1
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Brennan A, Leech JT, Kad NM, Mason JM. An Approach to Derive Functional Peptide Inhibitors of Transcription Factor Activity. JACS AU 2022; 2:996-1006. [PMID: 35557753 PMCID: PMC9088798 DOI: 10.1021/jacsau.2c00105] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Revised: 03/01/2022] [Accepted: 03/01/2022] [Indexed: 06/15/2023]
Abstract
We report the development of a high-throughput, intracellular "transcription block survival" (TBS) screening platform to derive functional transcription factor antagonists. TBS is demonstrated using the oncogenic transcriptional regulator cJun, with the development of antagonists that bind cJun and prevent both dimerization and, more importantly, DNA binding remaining a primary challenge. In TBS, cognate TRE sites are introduced into the coding region of the essential gene, dihydrofolate reductase (DHFR). Introduction of cJun leads to TRE binding, preventing DHFR expression by directly blocking RNA polymerase gene transcription to abrogate cell proliferation. Peptide library screening identified a sequence that both binds cJun and antagonizes function by preventing DNA binding, as demonstrated by restored cell viability and subsequent in vitro hit validation. TBS is an entirely tag-free genotype-to-phenotype approach, selecting desirable attributes such as high solubility, target specificity, and low toxicity within a complex cellular environment. TBS facilitates rapid library screening to accelerate the identification of therapeutically valuable sequences.
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Affiliation(s)
- Andrew Brennan
- Department
of Biology & Biochemistry, University
of Bath, Bath BA2 7AY, U.K.
| | - James T. Leech
- School
of Biosciences, University of Kent, Canterbury CT2 7NH, U.K.
| | - Neil M. Kad
- School
of Biosciences, University of Kent, Canterbury CT2 7NH, U.K.
| | - Jody M. Mason
- Department
of Biology & Biochemistry, University
of Bath, Bath BA2 7AY, U.K.
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2
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Brennan A, Leech JT, Kad NM, Mason JM. Selective antagonism of cJun for cancer therapy. J Exp Clin Cancer Res 2020; 39:184. [PMID: 32917236 PMCID: PMC7488417 DOI: 10.1186/s13046-020-01686-9] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2020] [Accepted: 08/20/2020] [Indexed: 01/10/2023] Open
Abstract
The activator protein-1 (AP-1) family of transcription factors modulate a diverse range of cellular signalling pathways into outputs which can be oncogenic or anti-oncogenic. The transcription of relevant genes is controlled by the cellular context, and in particular by the dimeric composition of AP-1. Here, we describe the evidence linking cJun in particular to a range of cancers. This includes correlative studies of protein levels in patient tumour samples and mechanistic understanding of the role of cJun in cancer cell models. This develops an understanding of cJun as a focal point of cancer-altered signalling which has the potential for therapeutic antagonism. Significant work has produced a range of small molecules and peptides which have been summarised here and categorised according to the binding surface they target within the cJun-DNA complex. We highlight the importance of selectively targeting a single AP-1 family member to antagonise known oncogenic function and avoid antagonism of anti-oncogenic function.
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Affiliation(s)
- Andrew Brennan
- Department of Biology & Biochemistry, University of Bath, Claverton Down, Bath, BA2 7AY, UK
| | - James T Leech
- School of Biosciences, University of Kent, Canterbury, CT2 7NH, UK
| | - Neil M Kad
- School of Biosciences, University of Kent, Canterbury, CT2 7NH, UK
| | - Jody M Mason
- Department of Biology & Biochemistry, University of Bath, Claverton Down, Bath, BA2 7AY, UK.
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3
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Liu J, Han Q, Peng T, Peng M, Wei B, Li D, Wang X, Yu S, Yang J, Cao S, Huang K, Hutchins AP, Liu H, Kuang J, Zhou Z, Chen J, Wu H, Guo L, Chen Y, Chen Y, Li X, Wu H, Liao B, He W, Song H, Yao H, Pan G, Chen J, Pei D. The oncogene c-Jun impedes somatic cell reprogramming. Nat Cell Biol 2015; 17:856-67. [PMID: 26098572 DOI: 10.1038/ncb3193] [Citation(s) in RCA: 98] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2014] [Accepted: 05/19/2015] [Indexed: 02/08/2023]
Abstract
Oncogenic transcription factors are known to mediate the conversion of somatic cells to tumour or induced pluripotent stem cells (iPSCs). Here we report c-Jun as a barrier for iPSC formation. c-Jun is expressed by and required for the proliferation of mouse embryonic fibroblasts (MEFs), but not mouse embryonic stem cells (mESCs). Consistently, c-Jun is induced during mESC differentiation, drives mESCs towards the endoderm lineage and completely blocks the generation of iPSCs from MEFs. Mechanistically, c-Jun activates mesenchymal-related genes, broadly suppresses the pluripotent ones, and derails the obligatory mesenchymal to epithelial transition during reprogramming. Furthermore, inhibition of c-Jun by shRNA, dominant-negative c-Jun or Jdp2 enhances reprogramming and replaces Oct4 among the Yamanaka factors. Finally, Jdp2 anchors 5 non-Yamanaka factors (Id1, Jhdm1b, Lrh1, Sall4 and Glis1) to reprogram MEFs into iPSCs. Our studies reveal c-Jun as a guardian of somatic cell fate and its suppression opens the gate to pluripotency.
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Affiliation(s)
- Jing Liu
- 1] Key Laboratory of Regenerative Biology, South China Institute for Stem Cell Biology and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530, China [2] Guangdong Provincial Key Laboratory of Stem Cell and Regenerative Medicine, South China Institute for Stem Cell Biology and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530, China
| | - Qingkai Han
- 1] Key Laboratory of Regenerative Biology, South China Institute for Stem Cell Biology and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530, China [2] Guangdong Provincial Key Laboratory of Stem Cell and Regenerative Medicine, South China Institute for Stem Cell Biology and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530, China
| | - Tianran Peng
- 1] Key Laboratory of Regenerative Biology, South China Institute for Stem Cell Biology and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530, China [2] Guangdong Provincial Key Laboratory of Stem Cell and Regenerative Medicine, South China Institute for Stem Cell Biology and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530, China
| | - Meixiu Peng
- 1] Key Laboratory of Regenerative Biology, South China Institute for Stem Cell Biology and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530, China [2] Guangdong Provincial Key Laboratory of Stem Cell and Regenerative Medicine, South China Institute for Stem Cell Biology and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530, China
| | - Bei Wei
- 1] Key Laboratory of Regenerative Biology, South China Institute for Stem Cell Biology and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530, China [2] Guangdong Provincial Key Laboratory of Stem Cell and Regenerative Medicine, South China Institute for Stem Cell Biology and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530, China
| | - Dongwei Li
- 1] Key Laboratory of Regenerative Biology, South China Institute for Stem Cell Biology and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530, China [2] Guangdong Provincial Key Laboratory of Stem Cell and Regenerative Medicine, South China Institute for Stem Cell Biology and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530, China
| | - Xiaoshan Wang
- 1] Key Laboratory of Regenerative Biology, South China Institute for Stem Cell Biology and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530, China [2] Guangdong Provincial Key Laboratory of Stem Cell and Regenerative Medicine, South China Institute for Stem Cell Biology and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530, China [3] Guangzhou Branch of the Supercomputing Center of Chinese Academy of Sciences, Guangzhou 510530, China
| | - Shengyong Yu
- 1] Key Laboratory of Regenerative Biology, South China Institute for Stem Cell Biology and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530, China [2] School of Bioscience and Bioengineering, South China University of Technology, Guangzhou 510006, China
| | - Jiaqi Yang
- 1] Key Laboratory of Regenerative Biology, South China Institute for Stem Cell Biology and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530, China [2] Guangdong Provincial Key Laboratory of Stem Cell and Regenerative Medicine, South China Institute for Stem Cell Biology and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530, China
| | - Shangtao Cao
- 1] Key Laboratory of Regenerative Biology, South China Institute for Stem Cell Biology and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530, China [2] Guangdong Provincial Key Laboratory of Stem Cell and Regenerative Medicine, South China Institute for Stem Cell Biology and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530, China
| | - Kaimeng Huang
- 1] Key Laboratory of Regenerative Biology, South China Institute for Stem Cell Biology and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530, China [2] Guangdong Provincial Key Laboratory of Stem Cell and Regenerative Medicine, South China Institute for Stem Cell Biology and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530, China
| | - Andrew Paul Hutchins
- 1] Key Laboratory of Regenerative Biology, South China Institute for Stem Cell Biology and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530, China [2] Guangdong Provincial Key Laboratory of Stem Cell and Regenerative Medicine, South China Institute for Stem Cell Biology and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530, China [3] Guangzhou Branch of the Supercomputing Center of Chinese Academy of Sciences, Guangzhou 510530, China
| | - He Liu
- 1] Key Laboratory of Regenerative Biology, South China Institute for Stem Cell Biology and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530, China [2] Guangdong Provincial Key Laboratory of Stem Cell and Regenerative Medicine, South China Institute for Stem Cell Biology and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530, China
| | - Junqi Kuang
- 1] Key Laboratory of Regenerative Biology, South China Institute for Stem Cell Biology and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530, China [2] School of Bioscience and Bioengineering, South China University of Technology, Guangzhou 510006, China
| | - Zhiwei Zhou
- 1] Key Laboratory of Regenerative Biology, South China Institute for Stem Cell Biology and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530, China [2] Guangdong Provincial Key Laboratory of Stem Cell and Regenerative Medicine, South China Institute for Stem Cell Biology and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530, China
| | - Jing Chen
- 1] Key Laboratory of Regenerative Biology, South China Institute for Stem Cell Biology and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530, China [2] Guangdong Provincial Key Laboratory of Stem Cell and Regenerative Medicine, South China Institute for Stem Cell Biology and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530, China
| | - Haoyu Wu
- 1] Key Laboratory of Regenerative Biology, South China Institute for Stem Cell Biology and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530, China [2] Department of Biological Engineering, College of Pharmacy, Jilin University, 1266 Fu Jin Road Changchun 130021, China
| | - Lin Guo
- 1] Key Laboratory of Regenerative Biology, South China Institute for Stem Cell Biology and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530, China [2] Guangdong Provincial Key Laboratory of Stem Cell and Regenerative Medicine, South China Institute for Stem Cell Biology and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530, China
| | - Yongqiang Chen
- 1] Key Laboratory of Regenerative Biology, South China Institute for Stem Cell Biology and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530, China [2] Guangdong Provincial Key Laboratory of Stem Cell and Regenerative Medicine, South China Institute for Stem Cell Biology and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530, China
| | - You Chen
- 1] Key Laboratory of Regenerative Biology, South China Institute for Stem Cell Biology and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530, China [2] Guangdong Provincial Key Laboratory of Stem Cell and Regenerative Medicine, South China Institute for Stem Cell Biology and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530, China
| | - Xuejia Li
- 1] Key Laboratory of Regenerative Biology, South China Institute for Stem Cell Biology and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530, China [2] Guangdong Provincial Key Laboratory of Stem Cell and Regenerative Medicine, South China Institute for Stem Cell Biology and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530, China
| | - Hongling Wu
- 1] Key Laboratory of Regenerative Biology, South China Institute for Stem Cell Biology and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530, China [2] Guangdong Provincial Key Laboratory of Stem Cell and Regenerative Medicine, South China Institute for Stem Cell Biology and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530, China
| | - Baojian Liao
- 1] Key Laboratory of Regenerative Biology, South China Institute for Stem Cell Biology and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530, China [2] Guangdong Provincial Key Laboratory of Stem Cell and Regenerative Medicine, South China Institute for Stem Cell Biology and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530, China
| | - Wei He
- 1] Key Laboratory of Regenerative Biology, South China Institute for Stem Cell Biology and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530, China [2] Guangdong Provincial Key Laboratory of Stem Cell and Regenerative Medicine, South China Institute for Stem Cell Biology and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530, China
| | - Hong Song
- 1] Key Laboratory of Regenerative Biology, South China Institute for Stem Cell Biology and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530, China [2] Guangdong Provincial Key Laboratory of Stem Cell and Regenerative Medicine, South China Institute for Stem Cell Biology and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530, China
| | - Hongjie Yao
- 1] Key Laboratory of Regenerative Biology, South China Institute for Stem Cell Biology and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530, China [2] Guangdong Provincial Key Laboratory of Stem Cell and Regenerative Medicine, South China Institute for Stem Cell Biology and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530, China
| | - Guangjin Pan
- 1] Key Laboratory of Regenerative Biology, South China Institute for Stem Cell Biology and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530, China [2] Guangdong Provincial Key Laboratory of Stem Cell and Regenerative Medicine, South China Institute for Stem Cell Biology and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530, China
| | - Jiekai Chen
- 1] Key Laboratory of Regenerative Biology, South China Institute for Stem Cell Biology and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530, China [2] Guangdong Provincial Key Laboratory of Stem Cell and Regenerative Medicine, South China Institute for Stem Cell Biology and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530, China [3] Guangzhou Branch of the Supercomputing Center of Chinese Academy of Sciences, Guangzhou 510530, China
| | - Duanqing Pei
- 1] Key Laboratory of Regenerative Biology, South China Institute for Stem Cell Biology and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530, China [2] Guangdong Provincial Key Laboratory of Stem Cell and Regenerative Medicine, South China Institute for Stem Cell Biology and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530, China [3] Guangzhou Branch of the Supercomputing Center of Chinese Academy of Sciences, Guangzhou 510530, China
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4
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Abstract
c-Jun NH2-terminal kinase (JNK) was discovered almost 20 years ago as the protein kinase responsible for phosphorylating c-Jun at Ser-63 and Ser-73. These sites had previously been demonstrated to be essential for the stimulation of c-Jun activity and for cooperation with Ha-ras in oncogenic transformation. This led to the idea that JNK was a positive regulator of cellular transformation. However, the analysis of jnk gene deletion in various mouse models of cancer has produced conflicting findings, with some studies supporting the pro-oncogenic function of JNK and others providing evidence that JNK acts as a tumor suppressor. This review will discuss how these unexpected findings have increased our understanding of the role of JNK signaling in cancer and have provided a source of new working hypotheses.
