CtIP appeared to be specific for the LMO subclass of LIM domain proteins and could be mediated by a single LIM motif of LMO4. We further identified the breast tumor suppressor BRCA1 as an LMO4-associated protein. The C-terminal BRCT domains of BRCA1, previously shown to bind CtIP, also mediated interaction with LMO4. Tumor-associated mutations within the BRCT repeats that abolish interaction between BRCA1 and CtIP had no effect on the association of BRCA1 with LMO4. A stable complex comprising LMO4, BRCA1, and CtIP was demonstrated in vivo. The LIM domain binding-protein Ldb1 also participated in this multiprotein complex. In functional assays, LMO4 was shown to repress BRCA1-mediated transcriptional activation in both yeast and mammalian cells. These findings reveal a novel complex between BRCA1, LMO4, and CtIP and indicate a role for LMO4 as a repressor of BRCA1 activity in breast tissue.

[1]  J. Visvader,et al.  The LIM domain gene LMO4 inhibits differentiation of mammary epithelial cells in vitro and is overexpressed in breast cancer , 2001, Proceedings of the National Academy of Sciences of the United States of America.

[2]  T. Miyake,et al.  Characterization of a Novel Trans-Activation Domain of BRCA1 That Functions in Concert with the BRCA1 C-terminal (BRCT) Domain* , 2000, The Journal of Biological Chemistry.

[3]  D. Livingston,et al.  In search of the tumour-suppressor functions of BRCA1 and BRCA2 , 2000, Nature.

[4]  A. Monteiro,et al.  BRCA1: exploring the links to transcription. , 2000, Trends in biochemical sciences.

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

[6]  R. Baer,et al.  Nuclear Localization and Cell Cycle-specific Expression of CtIP, a Protein That Associates with the BRCA1 Tumor Suppressor* , 2000, The Journal of Biological Chemistry.

[7]  I. Bach.  The LIM domain: regulation by association , 2000, Mechanisms of Development.

[8]  J. Nevins,et al.  A mechanism for Rb/p130-mediated transcription repression involving recruitment of the CtBP corepressor. , 1999, Proceedings of the National Academy of Sciences of the United States of America.

[9]  C. Osborne,et al.  Binding of CtIP to the BRCT Repeats of BRCA1 Involved in the Transcription Regulation of p21 Is Disrupted Upon DNA Damage* , 1999, The Journal of Biological Chemistry.

[10]  J. Sparano,et al.  Molecular cloning of LMO41, a new human LIM domain gene. , 1999, Biochimica et biophysica acta.

[11]  Chun-Fang Xu,et al.  Methylation of the BRCA1 promoter region in sporadic breast and ovarian cancer: correlation with disease characteristics , 1999, Oncogene.

[12]  Yanfen Hu,et al.  Chromatin remodeling and activation of chromosomal DNA replication by an acidic transcriptional activation domain from BRCA1. , 1999, Genes & development.

[13]  B. Karlan,et al.  Localization of human BRCA1 and its loss in high-grade, non-inherited breast carcinomas , 1999, Nature Genetics.

[14]  M. Rosenfeld,et al.  Mouse deformed epidermal autoregulatory factor 1 recruits a LIM domain factor, LMO-4, and CLIM coregulators. , 1998, Proceedings of the National Academy of Sciences of the United States of America.

[15]  T. Rabbitts,et al.  Identification of the LMO4 gene encoding an interaction partner of the LIM-binding protein LDB1/NLI1: a candidate for displacement by LMO proteins in T cell acute leukaemia , 1998, Oncogene.

[16]  Sean V Tavtigian,et al.  Characterization of a carboxy-terminal BRCA1 interacting protein , 1998, Oncogene.

[17]  J. Rice,et al.  Aberrant methylation of the BRCA1 CpG island promoter is associated with decreased BRCA1 mRNA in sporadic breast cancer cells , 1998, Oncogene.

[18]  A. Bowcock,et al.  The C-terminal (BRCT) Domains of BRCA1 Interact in Vivo with CtIP, a Protein Implicated in the CtBP Pathway of Transcriptional Repression* , 1998, The Journal of Biological Chemistry.

[19]  Y. Saga,et al.  Identification and characterization of LMO4, an LMO gene with a novel pattern of expression during embryogenesis. , 1998, Proceedings of the National Academy of Sciences of the United States of America.

[20]  T. Rabbitts,et al.  LMO T-cell translocation oncogenes typify genes activated by chromosomal translocations that alter transcription and developmental processes. , 1998, Genes & development.

[21]  A. Reymond,et al.  Molecular cloning and characterization of a novel retinoblastoma-binding protein. , 1998, Genomics.

[22]  J. M. Boyd,et al.  Interaction between a Cellular Protein That Binds to the C-terminal Region of Adenovirus E1A (CtBP) and a Novel Cellular Protein Is Disrupted by E1A through a Conserved PLDLS Motif* , 1998, The Journal of Biological Chemistry.

[23]  Hui Tian,et al.  BRCA1 physically associates with p53 and stimulates its transcriptional activity , 1998, Oncogene.

[24]  J. J. Breen,et al.  LIM domains: multiple roles as adapters and functional modifiers in protein interactions. , 1998, Trends in genetics : TIG.

[25]  T. Rabbitts,et al.  The T cell leukemia LIM protein Lmo2 is necessary for adult mouse hematopoiesis. , 1998, Proceedings of the National Academy of Sciences of the United States of America.

[26]  F. O'Malley,et al.  CpG methylation within the 5′ regulatory region of the BRCA1 gene is tumor specific and includes a putative CREB binding site , 1998, Oncogene.

