DOCSLIB.ORG

Heterodimerization of the Transcription Factors E2F-1 and DP-1 Leads to Cooperative Trans-Activation

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Heterodimerization of the Transcription Factors E2F-1 and DP-1 Leads to Cooperative Trans-Activation Downloaded from genesdev.cshlp.org on September 26, 2021 - Published by Cold Spring Harbor Laboratory Press Heterodimerization of the transcription factors E2F-1 and DP-1 leads to cooperative trans-activation Kristian Helin, ~ Chin-Lee Wu, Ali R. Fattaey, Jacqueline A. Lees, Brian D. Dynlacht, Chidi Ngwu, and Ed Harlow Massachusetts General Hospital Cancer Center, Charlestown, Massachusetts 02129 USA The E2F transcription factor has been implicated in the regulation of genes whose products are involved in cell proliferation. Two proteins have recently been identified with E2F-like properties. One of these proteins, E2F-1, has been shown to mediate E2F-dependent trans-activation and to bind the hypophosphorylated form of the retinoblastoma protein {pRB). The other protein, mudne DP-1, was purified from an E2F DNA-affinity column, and it was subsequently shown to bind the consensus E2F DNA-binding site. To study a possible interaction between E2F-1 and DP-1, we have now isolated a cDNA for the human homolog of DP-1. Human DP-1 and E2F-1 associate both in vivo and in vitro, and this interaction leads to enhanced binding to E2F DNA-binding sites. The association of E2F-1 and DP-1 leads to cooperative activation of an E2F-responsive promoter. Finally, we demonstrate that E2F-1 and DP-1 association is required for stable interaction with pRB in vivo and that trans-activation by E2F-1/DP-1 heterodimers is inhibited by pRB. We suggest that "E2F" is the activity that is formed when an E2F-l-related protein and a DP-l-related protein dimerize. [Key Words: E2F/DP- 1; retinoblastoma protein; heterodimerization; trans-activation] Received July 1, 1993; revised version accepted August 11, 1993. The transcription factor E2F was originally identified as which is associated in a complex with cyclin A/cdk2 or a cellular protein whose DNA-binding activity was stim- cyclin E/cdk2 (Bandara et al. 1991; Cao et al. 1992; De- ulated upon adenovirus infection of cultured cells voto et al. 1992; Lees et al. 1992; Shirodkar et al. 1992) (Kovesdi et al. 1986; for review, see Nevins 1992; Helin and p130 (D. Cobrinik and R. Weinberg, pets. comm.). and Harlow 1993). This transcription factor appears to Several observations suggest that the association of E2F regulate the temporal expression of certain genes whose with these cellular proteins regulates its activity: E2F products are involved in cell proliferation. E2F DNA- associates with the underphosphorylated form of pRB binding sites have been identified in promoters for genes (Chellappan et al. 1991; Helin et al. 1992), which is a such as c-myc, N-myc, cdc2, DHFR, and DNA polymer- negative regulator of cell proliferation (Goodrich et al. ase a (Blake and Azizkhan 1989; Thalmeier et al. 1989; 1991; Hinds et al. 1992; Qin et al. 1992). These observa- Pearson et al. 1991; Dalton 1992). In the c-myc, cdc2, tions led to the suggestion that pRB negatively regulates and DHFR promoters the E2F sites have been demon- the activity of E2F by binding to this transcription factor. strated to contribute to transcriptional activation (Blake Experimental evidence for this hypothesis has been and Azizkhan 1989; Hiebert et al. 1989; Thalmeier et al. obtained from transfection experiments in which over- 1989; Dalton 1992}. Furthermore, the presence of a sin- expression of pRB has been shown to decrease E2F-de- gle E2F DNA-binding site in the DHFR promoter has pendent transcription {Hamel et al. 1992; Hiebert et al. been shown to be sufficient for the proper temporal ex- 1992; Zamanian and La Thangue 1992; Helin et al. pression of the DHFR gene (Means et al. 1992; Slansky et 1993). In a similar manner, it has been demonstrated that al. 1993). overexpression of p107 