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5
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Rajagopalan K, Qiu R, Mooney SM, Rao S, Shiraishi T, Sacho E, Huang H, Shapiro E, Weninger KR, Kulkarni P. The Stress-response protein prostate-associated gene 4, interacts with c-Jun and potentiates its transactivation. Biochim Biophys Acta Mol Basis Dis 2013; 1842:154-63. [PMID: 24263171 DOI: 10.1016/j.bbadis.2013.11.014] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2013] [Revised: 10/26/2013] [Accepted: 11/13/2013] [Indexed: 01/18/2023]
Abstract
The Cancer/Testis Antigen (CTA), Prostate-associated Gene 4 (PAGE4), is a stress-response protein that is upregulated in prostate cancer (PCa) especially in precursor lesions that result from inflammatory stress. In cells under stress, translocation of PAGE4 to mitochondria increases while production of reactive oxygen species decreases. Furthermore, PAGE4 is also upregulated in human fetal prostate, underscoring its potential role in development. However, the proteins that interact with PAGE4 and the mechanisms underlying its pleiotropic functions in prostatic development and disease remain unknown. Here, we identified c-Jun as a PAGE4 interacting partner. We show that both PAGE4 and c-Jun are overexpressed in the human fetal prostate; and in cell-based assays, PAGE4 robustly potentiates c-Jun transactivation. Single-molecule Förster resonance energy transfer experiments indicate that upon binding to c-Jun, PAGE4 undergoes conformational changes. However, no interaction is observed in presence of BSA or unilamellar vesicles containing the mitochondrial inner membrane diphosphatidylglycerol lipid marker cardiolipin. Together, our data indicate that PAGE4 specifically interacts with c-Jun and that, conformational dynamics may account for its observed pleiotropic functions. To our knowledge, this is the first report demonstrating crosstalk between a CTA and a proto-oncogene. Disrupting PAGE4/c-Jun interactions using small molecules may represent a novel therapeutic strategy for PCa.
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Affiliation(s)
- Krithika Rajagopalan
- Department of Urology, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
| | - Ruoyi Qiu
- Department of Physics, North Carolina State University, Raleigh, NC 27695, USA
| | - Steven M Mooney
- Department of Urology, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
| | - Shweta Rao
- Department of Urology, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
| | - Takumi Shiraishi
- Department of Urology, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
| | - Elizabeth Sacho
- Department of Physics, North Carolina State University, Raleigh, NC 27695, USA
| | - Hongying Huang
- Department of Urology, New York University School of Medicine, New York, NY 10016, USA
| | - Ellen Shapiro
- Department of Urology, New York University School of Medicine, New York, NY 10016, USA
| | - Keith R Weninger
- Department of Physics, North Carolina State University, Raleigh, NC 27695, USA.
| | - Prakash Kulkarni
- Department of Urology, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA; Oncology, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA.
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6
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Cheng JC, Bai A, Beckham TH, Marrison ST, Yount CL, Young K, Lu P, Bartlett AM, Wu BX, Keane BJ, Armeson KE, Marshall DT, Keane TE, Smith MT, Jones EE, Drake RR, Bielawska A, Norris JS, Liu X. Radiation-induced acid ceramidase confers prostate cancer resistance and tumor relapse. J Clin Invest 2013; 123:4344-58. [PMID: 24091326 DOI: 10.1172/jci64791] [Citation(s) in RCA: 91] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2012] [Accepted: 07/11/2013] [Indexed: 01/06/2023] Open
Abstract
Escape of prostate cancer (PCa) cells from ionizing radiation-induced (IR-induced) killing leads to disease progression and cancer relapse. The influence of sphingolipids, such as ceramide and its metabolite sphingosine 1-phosphate, on signal transduction pathways under cell stress is important to survival adaptation responses. In this study, we demonstrate that ceramide-deacylating enzyme acid ceramidase (AC) was preferentially upregulated in irradiated PCa cells. Radiation-induced AC gene transactivation by activator protein 1 (AP-1) binding on the proximal promoter was sensitive to inhibition of de novo ceramide biosynthesis, as demonstrated by promoter reporter and ChIP-qPCR analyses. Our data indicate that a protective feedback mechanism mitigates the apoptotic effect of IR-induced ceramide generation. We found that deregulation of c-Jun induced marked radiosensitization in vivo and in vitro, which was rescued by ectopic AC overexpression. AC overexpression in PCa clonogens that survived a fractionated 80-Gy IR course was associated with increased radioresistance and proliferation, suggesting a role for AC in radiotherapy failure and relapse. Immunohistochemical analysis of human PCa tissues revealed higher levels of AC after radiotherapy failure than those in therapy-naive PCa, prostatic intraepithelial neoplasia, or benign tissues. Addition of an AC inhibitor to an animal model of xenograft irradiation produced radiosensitization and prevention of relapse. These data indicate that AC is a potentially tractable target for adjuvant radiotherapy.
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7
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Abstract
The activation of AP-1 is a hallmark of cell transformation by tyrosine kinases. In this study, we characterize the role of AP-1 proteins in the transformation of chicken embryo fibroblasts (CEF) by v-Src. In normal CEF, the expression of a dominant negative mutant of c-Jun (TAM67) induced senescence. In contrast, three distinct phenotypes were observed when TAM67 was expressed in v-Src-transformed CEF. While senescent cells were also present, the inhibition of AP-1 caused apoptosis in a fraction of the v-Src-transformed cells. In addition, cells containing lipid-rich vesicles accumulated, suggesting that a subpopulation of the v-Src-transformed cells underwent differentiation in response to the inhibition of AP-1. JunD and Fra-2 were the main components of this factor, while c-Jun accounted for a minor fraction of AP-1 in v-Src-transformed CEF. The downregulation of c-Jun expression by short hairpin RNA (shRNA) induced senescence in normal and v-Src-transformed cells. In contrast, a high incidence of apoptosis was caused by the downregulation of JunD, suggesting that it is required for the survival of v-Src-transformed CEF. Levels of the p53 tumor suppressor were elevated under conditions of JunD inhibition. Repression of p53 by shRNA enhanced the survival and anchorage-independent proliferation of v-Src-transformed CEF with JunD/AP-1 inhibition. The inhibition of Fra-2 had no visible phenotype in normal CEF but caused the appearance of lipid-rich vesicles in v-Src-transformed CEF. Therefore, AP-1 facilitated transformation by acting as a survival factor, by inhibiting premature entry into senescence, and by blocking the differentiation of v-Src-transformed CEF.
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8
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Contreras I, Gómez MA, Nguyen O, Shio MT, McMaster RW, Olivier M. Leishmania-induced inactivation of the macrophage transcription factor AP-1 is mediated by the parasite metalloprotease GP63. PLoS Pathog 2010; 6:e1001148. [PMID: 20976196 PMCID: PMC2954837 DOI: 10.1371/journal.ppat.1001148] [Citation(s) in RCA: 104] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2009] [Accepted: 09/10/2010] [Indexed: 01/05/2023] Open
Abstract
Leishmania parasites have evolved sophisticated mechanisms to subvert macrophage immune responses by altering the host cell signal transduction machinery, including inhibition of JAK/STAT signalling and other transcription factors such as AP-1, CREB and NF-κB. AP-1 regulates pro-inflammatory cytokines, chemokines and nitric oxide production. Herein we show that upon Leishmania infection, AP-1 activity within host cells is abolished and correlates with lower expression of 5 of the 7 AP-1 subunits. Of interest, c-Jun, the central component of AP-1, is cleaved by Leishmania. Furthermore, the cleavage of c-Jun is dependent on the expression and activity of the major Leishmania surface protease GP63. Immunoprecipitation of c-Jun from nuclear extracts showed that GP63 interacts, and cleaves c-Jun at the perinuclear area shortly after infection. Phagocytosis inhibition by cytochalasin D did not block c-Jun down-regulation, suggesting that internalization of the parasite might not be necessary to deliver GP63 molecules inside the host cell. This observation was corroborated by the maintenance of c-Jun cleavage upon incubation with L. mexicana culture supernatant, suggesting that secreted, soluble GP63 could use a phagocytosis-independent mechanism to enter the host cell. In support of this, disruption of macrophage lipid raft microdomains by Methyl β-Cyclodextrin (MβCD) partially inhibits the degradation of full length c-Jun. Together our results indicate a novel role of the surface protease GP63 in the Leishmania-mediated subversion of host AP-1 activity.
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Affiliation(s)
- Irazú Contreras
- Department of Microbiology and Immunology, McGill University, Montreal, Quebec, Canada
- Centre for the Study of Host Resistance and the Research Institute of McGill University Health Centre, Montreal, Quebec, Canada
| | - María Adelaida Gómez
- Department of Microbiology and Immunology, McGill University, Montreal, Quebec, Canada
- Centre for the Study of Host Resistance and the Research Institute of McGill University Health Centre, Montreal, Quebec, Canada
| | - Oliver Nguyen
- Department of Microbiology and Immunology, McGill University, Montreal, Quebec, Canada
| | - Marina T. Shio
- Department of Microbiology and Immunology, McGill University, Montreal, Quebec, Canada
- Centre for the Study of Host Resistance and the Research Institute of McGill University Health Centre, Montreal, Quebec, Canada
| | - Robert W. McMaster
- Department of Medical Genetics, University of British Columbia, Vancouver Hospital, Vancouver, British Columbia, Canada
| | - Martin Olivier
- Department of Microbiology and Immunology, McGill University, Montreal, Quebec, Canada
- Centre for the Study of Host Resistance and the Research Institute of McGill University Health Centre, Montreal, Quebec, Canada
- * E-mail:
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9
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Sun KH, Lee HG, Smith MA, Shah K. Direct and indirect roles of cyclin-dependent kinase 5 as an upstream regulator in the c-Jun NH2-terminal kinase cascade: relevance to neurotoxic insults in Alzheimer's disease. Mol Biol Cell 2009; 20:4611-9. [PMID: 19776350 DOI: 10.1091/mbc.e09-05-0433] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Significant increase in JNK, c-Jun, and Cdk5 activities are reported in Alzheimer's disease (AD). Inhibition of c-Jun prevents neuronal cell death in in vivo AD models, highlighting it as a major JNK effector. Both JNK and Cdk5 promote neurodegeneration upon deregulation; however, Cdk5 has not been mechanistically linked to JNK or c-Jun. This study presents the first mechanism showing Cdk5 as a major regulator of the JNK cascade. Deregulated Cdk5 induces biphasic activation of JNK pathway. The first phase revealed c-Jun as a direct substrate of Cdk5, whose activation is independent of reactive oxygen species (ROS) and JNK. In the second phase, Cdk5 activates c-Jun via ROS-mediated activation of JNK. Rapid c-Jun activation is supported by in vivo data showing c-Jun phosphorylation in cerebral cortex upon p25 induction in transgenic mice. Cdk5-mediated biphasic activation of c-Jun highlights c-Jun, rather than JNK, as an important therapeutic target, which was confirmed in neuronal cells. Finally, Cdk5 inhibition endows superior protection against neurotoxicity, suggesting that Cdk5 is a preferable therapeutic target for AD relative to JNK and c-Jun.
