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Jahantigh D, Hosseinzadeh Colagar A. XRCC5 VNTR, XRCC6 -61C>G, and XRCC7 6721G>T Gene Polymorphisms Associated with Male Infertility Risk: Evidences from Case-Control and In Silico Studies. Int J Endocrinol 2017; 2017:4795076. [PMID: 28421111 PMCID: PMC5379132 DOI: 10.1155/2017/4795076] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/16/2016] [Revised: 12/26/2016] [Accepted: 01/04/2017] [Indexed: 11/17/2022] Open
Abstract
We evaluate the association between genetic polymorphisms of XRCC5 VNTR, XRCC6 -61C>G, and XRCC7 6721G>T with male infertility susceptibility. A total of 392 men including 178 infertile males (102 idiopathic azoospermia and 76 severe oligozoospermia) and 214 healthy controls were recruited. XRCC6 -61C>G and XRCC7 6721G>T genotyping was performed by PCR-RFLP whereas XRCC5 VNTR was performed by PCR. The 2R allele and 2R allele carriers of XRCC5 VNTR polymorphism significantly decreased risk of male infertility. The mutant GG genotypes and carriers of the CG and GG genotypes of XRCC6 -61C>G showed increased risk for the male infertility. Furthermore, the G allele of the XRCC6 -61C>G was correlated with increased susceptibility to male infertility. Likewise, the T allele of the XRCC7 6721G>T polymorphism was associated with increased susceptibility to male infertility in azoospermia. In silico analysis predicted that the presence of tandem repeats in XRCC5 gene prompter can be sequence to bind to more nuclear factors. Also, rs2267437 (C>G) variant was located in a well-conserved region in XRCC6 promoter and this variation might lead to differential allelic expression. The XRCC7 6721G>T gene polymorphism occurred in an acceptor-splicing site, but this polymorphism has no severe modification on XRCC7 mRNA splicing. Our results indicate the association of XRCC5 VNTR, XRCC6 -61C>G, and XRCC7 6721G>T gene polymorphisms with male infertility in Iranian men.
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Affiliation(s)
- Danial Jahantigh
- Department of Molecular and Cell Biology, Faculty of Basic Sciences, University of Mazandaran, Babolsar, Iran
| | - Abasalt Hosseinzadeh Colagar
- Department of Molecular and Cell Biology, Faculty of Basic Sciences, University of Mazandaran, Babolsar, Iran
- *Abasalt Hosseinzadeh Colagar:
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Mumbrekar KD, Goutham HV, Vadhiraja BM, Bola Sadashiva SR. Polymorphisms in double strand break repair related genes influence radiosensitivity phenotype in lymphocytes from healthy individuals. DNA Repair (Amst) 2016; 40:27-34. [PMID: 26974709 DOI: 10.1016/j.dnarep.2016.02.006] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2015] [Revised: 02/28/2016] [Accepted: 02/29/2016] [Indexed: 01/11/2023]
Abstract
BACKGROUND A range of individual radiosensitivity observed in humans can influence individual's susceptibility toward cancer risk and radiotherapy outcome. Therefore, it is important to measure the variation in radiosensitivity and to identify the genetic factors influencing it. METHODS By adopting a pathway specific genotype-phenotype design, we established the variability in cellular radiosensitivity by performing γ-H2AX foci assay in healthy individuals. Further, we genotyped ten selected SNPs in candidate genes XRCC3 (rs861539), XRCC4 (rs1805377), XRCC5 (rs3835), XRCC6 (rs2267437), ATM (rs3218698, rs1800057), LIG4 (rs1805388), NBN (rs1805794), RAD51 (rs1801320) and PRKDC (rs7003908), and analysed their influence on observed variation in radiosensitivity. RESULTS The rs2267437 polymorphisms in XRCC6 was associated (P=0.0326) with increased DSB induction while rs1805388 in LIG4 (P=0.0240) was associated with increased radioresistance. Further, multiple risk alleles decreased the DSB repair capacity in an additive manner. Polymorphisms in candidate DSB repair genes can act individually or in combination to the efficacy of DSB repair process, resulting in variation of cellular radiosensitivity. CONCLUSIONS Current study suggests that γ-H2AX assay may fulfil the role of a rapid and sensitive biomarker that can be used for epidemiological studies to measure variations in radiosensitivity. DSB repair gene polymorphisms can impact the formation and repair of DSBs. IMPACT γ-H2AX foci analysis as well as DSBs repair gene polymorphisms can be used to assess cellular radiosensitivity, which will be useful in population risk assessment, disease prediction, individualization of radiotherapy and also in setting the radiation protection standards.