leads to decreased E2F activity E2F is present in multiple complexes in the cell when (Schwarz et al. 1993; Zamanian and La Thangue 1993; bound to DNA (Bagchi et al. 1990). These complexes Zhu et al. 1993). The functional consequences of the include key regulators of cell proliferation, such as the cyclin A/cdk2 or cyclin E/cdk2 kinase interaction with retinoblastoma protein (pRB) (Bagchi et al. 1991; Bandara p107 have yet to be established, and it is still a possibil- and La Thangue 1991; Chellappan et al. 1991; Chit- ity that E2F in association with one or several of the tenden et al. 1991), and the pRB-related proteins, pi07, described cellular proteins is active. Interestingly, the adenovirus E1A proteins associate with pRB, p107, and p130 (Yee and Branton 1985; Harlow et al. 1986), and the 1Corresponding author. binding of E1A to these proteins has been shown to dis- 1850 GENES& DEVELOPMENT 7:1850-1861 91993 by Cold Spring Harbor Laboratory Press ISSN 0890-9369/93 $5.00 Downloaded from genesdev.cshlp.org on September 26, 2021 - Published by Cold Spring Harbor Laboratory Press Cooperative trans-activation by E2F-1 and DP-1 sociate E2F, thereby generating "free E2F" (Bagchi et al. Human 1 MAKDAGLIE]U~]GELKVFIDQNLSPGKGWSLVAVHPSTVIqPLGKQLLPKT 50 Ill. lli ill ill lili Ill ill liJ iJ lili Ill 1990). In this setting E1A is a potent activator of E2F- Mouse 1 MAKDASLIEANGELKVFIDQNLSPGKGVVSLVAVHPSTVNTLGKQLLPKT 50 mediated transcription (Yee et al. 1989). The ability of 51 FGQSNVNIAQQVVIGTPQRPAASNTLVVGSPHTPSTHFASQNQPSDSSPW I00 E1A to release free E2F and activate transcription llll l.i Ill Ill It I l:l ilr t. flll I ill 51 FGQSNVIqITQQWIGTPQRPAASNTIWGSPHTPNTHFVSQNQTSDSSPW i00 through E2F-bindmg sites suggests that E2F in its free i01 SAGKRNRKGEKNGKGLRHFSMKVCEKVQRKGTTSYNEVADELVAEFSAAD 150 form is the active transcription factor, thereby support- tit Ill li ~ii III il III II illlL11 Ill ing the notion that the E2F-associated proteins are neg- i01 SAGKRNRKGEKNGKGLRHFSMKVCEKVQRKGTTSYNEVADELVAEFSAAD 150 ative regulators of E2F activity. 151 NHILPNESAYDQKNIRRRVYDALNVLMAMIqIISKEKKEIKWIGLPTNSAQ 200 I I III II III I,I II III I, llllIll III A eDNA encoding a protein with many of the proper- 151 NHILPNESAYDQKNIRPd{VYDALNVLMuA/'4NIISKEKKEIKWIGLPTNSAQ 200 ties of human E2F has been cloned (Helin et al. 1992; 201 ECQNLEVERQRP.LERIKQKQSQLQELILQQIA/'KNLVQR!~RHAEQQASRP 250 Jl III II llJ lli ii lil II Ill,ill li Kaelin et al. 1992; Shan et al. 1992). This protein, called 201 ECQNLEVERQRI:{LERIKQKQSQLQELILQQIAFKNLV{RNRQAEQQA]:qRP 250 E2F-1, was shown to bind to pRB in vivo and in vitro 251PPPNSVIHLP~IIWTSKKTWDCSlSNDKFEYLFNFDN}~E~HDDIEV~ 3O0 li i ti II if: lli ii Ell il I [lilii I[[ (Helm et al. 1992; Kaelm et al. 1992; Shah et al. 1992). 251 PPPNSVIHLPFIIVNTSRKTVIDCSISNDKFEYLFNFDNTFEIHDDIEVL 300 Furthermore, when transfected into cultured cells, E2F-1 301 KRMGMACGL{SGSCSAEDLKMARSLVPKA{EPYVTEMAQGTVGGVFITTI 350 was able to mediate transcription dependent on the pres- II llilt 9 lli I.I il itl tl lil.:lll :II. ence of E2F DNA-binding sites (Helin et al. 1992; Shah et 301 KRMGMACGLESGNCSAEDLKVARSLVPKALEPYVTEMAQGSIGGVFVTTT 350 351 GSTSNGTRFSASDLTNGADGMLATSSNGSQYSGSRVETPQSYVGEDDEED 400 al. 1992). Structural analyses have shown that E2F-1 con- II ll:llll .111 Ill tl Ill Ill IIIIIIII I::1 tains discrete domains capable of mediating DNA bind- 351 GSTSNGTRLSASDLSNGADGMLATSSNGSQYSGSRVETPVSYVGEDDDDD 400 ing, trans-activation, and pRB binding (Helm et al. 1992; 401 DDFNENDEDD* 410 Kaelin et al. 1992; Shan et al. 1992). The pRB-binding 401 DDFNENDEED* 410 domain of E2F-1 is situated within the trans-activation Figure I. Amino acid alignment of human DP-I and mouse region, and further analysis has demonstrated that direct DP- 1. Alignment of the predicted open reading frames of human binding of pRB to E2F-1 is required for inhibition of E2F- (top) and mouse DP-ls show that the two proteins are 95% 1-dependent trans-activation (Helin et al. 1993). identical. The eDNA for