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Affiliation(s)
- Kai-Hui Sun
- Department of Chemistry and Purdue Center for Cancer Research, Purdue University, West Lafayette, IN 47907, USA
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10
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Abstract
Colon cancer accounts for more than 10% of all cancer deaths annually. Our genetic evidence from Drosophila and previous in vitro studies of mammalian Atonal homolog 1 (Atoh1, also called Math1 or Hath1) suggest an anti-oncogenic function for the Atonal group of proneural basic helix-loop-helix transcription factors. We asked whether mouse Atoh1 and human ATOH1 act as tumor suppressor genes in vivo. Genetic knockouts in mouse and molecular analyses in the mouse and in human cancer cell lines support a tumor suppressor function for ATOH1. ATOH1 antagonizes tumor formation and growth by regulating proliferation and apoptosis, likely via activation of the Jun N-terminal kinase signaling pathway. Furthermore, colorectal cancer and Merkel cell carcinoma patients show genetic and epigenetic ATOH1 loss-of-function mutations. Our data indicate that ATOH1 may be an early target for oncogenic mutations in tissues where it instructs cellular differentiation.
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11
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Critical role of c-Jun overexpression in liver metastasis of human breast cancer xenograft model. BMC Cancer 2007; 7:145. [PMID: 17672916 PMCID: PMC1959235 DOI: 10.1186/1471-2407-7-145] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2007] [Accepted: 08/01/2007] [Indexed: 02/06/2023] Open
Abstract
Background c-Jun/AP-1 has been linked to invasive properties of aggressive breast cancer. Recently, it has been reported that overexpression of c-Jun in breast cancer cell line MCF-7 resulted in increased AP-1 activity, motility and invasiveness of the cells in vitro and tumor formation in nude mice. However, the role of c-Jun in metastasis of human breast cancer in vivo is currently unknown. Methods To further investigate the direct involvement of c-Jun in tumorigenesis and metastasis, in the present study, the effects of c-Jun overexpression were studied in both in vitro and in nude mice. Results Ectopic overexpression of c-Jun promoted the growth of MCF-7 cells and resulted in a significant increase in the percentage of cells in S phase and increased motility and invasiveness. Introduction of c-Jun gene alone into weakly invasive MCF-7 cells resulted in the transfected cells capable of metastasizing to the nude mouse liver following tail vein injection. Conclusion The present study confirms that overexpression of c-Jun contributes to a more invasive phenotype in MCF-7 cells. It indicates an interesting relationship between c-Jun expression and increased property of adhesion, migration and in vivo liver metastasis of MCF-7/c-Jun cells. The results provide further evidence that c-Jun is involved in the metastasis of breast cancer. The finding also opens an opportunity for development of anti-c-Jun strategies in breast cancer therapy.
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12
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Drosatos K, Sanoudou D, Kypreos KE, Kardassis D, Zannis VI. A dominant negative form of the transcription factor c-Jun affects genes that have opposing effects on lipid homeostasis in mice. J Biol Chem 2007; 282:19556-64. [PMID: 17456467 PMCID: PMC2745720 DOI: 10.1074/jbc.m700986200] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
c-Jun is a transcription factor activated by phosphorylation by the stress-activated protein kinase/c-Jun N-terminal kinase pathway in response to extracellular signals and cytokines. We show that adenovirus-mediated gene transfer of the dominant negative form of c-Jun (dn-c-Jun) in C57BL/6 mice increased greatly apoE hepatic mRNA and plasma levels, increased plasma cholesterol, triglyceride, and very low density lipoprotein levels, and resulted in the accumulation of discoidal high density lipoprotein particles. A similar but more severe phenotype was generated by overexpression of the mouse apoE in C57BL/6 mice, suggesting that dyslipidemia induced by dn-c-Jun was the result of apoE overexpression. Unexpectedly, infection of apoE(-/-) mice with adenovirus expressing dn-c-Jun reduced plasma cholesterol by 70%, suggesting that dn-c-Jun affected other genes that control plasma cholesterol levels. To identify these genes, we performed whole genome expression analysis (34,000 genes) of isolated livers from two groups of five apoE(-/-) mice, infected with adenoviruses expressing either the dn-c-Jun or the green fluorescence protein. Bioinformatic analysis and Northern blotting validation revealed that dn-c-Jun increased 40-fold the apoE mRNA and reduced by 70% the Scd-1 (stearoyl-CoA-desaturase 1) mRNA. The involvement of Scd-1 in lowering plasma cholesterol was confirmed by restoration of high cholesterol levels of apoE(-/-) mice following coinfection with adenoviruses expressing dn-c-Jun and Scd-1. In conclusion, dn-c-Jun appears to trigger two opposing events in mice that affect plasma cholesterol and triglyceride levels as follows: one results in apoE overexpression and triggers dyslipidemia and the other results in inhibition of Scd-1 and offsets dyslipidemia.
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Affiliation(s)
- Konstantinos Drosatos
- Department of Basic Sciences, University of Crete Medical School, Heraklion GR-71110, Greece
- Molecular Genetics, Departments of Medicine and Biochemistry, Whitaker Cardiovascular Institute, Boston University School of Medicine, Boston, Massachusetts 02118
| | - Despina Sanoudou
- Molecular Biology Division, Center for Basic Research, Foundation for Biomedical Research of the Academy of Athens, Athens 11527, Greece
| | - Kyriakos E. Kypreos
- Molecular Genetics, Departments of Medicine and Biochemistry, Whitaker Cardiovascular Institute, Boston University School of Medicine, Boston, Massachusetts 02118
| | - Dimitris Kardassis
- Department of Basic Sciences, University of Crete Medical School, Heraklion GR-71110, Greece
- Institute of Molecular Biology and Biotechnology, Foundation of Research and Technology-Hellas, Heraklion GR-71110, Greece
| | - Vassilis I. Zannis
- Department of Basic Sciences, University of Crete Medical School, Heraklion GR-71110, Greece
- Molecular Genetics, Departments of Medicine and Biochemistry, Whitaker Cardiovascular Institute, Boston University School of Medicine, Boston, Massachusetts 02118
- To whom correspondence should be addressed: 700 Albany St., W509, Boston, MA 02118-2934. Tel.: 617-638-5085; Fax: 617-638-5141;
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13
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Wu K, Liu M, Li A, Donninger H, Rao M, Jiao X, Lisanti MP, Cvekl A, Birrer M, Pestell RG. Cell fate determination factor DACH1 inhibits c-Jun-induced contact-independent growth. Mol Biol Cell 2006; 18:755-67. [PMID: 17182846 PMCID: PMC1805093 DOI: 10.1091/mbc.e06-09-0793] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The cell fate determination factor DACH1 plays a key role in cellular differentiation in metazoans. DACH1 is engaged in multiple context-dependent complexes that activate or repress transcription. DACH1 can be recruited to DNA via the Six1/Eya bipartite transcription (DNA binding/coactivator) complex. c-Jun is a critical component of the activator protein (AP)-1 transcription factor complex and can promote contact-independent growth. Herein, DACH1 inhibited c-Jun-induced DNA synthesis and cellular proliferation. Excision of c-Jun with Cre recombinase, in c-jun(f1/f1) 3T3 cells, abrogated DACH1-mediated inhibition of DNA synthesis. c-Jun expression rescued DACH1-mediated inhibition of cellular proliferation. DACH1 inhibited induction of c-Jun by physiological stimuli and repressed c-jun target genes (cyclin A, beta-PAK, and stathmin). DACH1 bound c-Jun and inhibited AP-1 transcriptional activity. c-jun and c-fos were transcriptionally repressed by DACH1, requiring the conserved N-terminal (dac and ski/sno [DS]) domain. c-fos transcriptional repression by DACH1 requires the SRF site of the c-fos promoter. DACH1 inhibited c-Jun transactivation through the delta domain of c-Jun. DACH1 coprecipitated the histone deacetylase proteins (HDAC1, HDAC2, and NCoR), providing a mechanism by which DACH1 represses c-Jun activity through the conserved delta domain. An oncogenic v-Jun deleted of the delta domain was resistant to DACH1 repression. Collectively, these studies demonstrate a novel mechanism by which DACH1 blocks c-Jun-mediated contact-independent growth through repressing the c-Jun delta domain.
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Affiliation(s)
- Kongming Wu
- *Department of Cancer Biology, Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA 19107
| | - Manran Liu
- *Department of Cancer Biology, Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA 19107
| | - Anping Li
- *Department of Cancer Biology, Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA 19107
| | - Howard Donninger
- Cell and Cancer Biology Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892
| | - Mahadev Rao
- Lombardi Comprehensive Cancer Center, Georgetown University, Washington, DC 20057; and
| | - Xuanmao Jiao
- *Department of Cancer Biology, Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA 19107
| | - Michael P. Lisanti
- *Department of Cancer Biology, Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA 19107
| | - Ales Cvekl
- Departments of Ophthalmology and Visual Sciences and Molecular Genetics, Albert Einstein College of Medicine, New York, NY 10461
| | - Michael Birrer
- Cell and Cancer Biology Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892
| | - Richard G. Pestell
- *Department of Cancer Biology, Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA 19107
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14
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Villanueva R, Morales-Peza N, Castelán-Sánchez I, García-Villa E, Tapia R, Cid-Arregui Á, García-Carrancá A, López-Bayghen E, Gariglio P. Heparin (GAG-hed) inhibits LCR activity of human papillomavirus type 18 by decreasing AP1 binding. BMC Cancer 2006; 6:218. [PMID: 16945153 PMCID: PMC1574339 DOI: 10.1186/1471-2407-6-218] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2006] [Accepted: 08/31/2006] [Indexed: 11/17/2022] Open
Abstract
BACKGROUND High risk HPVs are causative agents of anogenital cancers. Viral E6 and E7 genes are continuously expressed and are largely responsible for the oncogenic activity of these viruses. Transcription of the E6 and E7 genes is controlled by the viral Long Control Region (LCR), plus several cellular transcription factors including AP1 and the viral protein E2. Within the LCR, the binding and activity of the transcription factor AP1 represents a key regulatory event in maintaining E6/E7 gene expression and uncontrolled cell proliferation. Glycosaminoglycans (GAGs), such as heparin, can inhibit tumour growth; they have also shown antiviral effects and inhibition of AP1 transcriptional activity. The purpose of this study was to test the heparinoid GAG-hed, as a possible antiviral and antitumoral agent in an HPV18 positive HeLa cell line. METHODS Using in vivo and in vitro approaches we tested GAG-hed effects on HeLa tumour cell growth, cell proliferation and on the expression of HPV18 E6/E7 oncogenes. GAG-hed effects on AP1 binding to HPV18-LCR-DNA were tested by EMSA. RESULTS We were able to record the antitumoral effect of GAG-hed in vivo by using as a model tumours induced by injection of HeLa cells into athymic female mice. The antiviral effect of GAG-hed resulted in the inhibition of LCR activity and, consequently, the inhibition of E6 and E7 transcription. A specific diminishing of cell proliferation rates was observed in HeLa but not in HPV-free colorectal adenocarcinoma cells. Treated HeLa cells did not undergo apoptosis but the percentage of cells in G2/M phase of the cell cycle was increased. We also detected that GAG-hed prevents the binding of the transcription factor AP1 to the LCR. CONCLUSION Direct interaction of GAG-hed with the components of the AP1 complex and subsequent interference with its ability to correctly bind specific sites within the viral LCR may contribute to the inhibition of E6/E7 transcription and cell proliferation. Our data suggest that GAG-hed could have antitumoral and antiviral activity mainly by inhibiting AP1 binding to the HPV18-LCR.