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Affiliation(s)
- Kamalesh Dattaram Mumbrekar
- Department of Radiation Biology & Toxicology, School of Life Sciences, Manipal University, Manipal, Karnataka, India
| | - Hassan Venkatesh Goutham
- Department of Radiation Biology & Toxicology, School of Life Sciences, Manipal University, Manipal, Karnataka, India
| | | | - Satish Rao Bola Sadashiva
- Department of Radiation Biology & Toxicology, School of Life Sciences, Manipal University, Manipal, Karnataka, India.
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Association of the Genetic Polymorphisms in XRCC6 and XRCC5 with the Risk of ESCC in a High-incidence Region of North China. TUMORI JOURNAL 2015; 101:24-9. [PMID: 25702660 DOI: 10.5301/tj.5000206] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/02/2014] [Indexed: 11/20/2022]
Abstract
Background The XRCC6 and XRCC5 genes are part of the nonhomologous end-joining (NHEJ) pathway, which is the main mechanism repairing DNA double-strand breaks (DSBs) in human cells. Genetic variations of XRCC6 and XRCC5 might contribute to esophageal squamous cell carcinoma (ESCC) susceptibility. Methods ESCC patients (n = 189) and cancer-free controls (n = 189) were recruited in an ESCC high-risk area of north China. Then the rs2267437 (XRCC6), rs3835 (XRCC5) and rs16855458 (XRCC5) polymorphisms were genotyped using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis. Results A significant difference in genotype distribution and allele frequency of rs2267437 (XRCC6) was observed between the cases and controls. The CG carriers were at higher risk of ESCC (p = 0.001, odds ratio [OR] = 2.040, 95% confidence interval [95% CI], 1.323-3.147). G allele carriers were also associated with an increased ESCC risk (p = 0.003, OR = 1.868, 95% CI, 1.230-2.836). In the 2 polymorphisms of XRCC5, no significant difference was found between both groups in the distribution of either genotype or allelic frequency. But in the haplotypes established by the single nucleotide polymorphisms (SNPs) of XRCC5, the haplotype AT and CC separately increased by 4.28- and 2.31-fold the risk ratio of ESCC (p = 0.01, OR = 4.28, 95% CI, 1.40-13.05; p = 0.03, OR = 2.31, 95% CI, 1.11-4.80, respectively). In addition, gene-smoking or gene-drinking interactions, and their effect on the risk of ESCC were observed, but no significant gene-environment interaction was demonstrated. Conclusions In conclusion, both the CG carriers/G allele carriers of rs2267437 (XRCC6) and the haplotype AT/CC established by the SNPs of XRCC5 are associated with ESCC susceptibility.
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Cell-type-specific transcriptional regulation of PIGM underpins the divergent hematologic phenotype in inherited GPl deficiency. Blood 2014; 124:3151-4. [PMID: 25293775 DOI: 10.1182/blood-2014-09-598813] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
A rare point mutation in the core promoter -270GC-rich box of PIGM, a housekeeping gene, disrupts binding of the generic transcription factor (TF) Sp1 and causes inherited glycosylphosphatidylinositol (GPI) deficiency (IGD). We show that whereas PIGM messenger RNA levels and surface GPI expression in IGD B cells are low, GPI expression is near normal in IGD erythroid cells. This divergent phenotype results from differential promoter chromatin accessibility and binding of Sp1. Specifically, whereas PIGM transcription in B cells is dependent on Sp1 binding to the -270GC-rich box and is associated with lower promoter accessibility, in erythroid cells, Sp1 activates PIGM transcription by binding upstream of (but not to) the -270GC-rich box. These findings explain intact PIGM transcription in IGD erythroid cells and the lack of clinically significant intravascular hemolysis in patients with IGD. Furthermore, they provide novel insights into tissue-specific transcriptional control of a housekeeping gene by a generic TF.
