1
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Khokhar M, Kartha P, Hassan S, Pandey RK. Decoding dysregulated genes, molecular pathways and microRNAs involved in cervical cancer. J Gene Med 2024; 26:e3713. [PMID: 38949075 DOI: 10.1002/jgm.3713] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2023] [Revised: 03/30/2024] [Accepted: 06/02/2024] [Indexed: 07/02/2024] Open
Abstract
BACKGROUND The present study aimed to identify dysregulated genes, molecular pathways, and regulatory mechanisms in human papillomavirus (HPV)-associated cervical cancers. We have investigated the disease-associated genes along with the Gene Ontology, survival prognosis, transcription factors and the microRNA (miRNA) that are involved in cervical carcinogenesis, enabling a deeper comprehension of cervical cancer linked to HPV. METHODS We used 10 publicly accessible Gene Expression Omnibus (GEO) datasets to examine the patterns of gene expression in cervical cancer. Differentially expressed genes (DEGs), which showed a clear distinction between cervical cancer and healthy tissue samples, were analyzed using the GEO2R tool. Additional bioinformatic techniques were used to carry out pathway analysis and functional enrichment, as well as to analyze the connection between altered gene expression and HPV infection. RESULTS In total, 48 DEGs were identified to be differentially expressed in cervical cancer tissues in comparison to healthy tissues. Among DEGs, CCND1, CCNA2 and SPP1 were the key dysregulated genes involved in HPV-associated cervical cancer. The five common miRNAs that were identified against these genes are miR-7-5p, miR-16-5p, miR-124-3p, miR-10b-5p and miR-27a-3p. The hub-DEGs targeted by miRNA hsa-miR-27a-3p are controlled by the common transcription factor SP1. CONCLUSIONS The present study has identified DEGs involved in HPV-associated cervical cancer progression and the various molecular pathways and transcription factors regulating them. These findings have led to a better understanding of cervical cancer resulting in the development and identification of possible therapeutic and intervention targets, respectively.
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Affiliation(s)
- Manoj Khokhar
- Department of Biochemistry, All India Institute of Medical Sciences Jodhpur, Jodhpur, Rajasthan, India
| | - Purnima Kartha
- Rajiv Gandhi Centre for Biotechnology, Thiruvananthapuram, Kerala, India
| | - Sana Hassan
- Department of Life Sciences, Manipal Academy of Higher Education, Dubai, United Arab Emirates
| | - Rajan Kumar Pandey
- Department of Medical Biochemistry and Biophysics, Karolinska Institute, Stockholm, Sweden
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2
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Kwon J, Aoki Y, Takahashi H, Nakata R, Kawarasaki S, Ni Z, Yu R, Inoue H, Inoue K, Kawada T, Goto T. Inflammation-induced nitric oxide suppresses PPARα expression and function via downregulation of Sp1 transcriptional activity in adipocytes. BIOCHIMICA ET BIOPHYSICA ACTA. GENE REGULATORY MECHANISMS 2023; 1866:194987. [PMID: 37739218 DOI: 10.1016/j.bbagrm.2023.194987] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Revised: 09/05/2023] [Accepted: 09/15/2023] [Indexed: 09/24/2023]
Abstract
The activation of peroxisome proliferator-activated receptor alpha (PPARα), a ligand-dependent transcription factor that regulates lipid oxidation-related genes, has been employed to treat hyperlipidemia. Emerging evidence indicates that Ppara gene expression decreases in adipose tissue under obese conditions; however, the underlying molecular mechanisms remain elusive. Here, we demonstrate that nitric oxide (NO) suppresses Ppara expression by regulating its promoter activity via suppression of specificity protein 1 (Sp1) transcriptional activity in adipocytes. NO derived from lipopolysaccharide (LPS) -activated macrophages or a NO donor (NOR5) treatment, suppressed Ppara mRNA expression in 10T1/2 adipocytes. In addition, Ppara transcript levels were reduced in the white adipose tissue (WAT) in both acute and chronic inflammation mouse models; however, such suppressive effects were attenuated via a nitric oxide synthase 2 (NOS2) inhibitor. Endoplasmic reticulum (ER) stress inhibitors attenuated the NO-induced repressive effects on Ppara gene expression in 10T1/2 adipocytes. Promoter mutagenesis and chromatin immunoprecipitation assays revealed that NO decreased the Sp1 occupancy in the proximal promoter regions of the Ppara gene, which might partially result from the reduced Sp1 expression levels by NO. This study delineated the molecular mechanism that modulates Ppara gene transcription upon NO stimulation in white adipocytes, suggesting a possible mechanism for the transcriptional downregulation of Ppara in WAT under obese conditions.
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Affiliation(s)
- Jungin Kwon
- Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Uji 611-0011, Japan
| | - Yumeko Aoki
- Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Uji 611-0011, Japan
| | - Haruya Takahashi
- Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Uji 611-0011, Japan
| | - Rieko Nakata
- Department of Food Science and Nutrition, Nara Women's University, Nara 630-8506, Japan
| | - Satoko Kawarasaki
- Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Uji 611-0011, Japan
| | - Zheng Ni
- Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Uji 611-0011, Japan
| | - Rina Yu
- Department of Food Science and Nutrition, University of Ulsan, Ulsan 44610, Republic of Korea
| | - Hiroyasu Inoue
- Department of Food Science and Nutrition, Nara Women's University, Nara 630-8506, Japan
| | - Kazuo Inoue
- Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Uji 611-0011, Japan; Research Unit for Physiological Chemistry, The Center for the Promotion of Interdisciplinary Education and Research, Kyoto University, Kyoto 606-8501, Japan
| | - Teruo Kawada
- Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Uji 611-0011, Japan; Research Unit for Physiological Chemistry, The Center for the Promotion of Interdisciplinary Education and Research, Kyoto University, Kyoto 606-8501, Japan
| | - Tsuyoshi Goto
- Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Uji 611-0011, Japan; Research Unit for Physiological Chemistry, The Center for the Promotion of Interdisciplinary Education and Research, Kyoto University, Kyoto 606-8501, Japan.
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3
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Ng LY, Ma HT, Poon RYC. Cyclin A-CDK1 suppresses the expression of the CDK1 activator CDC25A to safeguard timely mitotic entry. J Biol Chem 2023; 299:102957. [PMID: 36717077 PMCID: PMC9986519 DOI: 10.1016/j.jbc.2023.102957] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Revised: 01/19/2023] [Accepted: 01/20/2023] [Indexed: 01/29/2023] Open
Abstract
Cyclin A and CDC25A are both activators of cyclin-dependent kinases (CDKs): cyclin A acts as an activating subunit of CDKs and CDC25A a phosphatase of the inhibitory phosphorylation sites of the CDKs. In this study, we uncovered an inverse relationship between the two CDK activators. As cyclin A is an essential gene, we generated a conditional silencing cell line using a combination of CRISPR-Cas9 and degron-tagged cyclin A. Destruction of cyclin A promoted an acute accumulation of CDC25A. The increase of CDC25A after cyclin A depletion occurred throughout the cell cycle and was independent on cell cycle delay caused by cyclin A deficiency. Moreover, we determined that the inverse relationship with cyclin A was specific for CDC25A and not for other CDC25 family members or kinases that regulate the same sites in CDKs. Unexpectedly, the upregulation of CDC25A was mainly caused by an increase in transcriptional activity instead of a change in the stability of the protein. Reversing the accumulation of CDC25A severely delayed G2-M in cyclin A-depleted cells. Taken together, these data provide evidence of a compensatory mechanism involving CDC25A that ensures timely mitotic entry at different levels of cyclin A.
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Affiliation(s)
- Lau Yan Ng
- Division of Life Science, The Hong Kong University of Science and Technology, Hong Kong, China
| | - Hoi Tang Ma
- Department of Pathology, The University of Hong Kong, Hong Kong, China; State Key Laboratory of Liver Research, The University of Hong Kong, Hong Kong, China
| | - Randy Y C Poon
- Division of Life Science, The Hong Kong University of Science and Technology, Hong Kong, China; State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Hong Kong, China.
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4
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Venuti A, Romero-Medina MC, Melita G, Ceraolo MG, Brancaccio RN, Sirand C, Taverniti V, Steenbergen R, Gheit T, Tommasino M. Lyon IARC Polyomavirus Displays Transforming Activities in Primary Human Cells. J Virol 2022; 96:e0206121. [PMID: 35770990 PMCID: PMC9327700 DOI: 10.1128/jvi.02061-21] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Accepted: 06/13/2022] [Indexed: 01/01/2023] Open
Abstract
Several studies reported the presence of a recently discovered polyomavirus (PyV), Lyon IARC PyV (LIPyV), in human and domestic animal specimens. LIPyV has some structural similarities to well-established animal and human oncogenic PyVs, such as raccoon PyV and Merkel cell PyV (MCPyV), respectively. In this study, we demonstrate that LIPyV early proteins immortalize human foreskin keratinocytes. LIPyV LT binds pRb, accordingly cell cycle checkpoints are altered in primary human fibroblasts and keratinocytes expressing LIPyV early genes. Mutation of the pRb binding site in LT strongly affected the ability of LIPyV ER to induced HFK immortalization. LIPyV LT also binds p53 and alters p53 functions activated by cellular stresses. Finally, LIPyV early proteins activate telomerase reverse transcriptase (hTERT) gene expression, via accumulation of the Sp1 transcription factor. Sp1 recruitment to the hTERT promoter is controlled by its phosphorylation, which is mediated by ERK1 and CDK2. Together, these data highlight the transforming properties of LIPyV in in vitro experimental models, supporting its possible oncogenic nature. IMPORTANCE Lyon IARC PyV is a recently discovered polyomavirus that shows some structural similarities to well-established animal and human oncogenic PyVs, such as raccoon PyV and Merkel cell PyV, respectively. Here, we show the capability of LIPyV to efficiently promote cellular transformation of primary human cells, suggesting a possible oncogenic role of this virus in domestic animals and/or humans. Our study identified a novel virus-mediated mechanism of activation of telomerase reverse transcriptase gene expression, via accumulation of the Sp1 transcription factor. In addition, because the persistence of infection is a key event in virus-mediated carcinogenesis, it will be important to determine whether LIPyV can deregulate immune-related pathways, similarly to the well-established oncogenic viruses.
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Affiliation(s)
- Assunta Venuti
- International Agency for Research on Cancer (IARC), World Health Organization, Lyon Cedex, France
| | | | - Giusi Melita
- International Agency for Research on Cancer (IARC), World Health Organization, Lyon Cedex, France
| | - Maria Grazia Ceraolo
- International Agency for Research on Cancer (IARC), World Health Organization, Lyon Cedex, France
| | | | - Cecilia Sirand
- International Agency for Research on Cancer (IARC), World Health Organization, Lyon Cedex, France
| | - Valerio Taverniti
- International Agency for Research on Cancer (IARC), World Health Organization, Lyon Cedex, France
| | - Renske Steenbergen
- VU University Medical Center Amsterdam, Department of Pathology, Amsterdam, The Netherlands
| | - Tarik Gheit
- International Agency for Research on Cancer (IARC), World Health Organization, Lyon Cedex, France
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5
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G1/S restriction point coordinates phasic gene expression and cell differentiation. Nat Commun 2022; 13:3696. [PMID: 35760790 PMCID: PMC9237072 DOI: 10.1038/s41467-022-31101-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2021] [Accepted: 05/31/2022] [Indexed: 01/19/2023] Open
Abstract
Pluripotent embryonic stem cells have a unique cell cycle structure with a suppressed G1/S restriction point and little differential expression across the cell cycle phases. Here, we evaluate the link between G1/S restriction point activation, phasic gene expression, and cellular differentiation. Expression analysis reveals a gain in phasic gene expression across lineages between embryonic days E7.5 and E9.5. Genetic manipulation of the G1/S restriction point regulators miR-302 and P27 respectively accelerates or delays the onset of phasic gene expression in mouse embryos. Loss of miR-302-mediated p21 or p27 suppression expedites embryonic stem cell differentiation, while a constitutive Cyclin E mutant blocks it. Together, these findings uncover a causal relationship between emergence of the G1/S restriction point with a gain in phasic gene expression and cellular differentiation.