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Affiliation(s)
- Rita Villanueva
- Departamento de Genética y Biología Molecular, Centro de Investigación y de Estudios Avanzados, Apartado Postal 14-740, México D.F. 07000, México
| | - Néstor Morales-Peza
- Unidad de Investigación Biomedica en Cáncer, UNAM- Instituto Nacional de Cancerología, Av. San Fernando 22, México D.F. 14000, México
| | - Irma Castelán-Sánchez
- Departamento de Genética y Biología Molecular, Centro de Investigación y de Estudios Avanzados, Apartado Postal 14-740, México D.F. 07000, México
| | - Enrique García-Villa
- Departamento de Genética y Biología Molecular, Centro de Investigación y de Estudios Avanzados, Apartado Postal 14-740, México D.F. 07000, México
| | - Rocio Tapia
- Departamento de Genética y Biología Molecular, Centro de Investigación y de Estudios Avanzados, Apartado Postal 14-740, México D.F. 07000, México
| | - Ángel Cid-Arregui
- Tumor Gene Therapy German Cancer Research Center (DKFZ) Im Neuenheimer Feld 280 69120-Heidelberg, Germany
| | - Alejandro García-Carrancá
- Unidad de Investigación Biomedica en Cáncer, UNAM- Instituto Nacional de Cancerología, Av. San Fernando 22, México D.F. 14000, México
| | - Esther López-Bayghen
- Departamento de Genética y Biología Molecular, Centro de Investigación y de Estudios Avanzados, Apartado Postal 14-740, México D.F. 07000, México
| | - Patricio Gariglio
- Departamento de Genética y Biología Molecular, Centro de Investigación y de Estudios Avanzados, Apartado Postal 14-740, México D.F. 07000, México
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15
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Ozanne BW, Spence HJ, McGarry LC, Hennigan RF. Transcription factors control invasion: AP-1 the first among equals. Oncogene 2006; 26:1-10. [PMID: 16799638 DOI: 10.1038/sj.onc.1209759] [Citation(s) in RCA: 196] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Metastasis, the aggressive spread of a malignant tumor to distant organs, is a major cause of death in cancer patients. Despite this critical role in cancer outcomes, the molecular mechanisms that control this process are just beginning to be understood. Metastasis is largely dependent upon the ability of tumor cells to invade the barrier formed by the basement membrane and to migrate through neighboring tissues. This review will summarize the evidence that tumor cell invasion is the result of oncogene-mediated signal transduction pathways that control the expression of a specific set of genes that together mediate tumor cell invasion. We focus on the role of the transcription factor AP-1 to both induce the expression of genes that function as invasion effectors and repress other genes that function as invasion suppressors. This identifies AP-1 as a critical regulator of a complex program of gene expression that defines the invasive phenotype.
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Affiliation(s)
- B W Ozanne
- Invasion and Metastasis Laboratory, Beatson Institute for Cancer Research, Garscube Estate, Switchback Road, Bearsden, Glasgow, G61 1BD Scotland, UK
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16
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Lu C, Shen Q, DuPré E, Kim H, Hilsenbeck S, Brown PH. cFos is critical for MCF-7 breast cancer cell growth. Oncogene 2005; 24:6516-24. [PMID: 16027729 DOI: 10.1038/sj.onc.1208905] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The activating protein-1 (AP-1) transcription factor is a converging point of multiple signal transduction pathways in many cells. We have previously demonstrated that overexpressing Tam67, a dominant-negative (DN) form of cJun, blocks AP-1 activity and inhibits breast cancer cell growth. We hypothesized that Tam67 forms dimers with other AP-1 proteins to suppress the growth of breast cancer cells. In the present study, we used immunoprecipitation-Western blotting to demonstrate that Tam67 binds all Jun and Fos proteins in breast cancer cells. In addition, we used two variants of the Tam67 mutant to investigate whether Jun or Fos protein was required for breast cancer cell growth. We created a Tam/Fos mutant in which the cJun dimerization domain was replaced by the cFos dimerization domain, and a Tam/Squelcher mutant in which the cJun dimerization domain was deleted. We then isolated MCF-7 cell lines that stably expressed these cJun-DN mutants under the control of an inducible promoter. Using AP-1-dependent reporter assays, we observed that Tam67 and Tam/Fos mutants inhibited AP-1 transcriptional activity, while the Tam/Squelcher mutant did not. We then determined whether Tam/Fos or Tam/Squelcher inhibited breast cell growth as well as Tam67. We found that while Tam67 repressed cell growth, neither Tam/Fos nor Tam/Squelcher mutant affected cell growth. These results indicate that Tam67 likely inactivates Fos family member proteins to suppress breast cancer cell growth. Finally, we performed antisense experiments to knock down the expression of individual family members (cJun or cFos). Our results demonstrated that antisense cFos inhibited breast cancer cell proliferation and colony formation, while antisense cJun did not. These results suggest that Tam67 suppresses breast cancer cell growth by interacting with Fos family members, specifically with cFos, to produce an inactive AP-1 complex.
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Affiliation(s)
- Chunhua Lu
- Department of Medicine, Baylor College of Medicine, Breast Center, One Baylor Plaza MS600, Houston, TX 77030, USA
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17
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Sanna B, Bueno OF, Dai YS, Wilkins BJ, Molkentin JD. Direct and indirect interactions between calcineurin-NFAT and MEK1-extracellular signal-regulated kinase 1/2 signaling pathways regulate cardiac gene expression and cellular growth. Mol Cell Biol 2005; 25:865-78. [PMID: 15657416 PMCID: PMC544001 DOI: 10.1128/mcb.25.3.865-878.2005] [Citation(s) in RCA: 116] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
MEK1, a member of the mitogen-activated protein kinase (MAPK) cascade that directly activates extracellular signal-regulated kinase (ERK), induces cardiac hypertrophy in transgenic mice. Calcineurin is a calcium-regulated protein phosphatase that also functions as a positive regulator of cardiac hypertrophic growth through a direct mechanism involving activation of nuclear factor of activated T-cell (NFAT) transcription factors. Here we determined that calcineurin-NFAT and MEK1-ERK1/2 signaling pathways are interdependent in cardiomyocytes, where they directly coregulate the hypertrophic growth response. For example, genetic deletion of the calcineurin Abeta gene reduced the hypertrophic response elicited by an activated MEK1 transgene in the heart, while inhibition of calcineurin or NFAT in cultured neonatal cardiomyocytes also blunted the hypertrophic response driven by activated MEK1. Conversely, targeted inhibition of MEK1-ERK1/2 signaling in cultured cardiomyocytes attenuated the hypertrophic growth response directed by activated calcineurin. However, targeted inhibition of MEK1-ERK1/2 signaling did not directly affect calcineurin-NFAT activation, nor was MEK1-ERK1/2 activation altered by targeted inhibition of calcineurin-NFAT. Mechanistically, we show that MEK1-ERK1/2 signaling augments NFAT transcriptional activity independent of calcineurin, independent of changes in NFAT nuclear localization, and independent of alterations in NFAT transactivation potential. In contrast, MEK1-ERK1/2 signaling enhances NFAT-dependent gene expression through an indirect mechanism involving induction of cardiac AP-1 activity, which functions as a necessary NFAT-interacting partner. As a second mechanism, MEK1-ERK1/2 and calcineurin-NFAT proteins form a complex in cardiac myocytes, resulting in direct phosphorylation of NFATc3 within its C terminus. MEK1-ERK1/2-mediated phosphorylation of NFATc3 directly augmented its DNA binding activity, while inhibition of MEK1-ERK1/2 signaling reduced NFATc3 DNA binding activity. Collectively, these results indicate that calcineurin-NFAT and MEK1-ERK1/2 pathways constitute a codependent signaling module in cardiomyocytes that coordinately regulates the growth response through two distinct mechanisms.
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Affiliation(s)
- Bastiano Sanna
- Division of Molecular Cardiovascular Biology, Cincinnati Children's Hospital Medical Center, 3333 Burnet Ave., MLC7020, Cincinnati, OH 45229-3039, USA
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18
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Laderoute KR, Calaoagan JM, Gustafson-Brown C, Knapp AM, Li GC, Mendonca HL, Ryan HE, Wang Z, Johnson RS. The response of c-jun/AP-1 to chronic hypoxia is hypoxia-inducible factor 1 alpha dependent. Mol Cell Biol 2002; 22:2515-23. [PMID: 11909946 PMCID: PMC133718 DOI: 10.1128/mcb.22.8.2515-2523.2002] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Hypoxia (low-oxygen tension) is an important physiological stress that influences responses to a wide range of pathologies, including stroke, infarction, and tumorigenesis. Prolonged or chronic hypoxia stimulates expression of the stress-inducible transcription factor gene c-jun and transient activation of protein kinase and phosphatase activities that regulate c-Jun/AP-1 activity. Here we describe evidence obtained by using wild-type and HIF-1 alpha nullizygous mouse embryonic fibroblasts (mEFs) that the induction of c-jun mRNA expression and c-Jun phosphorylation by prolonged hypoxia are completely dependent on the presence of the oxygen-regulated transcription factor hypoxia-inducible factor 1 alpha (HIF-1 alpha). In contrast, transient hypoxia induced c-jun expression in both types of mEFs, showing that the early or rapid induction of this gene is independent of HIF-1 alpha. These findings indicate that the c-jun gene has a biphasic response to hypoxia consisting of inductions that depend on the degree or duration of exposure. To more completely define the relationship between prolonged hypoxia and c-Jun phosphorylation, we used mEFs from mice containing inactivating mutations of critical phosphorylation sites in the c-Jun N-terminal region (serines 63 and 73 or threonines 91 and 93). Exposure of these mEFs to prolonged hypoxia demonstrated an absolute requirement for N-terminal sites for HIF-1 alpha-dependent phosphorylation of c-Jun. Taken together, these findings suggest that c-Jun/AP-1 and HIF-1 cooperate to regulate gene expression in pathophysiological microenvironments.
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Affiliation(s)
- Keith R Laderoute
- Pharmaceutical Discovery Division, SRI International, Menlo Park, California 94025, USA.
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Tang Q, Chen W, Gonzales MS, Finch J, Inoue H, Bowden GT. Role of cyclic AMP responsive element in the UVB induction of cyclooxygenase-2 transcription in human keratinocytes. Oncogene 2001; 20:5164-72. [PMID: 11526505 DOI: 10.1038/sj.onc.1204667] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2001] [Revised: 05/17/2001] [Accepted: 05/24/2001] [Indexed: 11/10/2022]
Abstract
It has been shown that UVB irradiation induces expression of COX-2 and up-regulation of COX-2 plays a functional role in UVB tumor promotion. In this study, we examined the cis-elements in the human COX-2 promoter that may be responsible for the UVB induction of COX-2. Analyses with the COX-2 promoter region revealed that the cyclic AMP responsive element near the TATA box was essential for both basal and UVB induced COX-2 expression. This was further supported by studies using a dominant negative mutant of CREB, which strongly inhibited the activity of COX-2 promoter. Electrophoretic mobility shift assays indicated that CREB and ATF-1 were the major proteins binding to the COX-2 CRE. CREB and ATF-1 were phosphorylated upon UVB treatment, and SB202190, a p38 MAPK inhibitor, decreased the phosphorylation of CREB/ATF-1 and suppressed COX-2 promoter activity. In contrast, treatment with forskolin, an activator of adenylyl cyclase, led to phosphorylation of CREB and ATF-1 and activation of COX-2 promoter. Finally, enhanced binding of phospho-CREB/ATF-1 to the COX-2 CRE was observed after UVB induction. Thus, one signaling pathway for UVB induction of human COX-2 involves activation of p38, subsequent phosphorylation of CREB/ATF-1, and activation of the COX-2 CRE through enhanced binding of phosphorylated CREB/ATF-1.
