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DHX33 Interacts with AP-2β To Regulate Bcl-2 Gene Expression and Promote Cancer Cell Survival. Mol Cell Biol 2019; 39:MCB.00017-19. [PMID: 31182639 DOI: 10.1128/mcb.00017-19] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2019] [Accepted: 05/29/2019] [Indexed: 12/31/2022] Open
Abstract
The RNA helicase DHX33 has been found to be overexpressed in human cancers, where it promotes cancer development. Previous reports have shown that DHX33 deficiency caused cancer cell apoptosis, but the underlying mechanism remains unknown. In this study, we discovered that DHX33 regulates Bcl-2 family protein expression. In multiple human cancer cell lines, DHX33 was found to stimulate the transcription of Bcl-2 Mechanistically, we found that DHX33 interacts with the AP-2β transcription factor and acts as a coactivator to stimulate Bcl-2 gene transcription. DHX33 deficiency abolished the loading of AP-2β onto the promoter of Bcl-2 and thereby reduced the recruitment of active RNA polymerase II during transcription initiation. Acute knockdown of DHX33 in multiple human cancer cells caused decreased Bcl-2 protein level, which ultimately triggered mitochondrion-mediated cellular apoptosis. In addition, we found that normal human lung and mammary epithelial cells were less sensitive to acute DHX33 knockdown, implying that cancer cells are uniquely responsive to DHX33 reduction. These data support the notion that disruption of DHX33 function could be an important application for cancer therapy.
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2
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Sasaki K, Kakuwa T, Akimoto K, Koga H, Ohno S. Regulation of epithelial cell polarity by PAR-3 depends on Girdin transcription and Girdin-Gαi3 signaling. J Cell Sci 2015; 128:2244-58. [PMID: 25977476 DOI: 10.1242/jcs.160879] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2014] [Accepted: 05/07/2015] [Indexed: 12/31/2022] Open
Abstract
Epithelial apicobasal polarity has fundamental roles in epithelial physiology and morphogenesis. The PAR complex, comprising PAR-3, PAR-6 and atypical protein kinase C (aPKC), is involved in determining cell polarity in various biological contexts, including in epithelial cells. However, it is not fully understood how the PAR complex induces apicobasal polarity. In this study, we found that PAR-3 regulates the protein expression of Girdin (also known as GIV or CCDC88A), a guanine-nucleotide-exchange factor (GEF) for heterotrimeric Gαi subunits, at the transcriptional level by cooperating with the AP-2 transcription factor. In addition, we confirmed that PAR-3 physically interacts with Girdin, and show that Girdin, together with the Gαi3 (also known as GNAI3), controls tight junction formation, apical domain development and actin organization downstream of PAR-3. Taken together, our findings suggest that transcriptional upregulation of Girdin expression and Girdin-Gαi3 signaling play crucial roles in regulating epithelial apicobasal polarity through the PAR complex.