human DP-1 contains an open reading Although free E2F is thought to be the active protein frame of 410 amino acids and a predicted molecular mass is of for trans-activation, it appears that more than one poly- 45,070 dahons. We have modified the open reading frame of peptide is needed to create a high-affinity E2F-DNA in- mouse DP-1 relative to the published sequence (Girling et al. teraction {Huber et al. 1993). Recently, another protein 1993), because we have identified an additional cytosine at nu- with some of the properties of E2F has been identified in cleotide 1218 in mouse DP-I, numbered according to Girling et al. (1993). This additional nucleotide changes the reading frame murine cells (Girling et al. 1993). A eDNA for this pro- of the last 40 amino acids compared with the published se- tein, called DP-1, was isolated, and the bacterially pro- quence, and the mouse DP-1 gene therefore encodes a 410- duced protein was shown to have some affinity for an amino-acid protein with a predicted molecular mass of ~45 kD. E2F DNA-binding site (Girling et al. 1993). The exis- tence of two E2F DNA-binding proteins, together with the observation that E2F probably binds DNA as a het- depicted in Figure 1 is slightly different than that pub- erodimer, led us to investigate whether there was an in- lished by Girling et al. (1993). Sequencing of mouse DP-1 teraction between E2F-1 and DP-1. We have isolated the (kindly provided by R. Girling) identified an extra cy- eDNA for human DP-1 and show that the human DP-1 tosine at nucleotide 1218 (numbered according to can bud to E2F-1 in vivo and in vitro. Furthermore, we Girling et al. 1993), which changes the reading frame of show that the interaction between E2F-1 and DP-1 leads the last 40 amino acids in tl~e published sequence. Thus, to enhanced binding to E2F sites and increased trans- the open reading frame of mouse DP-1 is 410 amino acids activation of a promoter containing these sites.
Load more

Recommended publications
  • Retinoblastoma Protein Positively Regulates Terminal Adipocyte Differentiation Through Direct Interaction with C/Ebps
    Downloaded from genesdev.cshlp.org on October 3, 2021 - Published by Cold Spring Harbor Laboratory Press Retinoblastoma protein positively regulates terminal adipocyte differentiation through direct interaction with C/EBPs Phang-Lang Chen, Daniel J. Riley, Yumay Chen, and Wen-Hwa Lee l Center for Molecular Medicine, Institute of Biotechnology, The University of Texas Health Science Center at San Antonio, San Antonio, Texas 78245 USA To define a mechanism by which retinoblastoma protein (Rb) functions in cellular differentiation, we studied primary fibroblasts from the lung buds of wild-type (RB + / +) and null-mutant (RB-/-) mouse embryos. In culture, the RB +/+ fibroblasts differentiated into fat-storing cells, either spontaneously or in response to hormonal induction; otherwise syngenic RB -/- fibroblasts cultured in identical conditions did not. Ectopic expression of normal Rb, but not Rb with a single point mutation, enabled RB-/- fibroblasts to differentiate into adipocytes. Rb appears in murine fibroblasts to activate CCAAT/enhancer-binding proteins (C/EBPs), a family of transcription factors crucial for adipocyte differentiation. Physical interaction between Rb and C/EBPs was demonstrated by reciprocal coimmunoprecipitation, but occurred only in differentiating cells. Wild-type Rb also enhanced the binding of C/EBP to cognate DNA sequences in vitro and the transact[vat[on of a C/EBPl$-responsive promoter in cells. Taken together, these observations establish a direct and positive role for Rb in terminal differentiation. Such a role contrasts with the function of Rb in arresting cell cycle progression in G1 by negative regulation of other transcription factors like E2F-1. [Key Words: C/EBP; transcription factors; cell cycle; adipocyte differentiation; tumor suppressor protein] Received July 18, 1996; revised version accepted September 5, 1996.