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6
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Swift ML, Azizkhan-Clifford J. DNA damage-induced sumoylation of Sp1 induces its interaction with RNF4 and degradation in S phase to remove 53BP1 from DSBs and permit HR. DNA Repair (Amst) 2022; 111:103289. [DOI: 10.1016/j.dnarep.2022.103289] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Revised: 01/26/2022] [Accepted: 01/29/2022] [Indexed: 02/06/2023]
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7
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Swift ML, Beishline K, Flashner S, Azizkhan-Clifford J. DSB repair pathway choice is regulated by recruitment of 53BP1 through cell cycle-dependent regulation of Sp1. Cell Rep 2021; 34:108840. [PMID: 33730584 DOI: 10.1016/j.celrep.2021.108840] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2020] [Revised: 09/13/2020] [Accepted: 02/17/2021] [Indexed: 12/14/2022] Open
Abstract
Although many of the factors, epigenetic changes, and cell cycle stages that distinguish repair of double-strand breaks (DSBs) by homologous recombination (HR) from non-homologous end joining (NHEJ) are known, the underlying mechanisms that determine pathway choice are incompletely understood. Previously, we found that the transcription factor Sp1 is recruited to DSBs and is necessary for repair. Here, we demonstrate that Sp1 localizes to DSBs in G1 and is necessary for recruitment of the NHEJ repair factor, 53BP1. Phosphorylation of Sp1-S59 in early S phase evicts Sp1 and 53BP1 from the break site; inhibition of that phosphorylation results in 53BP1 and Sp1 remaining at DSBs in S phase cells, precluding BRCA1 binding and suppressing HR. Expression of Sp1-S59A increases sensitivity of BRCA1+/+ cells to poly (ADP-ribose) polymerase (PARP) inhibition similar to BRCA1 deficiency. These data demonstrate how Sp1 integrates the cell cycle and DSB repair pathway choice to favor NHEJ.
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Affiliation(s)
- Michelle L Swift
- Department of Biochemistry and Molecular Biology, Drexel University College of Medicine, Philadelphia, PA, USA
| | - Kate Beishline
- Department of Biochemistry and Molecular Biology, Drexel University College of Medicine, Philadelphia, PA, USA
| | - Samuel Flashner
- Department of Biochemistry and Molecular Biology, Drexel University College of Medicine, Philadelphia, PA, USA
| | - Jane Azizkhan-Clifford
- Department of Biochemistry and Molecular Biology, Drexel University College of Medicine, Philadelphia, PA, USA.
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8
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Tange R, Tachibana R, Sato T. Phosphorylation of Specificity Protein 3 Is Critical for Activation of β4-Galactosyltransferase 3 Gene Promoter in SH-SY5Y Human Neuroblastoma Cell Line. Biol Pharm Bull 2021; 44:557-563. [PMID: 33504757 DOI: 10.1248/bpb.b20-00906] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Elevated expression of β4-galactosyltransferase (β4GalT) 3 is correlated with poor clinical outcome of neuroblastoma patients. Our recent study has revealed that the transcription of the β4GalT3 gene is activated by Specificity protein (Sp) 3 in SH-SY5Y human neuroblastoma cell line. Here we report the biological significance of the Sp3 phosphorylation in the transcriptional activation of the β4GalT3 gene. The treatment of SH-SY5Y cells with 10% fetal bovine serum (FBS) increased the mitogen-activated protein kinase (MAPK) signaling and the promoter activity of the β4GalT3 gene. Meanwhile, the treatment with U0126, an inhibitor for MAPK kinase, decreased the MAPK signaling and the promoter activity. These findings indicate that the transcriptional activation of the β4GalT3 gene is mediated by the MAPK signaling. In SH-SY5Y cells cultured in the medium containing 10% FBS, the serine (Ser) residues in Sp3 were phosphorylated. Human Sp3 contains four Ser residues, Ser73, Ser563, Ser566, and Ser646, as the putative phosphorylation sites. Sp3 mutant with the mutation of Ser73 did not decrease the promoter activation of the β4GalT3 gene, indicating that Ser73 is uninvolved in the promoter activation of the β4GalT3 gene by Sp3. In contrast, Sp3 mutants with the mutations of Ser563, Ser566, and Ser646 significantly reduced the promoter activation by Sp3. The results suggest that the phosphorylation of these Ser residues is implicated in the promoter activation by Sp3. This study demonstrates that the phosphorylation of Sp3 plays important roles in the transcriptional activation of the β4GalT3 gene in human neuroblastoma.
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Affiliation(s)
- Riho Tange
- Laboratory of Glycobiology, Department of Bioengineering, Nagaoka University of Technology
| | - Ryuji Tachibana
- Laboratory of Glycobiology, Department of Bioengineering, Nagaoka University of Technology
| | - Takeshi Sato
- Laboratory of Glycobiology, Department of Bioengineering, Nagaoka University of Technology
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9
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Moradifard S, Hoseinbeyki M, Emam MM, Parchiniparchin F, Ebrahimi-Rad M. Association of the Sp1 binding site and -1997 promoter variations in COL1A1 with osteoporosis risk: The application of meta-analysis and bioinformatics approaches offers a new perspective for future research. MUTATION RESEARCH. REVIEWS IN MUTATION RESEARCH 2020; 786:108339. [PMID: 33339581 DOI: 10.1016/j.mrrev.2020.108339] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2019] [Revised: 08/11/2020] [Accepted: 10/06/2020] [Indexed: 12/21/2022]
Abstract
As a complex disease, osteoporosis is influenced by several genetic markers. Many studies have examined the link between the Sp1 binding site +1245 G > T (rs1800012) and -1997 G > T (rs1107946) variations in the COL1A1 gene with osteoporosis risk. However, the findings of these studies have been contradictory; therefore, we performed a meta-analysis to aggregate additional information and obtain increased statistical power to more efficiently estimate this correlation. A meta-analysis was conducted with studies published between 1991-2020 that were identified by a systematic electronic search of the Scopus and Clarivate Analytics databases. Studies with bone mineral density (BMD) data and complete genotypes of the single-nucleotide variations (SNVs) for the overall and postmenopausal female population were included in this meta-analysis and analyzed using the R metaphor package. A relationship between rs1800012 and significantly decreased BMD values at the lumbar spine and femoral neck was found in individuals carrying the "ss" versus the "SS" genotype in the overall population according to a random effects model (p < 0.0001). Similar results were also found in the postmenopausal female population (p = 0.003 and 0.0002, respectively). Such findings might be an indication of increased osteoporosis risk in both studied groups in individuals with the "ss" genotype. Although no association was identified between the -1997 G > T and low BMD in the overall population, those individuals with the "GT" genotype showed a higher level of BMD than those with "GG" in the subgroup analysis (p = 0.007). To determine which transcription factor (TF) might bind to the -1997 G > T in COL1A1, 45 TFs were identified based on bioinformatics predictions. According to the GSE35958 microarray dataset, 16 of 45 TFs showed differential expression profiles in osteoporotic human mesenchymal stem cells relative to normal samples from elderly donors. By identifying candidate TFs for the -1997 G > T site, our study offers a new perspective for future research.
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Affiliation(s)
| | | | - Mohammad Mehdi Emam
- Rheumatology Ward, Loghman Hospital, Shahid Beheshti Medical University (SBMU), Tehran, Iran
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Vagapova ER, Lebedev TD, Tikhonova AD, Goikhman BV, Ivanenko KA, Spirin PV, Prassolov VS. High Expression Level of SP1, CSF1R, and PAK1 Correlates with Sensitivity of Leukemia Cells to the Antibiotic Mithramycin. Mol Biol 2020. [DOI: 10.1134/s002689332003019x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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11
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Vellingiri B, Iyer M, Devi Subramaniam M, Jayaramayya K, Siama Z, Giridharan B, Narayanasamy A, Abdal Dayem A, Cho SG. Understanding the Role of the Transcription Factor Sp1 in Ovarian Cancer: from Theory to Practice. Int J Mol Sci 2020; 21:E1153. [PMID: 32050495 PMCID: PMC7038193 DOI: 10.3390/ijms21031153] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Revised: 02/01/2020] [Accepted: 02/04/2020] [Indexed: 12/23/2022] Open
Abstract
Ovarian cancer (OC) is one of the deadliest cancers among women contributing to high risk of mortality, mainly owing to delayed detection. There is no specific biomarker for its detection in early stages. However, recent findings show that over-expression of specificity protein 1 (Sp1) is involved in many OC cases. The ubiquitous transcription of Sp1 apparently mediates the maintenance of normal and cancerous biological processes such as cell growth, differentiation, angiogenesis, apoptosis, cellular reprogramming and tumorigenesis. Sp1 exerts its effects on cellular genes containing putative GC-rich Sp1-binding site in their promoters. A better understanding of the mechanisms underlying Sp1 transcription factor (TF) regulation and functions in OC tumorigenesis could help identify novel prognostic markers, to target cancer stem cells (CSCs) by following cellular reprogramming and enable the development of novel therapies for future generations. In this review, we address the structure, function, and biology of Sp1 in normal and cancer cells, underpinning the involvement of Sp1 in OC tumorigenesis. In addition, we have highlighted the influence of Sp1 TF in cellular reprogramming of iPSCs and how it plays a role in controlling CSCs. This review highlights the drugs targeting Sp1 and their action on cancer cells. In conclusion, we predict that research in this direction will be highly beneficial for OC treatment, and chemotherapeutic drugs targeting Sp1 will emerge as a promising therapy for OC.