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Affiliation(s)
- Kazunori Sasaki
- Department of Molecular Biology, Yokohama City University Graduate School of Medical Science, 3-9 Fuku-ura, Kanazawa-ku, Yokohama 236-0004, Japan
| | - Taku Kakuwa
- Department of Molecular Biology, Yokohama City University Graduate School of Medical Science, 3-9 Fuku-ura, Kanazawa-ku, Yokohama 236-0004, Japan
| | - Kazunori Akimoto
- Department of Molecular Biology, Yokohama City University Graduate School of Medical Science, 3-9 Fuku-ura, Kanazawa-ku, Yokohama 236-0004, Japan Department of Molecular Medical Science, Faculty of Pharmaceutical Sciences, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan
| | - Hisashi Koga
- Department of Human Genome Research, Kazusa DNA Research Institute, 2-6-7 Kazusa-Kamatari, Kisarazu, Chiba 292-0818, Japan
| | - Shigeo Ohno
- Department of Molecular Biology, Yokohama City University Graduate School of Medical Science, 3-9 Fuku-ura, Kanazawa-ku, Yokohama 236-0004, Japan
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3
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Sun J, Du N, Li J, Zhou J, Tao G, Sun S, He J. Transcription Factor AP2ε: A Potential Predictor of Chemoresistance in Patients With Gastric Cancer. Technol Cancer Res Treat 2015; 15:285-95. [PMID: 25810491 DOI: 10.1177/1533034615577028] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2014] [Accepted: 02/09/2015] [Indexed: 01/14/2023] Open
Abstract
Chemotherapy is a mainstay of therapy for advanced gastric cancer (GC); however, owing to drug resistances, the effectiveness of chemotherapy is not satisfactory for some patients with GC. Therefore, identification of a marker that predicts treatment response is beneficial to patients. Hypermethylation of transcription factor activating enhancer-binding protein 2∊ (TFAP2E) has been implicated in chemotherapy resistance to fluorouracil-based chemotherapy in patients with colorectal cancer, but its role in GC is still unknown. In this study, we investigated TFAP2E as a predictor of treatment response in GC. We used methylation-sensitive high-resolution melting analysis to study the methylation of TFAP2E in 141 GC tissue specimens and 45 adjacent nontumor tissue specimens. In vitro experiments, we analyzed the expression and methylation of TFAP2E and to examine the sensitivity of GC cell lines to 5-fluorouracil (5-FU). The TFAP2E methylation occurred at a significantly higher incidence rate in tumor tissues compared to adjacent nontumor tissues (chi-square [χ2] = 38.919, P < .001). Hypermethylation of TFAP2E occurred more frequently in tumors with lower differentiation grades (P < .001) and was significantly associated with nonresponse to fluorouracil-based chemotherapy (P = .010). Hypermethylation was also associated with decreased expression of TFAP2E (P < .01) and nonresponse to 5-FU exposure in vitro (P < .001). Hypermethylation of TFAP2E was associated with lack of response to fluorouracil-based chemotherapy, indicating that it might be a potential predictor of treatment response in patients with GC.
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Affiliation(s)
- Jingyue Sun
- Department of Oncology, The Huai'an First People's Hospital, Affiliated to Nanjing Medical University, Huai'an, Jiangsu Province, China
| | - Nan Du
- Department of Oncology, The Huai'an First People's Hospital, Affiliated to Nanjing Medical University, Huai'an, Jiangsu Province, China
| | - Jin Li
- Department of Oncology, The Huai'an First People's Hospital, Affiliated to Nanjing Medical University, Huai'an, Jiangsu Province, China
| | - Jianwei Zhou
- Department of Molecular Cell Biology and Toxicology, School of Public Health, Nanjing Medical University, Nanjing, Jiangsu Province, China
| | - Guoquan Tao
- Department of Gastrointestinal surgery, The Huai'an First People's Hospital, Affiliated to Nanjing Medical University, Huai'an, Jiangsu Province, China
| | - Suan Sun
- Department of Pathology, The Huai'an First People's Hospital, Affiliated to Nanjing Medical University, Huai'an, Jiangsu Province, China
| | - Jingdong He
- Department of Oncology, The Huai'an First People's Hospital, Affiliated to Nanjing Medical University, Huai'an, Jiangsu Province, China
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4
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Li H, Sheridan R, Williams T. Analysis of TFAP2A mutations in Branchio-Oculo-Facial Syndrome indicates functional complexity within the AP-2α DNA-binding domain. Hum Mol Genet 2013; 22:3195-206. [PMID: 23578821 DOI: 10.1093/hmg/ddt173] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Multiple lines of evidence indicate that the AP-2 transcription factor family has an important regulatory function in human craniofacial development. Notably, mutations in TFAP2A, the gene encoding AP-2α, have been identified in patients with Branchio-Oculo-Facial Syndrome (BOFS). BOFS is an autosomal-dominant trait that commonly presents with facial clefting, eye defects and branchial skin anomalies. Examination of multiple cases has suggested either simple haploinsufficiency or more complex genetic causes for BOFS, especially as the clinical manifestations are variable, with no clear genotype-phenotype correlation. Mutations occur throughout TFAP2A, but mostly within conserved sequences within the DNA contact domain of AP-2α. However, the consequences of the various mutations for AP-2α protein function have not been evaluated. Therefore, it remains unclear if all BOFS mutations result in similar changes to the AP-2α protein or if they each produce specific alterations that underlie the spectrum of phenotypes. Here, we have investigated the molecular consequences of the mutations that localize to the DNA-binding region. We show that although individual mutations have different effects on DNA binding, they all demonstrate significantly reduced transcriptional activities. Moreover, all mutant derivatives have an altered nuclear:cytoplasmic distribution compared with the predominantly nuclear localization of wild-type AP-2α and several can exert a dominant-negative activity on the wild-type AP-2α protein. Overall, our data suggest that the individual TFAP2A BOFS mutations can generate null, hypomorphic or antimorphic alleles and that these differences in activity, combined with a role for AP-2α in epigenetic events, may influence the resultant pathology and the phenotypic variability.