    [Show full text]
  • Nuclear Localization of DP and E2F Transcription Factors by Heterodimeric Partners and Retinoblastoma Protein Family Members
    Journal of Cell Science 109, 1717-1726 (1996) 1717 Printed in Great Britain © The Company of Biologists Limited 1996 JCS7086 Nuclear localization of DP and E2F transcription factors by heterodimeric partners and retinoblastoma protein family members Junji Magae1, Chin-Lee Wu2, Sharon Illenye1, Ed Harlow2 and Nicholas H. Heintz1,* 1Department of Pathology, University of Vermont, Burlington VT 05405, USA 2Massachusetts General Hospital Cancer Center, Charlestown MA 02129, USA *Author for correspondence SUMMARY E2F is a family of transcription factors implicated in the showed that regions of E2F-1 and DP-1 that are required regulation of genes required for progression through G1 for stable association of the two proteins were also required and entry into the S phase. The transcriptionally active for nuclear localization of DP-1. Unlike E2F-1, -2, and -3, forms of E2F are heterodimers composed of one polypep- E2F-4 did not accumulate in the nucleus unless it was coex- tide encoded by the E2F gene family and one polypeptide pressed with DP-2. p107 and p130, but not pRb, stimulated encoded by the DP gene family. The transcriptional activity nuclear localization of E2F-4, either alone or in combina- of E2F/DP heterodimers is influenced by association with tion with DP-2. These results indicate that DP proteins the members of the retinoblastoma tumor suppressor preferentially associate with specific E2F partners, and protein family (pRb, p107, and p130). Here the intracellu- suggest that the ability of specific E2F/DP heterodimers to lar distribution of E2F and DP proteins was investigated in localize in the nucleus contributes to the regulation of E2F transiently transfected Chinese hamster and human cells.
    [Show full text]
  • TP63 and TP73 in Cancer, an Unresolved В€Œfamily∕ Puzzle Of
    View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Elsevier - Publisher Connector FEBS Letters 588 (2014) 2590–2599 journal homepage: www.FEBSLetters.org Review TP63 and TP73 in cancer, an unresolved ‘‘family’’ puzzle of complexity, redundancy and hierarchy Antonio Costanzo a, Natalia Pediconi b,c, Alessandra Narcisi a, Francesca Guerrieri c,d, Laura Belloni c,d, ⇑ Francesca Fausti a, Elisabetta Botti a, Massimo Levrero c,d, a Dermatology Unit, Department of Neuroscience, Mental Health and Sensory Organs (NESMOS), Sapienza University of Rome, Italy b Laboratory of Molecular Oncology, Department of Molecular Medicine, Sapienza University of Rome, Italy c Center for Life Nanosciences (CNLS) – IIT/Sapienza, Rome, Italy d Laboratory of Gene Expression, Department of Internal Medicine (DMISM), Sapienza University of Rome, Italy article info abstract Article history: TP53 belongs to a small gene family that includes, in mammals, two additional paralogs, TP63 and Received 19 May 2014 TP73. The p63 and p73 proteins are structurally and functionally similar to p53 and their activity as Revised 16 June 2014 transcription factors is regulated by a wide repertoire of shared and unique post-translational mod- Accepted 16 June 2014 ifications and interactions with regulatory cofactors. p63 and p73 have important functions in Available online 28 June 2014 embryonic development and differentiation but are also involved in tumor suppression. The biology Edited by Shairaz Baksh, Giovanni Blandino of p63 and p73 is complex since both TP63 and TP73 genes are transcribed into a variety of different and Wilhelm Just isoforms that give rise to proteins with antagonistic properties, the TA-isoforms that act as tumor- suppressors and DN-isoforms that behave as proto-oncogenes.