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Affiliation(s)
- Balachandar Vellingiri
- Human Molecular Cytogenetics and Stem Cell Laboratory, Department of Human Genetics and Molecular Biology, Bharathiar University, Coimbatore 641046, India
| | - Mahalaxmi Iyer
- Department of Zoology, Avinashilingam Institute for Home Science and Higher Education for Women, Coimbatore 641043, India; (M.I.); (K.J.)
| | - Mohana Devi Subramaniam
- Department of Genetics and Molecular Biology, Vision Research Foundation, Sankara Nethralaya, Chennai 600006, India;
| | - Kaavya Jayaramayya
- Department of Zoology, Avinashilingam Institute for Home Science and Higher Education for Women, Coimbatore 641043, India; (M.I.); (K.J.)
| | - Zothan Siama
- Department of Zoology, School of Life-science, Mizoram University, Aizawl 796004, Mizoram, India;
| | - Bupesh Giridharan
- R&D Wing, Sree Balaji Medical College and Hospital (SBMCH), BIHER, Chromepet, Chennai 600044, Tamil Nadu, India;
| | - Arul Narayanasamy
- Disease Proteomics Laboratory, Department of Zoology, Bharathiar University, Coimbatore 641046, Tamil Nadu, India;
| | - Ahmed Abdal Dayem
- Molecular & Cellular Reprogramming Center, Department of Stem Cell & Regenerative Biotechnology, Konkuk University, Seoul 05029, Korea;
| | - Ssang-Goo Cho
- Molecular & Cellular Reprogramming Center, Department of Stem Cell & Regenerative Biotechnology, Konkuk University, Seoul 05029, Korea;
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Tange R, Tomatsu T, Sato T. Transcription of human β4-galactosyltransferase 3 is regulated by differential DNA binding of Sp1/Sp3 in SH-SY5Y human neuroblastoma and A549 human lung cancer cell lines. Glycobiology 2019; 29:211-221. [PMID: 30561605 DOI: 10.1093/glycob/cwy109] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2018] [Revised: 12/02/2018] [Accepted: 12/17/2018] [Indexed: 12/28/2022] Open
Abstract
Poor prognosis of neuroblastoma patients has been shown to be associated with increased expression of β4-galactosyltransferase (β4GalT) 3. To address the underlying mechanism of the increased expression of β4GalT3, the transcriptional regulation of the human β4GalT3 gene was investigated in SH-SY5Y human neuroblastoma cell line comparing with A549 human lung cancer cell line, in which the β4GalT3 gene expression was the lowest among four cancer cell lines examined. The core promoter region was identified between nucleotides -69 and -6 relative to the transcriptional start site, and the same region was utilized in both cell lines. The promoter region contained two Specificity protein (Sp)1/3-binding sites at nucleotide positions -39/-30 and -19/-10, and the sites were crucial for the promoter activity. Although the gene expression of Sp family transcription factors Sp1 and Sp3 was comparable in each cell line, Sp3 bound to the promoter region in SH-SY5Y cells whereas Sp1 bound to the region in A549 cells. The promoter activities were enhanced by Sp1 and Sp3 in SH-SY5Y cells. In contrast, the promoter activities were enhanced by Sp1 but reduced by Sp3 in A549 cells. Furthermore, the function of each Sp1/3-binding site differed between SH-SY5Y and A549 cells due to the differential binding of Sp1/Sp3. These findings suggest that the transcription of the β4GalT3 gene is regulated by differential DNA binding of Sp3 and Sp1 in neuroblastoma and lung cancer. The increased expression of β4GalT3 in neuroblastoma may be ascribed to the enhanced expression of Sp3, which is observed for various cancers.
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Affiliation(s)
- Riho Tange
- Laboratory of Glycobiology, Department of Bioengineering, Nagaoka University of Technology, Nagaoka, Niigata, Japan
| | - Takuya Tomatsu
- Laboratory of Glycobiology, Department of Bioengineering, Nagaoka University of Technology, Nagaoka, Niigata, Japan
| | - Takeshi Sato
- Laboratory of Glycobiology, Department of Bioengineering, Nagaoka University of Technology, Nagaoka, Niigata, Japan
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Silencing of Transcription Factor Sp1 Promotes SN1 Transporter Regulation by Ammonia in Mouse Cortical Astrocytes. Int J Mol Sci 2019; 20:ijms20020234. [PMID: 30634395 PMCID: PMC6359076 DOI: 10.3390/ijms20020234] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2018] [Revised: 12/27/2018] [Accepted: 12/27/2018] [Indexed: 12/15/2022] Open
Abstract
The involvement of the astrocytic SN1 (SNAT3) transporter in ammonia-induced l-glutamine retention was recently documented in mouse-cultured astrocytes. Here we investigated the involvement of specificity protein 1 (Sp1) transcription factor in SN1 regulation in ammonium chloride (“ammonia”)-treated astrocytes. Sp1 expression and its cellular localization were determined using real-time qPCR, Western blot, and confocal microscopy. Sp1 binding to Snat3 promoter was analyzed by chromatin immunoprecipitation. The role of Sp1 in SN1 expression and SN1-mediated [3H]glutamine uptake in ammonia-treated astrocytes was verified using siRNA and mithramycin A. The involvement of protein kinase C (PKC) isoforms in Sp1 level/phosphorylation status was verified using siRNA technology. Sp1 translocation to the nuclei and its enhanced binding to the Snat3 promoter, along with Sp1 dependence of system N-mediated [3H]glutamine uptake, were observed in astrocytes upon ammonia exposure. Ammonia decreased the level of phosphorylated Sp1, and the effect was reinforced by long-term incubation with PKC modulator, phorbol 12-myristate 13-acetate, which is a treatment likely to dephosphorylate Sp1. Furthermore, silencing of the PKCδ isoform appears to enhance the ammonia effect on the Sp1 level. Collectively, the results demonstrate the regulatory role of Sp1 in regulation of SN1 expression and activity in ammonia-treated astrocytes and implicate altered Sp1 phosphorylation status in this capacity.
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14
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Liu R, Tan Q, Luo Q. Decreased expression level and DNA-binding activity of specificity protein 1 via cyclooxygenase-2 inhibition antagonizes radiation resistance, cell migration and invasion in radiation-resistant lung cancer cells. Oncol Lett 2018; 16:3029-3037. [PMID: 30127893 PMCID: PMC6096147 DOI: 10.3892/ol.2018.9035] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2015] [Accepted: 04/27/2018] [Indexed: 12/15/2022] Open
Abstract
Radiation is able to inhibit tumor growth, promote tumor cell apoptosis and prolong patient survival. However, radiation resistance remains a major impediment to radiotherapy. Local and metastatic recurrences following radiation are still large impediments to overall survival. Although cyclooxygenase-2 (COX-2) inhibitors may induce radiation sensitivity in cancer cells, the underlying mechanisms are not fully understood. The present study demonstrated high potential for cell proliferation, migration and invasion in radiation-resistant lung cancer cell lines. The present study observed the overexpression of specificity protein 1 (Sp1) in these cells, and the overexpression of Sp1 induced upregulation of matrix metalloproteinase (MMP)-2, MMP-9, B cell lymphoma-2, in addition to a high potential for radiation resistance, migration and invasion in these cells. The present study revealed that the COX-2 selective inhibitor, celecoxib, enhanced radiation sensitivity and inhibited migration and invasion in these cells by inhibiting the expression and DNA-binding activity of Sp1. Furthermore, celecoxib downregulated Sp1 by inhibiting c-Jun N-terminal kinase (JNK). Taken together, the present study demonstrated that Sp1 overexpression in radiation-resistant cancer cells and COX-2 inhibitors enhanced radiation sensitivity and inhibited the migration and invasion of cancer cells, at least partially, via inactivation of the JNK/Sp1 signaling pathway and a decrease in Sp1 DNA-binding activity.
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Affiliation(s)
- Ruijun Liu
- Department of Shanghai Lung Cancer Center, Shanghai Chest Hospital, Shanghai Jiao Tong University, Shanghai 200030, P.R. China
| | - Qiang Tan
- Department of Shanghai Lung Cancer Center, Shanghai Chest Hospital, Shanghai Jiao Tong University, Shanghai 200030, P.R. China
| | - Qingquan Luo
- Department of Shanghai Lung Cancer Center, Shanghai Chest Hospital, Shanghai Jiao Tong University, Shanghai 200030, P.R. China
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15
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Gga-miR-130b-3p inhibits MSB1 cell proliferation, migration, invasion, and its downregulation in MD tumor is attributed to hypermethylation. Oncotarget 2018; 9:24187-24198. [PMID: 29849932 PMCID: PMC5966247 DOI: 10.18632/oncotarget.24679] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2017] [Accepted: 02/27/2018] [Indexed: 01/07/2023] Open
Abstract
Marek's disease is an oncogenic and lymphoproliferative disease of chickens caused by Marek's disease virus. Hypermethylation or hypomethylation of CpG islands in gene promoter region are involved in the initiation and progression of carcinogenesis. In this study, we analyzed differential methylation levels of upstream region of gga-miR-130b-3p gene between Marek's disease virus-infected tumorous and non-infected spleens. Around the upstream 1 kb of gga-miR-130b-3p gene, two amplicons were designed that covered 616 bp. There were forty-eight CpG sites in this region. CpG sites in this region presented higher methylation level in tumorous spleens compared with that in non-infected ones. There were eight CpG sites significantly hypermethylated in tumorous spleens. The expression level of three DNA methyltransferases including DNMT1, DNMT3a and DNMT3b increased and the expression level of Tet ten-eleven translocation protein 2 remarkably decreased in tumorous spleens. Hypermethylation in the upstream region of gga-miR-130b-3p gene might be a direct reason for its downregulation in MD tumorous tissues. Moreover, cell proliferation of Marek's disease lymphoblastoid cell line MDCC-MSB1 was remarkably inhibited at 24, 36, 48, 60 and 72 h post-gga-miR-130b-3p-agomir transfection. The transwell migration assay indicated cell number of migration was significantly lower in miRNA agomir transfection group. Matrix metalloproteinases MMP2 and MMP9 are involved in tumor invasion, and their protein levels were significantly downregulated at 72 h post-miRNA-agomir transfection. Collectively, these results indicated that hypermethylation in upstream region of gga-miR-130b-3p gene contributed to its downregulation in tumorous tissues. Gga-miR-130b-3p plays an inhibitory role in lymphomatous cell transformation.
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16
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Lee MH, Dong Z, Surh YJ, Choi BY. hYSK1 promotes cancer cell proliferation and migration through negative regulation of p16 INK4a under hypoxic conditions. Oncotarget 2017; 8:89072-89085. [PMID: 29179500 PMCID: PMC5687670 DOI: 10.18632/oncotarget.21654] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Accepted: 08/27/2017] [Indexed: 11/25/2022] Open
Abstract
The alteration of expression of p16INK4a, a well-known cyclin-dependent kinase inhibitor involved in cell cycle control, in tumors is unclear, especially under hypoxic conditions. To evaluate p16INK4a regulation, we performed a protein microarray analysis. Among 1,800 proteins in the array, we identified hYSK1 as a novel protein that interacts with the tumor suppressor p16INK4a. hYSK1, a member of the Ste20 family of serine/threonine protein kinases, promotes cell migration and tumorigenesis and is activated by oxidative stress. However, the molecular mechanisms underlying the oncogenic potential of hYSK1 remain elusive. Here, we report that hYSK1 interacts with p16INK4a under hypoxic conditions in tumors, where it negatively regulates p16INK4a, enhancing cancer cell migration. Hypoxic stimulation of hYSK1 reduces p16INK4a accumulation through p16 promoter regulation to interact with unphosporylated SP-1 and increases matrix metalloproteinase-2 (MMP-2) expression by activating the MMP-2 promoter associated with cell migration and proliferation.Conversely, knocking down hYSK1 expression activated p16INK4a expression and suppressed MMP-2 expression. Thus, hYSK1 is necessary as a trigger for inactivating p16INK4a and activating MMP-2 during tumor migration, suggesting that hYSK1 is a specific negative regulator of the tumor suppressor p16INK4a and may represent a novel molecular target for reactivation of tumor suppressor genes in humans.