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Affiliation(s)
- Hong Li
- Department of Craniofacial Biology and Cell and Developmental Biology, University of Colorado Denver, Aurora, CO 80045, USA
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5
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Finlay-Schultz J, Canastar A, Short M, El Gazzar M, Coughlan C, Leonard S. Transcriptional repression of the α7 nicotinic acetylcholine receptor subunit gene (CHRNA7) by activating protein-2α (AP-2α). J Biol Chem 2011; 286:42123-42132. [PMID: 21979958 DOI: 10.1074/jbc.m111.276014] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
The CHRNA7 gene, which encodes the α7 nicotinic acetylcholine receptor (α7*nAChR), has been implicated as a candidate gene in schizophrenia. Expression of the α7*nAChR mRNA and protein are reduced in multiple regions of post-mortem brain from patients diagnosed with schizophrenia. Transcriptional regulation may therefore be an important mechanism for the regulation of this gene. A 230-bp proximal promoter fragment, necessary for transcription in cultured neuroblastoma cells, was used to study a putative AP-2α binding site. Mutation of the site indicates that AP-2α plays a negative role in regulating CHRNA7 transcription. This was confirmed through knockdown and overexpression of AP-2α. Electrophoretic mobility shift assays (EMSAs) identified positive DNA-protein interaction at this same site, and supershift assays indicate that the complex includes AP-2α. The interaction was confirmed in cells using chromatin immunoprecipitation (ChIP). DNA methylation was discovered as an anomalous mechanism for CHRNA7 regulation in one cell line. These studies suggest a role for AP-2α regulation of CHRNA7 mRNA expression in multiple tissues during development.
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Affiliation(s)
- Jessica Finlay-Schultz
- Departments of Biochemistry and Molecular Genetics, University of Colorado Denver Anschutz Medical Campus, Aurora, Colorado 80045; Department of Psychiatry, University of Colorado Denver Anschutz Medical Campus, Aurora, Colorado 80045
| | - Andrew Canastar
- Department of Psychiatry, University of Colorado Denver Anschutz Medical Campus, Aurora, Colorado 80045
| | - Margaret Short
- Denver Veterans Affairs Medical Center, Denver, Colorado 80220
| | - Mohamed El Gazzar
- Department of Psychiatry, University of Colorado Denver Anschutz Medical Campus, Aurora, Colorado 80045
| | - Christina Coughlan
- Biological Sciences Department, University of Denver, Denver, Colorado 80208
| | - Sherry Leonard
- Department of Psychiatry, University of Colorado Denver Anschutz Medical Campus, Aurora, Colorado 80045; Denver Veterans Affairs Medical Center, Denver, Colorado 80220; Department of Pharmacology, University of Colorado Denver Anschutz Medical Campus, Aurora, Colorado 80045.