    [Show full text]
  • RB1 and P53 at the Crossroad of EMT and Triple Negative Breast Cancer
    PERSPECTIVE PERSPECTIVE Cell Cycle 10:10, 1-8; May 15, 2011; © 2011 Landes Bioscience RB1 and p53 at the crossroad of EMT and triple negative breast cancer Zhe Jiang,1 Robert Jones,1 Jeff C. Liu,1 Tao Deng,1 Tyler Robinson,1 Philip E.D. Chung,1 Sharon Wang,1 Jason I. Herschkowitz,2 Sean E. Egan,3 Charles M. Perou4 and Eldad Zacksenhaus1,* 1Division of Cell and Molecular Biology; Toronto General Research Institute; University Health Network; Toronto, Ontario, Canada; 2Department of Molecular and Cellular Biology; Baylor College of Medicine; Houston, TX USA; 3Program in Developmental and Stem Cell Biology; The Hospital for Sick Children; Department of Molecular Genetics; University of Toronto; Toronto, Ontario, Canada; 4Lineberger Comprehensive Cancer Center; Department of Genetics and Pathology; University of North Carolina at Chapel Hill; Chapel Hill, NC USA riple negative breast cancer (TNBC) NEU-positive and Triple Negative (TN) Tis a heterogeneous disease that tumors, the latter of which do not express includes Basal-like and Claudin-low hormone receptors or HER2.1-7 TNBC tumors. The Claudin-low tumors are affects 15–30% of patients. By IHC it can enriched for features associated with be further divided into Basal-like breast epithelial-to-mesenchymal transition cancer and non-basal tumors, some of (EMT) and possibly for tumor initiating which exhibit features of EMT.8 Basal-like cells. Primary TNBCs respond relatively BCs express the basal cytokeratins (CK) well to conventional chemotherapy; CK5/6, CK14, CK17, and/or epidermal © 2011 Landes Bioscience. Landes ©2011 however, metastatic disease is virtually growth factor receptor (EGFR), whereas incurable.
    [Show full text]
  • A Thyroid Hormone Receptor Coactivator Negatively Regulated by the Retinoblastoma Protein
    Proc. Natl. Acad. Sci. USA Vol. 94, pp. 9040–9045, August 1997 Biochemistry A thyroid hormone receptor coactivator negatively regulated by the retinoblastoma protein KAI-HSUAN CHANG*†,YUMAY CHEN*†,TUNG-TI CHEN*†,WEN-HAI CHOU*†,PHANG-LANG CHEN*, YEN-YING MA‡,TERESA L. YANG-FENG‡,XIAOHUA LENG§,MING-JER TSAI§,BERT W. O’MALLEY§, AND WEN-HWA LEE*¶ *Department of Molecular Medicine and Institute of Biotechnology, University of Texas Health Science Center at San Antonio, 15355 Lambda Drive, San Antonio, TX 78245; ‡Department of Genetics, Obstetrics, and Gynecology, Yale University School of Medicine, New Haven, CT 06510; and §Department of Cell Biology, Baylor College of Medicine, Houston, TX 77030 Contributed by Bert W. O’Malley, June 9, 1997 ABSTRACT The retinoblastoma protein (Rb) plays a E2F-1, a transcription factor important for the expression of critical role in cell proliferation, differentiation, and devel- several genes involved in cell cycle progression from G1 to S opment. To decipher the mechanism of Rb function at the (18). Rb inhibits E2F-1 activity by blocking its transactivation molecular level, we have systematically characterized a num- region (19–21). In contrast, Rb has been shown to have the ber of Rb-interacting proteins, among which is the clone C5 ability to increase the transactivating activity of the members described here, which encodes a protein of 1,978 amino acids of the CCAATyenhancer binding protein (CyEBP) family, and with an estimated molecular mass of 230 kDa. The corre- to be required for CyEBPs-dependent adipocyte and mono- sponding gene was assigned to chromosome 14q31, the same cytes differentiation (16–17).