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Affiliation(s)
- Mee-Hyun Lee
- China-US (Henan) Hormel Cancer Institute, Zhengzhou 450008, China
| | - Zigang Dong
- China-US (Henan) Hormel Cancer Institute, Zhengzhou 450008, China.,The Hormel Institute, University of Minnesota, Austin, MN 55912, USA
| | - Young-Joon Surh
- Tumor Microenvironment Global Core Research Center, College of Pharmacy, Seoul National University, Seoul 08826, South Korea.,Research Institute of Pharmaceutical Sciences, College of Pharmacy, Seoul National University, Seoul 08826, South Korea.,Department of Molecular Medicine and Biopharmaceutical Sciences, Graduate School of Convergence Sciences and Technology, Seoul National University, Seoul 08826, South Korea.,Cancer Research Institute, Seoul National University, Seoul 110-744, South Korea
| | - Bu Young Choi
- Department of Pharmaceutical Science & Engineering, Seowon University, Cheongju 28674, South Korea
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Bajpai R, Nagaraju GP. Specificity protein 1: Its role in colorectal cancer progression and metastasis. Crit Rev Oncol Hematol 2017; 113:1-7. [PMID: 28427500 DOI: 10.1016/j.critrevonc.2017.02.024] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2016] [Indexed: 01/20/2023] Open
Abstract
Specificity protein 1 (Sp1) is a widely expressed transcription factor that plays an important role in the promotion of oncogenes required for tumor survival, progression and metastasis. Sp1 is highly expressed in several cancers including colorectal cancer (CRC) and is related to poor prognosis. Therefore, targeting Sp1 is a rational for CRC therapy. In this review, we will recapitulate the current understanding of Sp1 signaling, its molecular mechanisms, and its potential involvement in CRC growth, progression and metastasis. We will also discuss the current therapeutic drugs for CRC and their mechanism of action via Sp1.
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Affiliation(s)
- Richa Bajpai
- Department of Hematology and Medical Oncology, Winship Cancer Institute of Emory University, Atlanta, GA, 30322, USA
| | - Ganji Purnachandra Nagaraju
- Department of Hematology and Medical Oncology, Winship Cancer Institute of Emory University, Atlanta, GA, 30322, USA.
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18
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Fong Y, Wu CY, Chang KF, Chen BH, Chou WJ, Tseng CH, Chen YC, Wang HMD, Chen YL, Chiu CC. Dual roles of extracellular signal-regulated kinase (ERK) in quinoline compound BPIQ-induced apoptosis and anti-migration of human non-small cell lung cancer cells. Cancer Cell Int 2017; 17:37. [PMID: 28286419 PMCID: PMC5339964 DOI: 10.1186/s12935-017-0403-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2016] [Accepted: 02/16/2017] [Indexed: 02/06/2023] Open
Abstract
Background 2,9-Bis[2-(pyrrolidin-1-yl)ethoxy]-6-{4-[2-(pyrrolidin-1-yl)ethoxy] phenyl}-11H-indeno[1,2-c]quinoline-11-one (BPIQ), is a synthetic quinoline analog. A previous study showed the anti-cancer potential of BPIQ through modulating mitochondrial-mediated apoptosis. However, the effect of BPIQ on cell migration, an index of cancer metastasis, has not yet been examined. Furthermore, among signal pathways involved in stresses, the members of the mitogen-activated protein kinase (MAPK) family are crucial for regulating the survival and migration of cells. In this study, the aim was to explore further the role of MAPK members, including JNK, p38 and extracellular signal-regulated kinase (ERK) in BPIQ-induced apoptosis and anti-migration of human non-small cell lung cancer (NSCLC) cells. Methods Western Blot assay was performed for detecting the activation of MAPK members in NSCLC H1299 cells following BPIQ administration. Cellular proliferation was determined using a trypan blue exclusion assay. Cellular apoptosis was detected using flow cytometer-based Annexin V/propidium iodide dual staining. Cellular migration was determined using wound-healing assay and Boyden’s chamber assay. Zymography assay was performed for examining MMP-2 and -9 activities. The assessment of MAPK inhibition was performed for further validating the role of JNK, p38, and ERK in BPIQ-induced growth inhibition, apoptosis, and migration of NSCLC cells. Results Western Blot assay showed that BPIQ treatment upregulates the phosphorylated levels of both MAPK proteins JNK and ERK. However, only ERK inhibitor rescues BPIQ-induced growth inhibition of NSCLC H1299 cells. The results of Annexin V assay further confirmed the pro-apoptotic role of ERK in BPIQ-induced cell death of H1299 cells. The results of wound healing and Boyden chamber assays showed that sub-IC50 (sub-lethal) concentrations of BPIQ cause a significant inhibition of migration in H1299 cells accompanied with downregulating the activity of MMP-2 and -9, the motility index of cancer cells. Inhibition of ERK significantly enhances BPIQ-induced anti-migration of H1299 cells. Conclusions Our results suggest ERK may play dual roles in BPIQ-induced apoptosis and anti-migration, and it would be worthwhile further developing strategies for treating chemoresistant lung cancers through modulating ERK activity. Electronic supplementary material The online version of this article (doi:10.1186/s12935-017-0403-0) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Yao Fong
- Department of Thoracic Surgery, Chi-Mei Medical Center, Tainan, 710 Taiwan
| | - Chang-Yi Wu
- Department of Biological Sciences, National Sun Yat-sen University, Kaohsiung, 804 Taiwan.,Department of Biotechnology, Kaohsiung Medical University, Kaohsiung, 807 Taiwan
| | - Kuo-Feng Chang
- Department of Biotechnology, Kaohsiung Medical University, Kaohsiung, 807 Taiwan
| | - Bing-Hung Chen
- Department of Biotechnology, Kaohsiung Medical University, Kaohsiung, 807 Taiwan.,The Institute of Biomedical Sciences, National Sun Yat-Sen University, Kaohsiung, 804 Taiwan
| | - Wan-Ju Chou
- Department of Biotechnology, Kaohsiung Medical University, Kaohsiung, 807 Taiwan
| | - Chih-Hua Tseng
- School of Pharmacy, Kaohsiung Medical University, Kaohsiung, 807 Taiwan
| | - Yen-Chun Chen
- Department of Biotechnology, Kaohsiung Medical University, Kaohsiung, 807 Taiwan
| | - Hui-Min David Wang
- Graduate Institute of Biomedical Engineering, National Chung Hsing University, Taichung, 402 Taiwan
| | - Yeh-Long Chen
- Department of Medicinal and Applied Chemistry, Kaohsiung Medical University, Kaohsiung, 807 Taiwan
| | - Chien-Chih Chiu
- Department of Biological Sciences, National Sun Yat-sen University, Kaohsiung, 804 Taiwan.,Department of Biotechnology, Kaohsiung Medical University, Kaohsiung, 807 Taiwan.,Translational Research Center, Cancer Center and Department of Medical Research, Kaohsiung Medical University Hospital, Kaohsiung, 807 Taiwan.,Research Center for Environment Medicine, Kaohsiung Medical University, Kaohsiung, 807 Taiwan.,Graduate Institute of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, 807 Taiwan
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19
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O’Connor L, Gilmour J, Bonifer C. The Role of the Ubiquitously Expressed Transcription Factor Sp1 in Tissue-specific Transcriptional Regulation and in Disease. THE YALE JOURNAL OF BIOLOGY AND MEDICINE 2016; 89:513-525. [PMID: 28018142 PMCID: PMC5168829] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Sp1 belongs to the 26 member strong Sp/KLF family of transcription factors. It is a paradigm for a ubiquitously expressed transcription factor and is involved in regulating the expression of genes associated with a wide range of cellular processes in mammalian cells. Sp1 can interact with a range of proteins, including other transcription factors, members of the transcription initiation complex and epigenetic regulators, enabling tight regulation of its target genes. In this review, we discuss the mechanisms involved in Sp1-mediated transcriptional regulation, as well as how a ubiquitous transcription factor can be involved in establishing a tissue-specific pattern of gene expression and mechanisms by which its activity may be regulated. We also consider the role of Sp1 in human diseases, such as cancer.
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Affiliation(s)
- Leigh O’Connor
- Institute of Cancer and Genomic Sciences, Institute of Biomedical Research, College of Medical and Dental Sciences, University of Birmingham, UK
| | - Jane Gilmour
- Institute of Cancer and Genomic Sciences, Institute of Biomedical Research, College of Medical and Dental Sciences, University of Birmingham, UK
| | - Constanze Bonifer
- Institute of Cancer and Genomic Sciences, Institute of Biomedical Research, College of Medical and Dental Sciences, University of Birmingham, UK
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20
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Yang F, Du Y, Zhang J, Jiang Z, Wang L, Hong B. Low-density lipoprotein upregulate SR-BI through Sp1 Ser702 phosphorylation in hepatic cells. BIOCHIMICA ET BIOPHYSICA ACTA 2016; 1861:1066-1075. [PMID: 27320013 DOI: 10.1016/j.bbalip.2016.06.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2016] [Revised: 05/04/2016] [Accepted: 06/10/2016] [Indexed: 01/25/2023]
Abstract
Scavenger receptor class B type I (SR-BI) is one of the key proteins in the process of reverse cholesterol transport (RCT), and its major function is to uptake high density lipoprotein (HDL) cholesterol from plasma into liver cells. The regulation of SR-BI expression is important for controlling serum lipid content and reducing the risks of cardiovascular diseases. Here we found that SR-BI expression was significantly increased by LDL in vivo and in vitro, and the transcription factor specific protein 1 (Sp1) plays a critical role in this process. Results from co-immunoprecipitation experiments indicate that the activation of SR-BI was associated with Sp1-recruited protein complexes in the promoter region of SR-BI, where histone acetyltransferase p300 was recruited and histone deacetylase HDAC1 was dismissed. As a result, histone acetylation increased, leading to activation of SR-BI transcription. With further investigation, we found that LDL phosphorylated Sp1 through ERK1/2 pathway, which affected Sp1 protein complexes formation in SR-BI promoter. Using mass spectrometry and site directed mutagenesis, a new Sp1 phosphorylation site Ser702 was defined to be associated with Sp1-HDAC1 interaction and may be important in SR-BI activation, shedding light on the knowledge of delicate mechanism of hepatic HDL receptor SR-BI gene modulation by LDL.
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Affiliation(s)
- Fan Yang
- Key Laboratory of Biotechnology of Antibiotics of Ministry of Health, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences and Peking Union Medical College, No. 1 Tiantan Xili, Beijing 100050, China
| | - Yu Du
- Key Laboratory of Biotechnology of Antibiotics of Ministry of Health, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences and Peking Union Medical College, No. 1 Tiantan Xili, Beijing 100050, China
| | - Jin Zhang
- Key Laboratory of Biotechnology of Antibiotics of Ministry of Health, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences and Peking Union Medical College, No. 1 Tiantan Xili, Beijing 100050, China
| | - Zhibo Jiang
- Key Laboratory of Biotechnology of Antibiotics of Ministry of Health, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences and Peking Union Medical College, No. 1 Tiantan Xili, Beijing 100050, China
| | - Li Wang
- Key Laboratory of Biotechnology of Antibiotics of Ministry of Health, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences and Peking Union Medical College, No. 1 Tiantan Xili, Beijing 100050, China.
| | - Bin Hong
- Key Laboratory of Biotechnology of Antibiotics of Ministry of Health, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences and Peking Union Medical College, No. 1 Tiantan Xili, Beijing 100050, China.