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6
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Wenke AK, Niebler S, Grässel S, Bosserhoff AK. The transcription factor AP-2ɛ regulates CXCL1 during cartilage development and in osteoarthritis. Osteoarthritis Cartilage 2011; 19:206-12. [PMID: 21134476 DOI: 10.1016/j.joca.2010.11.011] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/21/2010] [Revised: 11/13/2010] [Accepted: 11/26/2010] [Indexed: 02/02/2023]
Abstract
OBJECTIVE Recently, the transcription factor AP-2ɛ was shown to be a regulator of hypertrophy in cartilage and to be differentially expressed in osteoarthritis (OA). However, the only known target gene of AP-2ɛ up to date is integrin alpha10. To better characterize the function of AP-2ɛ in cartilage we screened for additional target genes. DESIGN Promoter analysis, ChIP-assays and electrophoretic mobility shift assay were used to characterize the regulation of a new AP-2ɛ target gene in detail. RESULTS In this study, we determined the chemokine CXCL1, already known to be important in osteoarthritis (OA), as a new target gene of AP-2ɛ. We could confirm that CXCL1 is expressed in chondrocytes and significantly over-expressed in OA-chondrocytes. Transient transfection of chondrocytes with an AP-2ɛ expression construct led to a significant increase of the CXCL1 mRNA level in these cells. We identified three potential AP-2 binding sites within the CXCL1 promoter and performed luciferase assays, indicating that an AP-2 binding motif (AP-2.2) ranging from position -135 to -144 bp relative to the translation start is responsive to AP-2ɛ. This result was further addressed by site-directed mutagenesis demonstrating that activation of the CXCL1 promoter by AP-2ɛ is exclusively dependent on AP-2.2. Chromatin immunoprecipitation and electromobility shift assays confirmed the direct binding of AP-2ɛ to the CXCL1 promoter in OA-chondrocytes at this site. CONCLUSION These findings revealed CXCL1 as a novel target gene of AP-2ɛ in chondrocytes and support the important role of AP-2ɛ in cartilage.
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Affiliation(s)
- A-K Wenke
- Institute of Pathology, University Regensburg, Regensburg 93053, Germany
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7
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Wenke AK, Bosserhoff AK. Roles of AP-2 transcription factors in the regulation of cartilage and skeletal development. FEBS J 2009; 277:894-902. [PMID: 20050923 DOI: 10.1111/j.1742-4658.2009.07509.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
During embryogenesis, most of the mammalian skeletal system is preformed as cartilaginous structures that ossify later. The different stages of cartilage and skeletal development are well described, and several molecular factors are known to influence the events of this enchondral ossification, especially transcription factors. Members of the AP-2 family of transcription factors play important roles in several cellular processes, such as apoptosis, migration and differentiation. Studies with knockout mice demonstrate that a main function of AP-2s is the suppression of terminal differentiation during embryonic development. Additionally, the specific role of these molecules as regulators during chondrogenesis has been characterized. This review gives an overview of AP-2s, and discusses the recent findings on the AP-2 family, in particular AP-2alpha, AP-2beta, and AP-2epsilon, as regulators of cartilage and skeletal development.
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8
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Wenke AK, Grässel S, Moser M, Bosserhoff AK. The cartilage-specific transcription factor Sox9 regulates AP-2ε expression in chondrocytes. FEBS J 2009; 276:2494-504. [DOI: 10.1111/j.1742-4658.2009.06973.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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9
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Li X, Glubrecht DD, Mita R, Godbout R. Expression of AP-2delta in the developing chick retina. Dev Dyn 2009; 237:3210-21. [PMID: 18924234 DOI: 10.1002/dvdy.21744] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
AP-2 is a family of transcription factors that play important roles during embryonic development. Two AP-2 genes, AP-2alpha and AP-2beta, have previously been characterized in chick retina. Here, we demonstrate that a third member of the chicken AP-2 family, AP-2delta, is primarily expressed in the retina and brain, with highest levels at embryonic days 7 to 11. By in situ hybridization and immunohistochemical analysis, we show that AP-2delta RNA and protein are found in a subset of ganglion cells in embryonic chick retina. Co-immunostaining with anti-Brn3a and anti-AP-2delta antibodies indicates that approximately one-third of Brn3a-positive ganglion cells express AP-2delta. AP-2delta RNA but not AP-2delta protein is also found in cells located in the outer half of the inner nuclear layer. The spatial and temporal distribution of AP-2delta protein in the retina suggests a transient role in a subset of late-born ganglion cells likely involving axonal trafficking or pathfinding.