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Affiliation(s)
- Q Tang
- Department of Radiation Oncology, Arizona Cancer Center, College of Medicine, The University of Arizona, 1515 North Campbell Avenue, Tucson, AZ 85724, USA
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20
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Hennigan RF, Stambrook PJ. Dominant negative c-jun inhibits activation of the cyclin D1 and cyclin E kinase complexes. Mol Biol Cell 2001; 12:2352-63. [PMID: 11514621 PMCID: PMC58599 DOI: 10.1091/mbc.12.8.2352] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The AP-1 transcription factor is activated by oncogenic signal transduction cascades and its function is critical for both mitogenesis and carcinogenesis. To define the role of AP-1 in the context of a human fibrosarcoma cell line, HT1080, we expressed a dominant negative c-jun mutant fused to the green fluorescent protein in an ecdysone-inducible system. We demonstrated that high levels of this mutant, GFP-TAM67, inhibit AP-1 activity and arrest cells predominantly in the G1 phase of the cell cycle. This arrest is reversible and occurs only above a threshold concentration; low to moderate levels of GFP-TAM67 are insufficient for growth arrest. Contrary to expectations based on the literature, GFP-TAM67 does not inhibit expression of cyclin D1, cyclin E, or their respective cyclin-dependent kinases. However, pRB is hypophosphorylated in GFP-TAM67-arrested cells and the activity of both the cyclin D1:cdk and the cyclin E:cdk complexes are impaired. Both of these complexes show an increased association with p21(CIP1/WAF1), concomitantly with induction of the p21 mRNA by GFP-TAM67. These results suggest a novel function of AP-1 in the activation of the G1 cyclin:cdk complexes in human tumor cells by regulating the expression of the p21(CIP1/WAF1) gene.
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Affiliation(s)
- R F Hennigan
- Department of Cell Biology, Neurobiology, and Anatomy, University of Cincinnati College of Medicine, Cincinnati, Ohio 45267-0521, USA.
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21
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Abstract
Cellular Jun (c-Jun) and viral Jun (v-Jun) can induce oncogenic transformation. For this activity, c-Jun requires an upstream signal, delivered by the Jun N-terminal kinase (JNK). v-Jun does not interact with JNK; it is autonomous and constitutively active. v-Jun and c-Jun address overlapping but not identical sets of genes. Whether all genes essential for transformation reside within the overlap of the v-Jun and c-Jun target spectra remains to be determined. The search for transformation-relevant targets of Jun is moving into a new stage with the application of DNA microarrays technology. Genetic screens and functional tests remain a necessity for the identification of genes that control the oncogenic phenotype.
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Affiliation(s)
- P K Vogt
- Department of Molecular and Experimental Medicine, The Scripps Reasearch Institute, 10550 North Torrey Pines Drive, La Jolla, California, CA 9203, USA
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22
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Abstract
A plethora of physiological and pathological stimuli induce and activate a group of DNA binding proteins that form AP-1 dimers. These proteins include the Jun, Fos and ATF subgroups of transcription factors. Recent studies using cells and mice deficient in individual AP-1 proteins have begun to shed light on their physiological functions in the control of cell proliferation, neoplastic transformation and apoptosis. Above all such studies have identified some of the target genes that mediate the effects of AP-1 proteins on cell proliferation and death. There is evidence that AP-1 proteins, mostly those that belong to the Jun group, control cell life and death through their ability to regulate the expression and function of cell cycle regulators such as Cyclin D1, p53, p21(cip1/waf1), p19(ARF) and p16. Amongst the Jun proteins, c-Jun is unique in its ability to positively regulate cell proliferation through the repression of tumor suppressor gene expression and function, and induction of cyclin D1 transcription. These actions are antagonized by JunB, which upregulates tumor suppressor genes and represses cyclin D1. An especially important target for AP-1 effects on cell life and death is the tumor suppressor p53, whose expression as well as transcriptional activity, are modulated by AP-1 proteins.
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Affiliation(s)
- E Shaulian
- Laboratory of Gene Regulation and Signal Transduction, Department of Pharmacology, University of California San Diego, 9500 Gilman Drive, La Jolla, California, CA 92093-0636, USA
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23
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Abstract
Genetically modified mice have provided important insights into the biological functions of the dimeric transcription factor complex AP-1. Extensive analyses of mice and cells with genetically modified Fos or Jun proteins provide novel insights into the physiological functions of AP-1 proteins. Using knock-out strategies it was found that some components, such as c-Fos, FosB and JunD are dispensable, whereas others, like c-Jun, JunB and Fra-1 are essential in embryonic development and/or in the adult organism. Besides the specific roles of AP-1 proteins in developmental processes, we are beginning to obtain a better molecular understanding of the cell-context dependent function of AP-1 in cell proliferation and apoptosis, in bone biology as well as in multistep tumorigenesis.
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Affiliation(s)
- W Jochum
- Research Institute of Molecular Pathology (I.M.P.), Dr. Bohr-Gasse 7, A-1030 Vienna, Austria
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24
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Abstract
The AP-1 transcription factor is composed of a mixture of homo- and hetero-dimers formed between Jun and Fos proteins. The different Jun and Fos family members vary significantly in their relative abundance and their interactions with additional proteins generating a complex network of transcriptional regulators. Thus, the functional activity of AP-1 in any given cell depends on the relative amount of specific Jun/Fos proteins which are expressed, as well as other potential interacting proteins. This diversity of AP-1 components has complicated our understanding of AP-1 function and resulted in a paucity of information about the precise role of individual AP-1 members in distinct cellular processes. We shall discuss recent studies which suggest that different Jun and Fos family members may have both opposite and overlapping functions in cellular proliferation and cell fate.
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Affiliation(s)
- F Mechta-Grigoriou
- Unité des virus oncogenes, CNRS URA 1644, Institut Pasteur, 25 rue du Docteur Roux, 75724 Paris Cedex 15, France
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Paasinen-Sohns A, Kielosto M, Kääriäinen E, Eloranta T, Laine A, Jänne OA, Birrer MJ, Hölttä E. c-Jun activation-dependent tumorigenic transformation induced paradoxically by overexpression or block of S-adenosylmethionine decarboxylase. J Cell Biol 2000; 151:801-10. [PMID: 11076965 PMCID: PMC2169445 DOI: 10.1083/jcb.151.4.801] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
All mammalian cells absolutely require polyamines (putrescine, spermidine, and spermine) for growth. Here we show that the overexpression of cDNA for S-adenosylmethionine decarboxylase (AdoMetDC), the main regulatory enzyme in the biosynthesis of higher polyamines, induces transformation of rodent fibroblasts when expressed in the sense or the antisense orientation. Both transformants were able to induce invasive tumors in nude mice. Neither transformation was associated with activation of the mitogen-activated protein kinases Erk1 and Erk2. Instead, the AdoMet DC sense, but not antisense, transformants displayed constitutive activation of the c-Jun NH(2)-terminal kinase (JNK) pathway. However, both transformations converged on persistent phosphorylation of endogenous c-Jun at Ser73. The phenotype of the AdoMetDC sense transformants was reversed by expression of dominant-negative mutants of SEK1 (MKK4), JNK1, and c-Jun (TAM-67), which were also found to impair cytokinesis. Similarly, TAM-67 reverted the morphology of the AdoMetDC-antisense expressors. This report is the first demonstration of a protein whose overexpression or block of synthesis can induce cell transformation. In addition, we show that the polyamine biosynthetic enzymes require c-Jun activation for eliciting their biological effects.
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Affiliation(s)
- A Paasinen-Sohns
- Haartman Institute, Department of Pathology, FIN-00014 University of Helsinki, Helsinki, Finland
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26
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Johnston IM, Spence HJ, Winnie JN, McGarry L, Vass JK, Meagher L, Stapleton G, Ozanne BW. Regulation of a multigenic invasion programme by the transcription factor, AP-1: re-expression of a down-regulated gene, TSC-36, inhibits invasion. Oncogene 2000; 19:5348-58. [PMID: 11103936 DOI: 10.1038/sj.onc.1203927] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The transcription factor AP-1 (activator protein-1) is required for transformation by many oncogenes, which function upstream of it in the growth factor-ras signal transduction pathway. Previously, we proposed that one role of AP-1 in transformation is to regulate the expression of a multigenic invasion programme. As a test of this proposal we sought to identify AP-1 regulated genes based upon their differential expression in 208F rat fibroblasts transformed by FBR-v-fos (FBR), and to determine if they functioned in the invasion programme. Subtracted cDNA libraries specific for up- or down-regulated genes in FBRs compared to 208Fs were constructed and analysed. Northern analysis revealed that the cDNAs in both libraries represented differentially expressed genes. Nucleic acid sequence analysis of randomly selected cDNA clones from each library coupled with searches of nucleic acid and amino acid sequence databases determined that many of the cDNAs represented proteins that function in various aspects of the invasion process. Functional analysis of one the down-regulated genes, TSC-36/follistatin-related protein (TSC-36/Frp), which has not previously been associated with invasion, demonstrated that its expression in FBRs inhibited in vitro invasion. These results support the proposal that AP-1 in transformed cells regulates a multigenic invasion programme.
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Affiliation(s)
- I M Johnston
- Beatson Institute for Cancer Research, CRC Beatson Laboratories, Bearsden, Glasgow
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27
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Basso J, Briggs J, Findlay C, Bos T. Directed mutation of the basic domain of v-Jun alters DNA binding specificity and abolishes its oncogenic activity in chicken embryo fibroblasts. Oncogene 2000; 19:4876-85. [PMID: 11039905 DOI: 10.1038/sj.onc.1203863] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Overexpression of v-Jun in chicken embryo fibroblasts (CEF) leads to oncogenic transformation phenotypically characterized by anchorage independent growth and release from contact inhibition (focus formation). The mechanisms involved in this oncogenic conversion however, are not yet clear. Because Jun is a transcription factor, it has been assumed that oncogenic transformation results directly from deregulated AP-1 target gene expression. However, a number of experimental observations in avian cell culture models fail to correlate oncogenesis with AP-1 activity suggesting that transformation induced by v-Jun may occur through an indirect mechanism. To test this possibility, we introduced point mutations into the basic DNA binding domain of v-Jun and created mutants that exhibit altered binding specificity. When expressed in CEF, these mutants fail to deregulate three known v-Jun target genes (JTAP-1, apolipoprotein A1, c-Jun) thus demonstrating in vivo specificity changes. Each of the binding specificity mutants was also tested for its ability to induce oncogenic transformation. Interestingly, expression of these mutants in CEF results in a phenotype indistinguishable from the vector control with respect to growth rate, focus formation and the ability to form colonies in soft agar. These results are consistent with a model requiring direct AP-1 target deregulation as a prerequisite of v-Jun induced cell transformation. With this in mind, we generated a series of additional mutants that retain the ability to bind AP-1 sequence elements, but vary in their oncogenic potential. We demonstrate the use of these mutants to screen v-Jun induced gene targets for a functional role in cell transformation.
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Affiliation(s)
- J Basso
- Department of Microbiology and Molecular Cell Biology, Eastern Virginia Medical School, Norfolk 23501, USA
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28
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Knapp JI, Heppner C, Hickman AB, Burns AL, Chandrasekharappa SC, Collins FS, Marx SJ, Spiegel AM, Agarwal SK. Identification and characterization of JunD missense mutants that lack menin binding. Oncogene 2000; 19:4706-12. [PMID: 11032020 DOI: 10.1038/sj.onc.1203832] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Menin, the product of the MEN1 tumor suppressor gene, binds to the AP1 transcription factor JunD and represses JunD transcriptional activity. The effects of human or mouse JunD missense mutations upon menin interaction were studied by random and alanine scanning mutagenesis of the menin binding region of JunD (amino acids 1-70). JunD mutant proteins were tested for menin binding in a reverse yeast two-hybrid assay, and for transcriptional regulation by menin in AP1-reporter assays. Random mutagenesis identified two different mutations that disrupted menin interaction at mouse JunD amino acid 42 (G42E and G42R). Mutation G42A generated by alanine scanning did not affect menin binding, likely reflecting the conserved nature of this amino acid substitution. Furthermore, by size exclusion chromatography menin co-migrated with wild type JunD but not with the JunD mutant tested (G42E). Alanine scanning mutagenesis of residues 30-55 revealed two different amino acids, P41 and P44, of mouse JunD that were critical for interaction with menin. Mouse JunD missense mutants P41A, G42R, G42E and P44A failed to bind menin and also escaped menin's control over their transcriptional activity. At lower amounts of transfected menin, the transcriptional effect of menin on the mutants P41A, G42R and G42E was changed from repression to activation, similar to that with c-jun. In conclusion, a small N-terminal region of JunD mediates a key difference between JunD and c-jun, and a component of this difference is dependent on JunD binding to menin.