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21
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Vizcaíno C, Mansilla S, Portugal J. Sp1 transcription factor: A long-standing target in cancer chemotherapy. Pharmacol Ther 2015; 152:111-24. [PMID: 25960131 DOI: 10.1016/j.pharmthera.2015.05.008] [Citation(s) in RCA: 271] [Impact Index Per Article: 30.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2015] [Accepted: 05/04/2015] [Indexed: 11/25/2022]
Abstract
Sp1 (specificity protein 1) is a well-known member of a family of transcription factors that also includes Sp2, Sp3 and Sp4, which are implicated in an ample variety of essential biological processes and have been proven important in cell growth, differentiation, apoptosis and carcinogenesis. Sp1 activates the transcription of many cellular genes that contain putative CG-rich Sp-binding sites in their promoters. Sp1 and Sp3 proteins bind to similar, if not the same, DNA tracts and compete for binding, thus they can enhance or repress gene expression. Evidences exist that the Sp-family of proteins regulates the expression of genes that play pivotal roles in cell proliferation and metastasis of various tumors. In patients with a variety of cancers, high levels of Sp1 protein are considered a negative prognostic factor. A plethora of compounds can interfere with the trans-activating activities of Sp1 and other Sp proteins on gene expression. Several pathways are involved in the down-regulation of Sp proteins by compounds with different mechanisms of action, which include not only the direct interference with the binding of Sp proteins to their putative DNA binding sites, but also promoting the degradation of Sp protein factors. Down-regulation of Sp transcription factors and Sp1-regulated genes is drug-dependent and it is determined by the cell context. The acknowledgment that several of those compounds are safe enough might accelerate their introduction into clinical usage in patients with tumors that over-express Sp1.
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Affiliation(s)
- Carolina Vizcaíno
- Instituto de Biología Molecular de Barcelona, CSIC, Parc Científic de Barcelona, E-08028 Barcelona, Spain
| | - Sylvia Mansilla
- Instituto de Biología Molecular de Barcelona, CSIC, Parc Científic de Barcelona, E-08028 Barcelona, Spain
| | - José Portugal
- Instituto de Biología Molecular de Barcelona, CSIC, Parc Científic de Barcelona, E-08028 Barcelona, Spain.
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22
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WANG WENJIE, SHENG WENJIONG, YU CHENXIAO, CAO JIANPING, ZHOU JUNDONG, WU JINCHANG, ZHANG HUOJUN, ZHANG SHUYU. REV3L modulates cisplatin sensitivity of non-small cell lung cancer H1299 cells. Oncol Rep 2015; 34:1460-8. [DOI: 10.3892/or.2015.4121] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2015] [Accepted: 06/03/2015] [Indexed: 11/05/2022] Open
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Beishline K, Azizkhan-Clifford J. Sp1 and the 'hallmarks of cancer'. FEBS J 2015; 282:224-58. [PMID: 25393971 DOI: 10.1111/febs.13148] [Citation(s) in RCA: 369] [Impact Index Per Article: 41.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2014] [Revised: 09/26/2014] [Accepted: 11/10/2014] [Indexed: 12/19/2022]
Abstract
For many years, transcription factor Sp1 was viewed as a basal transcription factor and relegated to a role in the regulation of so-called housekeeping genes. Identification of Sp1's role in recruiting the general transcription machinery in the absence of a TATA box increased its importance in gene regulation, particularly in light of recent estimates that the majority of mammalian genes lack a TATA box. In this review, we briefly consider the history of Sp1, the founding member of the Sp family of transcription factors. We review the evidence suggesting that Sp1 is highly regulated by post-translational modifications that positively and negatively affect the activity of Sp1 on a wide array of genes. Sp1 is over-expressed in many cancers and is associated with poor prognosis. Targeting Sp1 in cancer treatment has been suggested; however, our review of the literature on the role of Sp1 in the regulation of genes that contribute to the 'hallmarks of cancer' illustrates the extreme complexity of Sp1 functions. Sp1 both activates and suppresses the expression of a number of essential oncogenes and tumor suppressors, as well as genes involved in essential cellular functions, including proliferation, differentiation, the DNA damage response, apoptosis, senescence and angiogenesis. Sp1 is also implicated in inflammation and genomic instability, as well as epigenetic silencing. Given the apparently opposing effects of Sp1, a more complete understanding of the function of Sp1 in cancer is required to validate its potential as a therapeutic target.
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Affiliation(s)
- Kate Beishline
- Department of Biochemistry and Molecular Biology, Drexel University College of Medicine, Philadelphia, PA, USA
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Wutthisathapornchai A, Vongpipatana T, Muangsawat S, Boonsaen T, MacDonald MJ, Jitrapakdee S. Multiple E-boxes in the distal promoter of the rat pyruvate carboxylase gene function as a glucose-responsive element. PLoS One 2014; 9:e102730. [PMID: 25054881 PMCID: PMC4108332 DOI: 10.1371/journal.pone.0102730] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2014] [Accepted: 06/21/2014] [Indexed: 12/22/2022] Open
Abstract
Pyruvate carboxylase (PC) is an anaplerotic enzyme that regulates glucose-induced insulin secretion in pancreatic islets. Dysregulation of its expression is associated with type 2 diabetes. Herein we describe the molecular mechanism underlying the glucose-mediated transcriptional regulation of the PC gene. Incubation of the rat insulin cell line INS-1 832/13 with glucose resulted in a 2-fold increase in PC mRNA expression. Transient transfections of the rat PC promoter-luciferase reporter construct in the above cell line combined with mutational analysis indicated that the rat PC gene promoter contains the glucose-responsive element (GRE), comprising three canonical E-boxes (E1, E3 and E4) and one E-box-like element (E2) clustering between nucleotides –546 and –399, upstream of the transcription start site. Mutation of any of these E-boxes resulted in a marked reduction of glucose-mediated transcriptional induction of the reporter gene. Electrophoretic mobility shift assays revealed that the upstream stimulatory factors 1 and 2 (USF1 and USF2) bind to E1, the Specificity Protein-1 (Sp1) binds to E2, USF2 and the carbohydrate responsive element binding protein (ChREBP) binds to E4, while unknown factors binds to E3. High glucose promotes the recruitment of Sp1 to E2 and, USF2 and ChREBP to E4. Silencing the expression of Sp1, USF2 and ChREBP by their respective siRNAs in INS-1 832/13 cells blunted glucose-induced expression of endogenous PC. We conclude that the glucose-mediated transcriptional activation of the rat PC gene is regulated by at least these three transcription factors.
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Affiliation(s)
| | | | - Sureeporn Muangsawat
- Department of Biochemistry, Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Thirajit Boonsaen
- Department of Biochemistry, Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Michael J. MacDonald
- UW Childrens Diabetes Center, University of Wisconsin School of Medicine and Public Health, Madison, WI, United States of America
| | - Sarawut Jitrapakdee
- Department of Biochemistry, Faculty of Science, Mahidol University, Bangkok, Thailand
- * E-mail:
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25
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Dephosphorylation of Sp1 at Ser-59 by protein phosphatase 2A (PP2A) is required for induction of CYP1A1 transcription after treatment with 2,3,7,8-tetrachlorodibenzo-p-dioxin or omeprazole. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2013; 1839:107-15. [PMID: 24382322 DOI: 10.1016/j.bbagrm.2013.12.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2013] [Revised: 12/01/2013] [Accepted: 12/23/2013] [Indexed: 11/23/2022]
Abstract
The aryl hydrocarbon receptor (AhR) is a transcription factor that is activated by either 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) or omeprazole (OP). Activated AhR can induce CYP1A1 transcription by binding to the xenobiotic responsive element (XRE). However, the mechanism of activation of the CYP1A1 promoter region is poorly understood. Previous reports showed that Sp1 could bind to a GC-rich region near the CYP1A1 promoter. This study sought to clarify the function of Sp1 in CYP1A1 transcription. Phosphorylation of Sp1 at Ser-59 (pSer-59) was previously reported to be closely related to transcriptional regulation. We used a site-specific phospho-antibody to show that treatment with TCDD or OP drastically reduced the level of pSer-59 in Sp1 from HepG2 cells. This reduction was too much, we hypothesized that the reduced phosphorylation level resulted from activation of phosphatase activity. Given that pSer-59 is dephosphorylated by PP2A, we examined the effect of a PP2A inhibitor, okadaic acid (OA), on pSer-59 and transcription of CYP1A1. The results showed that OA blocked dephosphorylation of Ser-59 and drastically inhibited transcription of CYP1A1. Similar results were obtained after knockdown of PP2A. Treatment with OA had no effect on the expression of AhR, its nuclear translocation, or its ability to bind to the XRE. Furthermore, dephosphorylation of Sp1 at Ser-59 was not affected by knockdown of AhR. These results indicate that the signals from TCDD or OP caused PP2A-mediated dephosphorylation of Sp1 at Ser-59 and induced CYP1A1 transcription. This signaling pathway was independent of the AhR-mediated pathway.
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26
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DeMaster LK, Rose TM. A critical Sp1 element in the rhesus rhadinovirus (RRV) Rta promoter confers high-level activity that correlates with cellular permissivity for viral replication. Virology 2013; 448:196-209. [PMID: 24314650 DOI: 10.1016/j.virol.2013.10.013] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2013] [Revised: 08/25/2013] [Accepted: 10/08/2013] [Indexed: 10/26/2022]
Abstract
KSHV establishes characteristic latent infections in vitro, while RRV, a related macaque rhadinovirus, establishes characteristic permissive infections with virus replication. We identified cells that are not permissive for RRV replication and recapitulate the latent KSHV infection and reactivation processes. The RRV replication and transactivator (Rta) promoter was characterized in permissive and non-permissive cells and compared to the KSHV Rta promoter. Both promoters contained a critical Sp1 element, had equivalent activities in different cell types, and were inhibited by LANA. RRV and KSHV infections were non-permissive in cells with low Rta promoter activity. While RRV infections were permissive in cells with high basal promoter activity, KSHV infections remained non-permissive. Our studies suggest that RRV lacks the Rta-inducible LANA promoter that is responsible for LANA inhibition of the KSHV Rta promoter and induction of latency during KSHV infection. Instead, the outcome of RRV infection is determined by host factors, such as Sp1.
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Affiliation(s)
- Laura K DeMaster
- Department of Global Health, University of Washington, Seattle, WA 98195, USA; Center for Childhood Infections and Prematurity Research, Seattle Children's Research Institute, Seattle, WA 98101, USA.