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Affiliation(s)
- Xiaodong Li
- Department of Oncology, University of Alberta, Edmonton, Alberta, Canada
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10
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Iwamoto N, Abe-Dohmae S, Ayaori M, Tanaka N, Kusuhara M, Ohsuzu F, Yokoyama S. ATP-Binding Cassette Transporter A1 Gene Transcription Is Downregulated by Activator Protein 2α. Circ Res 2007; 101:156-65. [PMID: 17556657 DOI: 10.1161/circresaha.107.151746] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
ATP-binding cassette transporter A1 (ABCA1) is a rate-limiting factor for high-density lipoprotein (HDL) biogenesis. The ABCA1 gene expression is known to be upregulated by various transcriptional factors. However, negative regulation factors would be better targets for pharmacological modulation of HDL biogenesis. Doxazosin, an α
1
-adrenoceptor blocker, increased ABCA1 mRNA, its protein, and apolipoprotein A-I–mediated HDL biogenesis in THP-1 macrophages and CHO-K1 cells, independent of α
1
-adrenoceptor blockade. Analysis of the human ABCA1 promoter indicated that the region between the positions −368 and −147 that contains an activator protein (AP)2-binding site responsible for the effects of doxazosin. Overexpression of AP2α inhibited ABCA1 transcription in a dose-dependent fashion. Mutation in the AP2-binding site caused increase of the basal promoter activity and canceling both the transactivation by doxazosin and the trans-repression by AP2α. Doxazosin had no effect on ABCA1 mRNA level in HepG2 cells, which lack endogenous AP2α, and it reversed the inhibitory effect of AP2α expression in this type of cells. Chromatin immunoprecipitation and gel shift assays revealed that doxazosin reduced specific binding of AP2α to the ABCA1 promoter, as it suppressed phosphorylation of AP2α. Finally, doxazosin increased ABCA1 expression and plasma HDL in mice. We thus concluded that AP2α negatively regulates the ABCA1 gene transcription. Doxazosin inhibits AP2α activity independent of α
1
-adrenoceptor blockade and increases the ABCA1 expression and HDL biogenesis. AP2α is a potent pharmacological target for the increase of HDL.
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Affiliation(s)
- Noriyuki Iwamoto
- Biochemistry Department, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
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11
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Wajapeyee N, Britto R, Ravishankar HM, Somasundaram K. Apoptosis induction by activator protein 2alpha involves transcriptional repression of Bcl-2. J Biol Chem 2006; 281:16207-19. [PMID: 16533807 DOI: 10.1074/jbc.m600539200] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Activator protein 2alpha (AP-2alpha) induces cytotoxicity by inducing cell cycle arrest and apoptosis. In this study we investigated the mechanism of apoptosis induction by AP-2alpha. We found that AP-2alpha induced apoptosis efficiently in cells treated with benzyloxycar-bonyl-IETD-fluoromethyl ketone or FADD-silenced cells but failed to do so in benzyloxycarbonyl-LEHD-fluoromethyl ketone-treated or apoptosis protease activation factor-1 (Apaf1)-silenced cells, suggesting the central role of mitochondria in AP-2alpha-induced apoptosis. In good correlation, cells overexpressing AP-2alpha showed a reduction in mitochondrial membrane potential (Deltapsi(m)), cytochrome c and Smac/DIABLO release into cytosol, and Bax translocation into mitochondria. We found that the pro-apoptotic protein Bax is important for AP-2alpha-induced apoptosis as adenovirus AP2 failed to induce apoptosis in HCT116 Bax(-/-) cells. However, we found the IAP (inhibitor of apoptosis) inhibitor Smac/DIABLO may have a limited role in AP-2alpha-induced apoptosis as we found the IAP member Survivin down-regulated by AP-2alpha. Although the total Bax level remains unaltered, we found a time-dependent increase in the activated form of Bax in adenovirus AP2-infected cells. In addition, we show that AP-2alpha transcriptionally represses Bcl-2 by binding to its promoter both in vitro and in vivo and that this is essential for AP-2alpha-induced apoptosis as ectopic expression of Bcl-2 efficiently inhibited apoptosis induced by AP-2alpha. Furthermore, we show that chemotherapy-induced endogenous AP-2alpha down-regulates Bcl-2 and induces apoptosis in an AP-2alpha-dependent manner. Moreover, we demonstrate that inhibition of okadaic acid or staurosporine-sensitive pathways in AP-2alpha overexpressing breast cancer cells resulted in AP-2alpha-dependent apoptosis induction. These results suggest that AP-2alpha induces apoptosis by down-regulating Bcl-2 and utilizing a bax/cytochrome c/Apaf1/caspase 9-dependent mitochondrial pathway.