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Xu H, Zou P, Chen P, Zhao L, Zhao P, Lu A. Association between the XRCC6 Promoter rs2267437 polymorphism and cancer risk: evidence based on the current literature. Genet Test Mol Biomarkers 2013; 17:607-14. [PMID: 23745766 DOI: 10.1089/gtmb.2013.0083] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
BACKGROUND Increasing evidence suggests that the DNA repair gene XRCC6 (Ku70) may be critically involved in the aetiology of the human carcinogenesis. Many studies have investigated the association between the rs2267437 polymorphism and cancer susceptibility. However, the results of these studies have been controversial. This meta-analysis was conducted to quantitatively summarize the evidence for a relationship between the rs2267437 polymorphism and cancer risk. METHODS Electronic databases, including PUBMED and EMBASE, were searched for publications that met the inclusion criteria. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated to evaluate the strength of the association between the XRCC6 promoter rs2267437 polymorphism and cancer risk in a fixed-effects model (the Mantel-Haenszel method) or a random-effects model (the DerSimonian and Laird method), as appropriate. RESULTS A total of 13 case-control studies, involving 3675 cases and 4247 controls, investigating the XRCC6 rs2267437 polymorphism and cancer susceptibility were identified for the meta-analysis. The pooled analysis showed that there is a significant relationship between the XRCC6 rs2267437 polymorphism and cancer susceptibility (GG vs. CC: OR=1.28, 95% CI=1.03-1.60). Subgroup analyses based on the cancer type, ethnicity, and source of the controls were also performed, and these results indicated that the XRCC6 promoter rs2267437 polymorphism was associated with cancer risk in breast cancer studies (GG vs. CC: OR=1.79, 95% CI=1.25-2.56; GG vs. CG+CC: OR=1.40, 95% CI=1.01-1.95), in Asian populations (GG vs. CC: OR=1.33, 95% CI=1.01-1.74) and in population-based studies (GG vs. CC: OR=1.57, 95% CI=1.12-2.22; CG vs. CC: OR=1.35, 95% CI=1.11-1.64; GG+CG vs. CC: OR=1.37, 95% CI=1.14-1.65). CONCLUSION This meta-analysis suggests that the XRCC6 rs2267437 polymorphism may affect breast cancer susceptibility and increase the risk of cancer in Asian populations and in the general population. It is critical that further large-scale and well-designed studies be conducted to confirm the association between the rs2267437 genotype and cancer risk.
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Affiliation(s)
- Haitao Xu
- Department of Neurosurgery, The First Affiliated Hospital, Nanjing Medical University, Nanjing, China
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Ouimet M, Cassart P, Larivière M, Kritikou EA, Simard J, Sinnett D. Functional analysis of promoter variants in KU70 and their role in cancer susceptibility. Genes Chromosomes Cancer 2012; 51:1007-13. [PMID: 22833453 DOI: 10.1002/gcc.21983] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2012] [Revised: 06/15/2012] [Accepted: 06/19/2012] [Indexed: 11/09/2022] Open
Abstract
KU70 is involved in the DNA double-strand break repair pathway, which plays a critical role in maintaining genomic stability and preventing cancer. Genetic variation within the KU70 gene has been shown to be associated with increased risk of several types of cancers including breast cancer. Here, we used gene reporter and gel shift assays combined with site-directed mutagenesis to characterize genetic variation within the KU70 proximal promoter region and investigate the putative functional role of regulatory variation and altered KU70 expression in modulating an individual's susceptibility to disease. We show that the variant rs2267437C>G significantly influences KU70 transcriptional activity in an allele- specific manner and alters DNA-protein complex formation in breast cancer cell lines. Our data provide a possible molecular explanation for the associations observed between the KU70 regulatory variant rs2267437 and breast cancer risk.