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Functional role of post-translational modifications of Sp1 in tumorigenesis. J Biomed Sci 2012; 19:94. [PMID: 23148884 PMCID: PMC3503885 DOI: 10.1186/1423-0127-19-94] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2012] [Accepted: 10/03/2012] [Indexed: 12/17/2022] Open
Abstract
Specific protein 1 (Sp1), the first transcription factor to be isolated, regulates the expression of numerous genes involved in cell proliferation, apoptosis, and differentiation. Recent studies found that an increase in Sp1 transcriptional activity is associated with the tumorigenesis. Moreover, post-translational modifications of Sp1, including glycosylation, phosphorylation, acetylation, sumoylation, ubiquitination, and methylation, regulate Sp1 transcriptional activity and modulate target gene expression by affecting its DNA binding activity, transactivation activity, or protein level. In addition, recent studies have investigated several compounds with anti-cancer activity that could inhibit Sp1 transcriptional activity. In this review, we describe the effect of various post-translational modifications on Sp1 transcriptional activity and discuss compounds that inhibit the activity of Sp1.
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Transcriptional regulation by post-transcriptional modification—Role of phosphorylation in Sp1 transcriptional activity. Gene 2012; 508:1-8. [DOI: 10.1016/j.gene.2012.07.022] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2012] [Revised: 05/22/2012] [Accepted: 07/16/2012] [Indexed: 01/05/2023]
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Saito M, Kohara M, Tsukiyama-Kohara K. Hepatitis C virus promotes expression of the 3β-hydroxysterol δ24-reductase through Sp1. J Med Virol 2012; 84:733-46. [PMID: 22431021 DOI: 10.1002/jmv.23250] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Hepatitis C virus (HCV) establishes chronic infection, which often causes hepatocellular carcinoma. Overexpression of 3β-hydroxysterol Δ24-reductase (DHCR24) by HCV has been shown to impair the p53-mediated cellular response, resulting in tumorigenesis. In the present study, the molecular mechanism by which HCV promotes the expression of DHCR24 was investigated. A significant increase in DHCR24 mRNA transcription was observed in a cell line expressing complete HCV genome, whereas no significant difference in the expression of DHCR24 was seen in cell lines expressing individual viral proteins. The 5'-flanking genomic region of DHCR24 was characterized to explore the genomic region and host factor(s) involved in the transcriptional regulation of DHCR24. As a result, the HCV response element (-167/-140) was identified, which contains AP-2α, MZF-1, and Sp1 binding motifs. The binding affinity of the host factor to this response element was increased in nuclear extracts from cells infected with HCV and corresponded with augmented affinity of Sp1. Both mithramycin A (Sp1 inhibitor) and small interfering RNA targeting Sp1 prevented the binding of host factors to the response element. Silencing of Sp1 also downregulated the increased expression of DHCR24. The binding affinity of Sp1 to the response element was augmented by oxidative stress, whereas upregulation of DHCR24 in cells expressing HCV was blocked significantly by a reactive oxygen species scavenger. Elevated phosphorylation of Sp1 in response to oxidative stress was mediated by the ATM kinase. Thus, activation of Sp1 by oxidative stress is involved in the promotion of expression of DHCR24 by HCV.
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Affiliation(s)
- Makoto Saito
- Department of Experimental Phylaxiology, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan
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Kang DS, Hong KM, Park J, Bae CD. Cyclin A regulates a cell-cycle-dependent expression of CKAP2 through phosphorylation of Sp1. Biochem Biophys Res Commun 2012; 420:822-7. [PMID: 22465120 DOI: 10.1016/j.bbrc.2012.03.081] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2012] [Accepted: 03/15/2012] [Indexed: 11/15/2022]
Abstract
CKAP2 plays crucial roles in proper chromosome segregation and maintaining genomic stability. CKAP2 protein showed cell-cycle-dependent expression, which reached a maximum level at the G2/M phase and disappeared at the onset of G1 phase. To elucidate the mechanisms underlying cell cycle-dependent expression of CKAP2, we cloned and analyzed the human CKAP2 promoter. The upstream 115-bp region from the transcription start site was sufficient for minimal CKAP2 promoter activity. We identified 2 regulatory sequences; a CHR (-110 to -104 bp) and a GC box (-41 to -32 bp). We confirmed Sp1 bound to the GC box using a supershift assay and a ChIP assay. Mutation in the GC box resulted in a near complete loss of CKAP2 promoter activity while mutation in the CHR decreased the promoter activity by 50%. The CHR mutation showed enhanced activity at the G1/S phase, but still retained cyclic activity. The Chromatin IP revealed that the amount of Sp1 bound to the GC box gradually increased and reached a maximum level at the G2/M phase. The amount of Sp1 bound to the GC box was greatly reduced when Cyclin A was depleted, which was restored by adding Cyclin A/Cdk2 complex back into the nuclear extracts. Together, we concluded that the GC box was responsible for the cyclic activity of human CKAP2 promoter through the phosphorylation of Sp1, possibly by Cyclin A/Cdk complex.
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Affiliation(s)
- Du-Seock Kang
- Department of Molecular Cell Biology and Samsung Biomedical Research Institute, Sungkyunkwan University School of Medicine, 300 Chunchundong, Jangangu, Suwon 440-746, Republic of Korea
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Feng J, Zhang Y, Xing D. Low-power laser irradiation (LPLI) promotes VEGF expression and vascular endothelial cell proliferation through the activation of ERK/Sp1 pathway. Cell Signal 2012; 24:1116-25. [PMID: 22326662 DOI: 10.1016/j.cellsig.2012.01.013] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2011] [Revised: 01/10/2012] [Accepted: 01/26/2012] [Indexed: 12/11/2022]
Abstract
Angiogenesis, the growth of new blood vessels from pre-existing vessels, represents an excellent therapeutic target for the treatment of wound healing and cardiovascular disease. Herein, we report that LPLI (low-power laser irradiation) activates ERK/Sp1 (extracellular signal-regulated kinase/specificity protein 1) pathway to promote VEGF expression and vascular endothelial cell proliferation. We demonstrate for the first time that LPLI enhances DNA-binding and transactivation activity of Sp1 on VEGF promoter in vascular endothelial cells. Moreover, Sp1-regulated transcription is in an ERK-dependent manner. Activated ERK by LPLI translocates from cytoplasm to nuclear and leads to increasing interaction with Sp1, triggering a progressive phosphorylation of Sp1 on Thr453 and Thr739, resulting in the upregulation of VEGF expression. Furthermore, selective inhibition of Sp1 by mithramycin-A or shRNA suppresses the promotion effect of LPLI on cell cycle progression and proliferation, which is also significantly abolished by inhibition of ERK activity. These findings highlight the important roles of ERK/Sp1 pathway in angiogenesis, supplying potential strategy for angiogenesis-related diseases with LPLI treatment.
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Affiliation(s)
- Jie Feng
- MOE Key Laboratory of Laser Life Science & Institute of Laser Life Science, College of Biophotonics, South China Normal University, Guangzhou 510631, China
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Law AYS, Yeung BHY, Ching LY, Wong CKC. Sp1 is a transcription repressor to stanniocalcin-1 expression in TSA-treated human colon cancer cells, HT29. J Cell Biochem 2011; 112:2089-96. [PMID: 21465530 DOI: 10.1002/jcb.23127] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Our previous study demonstrated that, stanniocalcin-1 (STC1) was a target of histone deacetylase (HDAC) inhibitors and was involved in trichostatin A (TSA) induced apoptosis in the human colon cancer cells, HT29. In this study, we reported that the transcriptional factor, specificity protein 1 (Sp1) in association with retinoblastoma (Rb) repressed STC1 gene transcription in TSA-treated HT29 cells. Our data demonstrated that, a co-treatment of the cells with TSA and Sp1 inhibitor, mithramycin A (MTM) led to a marked synergistic induction of STC1 transcript levels, STC1 promoter (1 kb)-driven luciferase activity and an increase of apoptotic cell population. The knockdown of Sp1 gene expression in TSA treated cells, revealed the repressor role of Sp1 in STC1 transcription. Using a protein phosphatase inhibitor okadaic acid (OKA), an increase of Sp1 hyperphosphorylation and so a reduction of its transcriptional activity, led to a significant induction of STC1 gene expression. Chromatin immunoprecipitation (ChIP) assay revealed that Sp1 binding on STC1 proximal promoter in TSA treated cells. The binding of Sp1 to STC1 promoter was abolished by the co-treatment of MTM or OKA in TSA-treated cells. Re-ChIP assay illustrated that Sp1-mediated inhibition of STC1 transcription was associated with the recruitment of another repressor molecule, Rb. Collectively our findings identify STC1 is a downstream target of Sp1.
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Affiliation(s)
- Alice Y S Law
- Department of Biology, Hong Kong Baptist University, Kowloon Tong, Hong Kong
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Masuda K, Kimura A, Hanieh H, Nguyen NT, Nakahama T, Chinen I, Otoyo Y, Murotani T, Yamatodani A, Kishimoto T. Aryl hydrocarbon receptor negatively regulates LPS-induced IL-6 production through suppression of histamine production in macrophages. Int Immunol 2011; 23:637-45. [PMID: 21930594 DOI: 10.1093/intimm/dxr072] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Macrophages play a pivotal role in innate immune responses to pathogens via toll-like receptors. We previously demonstrated that aryl hydrocarbon receptor (Ahr) in combination with signal transducer and activator of transcription 1 (Stat1) negatively regulates pro-inflammatory cytokine production by inhibiting nuclear factor-κB activation in macrophages after LPS stimulation. Here, we show that Ahr also negatively regulates production of the pro-inflammatory cytokine IL-6 by suppressing histamine production in macrophages stimulated by LPS. We found that Ahr-Sp1 complex, independent of Stat1, represses histidine decarboxylase expression by inhibiting LPS-induced Sp1 phosphorylation on Ser residues in macrophages; this leads to suppression of histamine production. Moreover, we found that loratadine and chlorpromazine, histamine 1 receptor (H1R) antagonists, more effectively impair the production of LPS-induced IL-6 than that of other inflammatory cytokines in Ahr(-/-) macrophages. Collectively, these results demonstrate that Ahr negatively regulates IL-6 production via H1R signaling through the suppression of histamine production in macrophages following LPS stimulation.
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Affiliation(s)
- Kazuya Masuda
- Laboratory of Immune Regulation, Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan
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Infantino V, Convertini P, Iacobazzi F, Pisano I, Scarcia P, Iacobazzi V. Identification of a novel Sp1 splice variant as a strong transcriptional activator. Biochem Biophys Res Commun 2011; 412:86-91. [PMID: 21798247 DOI: 10.1016/j.bbrc.2011.07.047] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2011] [Accepted: 07/11/2011] [Indexed: 02/03/2023]
Abstract
The transcription factor Sp1 regulates expression of numerous genes involved in many cellular processes. Different post-transcriptional modifications can influence the transcriptional control activity and stability of Sp1. In addition to these modifications, alternative splicing isoforms may also be the basis of its distinct functional activities. In this study, we identified a novel alternative splice isoform of Sp1 named Sp1c. This variant is generated by exclusion of a short domain, which we designate α, through alternative splice acceptor site usage in the exon 3. The existence of this new isoform was confirmed in vivo by Western blotting analysis. Although at very low levels, Sp1c is ubiquitously expressed, as seen in its full-length Sp1. A preliminary characterization of Sp1c shows that: (a) Sp1c works as stronger activator of transcription than full-length Sp1; (b) percentage of HEK293 Sp1c-overexpressing cells is higher in G1 phase and lower in S phase than percentage of HEK293 Sp1-overexpressing cells.