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Affiliation(s)
- J I Knapp
- Metabolic Diseases Branch, NIDDK, NIH, Bethesda, Maryland 20892, USA
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29
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Smith LM, Wise SC, Hendricks DT, Sabichi AL, Bos T, Reddy P, Brown PH, Birrer MJ. cJun overexpression in MCF-7 breast cancer cells produces a tumorigenic, invasive and hormone resistant phenotype. Oncogene 1999; 18:6063-70. [PMID: 10557095 DOI: 10.1038/sj.onc.1202989] [Citation(s) in RCA: 161] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
We have previously demonstrated decreased Jun/AP-1 activity in the breast cancer cell line MCF-7 when compared to normal or immortalized mammary epithelial cells. In this paper, we overexpress Jun in MCF-7 cells (MCF7Jun) and demonstrate that it results in diverse biologic and biochemical changes, which mimic those seen clinically in breast cancer. Overexpression of Jun causes significant alterations in the composition of AP-1, decreased junB and increased fra-1 expression and results in an increased biologic aggressiveness. MCF7Jun cells exhibit increased cellular motility, increased expression of a matrix degrading enzyme MMP-9, increased in vitro chemoinvasion and tumor formation in nude mice in the absence of exogenous estrogens. Furthermore, MCF7Jun cells are unresponsive to the growth stimulating effects of estrogen and growth inhibitory effects of tamoxifen. Analysis of the estrogen receptor (ER) expression and activity showed that the MCF7Jun cells have no detectable ER. MCF-7 cells overexpressing mutant forms of cJun were responsive to the growth stimulatory effects of estrogen indicating that full-length cJun is required to acquire the estrogen-independent phenotype in breast cancer cells.
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Affiliation(s)
- L M Smith
- Department of Cell and Cancer Biology, Medicine Branch, National Cancer Institute, NIH, Rockville, Maryland, MD 20850, USA
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30
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Zhang X, Wrzeszczynska MH, Horvath CM, Darnell JE. Interacting regions in Stat3 and c-Jun that participate in cooperative transcriptional activation. Mol Cell Biol 1999; 19:7138-46. [PMID: 10490649 PMCID: PMC84707 DOI: 10.1128/mcb.19.10.7138] [Citation(s) in RCA: 189] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Independent but closely spaced DNA binding sites for Stat3 and c-Jun are required for maximal enhancer function in a number of genes, including the gene encoding the interleukin-6 (IL-6)-induced acute-phase response protein, alpha(2)-macroglobulin. In addition, a physical interaction of Stat3 with c-Jun, based on yeast two-hybrid interaction experiments, has been reported. Here we confirm the existence of an interaction between Stat3 and c-Jun both in vitro, with recombinant proteins, and in vivo, during transient transfection. Using fragments of both proteins, we mapped the interactive sites to the C-terminal region of c-Jun and to two regions in Stat3, within the coiled-coil domain and in a portion of the DNA binding domain distant from DNA contact sites. In transient-transfection experiments with the alpha(2)-macroglobulin enhancer, Stat3 and c-Jun cooperated to yield maximal enhancer function. Point mutations of Stat3 within the interacting domains blocked both physical interaction of Stat3 with c-Jun and their cooperation in IL-6-induced transcription directed by the alpha(2)-macroglobulin enhancer. While the amino acid sequences and the three-dimensional structures of Stat3 and Stat1 cores are very similar, fragments of Stat1 failed to bind c-Jun in vitro. Although Stat1 binds in vitro to the gamma interferon gene response (GAS) element in the alpha(2)-macroglobulin enhancer, Stat1 did not stimulate transcription, nor did Stat1 and c-Jun cooperate in driving transcription controlled by the alpha(2)-macroglobulin enhancer.
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Affiliation(s)
- X Zhang
- Laboratory of Molecular Cell Biology, The Rockefeller University, New York, New York 10021, USA
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31
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Kim S, Mao PL, Gagliardi M, Bédard PA. C/EBPbeta (NF-M) is essential for activation of the p20K lipocalin gene in growth-arrested chicken embryo fibroblasts. Mol Cell Biol 1999; 19:5718-31. [PMID: 10409760 PMCID: PMC84423 DOI: 10.1128/mcb.19.8.5718] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/1999] [Accepted: 05/05/1999] [Indexed: 11/20/2022] Open
Abstract
The p20K gene is induced in conditions of reversible growth arrest in chicken embryo fibroblasts (CEF). This expression is dependent on transcriptional activation and on a region of the promoter designated the quiescence-responsive unit (QRU). In this report, we describe the regulatory elements of the QRU responsible for activation in resting cells and characterize the trans-acting proteins interacting with these elements. We show that the QRU consists of functionally distinct domains including quiescence-specific and weak proliferation-responsive elements. The quiescence responsiveness of the QRU was mapped to two C/EBP binding sites, and the activity of the p20K promoter and its QRU was inhibited by the expression of a dominant negative mutant of C/EBPbeta in nondividing cells. The activation of QRU in response to serum starvation and contact inhibition correlated with the presence of a growth arrest-specific complex in electrophoretic mobility shift assays. This complex was supershifted by antibody for C/EBPbeta. C/EBPbeta accumulated in conditions of contact inhibition as a result of transcriptional activation. Therefore, C/EBPbeta was itself regulated as a growth arrest-specific gene in CEF. Finally, we show that the expression of p20K is regulated by linoleic acid, an essential fatty acid binding to p20K. The addition of linoleic acid to contact-inhibited CEF markedly repressed the synthesis of p20K without inducing mitogenesis. The activity of the QRU was inhibited by linoleic acid or the peroxisome proliferator-activated receptor PPARgamma2 in transient expression assays. Therefore, we have identified C/EBPbeta as a key activator of a growth arrest-specific gene in CEF and implicated an essential fatty acid, linoleic acid, in regulation of the QRU and the p20K lipocalin gene.
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Affiliation(s)
- S Kim
- Department of Biology, York University, Toronto, Ontario, Canada M3J 1P3
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32
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Jacobs-Helber SM, Wickrema A, Birrer MJ, Sawyer ST. AP1 regulation of proliferation and initiation of apoptosis in erythropoietin-dependent erythroid cells. Mol Cell Biol 1998; 18:3699-707. [PMID: 9632752 PMCID: PMC108952 DOI: 10.1128/mcb.18.7.3699] [Citation(s) in RCA: 88] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/1997] [Accepted: 03/29/1998] [Indexed: 02/07/2023] Open
Abstract
The transcription factor AP1 has been implicated in the induction of apoptosis in cells in response to stress factors and growth factor withdrawal. We report here that AP1 is necessary for the induction of apoptosis following hormone withdrawal in the erythropoietin (EPO)-dependent erythroid cell line HCD57. AP1 DNA binding activity increased upon withdrawal of HCD57 cells from EPO. A dominant negative AP1 mutant rendered these cells resistant to apoptosis induced by EPO withdrawal and blocked the downregulation of Bcl-XL. JunB is a major binding protein in the AP1 complex observed upon EPO withdrawal; JunB but not c-Jun was present in the AP1 complex 3 h after EPO withdrawal in HCD57 cells, with a concurrent increase in junB message and protein. Furthermore, analysis of AP1 DNA binding activity in an apoptosis-resistant subclone of HCD57 revealed a lack of induction in AP1 DNA binding activity and no change in junB mRNA levels upon EPO withdrawal. In addition, we determined that c-Jun and AP1 activities correlated with EPO-induced proliferation and/or protection from apoptosis. AP1 DNA binding activity increased over the first 3 h following EPO stimulation of HCD57 cells, and suppression of AP1 activity partially inhibited EPO-induced proliferation. c-Jun but not JunB was present in the AP1 complex 3 h after EPO addition. These results implicate AP1 in the regulation of proliferation and survival of erythroid cells and suggest that different AP1 factors may play distinct roles in both triggering apoptosis (JunB) and protecting erythroid cells from apoptosis (c-Jun).
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Affiliation(s)
- S M Jacobs-Helber
- Department of Pharmacology/Toxicology, Medical College of Virginia Campus of Virginia Commonwealth University, Richmond, Virginia 23298, USA
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33
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Zagariya A, Mungre S, Lovis R, Birrer M, Ness S, Thimmapaya B, Pope R. Tumor necrosis factor alpha gene regulation: enhancement of C/EBPbeta-induced activation by c-Jun. Mol Cell Biol 1998; 18:2815-24. [PMID: 9566900 PMCID: PMC110660 DOI: 10.1128/mcb.18.5.2815] [Citation(s) in RCA: 91] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/1997] [Accepted: 02/12/1998] [Indexed: 02/07/2023] Open
Abstract
Tumor necrosis factor alpha (TNF alpha) is a key regulatory cytokine whose expression is controlled by a complex set of stimuli in a variety of cell types. Previously, we found that the monocyte/macrophage-enriched nuclear transcription factor C/EBPbeta played an important role in the regulation of the TNF alpha gene in myelomonocytic cells. Abundant evidence suggests that other transcription factors participate as well. Here we have analyzed interactions between C/EBPbeta and c-Jun, a component of the ubiquitously expressed AP-1 complex. In phorbol myristate acetate (PMA)-treated Jurkat T cells, which did not possess endogenous C/EBPbeta, expression of c-Jun by itself had relatively little effect on TNF alpha promoter activity. However, the combination of C/EBPbeta and c-Jun was synergistic, resulting in greater than 130-fold activation. This effect required both the leucine zipper and DNA binding domains, but not the transactivation domain, of c-Jun, plus the AP-1 binding site centered 102/103 bp upstream of the transcription start site in the TNF alpha promoter. To determine if C/EBPbeta and c-Jun might cooperate to regulate the cellular TNF alpha gene in myelomonocytic cells, U937 cells that possess endogenous C/EBPbeta and were stably transfected with either wild-type c-Jun or the transactivation domain deletion mutant (TAM-67) were examined. U937 cells expressing ectopic wild-type c-Jun or TAM-67 secreted over threefold more TNF alpha than the control line in response to PMA plus lipopolysaccharide. Transient transfection of the U937 cells expressing TAM-67 suggested that TAM-67 binding to the -106/-99-bp AP-1 binding site cooperated with endogenous C/EBPbeta in the activation of the -120 TNF alpha promoter-reporter. DNA binding assays using oligonucleotides derived from the TNF alpha promoter suggested that C/EBPbeta and c-Jun interact in vitro and that the interaction may be DNA dependent. Our data demonstrate that the TNF alpha gene is regulated by the interaction of the ubiquitous AP-1 complex protein c-Jun and the monocyte/macrophage-enriched transcription factor C/EBPbeta and that this interaction contributes to the expression of the cellular TNF alpha gene in myelomonocytic cells. This interaction was unique in that it did not require the c-Jun transactivation domain, providing new insight into the cell-type-specific regulation of the TNF alpha gene.
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Affiliation(s)
- A Zagariya
- Department of Medicine, and Veterans Administration Lakeside Medical Center, Northwestern University Medical School, Chicago, Illinois 60611, USA
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34
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Nead MA, Baglia LA, Antinore MJ, Ludlow JW, McCance DJ. Rb binds c-Jun and activates transcription. EMBO J 1998; 17:2342-52. [PMID: 9545246 PMCID: PMC1170577 DOI: 10.1093/emboj/17.8.2342] [Citation(s) in RCA: 98] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The retinoblastoma protein (Rb) acts as a critical cell-cycle regulator and loss of Rb function is associated with a variety of human cancer types. Here we report that Rb binds to members of the AP-1 family of transcription factors, including c-Jun, and stimulates c-Jun transcriptional activity from an AP-1 consensus sequence. The interaction involves the leucine zipper region of c-Jun and the B pocket of Rb as well as a C-terminal domain. We also present evidence that the complexes are found in terminally differentiating keratinocytes and cells entering the G1 phase of the cell cycle after release from serum starvation. The human papillomavirus type 16 E7 protein, which binds to both c-Jun and Rb, inhibits the ability of Rb to activate c-Jun. The results provide evidence of a role for Rb as a transcriptional activator in early G1 and as a potential modulator of c-Jun expression during keratinocyte differentiation.