    [Show full text]
  • AP-1 in Cell Proliferation and Survival
    Oncogene (2001) 20, 2390 ± 2400 ã 2001 Nature Publishing Group All rights reserved 0950 ± 9232/01 $15.00 www.nature.com/onc AP-1 in cell proliferation and survival Eitan Shaulian1 and Michael Karin*,1 1Laboratory of Gene Regulation and Signal Transduction, Department of Pharmacology, University of California San Diego, 9500 Gilman Drive, La Jolla, California, CA 92093-0636, USA A plethora of physiological and pathological stimuli extensively discussed previously (Angel and Karin, induce and activate a group of DNA binding proteins 1991; Karin, 1995). that form AP-1 dimers. These proteins include the Jun, The mammalian AP-1 proteins are homodimers and Fos and ATF subgroups of transcription factors. Recent heterodimers composed of basic region-leucine zipper studies using cells and mice de®cient in individual AP-1 (bZIP) proteins that belong to the Jun (c-Jun, JunB proteins have begun to shed light on their physiological and JunD), Fos (c-Fos, FosB, Fra-1 and Fra-2), Jun functions in the control of cell proliferation, neoplastic dimerization partners (JDP1 and JDP2) and the closely transformation and apoptosis. Above all such studies related activating transcription factors (ATF2, LRF1/ have identi®ed some of the target genes that mediate the ATF3 and B-ATF) subfamilies (reviewed by (Angel eects of AP-1 proteins on cell proliferation and death. and Karin, 1991; Aronheim et al., 1997; Karin et al., There is evidence that AP-1 proteins, mostly those that 1997; Liebermann et al., 1998; Wisdom, 1999). In belong to the Jun group, control cell life and death addition, some of the Maf proteins (v-Maf, c-Maf and through their ability to regulate the expression and Nrl) can heterodimerize with c-Jun or c-Fos (Nishiza- function of cell cycle regulators such as Cyclin D1, p53, wa et al., 1989; Swaroop et al., 1992), whereas other p21cip1/waf1, p19ARF and p16.
    [Show full text]
  • Targeting the RB-E2F Pathway in Breast Cancer
    Oncogene (2016) 35, 4829–4835 © 2016 Macmillan Publishers Limited, part of Springer Nature. All rights reserved 0950-9232/16 www.nature.com/onc REVIEW Targeting the RB-E2F pathway in breast cancer J Johnson1, B Thijssen1, U McDermott2, M Garnett2, LFA Wessels1 and R Bernards1 Mutations of the retinoblastoma tumor-suppressor gene (RB1) or components regulating the CDK-RB-E2F pathway have been identified in nearly every human malignancy. Re-establishing cell cycle control through cyclin-dependent kinase (CDK) inhibition has therefore emerged as an attractive option in the development of targeted cancer therapy. The most successful example of this today is the use of the CDK4/6 inhibitor palbociclib combined with aromatase inhibitors for the treatment of estrogen receptor- positive breast cancers. Multiple studies have demonstrated that the CDK-RB-E2F pathway is critical for the control of cell proliferation. More recently, studies have highlighted additional roles of this pathway, especially E2F transcription factors themselves, in tumor progression, angiogenesis and metastasis. Specific E2Fs also have prognostic value in breast cancer, independent of clinical parameters. We discuss here recent advances in understanding of the RB-E2F pathway in breast cancer. We also discuss the application of genome-wide genetic screening efforts to gain insight into synthetic lethal interactions of CDK4/6 inhibitors in breast cancer for the development of more effective combination therapies. Oncogene (2016) 35, 4829–4835; doi:10.1038/onc.2016.32; published online 29 February 2016 INTRODUCTION multi-subunit protein complex containing partner (DP), RB-like, To maintain genome integrity, the mammalian cell cycle must be E2F and MuvB (DREAM) represses most if not all cell cycle gene 6 stringently regulated.
    [Show full text]
  • Aberrant Cytoplasmic Accumulation of Retinoblastoma Protein in Basal Cells May Lead to Increased Survival in Malignant Canine Mammary Tumours
    Original Paper Veterinarni Medicina, 59, 2014 (2): 76–80 Aberrant cytoplasmic accumulation of retinoblastoma protein in basal cells may lead to increased survival in malignant canine mammary tumours S. Gautam, N.K. Sood, K. Gupta Guru Angad Dev Veterinary and Animal Sciences University Ludhiana, Ludhiana, Punjab, India ABSTRACT: The retinoblastoma susceptibility geneRB-1 is a tumour suppressor gene that encodes a protein (Rb) that regulates the transition from the G1 phase to the S phase of the cell cycle. Inactivation of the Rb gene has been shown in a variety of human tumours, including breast, ovarian, hepatic, prostatic, and endometrial carcinomas. Although Rb protein is normally expressed in the nuclei of healthy cells, during carcinogenesis there is a partial or complete loss of nuclear expression. Recently, some reports have indicated aberrant cytoplasmic expression of Rb protein. However, little is known about its cytoplasmic expression and significance as a prognostic marker in canine mammary tumours (CMT). The present study was performed on 36 malignant CMT cases in order to assess the mutational status and prognostic significance of Rb in primary malignant CMT. We report an almost complete loss of nuclear expression of Rb protein with corresponding gain of aberrant cytoplasmic expression in basal/myoepithelial cells in CMT. Strikingly, our analysis reveals a significant positive correlation between survival time and cytoplasmic expression of Rb protein in basal cells. Moreover, cytoplasmic expression of Rb protein in basal cells was also correlated with tumour grade and stage. Keywords: canine mammary tumour; dogs; immunohistochemistry; retinoblastoma protein List of abbreviations CMT = canine mammary tumour, RB = retinoblastoma gene, Rb = retinoblastoma protein Breast cancer is the most frequent malignant tu- suppressors.