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Affiliation(s)
- Vittoria Infantino
- Department of Pharmaco-Biology, Laboratory of Biochemistry and Molecular Biology, University of Bari, Bari, Italy
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Waby JS, Bingle CD, Corfe BM. Post-translational control of sp-family transcription factors. Curr Genomics 2011; 9:301-11. [PMID: 19471608 PMCID: PMC2685645 DOI: 10.2174/138920208785133244] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2008] [Revised: 05/14/2008] [Accepted: 05/15/2008] [Indexed: 11/22/2022] Open
Abstract
Sp-family transcription factors are widely expressed in human tissues and involved in the regulation of many cellular processes and response to cellular microenvironment. These responses appear to be mediated by alterations in transcription factor affinity for DNA rather than altered protein level. How might such changes be effected? This review will identify the range of known post-translational modifications (PTMs) of Sp-factors and the sometimes conflicting literature about the roles of PTMs in regulating activity. We will speculate on the interaction between cell environment, chromatin microenvironment and the role of PTM in governing functionality of the proteins and the complexes to which they belong.
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Affiliation(s)
- J S Waby
- School of Medicine and Biomedical Sciences, University of Sheffield, Royal Hallamshire Hospital, Sheffield, S10 2JF, UK
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van der Watt PJ, Leaner VD. The nuclear exporter, Crm1, is regulated by NFY and Sp1 in cancer cells and repressed by p53 in response to DNA damage. BIOCHIMICA ET BIOPHYSICA ACTA 2011; 1809:316-26. [PMID: 21683812 DOI: 10.1016/j.bbagrm.2011.05.017] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2011] [Revised: 05/20/2011] [Accepted: 05/27/2011] [Indexed: 01/19/2023]
Abstract
The nuclear exporter protein, Crm1, plays a key role in normal cell functioning, mediating the nucleo-cytoplasmic transport of cargo proteins. Elevated Crm1 expression has recently been identified in various tumours; however, the mechanisms driving its expression have not been investigated to date. In this study we identified the Crm1 promoter and factors associated with its elevated expression and with its repression under conditions of DNA damage. The -1405 to +99 Crm1 promoter region was found to be significantly more active in cancer and transformed cells compared to normal, and the -175 to +99 region identified as responsible for the differential activity. Mutation of two CCAAT boxes and a GC box within this region significantly diminished Crm1 promoter activity and ChIP analysis revealed binding of NFY and Sp1 to these sites, with increased binding in transformed and cancer cells. In addition, p53 was found to repress Crm1 promoter activity, after induction with doxorubicin, with p53 siRNA blocking the effect. Crm1 promoter constructs with mutated CCAAT boxes were significantly less responsive to p53 repression, and in vivo binding of NFY to the CCAAT boxes was diminished upon p53 binding, suggesting that p53 mediates repression of the Crm1 promoter via interfering with NFY. This was confirmed using NFY knock-down cells, in which Crm1 promoter activity was significantly less responsive to p53. In vitro EMSAs revealed that NFY and p53 bind the CCAAT boxes as a single complex under conditions of DNA damage. In summary, this study is a first to analyse Crm1 promoter regulation and reveals NFY and Sp1 as contributors to Crm1 overexpression in cancer. In addition, this study reveals that Crm1 transcription is inhibited by DNA damage and that the mechanism of inhibition involves p53 interfering with NFY function.
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Affiliation(s)
- Pauline J van der Watt
- Institute of Infectious Disease and Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
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37
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Changes in gene expression induced by Sp1 knockdown differ from those caused by challenging Sp1 binding to gene promoters. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2011; 1809:327-36. [PMID: 21684359 DOI: 10.1016/j.bbagrm.2011.06.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2011] [Revised: 04/20/2011] [Accepted: 06/03/2011] [Indexed: 11/21/2022]
Abstract
C/G-rich DNA regions, which include those recognized by the Sp1 transcription factor in several gene promoters, also encompass potential binding sites for the DNA-intercalating anthracyclines doxorubicin and WP631. We explored the differences between changes in gene expression caused by the ability of these drugs to compete with Sp1 for binding to DNA and those produced by Sp1 knockdown. By quantitative RT-PCR of around 100 genes, most of them involved in control of cell cycle progression, we found that the treatment of human MDA-MB231 breast carcinoma cells with bis-anthracycline WP631 for 24 h produced a profile of gene down-regulation markedly different from the profile caused by doxorubicin treatment or by stable Sp1 knockdown. These observations are rationalized by considering a near-specific effect of WP631 on Sp1 interaction with several gene promoters, thus representing potential therapeutic targets for WP631, in contrast to a less specific effect of reducing the availability of Sp1 through RNA interference. Genes down-regulated upon each treatment were mapped to their molecular and biological functions, which documented the down-regulation, among other things, of genes involved in mRNA transcription regulation, granting us insights into the effects of challenging the transactivation of gene expression by Sp1.
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38
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Xu J, Zhu D, He S, Spee C, Ryan SJ, Hinton DR. Transcriptional regulation of bone morphogenetic protein 4 by tumor necrosis factor and its relationship with age-related macular degeneration. FASEB J 2011; 25:2221-33. [PMID: 21411747 DOI: 10.1096/fj.10-178350] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Bone morphogenetic protein-4 (BMP4) may be involved in the molecular switch that determines which late form of age-related macular degeneration (AMD) an individual develops. BMP4 expression is high in retinal pigment epithelium (RPE) cells in late, dry AMD patients, while BMP4 expression is low in the wet form of the disease, characterized by choroidal neovascularization (CNV). Here, we sought to determine the mechanism by which BMP4 is down-regulated in CNV. BMP4 expression was decreased within laser-induced CNV lesions in mice at a time when tumor necrosis factor (TNF) expression was high (7 d postlaser) and was reexpressed in RPE when TNF levels declined (14 d postlaser). We found that TNF, an important angiogenic stimulus, significantly down-regulates BMP4 expression in cultured human fetal RPE cells, ARPE-19 cells, and RPE cells in murine posterior eye cup explants. We identified two specificity protein 1 (Sp1) binding sites in the BMP4 promoter that are required for basal expression of BMP4 and its down-regulation by TNF. Through c-Jun NH(2)-terminal kinase (JNK) activation, TNF modulates Sp1 phosphorylation, thus decreasing its affinity to the BMP4 promoter. The down-regulation of BMP4 expression by TNF in CNV and mechanisms established might be useful for defining novel targets for AMD therapy.
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Affiliation(s)
- Jing Xu
- Neuroscience Graduate Program, Keck School of Medicine, University of Southern California, Los Angeles, CA 90089, USA
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Suzuki A, Horiuchi A, Ashida T, Miyamoto T, Kashima H, Nikaido T, Konishi I, Shiozawa T. Cyclin A2 confers cisplatin resistance to endometrial carcinoma cells via up-regulation of an Akt-binding protein, periplakin. J Cell Mol Med 2011; 14:2305-17. [PMID: 19583808 PMCID: PMC3822571 DOI: 10.1111/j.1582-4934.2009.00839.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Although overexpression of cyclin A2 is reportedly an indicator of a poor prognosis of various malignancies including endometrial carcinoma, its molecular mechanism remains undetermined. To address this issue, we examined the effect of cyclin A2 on the development of resistance to chemotherapeutic drugs. The expression of cyclin A2 protein was increased in advanced-stage and chemotherapy-refractory stage endometrial carcinomas compared with that in early-stage tumours. The expression levels of cyclin A2 in endometrial carcinoma cell lines correlated positively with the IC50 for cisplatin. Endometrial carcinoma HHUA cells that overexpressed cyclin A2 showed increased resistance to cisplatin in vitro and in vivo, via the activation of a survival pathway, the inositol-3 phosphate kinase (PI3K) cascade. The use of a cDNA microarray identified an Akt-binding protein, periplakin, as a novel target of cyclin A2. The cyclin A2-induced up-regulation of periplakin was mediated via direct binding of Sp1 to the promoter that was activated by cyclin A2 along with chromatin remodelling involving CBP/p300, and the siRNA-mediated silencing of periplakin suppressed the PI3K pathway. These results indicate cyclin A2 to be involved in the acquisition of aggressive behaviour of tumour cells through the activation of PI3K by cyclin A2-induced periplakin, and to be a promising therapeutic target.
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Affiliation(s)
- Akihisa Suzuki
- Department of Obstetrics and Gynecology, Shinshu University School of Medicine, Matsumoto, Japan
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Guo L, Eviatar-Ribak T, Miskimins R. Sp1 phosphorylation is involved in myelin basic protein gene transcription. J Neurosci Res 2010; 88:3233-42. [DOI: 10.1002/jnr.22486] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Hypoxia and adrenergic function: molecular mechanisms related to Egr-1 and Sp1 activation. Brain Res 2010; 1353:14-27. [PMID: 20654592 DOI: 10.1016/j.brainres.2010.07.036] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2010] [Revised: 05/12/2010] [Accepted: 07/14/2010] [Indexed: 01/05/2023]
Abstract
Hypoxia is shown to regulate the stress hormone epinephrine through its biosynthesis by phenylethanolamine N-methyltransferase (PNMT) via PNMT gene activation and transcription factors Egr-1 and Sp1 in adrenal medulla-derived PC12 cells. Moderate hypoxia (5% oxygen) markedly stimulates PNMT promoter-driven luciferase activity in the cells. Hypoxia increases Egr-1 and Sp1 mRNA and nuclear protein content and Egr-1 and Sp1 protein-DNA binding complex formation. Subsequent to transcription factor induction, endogenous PNMT mRNA and protein also increase. Egr-1 and Sp1 binding site inactivation or Egr-1 and Sp1 siRNA inhibit PNMT promoter stimulation by hypoxia. Hypoxia elevates protein kinase A (PKA), phospholipase C (PLC), phosphoinositide 3-kinase, protein kinase C, ERK1/2 mitogen-activated protein kinase and p38 mitogen-activated protein kinase expression while selective inhibitors of these signaling enzymes abrogate hypoxic induction of the PNMT promoter and the rise in Egr-1, Sp1 and PNMT mRNA and protein. PC12 cells lacking PKA or PLCgamma-1 show significant reduction in PNMT promoter activation by hypoxia. Signaling inhibitors do not affect these responses or reduce hypoxic induction of the PNMT promoter to a lesser extent. Findings suggest that Egr-1 and Sp1 through synergistic interaction are critical transcriptional activators for hypoxic stress-regulated adrenergic function controlled via cAMP/PKA and PLC signaling. Identification of Sp1 as a mediator of hypoxia-induced transcriptional activation of PNMT has not been previously been shown. The effects of hypoxia on PNMT and thereby epinephrine may have important ramifications for the stress hormone epinephrine, its ability to regulate behavioral and physiological processes associated with stress and stress-elicited illness.