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Affiliation(s)
- Manon Ouimet
- Division of Hematology-Oncology, Centre Hospitalier Universitaire Sainte-Justine, Montreal, Canada
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Wang W, Pan X, Huo X, Yan F, Wang M, Wang D, Gao Y, Cao Q, Luo D, Qin C, Yin C, Zhang Z. A functional polymorphism C-1310G in the promoter region of Ku70/XRCC6 is associated with risk of renal cell carcinoma. Mol Carcinog 2012; 51 Suppl 1:E183-90. [PMID: 22593040 DOI: 10.1002/mc.21914] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2011] [Revised: 01/13/2012] [Accepted: 03/19/2012] [Indexed: 11/11/2022]
Abstract
The DNA repair gene Ku70 plays a key role in the DNA double strand break (DSB) repair system. Defects in DSB repair capacity can lead to genomic instability. We hypothesized that the Ku70 C-1310G polymorphism (rs2267437) was associated with risk of renal cell carcinoma (RCC). We genotyped the Ku70 C-1310G polymorphism in a case-control study of 620 patients and 623 controls in a Chinese population and assessed the effects of C-1310G polymorphism on RCC susceptibility and survival. We then examined the functionality of this polymorphism. Compared with the Ku70-1310CC genotype, the CG and CG/GG genotypes had a significantly increased risk of RCC [adjusted odds ratio (OR) = 1.47, 95% confidence interval (CI) = 1.16-1.87 for CG and OR = 1.47, 95% CI = 1.16-1.86 for CG/GG]. However, the C-1310G polymorphism did not influence the survival of RCC. The in vivo experiments with normal renal tissues revealed statistically significantly lower Ku70 mRNA expression in samples with CG/GG genotypes relative to those with the CC genotype (P < 0.05). In vitro luciferase assays in various cell lines showed lower luciferase activity for the -1310G allele than for the -1310C allele. These results suggest that the Ku70 C-1310G polymorphism is involved in the etiology of RCC and thus may be a marker for genetic susceptibility to RCC in Chinese populations. Larger studies are warranted to validate our findings.
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Affiliation(s)
- Wei Wang
- Department of Clinical Laboratory, The Third Affiliated Hospital of Nanjing Medical University, Yizheng, China
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MacDonald MJ, Longacre MJ, Stoker SW, Kendrick M, Thonpho A, Brown LJ, Hasan NM, Jitrapakdee S, Fukao T, Hanson MS, Fernandez LA, Odorico J. Differences between human and rodent pancreatic islets: low pyruvate carboxylase, atp citrate lyase, and pyruvate carboxylation and high glucose-stimulated acetoacetate in human pancreatic islets. J Biol Chem 2011; 286:18383-96. [PMID: 21454710 DOI: 10.1074/jbc.m111.241182] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Anaplerosis, the net synthesis in mitochondria of citric acid cycle intermediates, and cataplerosis, their export to the cytosol, have been shown to be important for insulin secretion in rodent beta cells. However, human islets may be different. We observed that the enzyme activity, protein level, and relative mRNA level of the key anaplerotic enzyme pyruvate carboxylase (PC) were 80-90% lower in human pancreatic islets compared with islets of rats and mice and the rat insulinoma cell line INS-1 832/13. Activity and protein of ATP citrate lyase, which uses anaplerotic products in the cytosol, were 60-75% lower in human islets than in rodent islets or the cell line. In line with the lower PC, the percentage of glucose-derived pyruvate that entered mitochondrial metabolism via carboxylation in human islets was only 20-30% that in rat islets. This suggests human islets depend less on pyruvate carboxylation than rodent models that were used to establish the role of PC in insulin secretion. Human islets possessed high levels of succinyl-CoA:3-ketoacid-CoA transferase, an enzyme that forms acetoacetate in the mitochondria, and acetoacetyl-CoA synthetase, which uses acetoacetate to form acyl-CoAs in the cytosol. Glucose-stimulated human islets released insulin similarly to rat islets but formed much more acetoacetate. β-Hydroxybutyrate augmented insulin secretion in human islets. This information supports previous data that indicate beta cells can use a pathway involving succinyl-CoA:3-ketoacid-CoA transferase and acetoacetyl-CoA synthetase to synthesize and use acetoacetate and suggests human islets may use this pathway more than PC and citrate to form cytosolic acyl-CoAs.