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Affiliation(s)
- Narendra Wajapeyee
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore 560 012, India
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12
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Brewer S, Feng W, Huang J, Sullivan S, Williams T. Wnt1-Cre-mediated deletion of AP-2alpha causes multiple neural crest-related defects. Dev Biol 2004; 267:135-52. [PMID: 14975722 DOI: 10.1016/j.ydbio.2003.10.039] [Citation(s) in RCA: 125] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2003] [Revised: 10/27/2003] [Accepted: 10/27/2003] [Indexed: 12/15/2022]
Abstract
The AP-2alpha transcription factor is required for multiple aspects of vertebrate development and mice lacking the AP-2alpha gene (tcfap2a) die at birth from severe defects affecting the head and trunk. Several of the defects associated with the tcfap2a-null mutation affect neural crest cell (NCC) derivatives including the craniofacial skeleton, cranial ganglia, and heart outflow tract. Consequently, there is considerable interest in the role of AP-2alpha in neural crest cell function in development and evolution. In addition, the expression of the AP-2alpha gene is utilized as a marker for premigratory and migratory neural crest cells in many vertebrate species. Here, we have specifically addressed how the presence of AP-2alpha in neural crest cells affects development by creating a conditional (floxed) version of tcfap2a which has subsequently been intercrossed with mice expressing Cre recombinase under the control of Wnt1 cis-regulatory sequences. Neural crest-specific disruption of tcfap2a results in frequent perinatal lethality associated with neural tube closure defects and cleft secondary palate. A small but significant fraction of mutant mice can survive into adulthood, but have retarded craniofacial growth, abnormal middle ear development, and defects in pigmentation. The phenotypes obtained confirm that AP-2alpha directs important aspects of neural crest cell function. At the same time, we did not observe several neurocristopathies affecting the head and heart that might be expected based on the phenotype of the AP-2alpha-null mouse. These results have important implications for the evolution and function of the AP-2 gene family in both the neural crest and the vertebrate embryo.
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Affiliation(s)
- Stephanie Brewer
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT 06520, USA
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13
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Knight RD, Nair S, Nelson SS, Afshar A, Javidan Y, Geisler R, Rauch GJ, Schilling TF. lockjawencodes a zebrafishtfap2arequired for early neural crest development. Development 2003; 130:5755-68. [PMID: 14534133 DOI: 10.1242/dev.00575] [Citation(s) in RCA: 158] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The neural crest is a uniquely vertebrate cell type that gives rise to much of the craniofacial skeleton, pigment cells and peripheral nervous system, yet its specification and diversification during embryogenesis are poorly understood. Zebrafish homozygous for the lockjaw (low)mutation show defects in all of these derivatives and we show that low (allelic with montblanc) encodes a zebrafish tfap2a, one of a small family of transcription factors implicated in epidermal and neural crest development. A point mutation in lowtruncates the DNA binding and dimerization domains of tfap2a, causing a loss of function. Consistent with this, injection of antisense morpholino oligonucleotides directed against splice sites in tfap2a into wild-type embryos produces a phenotype identical to low. Analysis of early ectodermal markers revealed that neural crest specification and migration are disrupted in low mutant embryos. TUNEL labeling of dying cells in mutants revealed a transient period of apoptosis in crest cells prior to and during their migration. In the cranial neural crest, gene expression in the mandibular arch is unaffected in low mutants, in contrast to the hyoid arch, which shows severe reductions in dlx2 and hoxa2 expression. Mosaic analysis, using cell transplantation,demonstrated that neural crest defects in low are cell autonomous and secondarily cause disruptions in surrounding mesoderm. These studies demonstrate that low is required for early steps in neural crest development and suggest that tfap2a is essential for the survival of a subset of neural crest derivatives.