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Zheng B, Ohkawa S, Li H, Roberts-Wilson TK, Price SR. FOXO3a mediates signaling crosstalk that coordinates ubiquitin and atrogin-1/MAFbx expression during glucocorticoid-induced skeletal muscle atrophy. FASEB J 2010; 24:2660-9. [PMID: 20371624 DOI: 10.1096/fj.09-151480] [Citation(s) in RCA: 97] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Muscle atrophy is a consequence of chronic diseases (e.g., diabetes) and glucocorticoid-induced insulin resistance that results from enhanced activity of the ubiquitin-proteasome pathway. The PI3K/Akt pathway inhibits the FOXO-mediated transcription of the muscle-specific E3 ligase atrogin-1/MAFbx (AT-1), whereas the MEK/ERK pathway increases Sp1 activity and ubiquitin (UbC) expression. The observations raise a question about how the transcription of these atrogenes is synchronized in atrophic muscle. We tested a signaling model in which FOXO3a mediates crosstalk between the PI3K/Akt and MEK/ERK pathways to coordinate AT-1 and UbC expression. In rat L6 myotubes, dexamethasone (> or = 24 h) reduced insulin receptor substrate (IRS)-1 protein and PI3K/Akt signaling and increased AT-1 mRNA. IRS-2 protein, MEK/ERK signaling, Sp1 phosphorylation, and UbC transcription were simultaneously increased. Knockdown of IRS-1 using small interfering RNA or adenovirus-mediated expression of constitutively activated FOXO3a increased IRS-2 protein, MEK/ERK signaling, and UbC expression. Changes in PI3K/Akt and MEK/ERK signaling were recapitulated in rat muscles undergoing atrophy due to streptozotocin-induced insulin deficiency and concurrently elevated glucocorticoid production. IRS-1 and Akt phosphorylation were decreased, whereas MEK/ERK signaling and expression of IRS-2, UbC and AT-1 were increased. We conclude that FOXO3a mediates a reciprocal communication between the IRS-1/PI3K/Akt and IRS-2/MEK/ERK pathways that coordinates AT-1 and ubiquitin expression during muscle atrophy.
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Affiliation(s)
- Bin Zheng
- Renal Division, Emory University School of Medicine, Atlanta, GA 30322, USA
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Astrinidis A, Kim J, Kelly CM, Olofsson BA, Torabi B, Sorokina EM, Azizkhan-Clifford J. The transcription factor SP1 regulates centriole function and chromosomal stability through a functional interaction with the mammalian target of rapamycin/raptor complex. Genes Chromosomes Cancer 2010; 49:282-97. [PMID: 20013896 DOI: 10.1002/gcc.20739] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Specificity protein 1 (SP1) is an essential transcription factor implicated in the regulation of genes that control multiple cellular processes, including cell cycle, apoptosis, and DNA damage. Very few nontranscriptional roles for SP1 have been reported thus far. Using confocal microscopy and centrosome fractionation, we identified SP1 as a centrosomal protein. Sp1-deficient mouse embryonic fibroblasts and cells depleted of SP1 by RNAi have increased centrosome number associated with centriole splitting, decreased microtubule nucleation, chromosome misalignment, formation of multipolar mitotic spindles and micronuclei, and increased incidence of aneuploidy. Using mass spectrometry, we identified P70S6K, an effector of the mTOR/raptor (mTORC1) kinase complex, as a novel interacting protein of SP1. We found that SP1-deficient cells have increased phosphorylation of the P70S6K effector ribosomal protein S6, suggesting that SP1 participates in the regulation of the mTORC1/P70S6K/S6 signaling pathway. We previously reported that aberrant mTORC1 activation leads to supernumerary centrosomes, a phenotype rescued by the mTORC1 inhibitor rapamycin. Similarly, treatment with rapamycin rescued the multiple centrosome phenotype of SP1-deficient cells. Taken together, these data strongly support the hypothesis that SP1 is involved in the control of centrosome number via regulation of the mTORC1 pathway, and predict that loss of SP1 function can lead to aberrant centriole splitting, deregulated mTORC1 signaling, and aneuploidy, thereby contributing to malignant transformation.
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Affiliation(s)
- Aristotelis Astrinidis
- Department of Biochemistry and Molecular Biology, Drexel University College of Medicine, Philadelphia, PA 19102, USA
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Xiao L, Eto M, Kazanietz MG. ROCK mediates phorbol ester-induced apoptosis in prostate cancer cells via p21Cip1 up-regulation and JNK. J Biol Chem 2009; 284:29365-75. [PMID: 19667069 DOI: 10.1074/jbc.m109.007971] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
It is established that androgen-dependent prostate cancer cells undergo apoptosis upon treatment with phorbol esters and related analogs, an effect primarily mediated by PKCdelta. Treatment of LNCaP prostate cancer cells with phorbol 12-myristate 13-acetate (PMA) causes a strong and sustained activation of RhoA and its downstream effector ROCK (Rho kinase) as well as the formation of stress fibers. These effects are impaired in cells subjected to PKCdelta RNA interference depletion. Functional studies revealed that expression of a dominant negative RhoA mutant or treatment with the ROCK inhibitor Y-27632 inhibits the apoptotic effect of PMA in LNCaP cells. Remarkably, the cytoskeleton inhibitors cytochalasin B and blebbistatin blocked not only PMA-induced apoptosis but also the activation of JNK, a mediator of the cell death effect by the phorbol ester. In addition, we found that up-regulation of the cell cycle inhibitor p21(Cip1) is required for PMA-induced apoptosis and that inhibitors of ROCK or the cytoskeleton organization prevent p21(Cip1) induction. Real time PCR analysis and reporter gene assay revealed that PMA induces p21(Cip1) transcriptionally in a ROCK- and cytoskeleton-dependent manner. p21(Cip1) promoter analysis revealed that PMA induction is dependent on Sp1 elements in the p21(Cip1) promoter but independent of p53. Taken together, our studies implicate ROCK-mediated up-regulation of p21(Cip1) and the cytoskeleton in PKCdelta-dependent apoptosis in prostate cancer cells.
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Affiliation(s)
- Liqing Xiao
- Department of Pharmacology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104-6160, USA
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Devi YS, Shehu A, Stocco C, Halperin J, Le J, Seibold AM, Lahav M, Binart N, Gibori G. Regulation of transcription factors and repression of Sp1 by prolactin signaling through the short isoform of its cognate receptor. Endocrinology 2009; 150:3327-35. [PMID: 19342455 PMCID: PMC2703532 DOI: 10.1210/en.2008-1719] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Prolactin (PRL) affects the development and function of the reproductive system by binding to two types of receptors, which differ by the size of their intracellular domain in rodents. Whereas the signaling pathway through the long form of the receptor (PRL-RL) is well characterized, signaling through the short form (PRL-RS) remains obscure. In this investigation, we examined transcription factors regulated by PRL in the ovary and decidua of mice expressing only PRL-RS in a PRL receptor null background. These mice provide a powerful in vivo model to study the selective signaling mechanism of PRL through PRL-RS independent of PRL-RL. We also examined the regulation of transcription factors in ovarian and uterine cell lines stably transfected with PRL-RS or PRL-RL. We focused our investigation on transcription factors similarly regulated in both these tissues and clearly established that signaling through PRL-RS does not activate the JaK/Stat in vivo but leads to severe down-regulation of Sp1 expression, DNA binding activity, and nuclear localization, events that appear to involve the calmodulin-dependent protein kinase pathway. Our in vivo and in culture data demonstrate that the PRL-RS activates a signaling pathway distinct from that of the PRL-RL.
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Affiliation(s)
- Y Sangeeta Devi
- Department of Physiology and Biophysics, College of Medicine, University of Illinois at Chicago, 835 South Wolcott, M/C 901, Chicago, Illinois 60612, USA
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Mao XR, Moerman-Herzog AM, Chen Y, Barger SW. Unique aspects of transcriptional regulation in neurons--nuances in NFkappaB and Sp1-related factors. J Neuroinflammation 2009; 6:16. [PMID: 19450264 PMCID: PMC2693111 DOI: 10.1186/1742-2094-6-16] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2009] [Accepted: 05/18/2009] [Indexed: 12/11/2022] Open
Abstract
The unique physiology and function of neurons create differences in their cellular physiology, including their regulation of gene expression. We began several years ago exploring the relationships between the NFκB transcription factor, neuronal survival, and glutamate receptor activation in telencephalic neurons. These studies led us to conclude that this population of cells is nearly incapable of activating the NFκB that is nonetheless expressed at reasonable levels. A subset of the κB cis elements are instead bound by members of the Sp1 family in neurons. Also surprising was our discovery that Sp1 itself, typically described as ubiquitous, is severely restricted in expression within forebrain neurons; Sp4 seems to be substituted during neuronal differentiation. These findings and their implications for neuronal differentiation – as well as potential dedifferentiation during degenerative processes – are discussed here.
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Affiliation(s)
- Xianrong R Mao
- Department of Anesthesiology, Washington University School of Medicine, St Louis, MO 63110, USA.
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Kim HS, Lim IK. Phosphorylated extracellular signal-regulated protein kinases 1 and 2 phosphorylate Sp1 on serine 59 and regulate cellular senescence via transcription of p21Sdi1/Cip1/Waf1. J Biol Chem 2009; 284:15475-86. [PMID: 19318349 DOI: 10.1074/jbc.m808734200] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Expression of p21(Sdi1) downstream of p53 is essential for induction of cellular senescence, although cancer cell senescence can also occur in the p53 null condition. We report herein that senescence-associated phosphorylated extracellular signal-regulated protein kinases 1 and 2 (SA-pErk1/2) enhanced p21(Sdi1) transcription by phosphorylating Sp1 on Ser(59) downstream of protein kinase C (PKC) alpha. Reactive oxygen species (ROS), which was increased in cellular senescence, significantly activated both PKCalpha and PKCbetaI. However, PKCalpha, but not PKCbetaI, regulated ROS generation and cell proliferation in senescent cells along with activation of cdk2, proven by siRNAs. PKCalpha-siRNA also reduced SA-pErk1/2 expression in old human diploid fibroblast cells, accompanied with changes of senescence phenotypes to young cell-like. Regulation of SA-pErk1/2 was also confirmed by using catalytically active PKCalpha and its DN-mutant construct. These findings strongly suggest a new pathway to regulate senescence phenotypes by ROS via Sp1 phosphorylation between PKCalpha and SA-pErk1/2: employing GST-Sp1 mutants and MEK inhibitor analyses, we found that SA-pErk1/2 regulated Sp1 phosphorylation on the Ser(59) residue in vivo, but not threonine, in cellular senescence, which regulated transcription of p21(Sdi1) expression. In summary, PKCalpha, which was activated in senescent cells by ROS strongly activated Erk1/2, and the SA-pErk1/2 in turn phosphorylated Sp1 on Ser(59). Sp1-enhanced transcription of p21(Sdi1) resulted in regulation of cellular senescence in primary human diploid fibroblast cells.
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Affiliation(s)
- Hong Seok Kim
- Department of Biochemistry and Molecular Biology, Ajou University School of Medicine, Suwon 443-721, Korea
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Iwahori S, Yasui Y, Kudoh A, Sato Y, Nakayama S, Murata T, Isomura H, Tsurumi T. Identification of phosphorylation sites on transcription factor Sp1 in response to DNA damage and its accumulation at damaged sites. Cell Signal 2008; 20:1795-803. [DOI: 10.1016/j.cellsig.2008.06.007] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2008] [Accepted: 06/13/2008] [Indexed: 10/22/2022]
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