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Affiliation(s)
- Michael J MacDonald
- Department of Pediatrics, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin 53706, USA.
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Quan JX, Zheng F, Li XX, Hu LL, Sun ZY, Jiao YL, Wang BL. Cloning and analysis of rat osteoclast inhibitory lectin gene promoter. J Cell Biochem 2009; 106:599-607. [PMID: 19127542 DOI: 10.1002/jcb.22036] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Osteoclast inhibitory lectin (OCIL) is a novel regulator of bone remodeling, however, little is known concerning how OCIL is regulated to date. In this study, approximately 4.4 kb of the 5'-flanking sequence of rat OCIL gene was cloned into the promoter-less reporter vector pGL3-basic and transiently transfected into three different cell lines. The differences in the levels of luciferase activity paralleled well with the levels of OCIL mRNA expression in these cells, suggesting that the regulation of rat OCIL gene expression occurs mainly at the transcriptional level. Additional luciferase assays using a series of constructs containing unidirectionally deleted fragments showed that the construct-1819/pGL3 (-1819 to +118) exhibited the highest luciferase activity, suggesting the presence of functional promoter in this region. The region from -4370 to -2805 might contain negative regulatory elements, while the region from -1819 to -1336 might have important positive regulatory elements that enhance OCIL transcription. Sequence analysis of the promoter revealed the absence of both TATA and CAAT boxes. However, in the proximal promoter region (-81 to +118), several potential transcription factor binding sites that may be responsible for the basal transcriptional activity of rat OCIL promoter were observed. The promoter contains several potential Sp1 binding sites, and cotransfection of a shRNA expression plasmid that knockdowns Sp1 significantly reduced OCIL promoter activity and endogenous gene expression and moreover, overexpressing Sp7, a Sp1 family member that also binds to Sp1 binding sequence, increased OCIL promoter activity and gene expression, suggesting a role of Sp1 family proteins in regulation of OCIL transcription.
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Affiliation(s)
- Jin-Xing Quan
- Key Lab of Ministry of Health for Hormone and Development, Institute of Endocrinology, Tianjin Medical University, Tianjin, PR China
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Willems P, De Ruyck K, Van den Broecke R, Makar A, Perletti G, Thierens H, Vral A. A polymorphism in the promoter region of Ku70/XRCC6, associated with breast cancer risk and oestrogen exposure. J Cancer Res Clin Oncol 2009; 135:1159-68. [DOI: 10.1007/s00432-009-0556-x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2008] [Accepted: 01/26/2009] [Indexed: 01/09/2023]
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Lyng H, Brøvig RS, Svendsrud DH, Holm R, Kaalhus O, Knutstad K, Oksefjell H, Sundfør K, Kristensen GB, Stokke T. Gene expressions and copy numbers associated with metastatic phenotypes of uterine cervical cancer. BMC Genomics 2006; 7:268. [PMID: 17054779 PMCID: PMC1626467 DOI: 10.1186/1471-2164-7-268] [Citation(s) in RCA: 115] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2006] [Accepted: 10/20/2006] [Indexed: 12/26/2022] Open
Abstract
Background A better understanding of the development of metastatic disease and the identification of molecular markers for cancer spread would be useful for the design of improved treatment strategies. This study was conducted to identify gene expressions associated with metastatic phenotypes of locally advanced cervical carcinomas and investigate whether gains or losses of these genes could play a role in regulation of the transcripts. Gene expressions and copy number changes were determined in primary tumors from 29 patients with and 19 without diagnosed lymph node metastases by use of cDNA and genomic microarray techniques, respectively. Results Thirty-one genes that differed in expression between the node positive and negative tumors were identified. Expressions of eight of these genes (MRPL11, CKS2, PDK2, MRPS23, MSN, TBX3, KLF3, LSM3) correlated with progression free survival in univariate analysis and were therefore more strongly associated with metastatic phenotypes than the others. Immunohistochemistry data of CKS2 and MSN showed similar relationships to survival. The prognostic genes clustered into two groups, suggesting two major metastatic phenotypes. One group was associated with rapid proliferation, oxidative phosphorylation, invasiveness, and tumor size (MRPS23, MRPL11, CKS2, LSM3, TBX3, MSN) and another with hypoxia tolerance, anaerobic metabolism, and high lactate content (PDK2, KLF3). Multivariate analysis identified tumor volume and PDK2 expression as independent prognostic variables. Gene copy number changes of the differentially expressed genes were not frequent, but correlated with the expression level for seven genes, including MRPS23, MSN, and LSM3. Conclusion Gene expressions associated with known metastatic phenotypes of cervical cancers were identified. Our findings may indicate molecular mechanisms underlying development of these phenotypes and be useful as markers of cancer spread. Gains or losses of the genes may be involved in development of the metastatic phenotypes in some cases, but other mechanisms for transcriptional regulation are probably important in the majority of tumors.