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Affiliation(s)
- M A Nead
- Departments of Microbiology and Immunology, University of Rochester, Rochester, NY 14642, USA
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35
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Huang C, Ma WY, Young MR, Colburn N, Dong Z. Shortage of mitogen-activated protein kinase is responsible for resistance to AP-1 transactivation and transformation in mouse JB6 cells. Proc Natl Acad Sci U S A 1998; 95:156-61. [PMID: 9419345 PMCID: PMC18158 DOI: 10.1073/pnas.95.1.156] [Citation(s) in RCA: 153] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The JB6 mouse epidermal cell system, which includes tumor promotion-sensitive (P+) and tumor promotion-resistant (P-) cells, is a well-established and extensively used cell culture model for studying the mechanism of late-stage tumor promotion. Tumor promoters, such as 12-O-tetradecanoylphorbol 13-acetate (TPA) or epidermal growth factor (EGF), induce high levels of activator protein 1 (AP-1) activity and large, tumorigenic, anchorage-independent colonies in soft agar at a high frequency in JB6 P+ cells, but not in JB6 P- cells. We report here a molecular explanation for the defect in the AP-1 activation and promotion-resistant phenotype of P- cells. We demonstrate that the lack of AP-1 activation and cell transformation responses to TPA and EGF in P- cells appears attributable to the low level of mitogen-activated protein kinase (MAPK) (extracellular signal-regulated protein kinase, Erk) in these cells. TPA and EGF induce transactivation of AP-1 activity in P+ cells but not in P- cells. Nonphosphorylated forms and TPA- or EGF-induced phosphorylated forms of Erks (Erk1 and Erk2) in P- cells were much lower than those in P+ cells. Stable transfection of wild-type MAPK (Erk2) into P- cells restored its response to TPA and EGF for both AP-1 activation and cell transformation. These results suggest that the shortage of MAPK (Erk1 and Erk2) appears to be an important contributor to the tumor promotion-resistant phenotype in JB6 cells.
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Affiliation(s)
- C Huang
- The Hormel Institute, University of Minnesota, Austin, MN 55912, USA
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36
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Mettouchi A, Cabon F, Montreau N, Dejong V, Vernier P, Gherzi R, Mercier G, Binétruy B. The c-Jun-induced transformation process involves complex regulation of tenascin-C expression. Mol Cell Biol 1997; 17:3202-9. [PMID: 9154819 PMCID: PMC232173 DOI: 10.1128/mcb.17.6.3202] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
In cooperation with an activated ras oncogene, the site-dependent AP-1 transcription factor c-Jun transforms primary rat embryo fibroblasts (REF). Although signal transduction pathways leading to activation of c-Jun proteins have been extensively studied, little is known about c-Jun cellular targets. We identified c-Jun-upregulated cDNA clones homologous to the tenascin-C gene by differential screening of a cDNA library from REF. This tightly regulated gene encodes a rare extracellular matrix protein involved in cell attachment and migration and in the control of cell growth. Transient overexpression of c-Jun induced tenascin-C expression in primary REF and in FR3T3, an established fibroblast cell line. Surprisingly, tenascin-C synthesis was repressed after stable transformation by c-Jun compared to that in the nontransformed parental cells. As assessed by using the tenascin-C (-220 to +79) promoter fragment cloned in a reporter construct, the c-Jun-induced transient activation is mediated by two binding sites: one GCN4/AP-1-like site, at position -146, and one NF-kappaB site, at position -210. Furthermore, as demonstrated by gel shift experiments and cotransfections of the reporter plasmid and expression vectors encoding the p65 subunit of NF-kappaB and c-Jun, the two transcription factors bind and synergistically transactivate the tenascin-C promoter. We previously described two other extracellular matrix proteins, SPARC and thrombospondin-1, as c-Jun targets. Thus, our results strongly suggest that the regulation of the extracellular matrix composition plays a central role in c-Jun-induced transformation.
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Affiliation(s)
- A Mettouchi
- Institut de Recherche sur le Cancer, CNRS UPR9079, Villejuif, France
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37
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Huang C, Ma WY, Dawson MI, Rincon M, Flavell RA, Dong Z. Blocking activator protein-1 activity, but not activating retinoic acid response element, is required for the antitumor promotion effect of retinoic acid. Proc Natl Acad Sci U S A 1997; 94:5826-30. [PMID: 9159159 PMCID: PMC20865 DOI: 10.1073/pnas.94.11.5826] [Citation(s) in RCA: 171] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Retinoic acid is one of the most promising drugs for chemotherapy and chemoprevention of cancer. Either blocking activator protein-1 (AP-1) activity or activating retinoic acid response element (RARE) have been proposed to be responsible for its antitumor activity. However, evidence for this hypothesis is lacking in vivo studies. To address this issue, we used an AP-1-luciferase transgenic mouse as a carcinogenesis model and new synthetic retinoids that are either selective inhibitors of AP-1 activation or selective activators of the RARE. The results showed that the SR11302, an AP-1 inhibition-specific retinoid, and other AP-1 inhibitors such as trans-retinoic acid and fluocinolone acetonide, markedly inhibit both 12-O-tetradecanoylphorbol-13-acetate-induced papilloma formation and AP-1 activation in 7,12-dimethyl benz(a)anthracene-initiated mouse skin (P < 0.05). In contrast, repeated applications of SR11235, a retinoid with RARE transactivating activity, but devoid of AP-1 inhibiting effect, did not cause significant inhibition of papilloma formation and AP-1 activation (P > 0.05). These results provide the first in vivo evidence that the antitumor effect of retinoids is mediated by blocking AP-1 activity, but not by activation of RARE.
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Affiliation(s)
- C Huang
- The Hormel Institute, University of Minnesota, 801 16th Avenue, N.E., Austin, MN 55912, USA
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38
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Lenczowski JM, Dominguez L, Eder AM, King LB, Zacharchuk CM, Ashwell JD. Lack of a role for Jun kinase and AP-1 in Fas-induced apoptosis. Mol Cell Biol 1997; 17:170-81. [PMID: 8972197 PMCID: PMC231741 DOI: 10.1128/mcb.17.1.170] [Citation(s) in RCA: 190] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Cross-linking of Fas (CD95) induces apoptosis, a response that has been reported to depend upon the Ras activation pathway. Since many examples of apoptosis have been reported to involve AP-1 and/or the AP-1-activation pathway. Since many examples of apoptosis have been reported to involve AP-1 and/or the AP-1-activating enzyme Jun kinase (JNK), downstream effectors of Ras or Ras-like small GTP-binding proteins, we evaluated the role of these molecules in Fas-mediated apoptosis. Although cross-linking of Fas on Jurkat T cells did result in JNK activation, increased activity was observed relatively late, being detectable only after 60 min of stimulation. Expression of a dominant negative form of SEK1 that blocked Fas-mediated induction of JNK activity had no effect on Fas-mediated apoptosis. Furthermore, maximally effective concentrations of anti-Fas did not cause JNK activation if apoptosis was blocked by a cysteine protease inhibitor, suggesting that under these conditions, activation of JNK may be secondary to the stress of apoptosis rather than a direct result of Fas engagement. Despite the activation of JNK, there was no induction of AP-1 activity as determined by gel shift assay or induction of an AP-1-responsive reporter. The lack of a requirement for AP-1 induction in Fas-mediated death was further substantiated with Jurkat cells that were stably transfected with a dominant negative cJun, TAM-67. While TAM-67 effectively prevented AP-1-dependent transcription of both the interleukin-2 and cJun genes, it had no effect on Fas-induced cell death, even at limiting levels of Fas signaling. Thus, induction of JNK activity in Jurkat cells by ligation of Fas at levels sufficient to cause cell death is likely a result, rather than a cause, of the apoptotic response, and AP-1 function is not required for Fas-induced apoptosis.
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Affiliation(s)
- J M Lenczowski
- Laboratory of Immune Cell Biology, National Institutes of Health, Bethesda, Maryland 20892-1152, USA
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Huang C, Ma WY, Dong Z. Requirement for phosphatidylinositol 3-kinase in epidermal growth factor-induced AP-1 transactivation and transformation in JB6 P+ cells. Mol Cell Biol 1996; 16:6427-35. [PMID: 8887671 PMCID: PMC231644 DOI: 10.1128/mcb.16.11.6427] [Citation(s) in RCA: 123] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Phosphatidylinositol 3-kinase (PI 3-kinase) plays a role in a variety of biological processes, including regulation of gene expression, cell growth, and differentiation. However, little is known about its role in the cytoplasmic events involved in epidermal growth factor (EGF)-induced transduction of signals to the transcriptional machinery of the nucleus and in EGF-induced cell transformation. In this study, we examined whether PI 3-kinase is a mediator for the activation of AP-1 and neoplastic transformation by EGF in the murine epidermal cell line JB6. The results showed the following. (i) EGF not only induced a high level of PI 3-kinase activity by itself but also enhanced insulin-induced PI 3-kinase activity in JB6 P+ cells, the EGF-induced PI-3 kinase activity could be blocked by constitutive overexpression of a dominant negative P85 subunit of PI 3-kinase (deltaP85), and insulin could markedly promote EGF-induced AP-1 activity in a dose-dependent manner in JB6 P+ cells as well as promote EGF-induced JB6 P+ cell transformation. (ii) Inhibition of PI-3 kinase with wortmannin or LY294002 markedly decreased the AP-1 activity induced by insulin, EGF, or EGF and insulin in a dose-dependent manner, while wortmannin did not block UVB-induced AP-1 activity. (iii) AP-1 activation by insulin, EGF, or EGF and insulin could be completely inhibited by overexpression of deltaP85 in all the dose and time courses studied. (iv) Inhibitors of PI 3-kinase (wortmannin and LY294002) and stable overexpression of deltaP85 inhibited EGF-induced transformation but had no significant inhibitory effect on cell proliferation induced by EGF or EGF and insulin. These results demonstrate for the first time that PI 3-kinase appears to be required for EGF- or insulin-induced AP-1 transactivation and cell transformation but not cell proliferation in JB6 cells.
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Affiliation(s)
- C Huang
- The Hormel Institute, University of Minnesota, Austin 55912, USA
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40
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Benn J, Su F, Doria M, Schneider RJ. Hepatitis B virus HBx protein induces transcription factor AP-1 by activation of extracellular signal-regulated and c-Jun N-terminal mitogen-activated protein kinases. J Virol 1996; 70:4978-85. [PMID: 8764004 PMCID: PMC190451 DOI: 10.1128/jvi.70.8.4978-4985.1996] [Citation(s) in RCA: 226] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
The HBx protein of hepatitis B virus is a dual-specificity activator of transcription, stimulating signal transduction pathways in the cytoplasm and transcription factors in the nucleus, when expressed in cell lines in culture. In the cytoplasm, HBx was shown to stimulate the Ras-Raf-mitogen-activated protein kinase (MAP kinase) cascade, which is essential for activation of transcription factor AP-1. Here we show that HBx protein stimulates two independently regulated members of the MAP kinase family when expressed transiently in cells. HBx protein stimulates the extracellular signal-regulated kinases (ERKs) and the c-Jun N-terminal kinases (JNKs). HBx activation of ERKs and JNKs leads to induction and activation of AP-1 DNA binding activity involving transient de novo synthesis of c-Fos protein and prolonged synthesis of c-Jun, mediated by N-terminal phosphorylation of c-Jun carried out by HBx-activated JNK. New c-Jun synthesis was blocked by coexpression with a dominant-negative MAP kinase kinase (MEK kinase, MEKK-1), confirming that HBx stimulates the prolonged synthesis of c-Jun by activating JNK signalling pathways. Activation of the c-fos gene was blocked by coexpression with a Raf-C4 catalytic mutant, confirming that HBx induces c-Fos by acting on Ras-Raf linked pathways. HBx activation of ERK and JNK pathways resulted in prolonged accumulation of AP-1-c-Jun dimer complexes. HBx activation of JNK and sustained activation of c-jun, should they occur in the context of hepatitis B virus infection, might play a role in viral transformation and pathogenesis.
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Affiliation(s)
- J Benn
- Department of Biochemistry and Kaplan Cancer Center, New York University Medical Center, New York 10016, USA
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41
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Johnson R, Spiegelman B, Hanahan D, Wisdom R. Cellular transformation and malignancy induced by ras require c-jun. Mol Cell Biol 1996; 16:4504-11. [PMID: 8754851 PMCID: PMC231449 DOI: 10.1128/mcb.16.8.4504] [Citation(s) in RCA: 229] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
ras is an important oncogene in experimental animals and humans. In addition, activated ras proteins are potent inducers of the transcription factor AP-1, which is composed of heterodimeric complexes of Fos and Jun proteins. Together with the fact that deregulated expression of some AP-1 proteins can cause neoplastic transformation, this finding suggests that AP-1 may function as a critical ras effector. We have tested this hypothesis directly by analyzing the response to activated ras in cells that harbor a null mutation in the c-jun gene. The transcriptional response of AP-1-responsive genes to activated ras is severely impaired in c-jun null fibroblasts. Compared with wild-type cells, the c-jun null cells lack many characteristics of ras transformation, including loss of contact inhibition, anchorage independence, and tumorigenicity in nude mice; these properties are restored by forced expression of c-jun. Rare tumorigenic variants of ras-expressing c-jun null fibroblasts do arise. Analysis of these variants reveals a consistent restoration of AP-1 activity. The results provide genetic evidence that c-jun is a crucial effector for transformation by activated ras proteins.