[27]  P. Gunning,et al.  Identification of homo- and heteromeric interactions between members of the breast carcinoma-associated D52 protein family using the yeast two-hybrid system , 1998, Oncogene.

[28]  C. Begley,et al.  Oncostatin M induces the differentiation of breast cancer cells , 1998, International journal of cancer.

[29]  S. Orkin,et al.  The LIM-domain binding protein Ldb1 and its partner LMO2 act as negative regulators of erythroid differentiation. , 1997, Proceedings of the National Academy of Sciences of the United States of America.

[30]  A. Dobrovic,et al.  Methylation of the BRCA1 gene in sporadic breast cancer. , 1997, Cancer research.

[31]  R. Fimmers,et al.  Genomic deletions in the BRCA1, BRCA2 and TP53 regions associate with low expression of the estrogen receptor in sporadic breast carcinoma , 1997, International journal of cancer.

[32]  T. Rabbitts,et al.  The LIM‐only protein Lmo2 is a bridging molecule assembling an erythroid, DNA‐binding complex which includes the TAL1, E47, GATA‐1 and Ldb1/NLI proteins , 1997, The EMBO journal.

[33]  M. Rosenfeld,et al.  A family of LIM domain-associated cofactors confer transcriptional synergism between LIM and Otx homeodomain proteins. , 1997, Genes & development.

[34]  R. Young,et al.  BRCA1 is a component of the RNA polymerase II holoenzyme. , 1997, Proceedings of the National Academy of Sciences of the United States of America.

[35]  M. Gatei,et al.  Cellular localisation of the ataxia-telangiectasia (ATM) gene product and discrimination between mutated and normal forms , 1997, Oncogene.

[36]  A. Strasser,et al.  Bcl-2, Bcl-xL and adenovirus protein E1B19kD are functionally equivalent in their ability to inhibit cell death , 1997, Oncogene.

[37]  Yonghong Xiao,et al.  Association of BRCA1 with Rad51 in Mitotic and Meiotic Cells , 1997, Cell.

[38]  H. Hanafusa,et al.  Evidence for a transcriptional activation function of BRCA1 C-terminal region. , 1996, Proceedings of the National Academy of Sciences of the United States of America.

[39]  J. J. Breen,et al.  Interactions of the LIM-domain-binding factor Ldbl with LIM homeodomain proteins , 1996, Nature.

[40]  L. Jurata,et al.  Nuclear LIM interactor, a rhombotin and LIM homeodomain interacting protein, is expressed early in neuronal development. , 1996, Proceedings of the National Academy of Sciences of the United States of America.

[41]  I. Verma,et al.  Transcriptional activation by BRCA1 , 1996, Nature.

[42]  Eugene V. Koonin,et al.  …Functional motifs… , 1996, Nature Genetics.

[43]  David L. Page,et al.  Decreased expression of BRCA1 accelerates growth and is often present during sporadic breast cancer progression , 1995, Nature Genetics.

[44]  P. Sawchenko,et al.  P-Lim, a LIM homeodomain factor, is expressed during pituitary organ and cell commitment and synergizes with Pit-1. , 1995, Proceedings of the National Academy of Sciences of the United States of America.

[45]  M. Skolnick,et al.  A collaborative survey of 80 mutations in the BRCA1 breast and ovarian cancer susceptibility gene. Implications for presymptomatic testing and screening. , 1995, JAMA.

[46]  I. Dawid,et al.  Role of the LIM class homeodomain protein Xlim-1 in neural and muscle induction by the Spemann organizer in Xenopus , 1994, Nature.

[47]  Steven E. Bayer,et al.  A strong candidate for the breast and ovarian cancer susceptibility gene BRCA1. , 1994, Science.

[48]  J. Li,et al.  Specific in vivo association between the bHLH and LIM proteins implicated in human T cell leukemia. , 1994, The EMBO journal.

[49]  T. Rabbitts,et al.  The LIM domain: a new structural motif found in zinc-finger-like proteins. , 1994, Trends in genetics : TIG.

[50]  J. Li,et al.  The LIM protein RBTN2 and the basic helix-loop-helix protein TAL1 are present in a complex in erythroid cells. , 1994, Proceedings of the National Academy of Sciences of the United States of America.

[51]  T. Rabbitts,et al.  The cysteine‐rich LIM domains inhibit DNA binding by the associated homeodomain in Isl‐1. , 1993, The EMBO journal.

[52]  J. Visvader,et al.  GATA‐1 but not SCL induces megakaryocytic differentiation in an early myeloid line. , 1992, The EMBO journal.

[53]  W. Rutter,et al.  Synergistic activation of the insulin gene by a LIM-homeo domain protein and a basic helix-loop-helix protein: building a functional insulin minienhancer complex. , 1992, Genes & development.

[54]  J. Barrett,et al.  Detection of frequent allelic loss on proximal chromosome 17q in sporadic breast carcinoma using microsatellite length polymorphisms. , 1992, Cancer research.

[55]  D. Smith,et al.  Single-step purification of polypeptides expressed in Escherichia coli as fusions with glutathione S-transferase. , 1988, Gene.

[56]  L. Jurata,et al.  Structure and function of LIM domains. , 1998, Current topics in microbiology and immunology.

[57]  L. Zon,et al.  Genetics of erythropoiesis: induced mutations in mice and zebrafish. , 1997, Annual review of genetics.

[58]  F. Couch,et al.  Mutations and Polymorphisms in the familial early‐onset breast cancer (BRCA1) gene , 1996, Human mutation.