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Affiliation(s)
- Heidi Lyng
- Department of Radiation Biology, Health Enterprise Rikshospitalet – Radiumhospitalet, Oslo, Norway
| | - Runar S Brøvig
- Department of Radiation Biology, Health Enterprise Rikshospitalet – Radiumhospitalet, Oslo, Norway
| | - Debbie H Svendsrud
- Department of Radiation Biology, Health Enterprise Rikshospitalet – Radiumhospitalet, Oslo, Norway
| | - Ruth Holm
- Department of Pathology, Health Enterprise Rikshospitalet – Radiumhospitalet, Oslo, Norway
| | - Olav Kaalhus
- Department of Radiation Biology, Health Enterprise Rikshospitalet – Radiumhospitalet, Oslo, Norway
| | - Kjetil Knutstad
- Department of Roentgenology, Health Enterprise Rikshospitalet – Radiumhospitalet, Oslo, Norway
| | - Halldis Oksefjell
- Department of Gynecologic Oncology, Health Enterprise Rikshospitalet – Radiumhospitalet, Oslo, Norway
| | - Kolbein Sundfør
- Department of Gynecologic Oncology, Health Enterprise Rikshospitalet – Radiumhospitalet, Oslo, Norway
| | - Gunnar B Kristensen
- Department of Gynecologic Oncology, Health Enterprise Rikshospitalet – Radiumhospitalet, Oslo, Norway
- Department of Medical Informatics, University of Oslo, Oslo, Norway
| | - Trond Stokke
- Department of Radiation Biology, Health Enterprise Rikshospitalet – Radiumhospitalet, Oslo, Norway
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Abstract
Sp1 is one of the best characterized transcriptional activators. The biological importance of Sp1 is underscored by the fact that several hundreds of genes are thought to be regulated by this protein. However, during the last 5 years, a more extended family of Sp1-like transcription factors has been identified and characterized by the presence of a conserved DNA-binding domain comprising three Krüppel-like zinc fingers. Each distinct family member differs in its ability to regulate transcription, and, as a consequence, to influence cellular processes. Specific activation and repression domains located within the N-terminal regions of these proteins are responsible for these differences by facilitating interactions with various co-activators and co-repressors. The present review primarily focuses on discussing the structural, biochemical and biological functions of the repressor members of this family of transcription factors. The existence of these transcriptional repressors provides a tightly regulated mechanism for silencing a large number of genes that are already known to be activated by Sp1.