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Affiliation(s)
- Robert D Knight
- Department of Developmental and Cell Biology, University of California, Irvine, CA 92697, USA
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14
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Campillos M, García MA, Valdivieso F, Vázquez J. Transcriptional activation by AP-2alpha is modulated by the oncogene DEK. Nucleic Acids Res 2003; 31:1571-5. [PMID: 12595566 PMCID: PMC149840 DOI: 10.1093/nar/gkg247] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2002] [Revised: 11/15/2002] [Accepted: 01/12/2003] [Indexed: 12/30/2022] Open
Abstract
Cell differentiation and development are highly regulated processes at the transcriptional level. One of the main transcription factors that regulate these processes is AP-2alpha, a cell-type specific protein required for vertebrate development and embryogenesis. AP-2alpha also regulates apoptosis and cell-cycle specific events by interacting with the oncogene c-Myc. In searching for novel AP-2alpha- interacting factors, using an affinity chromatography approach, we have observed that oncoprotein DEK interacts with AP-2alpha in vitro. The existence of an interaction between AP-2alpha and DEK in cellular cultures was demonstrated by expression of a tagged AP-2alpha form followed by immunodetection. By transient co-expression experiments using a reporter for APOE promoter activity we have found that DEK stimulates the transactivation activity of AP-2alpha over APOE promoter. Finally, electrophoretic mobility shift assays suggested that DEK enhances the DNA-binding activity of AP-2alpha. Our data suggest a novel cellular function of DEK as a transcriptional co-activator.
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Affiliation(s)
- Mónica Campillos
- Centro de Biología Molecular Severo Ochoa, CSIC-Universidad Autónoma de Madrid, 28049 Cantoblanco, Madrid, Spain
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15
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Forde CE, McCutchen-Maloney SL. Characterization of transcription factors by mass spectrometry and the role of SELDI-MS. MASS SPECTROMETRY REVIEWS 2002; 21:419-439. [PMID: 12666149 DOI: 10.1002/mas.10040] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Over the last decade, much progress has been made in the field of biological mass spectrometry, with numerous advances in technology, resolution, and affinity capture. The field of genomics has also been transformed by the sequencing and characterization of entire genomes. Some of the next challenges lie in understanding the relationship between the genome and the proteome, the protein complement of the genome, and in characterizing the regulatory processes involved in progressing from gene to functional protein. In this new age of proteomics, development of mass spectrometry methods to characterize transcription factors promises to add greatly to our understanding of regulatory networks that govern expression. However, at this time, regulatory networks of transcription factors are mostly uncharted territory. In this review, we summarize the latest advances in characterization of transcription factors by mass spectrometry including affinity capture, identification of complexes of DNA-binding proteins, structural characterization, determination of protein-DNA and protein-protein interactions, assessment of modification sites and metal binding, studies of functional activity, and the latest chip technologies that use SELDI-MS that allow the rapid capture and identification of transcription factors.
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Affiliation(s)
- Cameron E Forde
- Biodefense Division, Biology and Biotechnology Research Program, Lawrence Livermore National Laboratory, California 94550, USA
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16
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Alexa A, Schmidt G, Tompa P, Ogueta S, Vázquez J, Kulcsár P, Kovács J, Dombrádi V, Friedrich P. The phosphorylation state of threonine-220, a uniquely phosphatase-sensitive protein kinase A site in microtubule-associated protein MAP2c, regulates microtubule binding and stability. Biochemistry 2002; 41:12427-35. [PMID: 12369833 DOI: 10.1021/bi025916s] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Phosphorylation of microtubule-associated protein 2 (MAP2) has a profound effect on microtubule stability and organization. In this work a consensus protein kinase A (PKA) phosphorylation site, T(220), of juvenile MAP2c is characterized. As confirmed by mass spectrometry, this site can be phosphorylated by PKA but shows less than average reactivity among the 3.5 +/- 0.5 phosphate residues incorporated into the protein. In contrast, T(220) is uniquely sensitive to dephosphorylation: three major Ser/Thr protein phosphatases, in the order of efficiency PP2B > PP2A(c) > PP1(c), remove this phosphate group first. MAP2c specifically dephosphorylated at this site binds and stabilizes microtubules stronger than either fully phosphorylated or nonphosphorylated MAP2c. Phosphorylation of this site also affects proteolytic sensitivity of MAP2c, which might represent a further level of control in this system. Thus, the phosphorylation state of T(220) may be a primary determinant of microtubule function.