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Affiliation(s)
- R Johnson
- Hormone Research Institute, University of California, San Francisco 94143, USA
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42
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Vandel L, Montreau N, Vial E, Pfarr CM, Binetruy B, Castellazzi M. Stepwise transformation of rat embryo fibroblasts: c-Jun, JunB, or JunD can cooperate with Ras for focus formation, but a c-Jun-containing heterodimer is required for immortalization. Mol Cell Biol 1996; 16:1881-8. [PMID: 8628254 PMCID: PMC231175 DOI: 10.1128/mcb.16.5.1881] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Among the Jun family of transcription factors, only c-Jun displays full transforming potential in cooperation with activated c-Ha-Ras in primary rat embryo fibroblasts. c-Jun in combination with Ras can both induce foci of transformed cells from rat embryo fibroblast monolayers and promote the establishment of these foci as tumoral cell lines. JunB can also cooperate with Ras to induce foci but is unable to promote immortalization. We report here that JunD, in cooperation with Ras, induces foci with an efficiency similar to that of JunB. Artificial Jun/eb1 derivatives from each of the three Jun proteins were also analyzed. These constructs carry a heterologous homodimerization domain from the viral EB1 transcription factor and are thought to form only homodimers in the cell. We show here that these Jun/eb1 chimeras are potent transactivators of AP1 sites and that they can cooperate with c-Ha-Ras to induce foci. However, among all the Ras-Jun and Ras-Jun/eb1 combinations tested, only foci from Ras-c-Jun can be efficiently expanded and maintained as long-term growing cultures. Therefore, we suggest that a heterodimer containing c-Jun might be required for in vitro establishment of these primary mammalian cells.
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Affiliation(s)
- L Vandel
- Unité de Virologie Humaine, INSERM-U412, Ecole Normale Supérieure, Paris, France
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43
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Xu RH, Dong Z, Maeno M, Kim J, Suzuki A, Ueno N, Sredni D, Colburn NH, Kung HF. Involvement of Ras/Raf/AP-1 in BMP-4 signaling during Xenopus embryonic development. Proc Natl Acad Sci U S A 1996; 93:834-8. [PMID: 8570644 PMCID: PMC40143 DOI: 10.1073/pnas.93.2.834] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Previously, we elucidated the role of bone morphogenetic protein 4 (BMP-4) in the dorsal-ventral patterning of the Xenopus embryo by using a dominant negative mutant of the BMP-4 receptor (DN-BR). The present paper describes the involvement of Ras, Raf, and activator protein 1 (AP-1) in BMP-4 signaling during Xenopus embryonic development. The AP-1 activity was determined by injecting an AP-1-dependent luciferase reporter gene into two-cell-stage Xenopus embryos and measuring the luciferase activity at various developmental stages. We found that injection of BMP-4 mRNA increased AP-1 activity, whereas injection of DN-BR mRNA inhibited AP-1 activity. Similar inhibitory effects were seen with injection of mRNAs encoding dominant negative mutants of c-Ha-Ras, c-Raf, or c-Jun. These results suggest that the endogenous AP-1 activity is regulated by BMP-4/Ras/Raf/Jun signals. We next investigated the effects of Ras/Raf/AP-1 signals on the biological functions of BMP-4. DN-BR-induced dorsalization of the embryo, revealed by the formation of a secondary body axis or dorsalization of the ventral mesoderm explant analyzed by histological and molecular criteria, was significantly reversed by coinjection of [Val12]Ha-Ras, c-Raf, or c-Jun mRNA. Furthermore, the BMP-4-stimulated erythroid differentiation in the ventral mesoderm was substantially inhibited by coinjection with the dominant negative c-Ha-Ras, c-Raf, or c-Jun mutant. Our results suggest the involvement of Ras/Raf/AP-1 in the BMP-4 signaling pathway.
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Affiliation(s)
- R H Xu
- Laboratory of Biochemical Physiology, National Cancer Institute-Frederick Cancer Research and Development Center, MD 21702-1201, USA
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44
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Westwick JK, Cox AD, Der CJ, Cobb MH, Hibi M, Karin M, Brenner DA. Oncogenic Ras activates c-Jun via a separate pathway from the activation of extracellular signal-regulated kinases. Proc Natl Acad Sci U S A 1994; 91:6030-4. [PMID: 8016110 PMCID: PMC44131 DOI: 10.1073/pnas.91.13.6030] [Citation(s) in RCA: 146] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
c-Jun transcriptional activity is augmented by expression of oncogenic Ras and Raf proteins. This study demonstrates a direct correlation between Ras transforming activity and c-Jun activation, supporting an important role for c-Jun in transformation by Ras. Since we observed that Ras activated c-Jun transcriptional activity by increasing phosphorylation of the c-Jun activation domain at residues Ser-63/Ser-73 and that oncogenic Ras proteins activated extracellular signal-regulated protein kinases (ERK1 and ERK2) (also known as mitogen-activated protein kinases), we evaluated the possibility that ERKs were directly responsible for c-Jun activation. Coexpression of wild-type ERKs with oncogenic Ras proteins potentiated, while kinase-defective ERKs inhibited, Ras-induced transcriptional activation from the Ras-responsive element (Ets-1/AP-1) present in the NVL-3 enhancer and the serum-response element in the c-fos promoter. In contrast, coexpression of either wild-type or kinase-defective ERKs inhibited Ras and Raf activation of c-Jun transcriptional activity. Thus, although activation of both ERK and c-Jun are downstream consequences of activation of the Ras signal transduction pathway, our results suggest that Ras-induced c-Jun phosphorylation and transcriptional activation are not a direct consequence of ERK1 and ERK2 activation.
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Affiliation(s)
- J K Westwick
- Department of Medicine, University of North Carolina, Chapel Hill 27599
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Dong Z, Birrer MJ, Watts RG, Matrisian LM, Colburn NH. Blocking of tumor promoter-induced AP-1 activity inhibits induced transformation in JB6 mouse epidermal cells. Proc Natl Acad Sci U S A 1994; 91:609-13. [PMID: 8290571 PMCID: PMC42998 DOI: 10.1073/pnas.91.2.609] [Citation(s) in RCA: 285] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
AP-1 transcriptional activity is stimulated by the transformation promoters phorbol 12-myristate 13-acetate ("12-O-tetradecanoylphorbol 13-acetate," TPA) and epidermal growth factor (EGF) in promotion-sensitive (P+) but not in promotion-resistant (P-) JB6 mouse epidermal cell lines. Although TPA stimulates expression of the jun and fos family genes, only c-jun expression shows higher elevation in P+ cells than in P- cells. The present study tests the hypothesis that induced AP-1 activity is required for tumor promoter-induced transformation in JB6 P+ cells. Both retinoic acid and the glucocorticoid fluocinolone acetonide inhibited basal and TPA-induced AP-1 activities that were tested with a stromelysin promoter-chloramphenicol acetyltransferase reporter gene in P+ cells. Since both retinoic acid and fluocinolone acetonide are active in inhibiting TPA-induced anchorage-independent transformation of P+ cells in the dose range that blocks TPA-induced AP-1 activity, their antipromoting effects may occur through inhibition of AP-1 activity. To test the hypothesis with a more specific inhibitor, stable clonal transfectants of P+ cells expressing dominant negative c-jun mutant encoding a transcriptionally inactive product were analyzed. All transfectants showed a block in TPA and EGF induction of AP-1 activity. All transfectants also showed inhibition of TPA-induced transformation, and most transfectants showed a block in EGF-induced transformation. These results indicate that AP-1 activity is required for TPA- or EGF-induced transformation. This work demonstrates that a specific block in induced AP-1 activity inhibits tumor promoter-induced transformation.
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Affiliation(s)
- Z Dong
- Biological Carcinogenesis and Development Program, PRI/DynCorp, Frederick, MD
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46
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Abstract
Fos and Jun transcription factors are induced during the normal course of the proliferative response of quiescent cells to serum or to growth factors. We have shown that delta FosB, an alternatively spliced form of FosB, is formed as rapidly as FosB in serum-stimulated Rat-1A cells. Although delta FosB lacks the C-terminal region of FosB carrying the transactivation function, constitutive expression of delta FosB transforms Rat-1A cells as does expression of FosB. The transforming ability of delta FosB suggests that delta FosB may lead to proliferative activation of quiescent cells without activating AP-1-responsive genes. To address this question, FosB or delta FosB was expressed as a fusion protein with the ligand binding domain of the human estrogen receptor (ER) in Rat-1A cells. After estrogen treatment, the fusion protein accumulates in nuclei and forms stable complexes with Jun proteins. We have shown that ER-delta FosB or to a lesser extent ER-FosB triggers quiescent Rat-1A cells to transit G1, initiate DNA replication, and ultimately undergo cell division at least once. Since ER-FosB, but not ER-delta FosB, induced expression of the AP-1-responsive transin/stromelysin gene, we concluded that the N-terminal region and the DNA binding domain of FosB or delta FosB itself have the potential to regulate cell proliferation and that the transactivation function carried by the C-terminal region of FosB is not essential for the proliferative activation of quiescent cells.
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47
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Monteclaro FS, Vogt PK. A Jun-binding protein related to a putative tumor suppressor. Proc Natl Acad Sci U S A 1993; 90:6726-30. [PMID: 8341691 PMCID: PMC47005 DOI: 10.1073/pnas.90.14.6726] [Citation(s) in RCA: 85] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
A lambda gt11 cDNA library of chicken embryo fibroblasts was screened with biotinylated Jun protein to identify Jun-binding clones. Eight such clones were isolated; one contains a gene referred to as jif-1 that is homologous to the putative tumor suppressor gene QM. jif-1 codes for a protein of 25 kDa that binds to the leucine zipper of viral and cellular Jun. The Jif-1 protein also binds to itself. Jif-1 does not contain a leucine zipper, and it does not bind to the 12-O-tetradecanoylphorbol 13-acetate response element DNA sequence. Complex formation of Jif-1 with Jun inhibits DNA binding and reduces transactivation by Jun. Addition of Fos protein to Jun-Jif-1 complexes restores DNA-binding activity. These observations suggest that Jif-1 is a negative regulator of Jun.
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Affiliation(s)
- F S Monteclaro
- Department of Microbiology, University of Southern California School of Medicine, Los Angeles
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48
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Nakabeppu Y, Oda S, Sekiguchi M. Proliferative activation of quiescent Rat-1A cells by delta FosB. Mol Cell Biol 1993; 13:4157-66. [PMID: 8321220 PMCID: PMC359965 DOI: 10.1128/mcb.13.7.4157-4166.1993] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Fos and Jun transcription factors are induced during the normal course of the proliferative response of quiescent cells to serum or to growth factors. We have shown that delta FosB, an alternatively spliced form of FosB, is formed as rapidly as FosB in serum-stimulated Rat-1A cells. Although delta FosB lacks the C-terminal region of FosB carrying the transactivation function, constitutive expression of delta FosB transforms Rat-1A cells as does expression of FosB. The transforming ability of delta FosB suggests that delta FosB may lead to proliferative activation of quiescent cells without activating AP-1-responsive genes. To address this question, FosB or delta FosB was expressed as a fusion protein with the ligand binding domain of the human estrogen receptor (ER) in Rat-1A cells. After estrogen treatment, the fusion protein accumulates in nuclei and forms stable complexes with Jun proteins. We have shown that ER-delta FosB or to a lesser extent ER-FosB triggers quiescent Rat-1A cells to transit G1, initiate DNA replication, and ultimately undergo cell division at least once. Since ER-FosB, but not ER-delta FosB, induced expression of the AP-1-responsive transin/stromelysin gene, we concluded that the N-terminal region and the DNA binding domain of FosB or delta FosB itself have the potential to regulate cell proliferation and that the transactivation function carried by the C-terminal region of FosB is not essential for the proliferative activation of quiescent cells.
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Affiliation(s)
- Y Nakabeppu
- Department of Biochemistry, Kyushu University, Fukuoka, Japan
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