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Affiliation(s)
- Gwen Lomberk
- *Gastroenterology Research Unit, Mayo Clinic, Rochester, MN 55901, U.S.A
| | - Raul Urrutia
- *Gastroenterology Research Unit, Mayo Clinic, Rochester, MN 55901, U.S.A
- †Tumor Biology Program, Mayo Clinic, Rochester, MN 55901, U.S.A
- ‡Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN 55901, U.S.A
- To whom correspondence should be addressed (email )
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Wooten LG, Ogretmen B. Sp1/Sp3-dependent regulation of human telomerase reverse transcriptase promoter activity by the bioactive sphingolipid ceramide. J Biol Chem 2005; 280:28867-76. [PMID: 15951564 DOI: 10.1074/jbc.m413444200] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In this study, the roles of Sp1/Sp3 transcription factors in the regulation of the activity of human telomerase reverse transcriptase (hTERT) promoter in response to ceramide were examined in the A549 human lung adenocarcinoma cells. The activity of the N-terminal truncated hTERT promoter, lacking the c-Myc recognition (E-box) region but containing multiple Sp1/Sp3 sites, was also significantly inhibited by C6-ceramide, indicating a role for ceramide in the regulation of Sp1/Sp3 function. Partial inhibition of Sp1 expression using small interfering RNA resulted in a significant inhibition of the hTERT promoter. Treatment with C6-ceramide inhibited the trans-activation function of overexpressed Sp1, whereas it induced the repressor effects of exogenous Sp3 on the hTERT promoter. The interaction between Sp1 and hTERT promoter DNA was significantly reduced in response to ceramide as assessed by chromatin immunoprecipitation analysis. In contrast, the promoter DNA-binding activity of Sp3 was slightly increased in response to C6-ceramide, resulting in the increased ratio of Sp3/Sp1 on the hTERT promoter, which was concomitant with the reduced recruitment of RNA polymerase II to the promoter. Furthermore, mutations of various Sp1/Sp3 recognition sequences significantly attenuated the activity of the promoter in the presence or absence of ceramide, demonstrating the importance of multiple Sp1/Sp3 recognition sites for the promoter activity. Mechanistically, the data demonstrated that C6-ceramide reduced the acetylation of Sp3 protein and partially blocked the activation of the hTERT promoter by the histone deacetylase inhibitor trichostatin A. The roles of endogenous long chain ceramide generated in response to gemcitabine in the inhibition of hTERT promoter activity and the regulation of Sp3 acetylation were also demonstrated.
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Affiliation(s)
- Leslie G Wooten
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, SC 29425, USA
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Di Pierro E, Cappellini MD, Mazzucchelli R, Moriondo V, Mologni D, Zanone Poma B, Riva A. A point mutation affecting an SP1 binding site in the promoter of the ferrochelatase gene impairs gene transcription and causes erythropoietic protoporphyria. Exp Hematol 2005; 33:584-91. [PMID: 15850836 DOI: 10.1016/j.exphem.2005.02.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2004] [Revised: 02/04/2005] [Accepted: 02/07/2005] [Indexed: 11/17/2022]
Abstract
OBJECTIVE Clinical manifestation of erythropoietic protoporphyria (EPP) results from coinheritance of a mutated allele and a wild-type low-expressed allele of the ferrochelatase (FECH) gene. Currently, up to 90 different mutations affecting the coding region or splicing junctions of the FECH gene have been identified. Despite the high molecular heterogeneity, no functional mutations have been previously reported in the promoter region. The weaker allele expression has been controversially associated to the presence of different intragenic polymorphisms. METHODS We applied a two-step screening strategy using denaturing gradient gel electrophoresis followed by direct sequencing in order to rapidly identify FECH gene mutations in Italian EPP patients. We identified two unrelated subjects showing a normal FECH coding region but a single G>C base substitution at position -250 in the FECH promoter and the -251G, IVS1-23T, and IVS3-48C polymorphisms in trans to the substitution. To investigate the effect of the -250G>C mutation on protein binding to the FECH promoter, we conducted electro mobility shift assay (EMSA) and supershift analysis. To determine its effect on the transcriptional activity, K562 and Jurkat cell lines were transiently transfected. RESULTS EMSA showed that the -250G>C mutation results in the loss of an SP1 binding site, and transient transfection assays demonstrated that such mutation strongly impairs promoter activity. Moreover, we showed that the -251A>G polymorphism, although unable to affect SP1 binding, displays a significant reduction in the transcriptional activity of the promoter. CONCLUSION This is the first report of a mutation in the FECH promoter affecting binding of a transcription factor and causing EPP phenotype.