    [Show full text]
  • Dialogue Between Estrogen Receptor and E2F Signaling Pathways: the Transcriptional Coregulator RIP140 at the Crossroads*
    Advances in Bioscience and Biotechnology, 2013, 4, 45-54 ABB http://dx.doi.org/10.4236/abb.2013.410A3006 Published Online October 2013 (http://www.scirp.org/journal/abb/) Dialogue between estrogen receptor and E2F signaling pathways: The transcriptional coregulator RIP140 at the * crossroads Marion Lapierre1,2,3,4, Aurélie Docquier1,2,3,4, Audrey Castet-Nicolas1,2,3,4, Stéphan Jalaguier1,2,3,4, Catherine Teyssier1,2,3,4, Patrick Augereau1,2,3,4, Vincent Cavaillès1,2,3,4 1IRCM—Institut de Recherche en Cancérologie de Montpellier, Montpellier, France 2INSERM, U896, Montpellier, France 3Université Montpellier1, Montpellier, France 4Institut Régional du Cancer Montpellier, Montpellier, France Email: [email protected] Received 25 July 2013; revised 25 August 2013; accepted 19 September 2013 Copyright © 2013 Marion Lapierre et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. ABSTRACT Estrogen Receptors; Gene Expression; Cell Proliferation; Breast Cancer; Endocrine Therapies Estrogen receptors and E2F transcription factors are the key players of two nuclear signaling pathways which exert a major role in oncogenesis, particularly 1. ESTROGEN RECEPTOR AND E2F in the mammary gland. Different levels of dialogue SIGNALING PATHWAYS between these two pathways have been deciphered 1.1. Estrogen Signaling in Breast Cancer Cells and deregulation of the E2F pathway has been shown to impact the response of breast cancer cells to endo- Estrogens are steroid hormones that regulate growth and crine therapies. The present review focuses on the differentiation of a large number of target tissues such as transcriptional coregulator RIP140/NRIP1 which is the mammary gland, the reproductive tract and skeletal involved in several regulatory feed-back loops and and cardiovascular systems [1].
    [Show full text]
  • Androgens Repress Bcl-2 Expression Via Activation of the Retinoblastoma (RB) Protein in Prostate Cancer Cells
    Oncogene (2004) 23, 2161–2176 & 2004 Nature Publishing Group All rights reserved 0950-9232/04 $25.00 www.nature.com/onc Androgens repress Bcl-2 expression via activation of the retinoblastoma (RB) protein in prostate cancer cells Haojie Huang1, Ofelia L. Zegarra-Moro1, Douglas Benson1 and Donald J Tindall*,1 1Departments of Urology and Biochemistry/Molecular Biology, Mayo Clinic/Foundation, Rochester, MN 55905, USA The oncogene Bcl-2 is upregulated frequently in prostate function of the normal prostate gland, but also for the tumors following androgen ablation therapy,and Bcl-2 proliferation and survival of androgen-sensitive and - overexpression may contribute to the androgen-refractory refractory prostate cancer cells (Grossmann et al., 2001; relapse of the disease. However,the molecular mechanism Huang and Tindall, 2002; Zegarra-Moro et al., 2002). underlying androgenic regulation of Bcl-2 in prostate Surgical or pharmaceutical ablation of testicular andro- cancer cells is understood poorly. In this study,we gens has been the most effective treatment of metastatic demonstrated that no androgen response element (ARE) prostate cancer since 1941 (Huggins and Hodge, 1941). was identified in the androgen-regulated region of the P1 Both normal and malignant epithelial cells of the promoter of Bcl-2 gene,whereas,we provided evidence prostate undergo programmed cell death (apoptosis)in that the androgenic effect is mediated by E2F1 protein the absence of androgens (Isaacs, 1984; Kyprianou et al., through a putative E2F-binding site in the promoter. We 1990). However, a majority of prostate cancer patients further demonstrated that retinoblastoma (RB) protein usually relapse with tumors becoming refractory to plays a critical role in androgen regulation of Bcl-2.