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Affiliation(s)
- A Alexa
- Institute of Enzymology, Biological Research Center, Hungarian Academy of Sciences, Budapest, Hungary
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17
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Buchli R, De Jong A, Robbins DL. Genomic organization of an intron-containing sperm protein 17 gene (Sp17-1) and an intronless pseudogene (Sp17-2) in humans: a new model. BIOCHIMICA ET BIOPHYSICA ACTA 2002; 1578:29-42. [PMID: 12393185 DOI: 10.1016/s0167-4781(02)00478-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Sp17 was initially thought to be a sperm specific protein involved in the interaction of the spermatozoon with the oocyte's surrounding extracellular glycoprotein matrix. Recent reports, however, indicate that Sp17 expression is neither testis-specific nor is it exclusively used for binding to the zona pellucida of the oocyte. In this study, we provide comprehensive characterization of the genomic structure of Sp17. We identified an intron-containing gene (Sp17-1) containing five exonic and four intronic sequences. Analysis of Sp17 transcripts using rapid amplification of DNA complementary to RNA (cDNA) ends (RACE) and polymerase chain reaction (PCR) techniques showed the presence of alternative polyadenylation resulting in the production of varying lengths of mRNAs as well as the usage of different transcriptional start sites. Moreover, an earlier description of the human Sp17 mRNA describing a splice variant could not be confirmed. Comparison to mouse Sp17 gene organization demonstrated a high degree of conservation, suggesting selective evolutionary pressure for this protein to retain a conserved gene architecture. Additionally, we identified a second gene (Sp17-2), whose most striking characteristic was the complete absence of introns. This Sp17-2 gene has likely arisen by reverse transcription (RT) of a spliced Sp17-1 mRNA with subsequent integration into the human genome. Its open reading frame (ORF) is interrupted by stop codons, giving rise to a pseudogene. Furthermore, Southern blot analysis of human genomic DNA indicated the possibility of additional Sp17 species within the human genome.
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Affiliation(s)
- Rico Buchli
- Division of Rheumatology/Allergy and Clinical Immunology, Department of Internal Medicine, University of California-Davis, 1 Shields Avenue, TB 192, Davis, CA 95616, USA
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18
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Cheng C, Ying K, Xu M, Zhao W, Zhou Z, Huang Y, Wang W, Xu J, Zeng L, Xie Y, Mao Y. Cloning and characterization of a novel human transcription factor AP-2 beta like gene (TFAP2BL1). Int J Biochem Cell Biol 2002; 34:78-86. [PMID: 11733187 DOI: 10.1016/s1357-2725(01)00098-x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The AP-2 transcription factor has been shown to play an important role in development, morphogenesis, apoptosis, cell-cycle control and has also been implicated in mammary oncogenesis. Here we report the cloning and characterization of a novel human transcription factor AP-2 like gene (TFAP2BL1), which is located on human chromosome 6p12.1-21.1. The TFAP2BL1 cDNA is 2076 base pairs in length, encoding a 452-amino acid polypeptide related to human Ap-2protein. TFAP2BL1 gene has significantly high homology to transcription factor AP-2 gene of human, mouse, chicken, sheep, fruit fly, and C. elegans at amino acid level. RT-PCR analysis shows its relatively high expression level in adult thymus, prostate, small intestine, skeletal muscle, placenta, brain, and testis tissues.
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Affiliation(s)
- Chao Cheng
- State Key Laboratory of Genetic Engineering, Institute of Genetics, School of Life Sciences, Fudan University, Shanghai 200433, People's Republic of China
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