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Affiliation(s)
- Elena Di Pierro
- Department of Internal Medicine, Centro Anemie Congenite, Maggiore Policlinico Hospital IRCCS, University of Milan, Milan, Italy
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Sunyakumthorn P, Boonsaen T, Boonsaeng V, Wallace JC, Jitrapakdee S. Involvement of specific proteins (Sp1/Sp3) and nuclear factor Y in basal transcription of the distal promoter of the rat pyruvate carboxylase gene in β-cells. Biochem Biophys Res Commun 2005; 329:188-96. [PMID: 15721292 DOI: 10.1016/j.bbrc.2005.01.108] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2004] [Indexed: 10/25/2022]
Abstract
Pyruvate carboxylase plays diverse roles in different biosynthetic pathways, including glucose-induced insulin secretion in pancreatic beta-cells. We have localized the control region of the P2 promoter by generating a series of 5'-nested deletion constructs, and both 25- and 9-bp internal deletion constructs, as well as by performing site-directed mutagenesis. Transient transfections of these constructs into INS-1 cells identified a CCAAT box and a GC box that are located at -65/-61 and -48/-41, respectively, as the important determinants. Disruption of the GC box resulted in a 4-fold reduction of the reporter activity, while disruption of the proximal CCAAT box (-65/-61) but not the distal CCAAT box (-95/-91) increased the reporter activity by 3-fold. Simultaneous disruptions of both the GC box and the CCAAT box reduced the reporter activity to a level that was close to that of the single GC box mutation. Electrophoretic mobility shift assays (EMSAs) and supershift EMSAs using nuclear extract from INS-1 cells demonstrated that Sp1 and Sp3 bind a GC box while the nuclear factor Y was shown to bind the proximal but not the distal CCAAT box.
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Affiliation(s)
- Piyanate Sunyakumthorn
- Department of Biochemistry, Faculty of Science, Mahidol University, Bangkok 10400, Thailand
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16
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O'Leary DA, Koleski D, Kola I, Hertzog PJ, Ristevski S. Identification and expression analysis of alternative transcripts of the mouse GA-binding protein (Gabp) subunits α and β1. Gene 2005; 344:79-92. [PMID: 15656975 DOI: 10.1016/j.gene.2004.09.031] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2004] [Revised: 09/02/2004] [Accepted: 09/23/2004] [Indexed: 11/20/2022]
Abstract
The erythroblast transformation specific (ETS) transcription factor GA-binding protein (Gabp) is widely expressed and acts on a diverse range of target genes, including nuclear-encoded mitochondrial proteins and neuromuscular-specific genes. The GABPalpha subunit contains an ETS DNA binding domain and the beta subunit contains a nuclear localization signal (NLS) and transactivation domain. Here, we show coincident expression of Gabpalpha and beta1 throughout mouse embryogenesis, consistent with the gene products functioning in a complex. We have also identified 2 alternatively spliced, tissue-specific exons 1 (5' untranslated regions) of mouse Gabpalpha and 4 alternative 3' polyadenylation signals that, in combination, result in 12 transcripts for Gabpalpha. These alternative transcripts are suggested to have altered stability, subcellular localization and/or translation efficiency. Further, we identified nine differentially expressed splice variants of mouse Gabpbeta1 that encode beta protein forms lacking functional domains, suggesting a dominant negative function. Together, alternative transcripts of Gabpalpha and beta1 provide a mechanism for tissue-specific regulation of Gabp activity.
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MESH Headings
- 3T3 Cells
- Alternative Splicing/genetics
- Animals
- Binding Sites/genetics
- DNA, Complementary/chemistry
- DNA, Complementary/genetics
- DNA-Binding Proteins/genetics
- Embryo, Mammalian/metabolism
- Female
- GA-Binding Protein Transcription Factor
- Gene Expression Profiling
- Gene Expression Regulation, Developmental
- In Situ Hybridization
- Luciferases/genetics
- Luciferases/metabolism
- Male
- Mice
- Mice, Inbred C57BL
- Mice, Inbred CBA
- Molecular Sequence Data
- Promoter Regions, Genetic/genetics
- Protein Subunits/genetics
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Recombinant Fusion Proteins/genetics
- Recombinant Fusion Proteins/metabolism
- Reverse Transcriptase Polymerase Chain Reaction
- Sequence Analysis, DNA
- Transcription Factors/genetics
- Transcription, Genetic/genetics
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Affiliation(s)
- Debra A O'Leary
- Centre for Functional Genomics and Human Disease, Monash Institute of Reproduction and Development, Monash Medical Centre, Monash University, Clayton 246 Clayton Road, Clayton, Victoria 3168, Australia
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