    [Show full text]
  • Identification of a 60-Kilodalton Rb-Binding Protein, RBP60, That
    MOLECULARi AND CELLULAR BIOLOGY, OCt. 1992, p. 4327-4333 Vol. 12, No. 10 0270-7306/92/104327-07$02.00/0 Copyright © 1992, American Society for Microbiology Identification of a 60-Kilodalton Rb-Binding Protein, RBP60, That Allows the Rb-E2F Complex To Bind DNA SUBIR KUMAR RAY, MAY ARROYO, SRILATA BAGCHI, AND PRADIP RAYCHAUDHURI* Department ofBiochemistry (MIC 536), University ofIllinois at Chicago, Box 6998, Chicago, Illinois 60680 Received 11 March 1992/Returned for modification 17 April 1992/Accepted 1 July 1992 Several reports have indicated that the product of the retinoblastoma gene (Rb) complexes with the transcription factor E2F. We present evidence that the DNA-binding of the Rb-E2F complex involves another cellular factor. Addition of Rb to purified preparations of E2F does not generate an Rb-E2F complex that can bind DNA, and in fact, we see an inhibition of the DNA-binding ability of E2F. On the other hand, addition of Rb to cruder preparations of E2F results in the formation of an Rb-E2F complex (E2Fr) that can bind DNA and produces a distinct complex in gel retardation assays. We have identified and purified a 60-kDa protein that allows the Rb-E2F complex to bind DNA, and we show that this 60-kDa protein exerts its effect by directly interacting with Rb. The retinoblastoma gene is one of the best characterized contrast, Rb induces formation of a complex involving E2F tumor suppressor genes. The protein encoded by the reti- and its cognate sequence. By fractionating extracts from noblastoma gene, Rb, binds several DNA tumor virus onco- mouse L cells, we have identified and purified a factor, proteins (12, 15, 16) including adenovirus ElA, simian virus RBP60, that protects E2F from Rb inhibition and allows 40 T antigen, and papillomavirus E7 protein.
    [Show full text]
  • Rb and N-Ras Function Together to Control Differentiation in the Mouse
    Rb and N-ras Function Together to Control Differentiation in the Mouse The Harvard community has made this article openly available. Please share how this access benefits you. Your story matters Citation Takahashi, C., R. T. Bronson, M. Socolovsky, B. Contreras, K. Y. Lee, T. Jacks, M. Noda, R. Kucherlapati, and M. E. Ewen. 2003. “Rb and N-Ras Function Together To Control Differentiation in the Mouse.” Molecular and Cellular Biology 23 (15): 5256–68. doi:10.1128/ MCB.23.15.5256-5268.2003. Citable link http://nrs.harvard.edu/urn-3:HUL.InstRepos:41543053 Terms of Use This article was downloaded from Harvard University’s DASH repository, and is made available under the terms and conditions applicable to Other Posted Material, as set forth at http:// nrs.harvard.edu/urn-3:HUL.InstRepos:dash.current.terms-of- use#LAA MOLECULAR AND CELLULAR BIOLOGY, Aug. 2003, p. 5256–5268 Vol. 23, No. 15 0270-7306/03/$08.00ϩ0 DOI: 10.1128/MCB.23.15.5256–5268.2003 Copyright © 2003, American Society for Microbiology. All Rights Reserved. Rb and N-ras Function Together To Control Differentiation in the Mouse Chiaki Takahashi,1† Roderick T. Bronson,2,3 Merav Socolovsky,4 Bernardo Contreras,1 Kwang Youl Lee,1‡ Tyler Jacks,5 Makoto Noda,6 Raju Kucherlapati,7 and Mark E. Ewen1* Department of Medical Oncology and Medicine, Dana-Farber Cancer Institute and Harvard Medical School,1 and Rodent Histopathology Core3 and Harvard-Partners Center for Genetics and Genomics,7 Harvard Medical School, Boston, Massachusetts 02115; Department of Pathology, Tufts University Schools
    [Show full text]