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Zamanian MY, Golmohammadi M, Amin RS, Bustani GS, Romero-Parra RM, Zabibah RS, Oz T, Jalil AT, Soltani A, Kujawska M. Therapeutic Targeting of Krüppel-Like Factor 4 and Its Pharmacological Potential in Parkinson's Disease: a Comprehensive Review. Mol Neurobiol 2024; 61:3596-3606. [PMID: 37996730 PMCID: PMC11087351 DOI: 10.1007/s12035-023-03800-2] [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: 08/11/2023] [Accepted: 11/10/2023] [Indexed: 11/25/2023]
Abstract
Krüppel-like factor 4 (KLF4), a zinc finger transcription factor, is found in different human tissues and shows diverse regulatory activities in a cell-dependent manner. In the brain, KLF4 controls various neurophysiological and neuropathological processes, and its contribution to various neurological diseases has been widely reported. Parkinson's disease (PD) is an age-related neurodegenerative disease that might have a connection with KLF4. In this review, we discussed the potential implication of KLF4 in fundamental molecular mechanisms of PD, including aberrant proteostasis, neuroinflammation, apoptosis, oxidative stress, and iron overload. The evidence collected herein sheds new light on KLF4-mediated pathways, which manipulation appears to be a promising therapeutic target for PD management. However, there is a gap in the knowledge on this topic, and extended research is required to understand the translational value of the KLF4-oriented therapeutical approach in PD.
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Affiliation(s)
- Mohammad Yasin Zamanian
- Neurophysiology Research Center, Hamadan University of Medical Sciences, Hamadan, 6718773654, Iran
- Department of Pharmacology and Toxicology, School of Pharmacy, Hamadan University of Medical Sciences, Hamadan, 6718773654, Iran
| | - Maryam Golmohammadi
- School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, 1988873554, Iran
| | | | | | | | - Rahman S Zabibah
- Medical Laboratory Technology Department, College of Medical Technology, The Islamic University, Najaf, Iraq
| | - Tuba Oz
- Department of Toxicology, Poznan University of Medical Sciences, Rokietnicka 3, 60-806, Poznan, Poland
| | - Abduladheem Turki Jalil
- Medical Laboratories Techniques Department, Al-Mustaqbal University College, Babylon, Hilla, 51001, Iraq
| | - Afsaneh Soltani
- School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, 1988873554, Iran.
| | - Małgorzata Kujawska
- Department of Toxicology, Poznan University of Medical Sciences, Rokietnicka 3, 60-806, Poznan, Poland.
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2
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Zaragoza-Ojeda M, Apatiga-Vega E, Arenas-Huertero F. Role of aryl hydrocarbon receptor in central nervous system tumors: Biological and therapeutic implications. Oncol Lett 2021; 21:460. [PMID: 33907570 PMCID: PMC8063300 DOI: 10.3892/ol.2021.12721] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2020] [Accepted: 01/25/2021] [Indexed: 12/12/2022] Open
Abstract
Aryl hydrocarbon receptor (AHR) is a ligand-activated transcription factor, whose canonical pathway mainly regulates the genes involved in xenobiotic metabolism. However, it can also regulate several responses in a non-canonical manner, such as proliferation, differentiation, cell death and cell adhesion. AhR plays an important role in central nervous system tumors, as it can regulate several cellular responses via different pathways. The polymorphisms of the AHR gene have been associated with the development of gliomas. In addition, the metabolism of tumor cells promotes tumor growth, particularly in tryptophan synthesis, where some metabolites, such as kynurenine, can activate the AhR pathway, triggering cell proliferation in astrocytomas, medulloblastomas and glioblastomas. Furthermore, as part of the changes in neuroblastomas, AHR is able to downregulate the expression of proto-oncogene c-Myc, induce differentiation in tumor cells, and cause cell cycle arrest and apoptosis. Collectively, these data suggested that the modulation of the AhR pathway may downregulate tumor growth, providing a novel strategy for applications for the treatment of certain tumors through the control of the AhR pathway.
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Affiliation(s)
- Montserrat Zaragoza-Ojeda
- Laboratorio de Investigación en Patología Experimental, Hospital Infantil de México Federico Gómez, Mexico City 06720, México.,Posgrado en Ciencias Biológicas, Facultad de Medicina, Universidad Nacional Autónoma de México (UNAM), Mexico City 04510, México
| | - Elisa Apatiga-Vega
- Laboratorio de Investigación en Patología Experimental, Hospital Infantil de México Federico Gómez, Mexico City 06720, México
| | - Francisco Arenas-Huertero
- Laboratorio de Investigación en Patología Experimental, Hospital Infantil de México Federico Gómez, Mexico City 06720, México
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3
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Hu K, Zheng QK, Ma RJ, Ma C, Sun ZG, Zhang N. Krüppel-Like Factor 6 Splice Variant 1: An Oncogenic Transcription Factor Involved in the Progression of Multiple Malignant Tumors. Front Cell Dev Biol 2021; 9:661731. [PMID: 33816511 PMCID: PMC8017371 DOI: 10.3389/fcell.2021.661731] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2021] [Accepted: 02/23/2021] [Indexed: 01/03/2023] Open
Abstract
Krüppel-like factor 6 (KLF6) is one of the most studied members of the specificity protein/Krüppel-like factor (SP/KLF) transcription factor family. It has a typical zinc finger structure and plays a pivotal role in regulating the biological processes of cells. Recently, it has been considered to play a role in combatting cancer. Krüppel-like factor 6 splice variant 1 (KLF6-SV1), being one of the alternative KLF6 splicing isoforms, participates in tumor occurrence and development and has the potential to become a new target for molecular targeted therapy, although its action mechanism remains to be determined. The purpose of this article is to provide a comprehensive and systematic review of the important role of KLF6-SV1 in human malignant tumors to provide novel insights for oncotherapy.
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Affiliation(s)
- Kang Hu
- School of Clinical Medicine, Weifang Medical University, Weifang, China
| | - Qing-Kang Zheng
- School of Clinical Medicine, Weifang Medical University, Weifang, China
| | - Rui-Jie Ma
- Cheeloo College of Medicine, Shandong University, Jinan, China
| | - Chao Ma
- School of Clinical Medicine, Weifang Medical University, Weifang, China
| | - Zhi-Gang Sun
- Department of Thoracic Surgery, Jinan Central Hospital, Cheeloo College of Medicine, Shandong University, Jinan, China
| | - Nan Zhang
- Department of Oncology, Jinan Central Hospital, Cheeloo College of Medicine, Shandong University, Jinan, China
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4
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Li L, Zhang S, Li LM. Dual Eigen-modules of Cis-Element Regulation Profiles and Selection of Cognition-Language Eigen-direction along Evolution in Hominidae. Mol Biol Evol 2020; 37:1679-1693. [PMID: 32068872 PMCID: PMC10615152 DOI: 10.1093/molbev/msaa036] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
To understand the genomic basis accounting for the phenotypic differences between human and apes, we compare the matrices consisting of the cis-element frequencies in the proximal regulatory regions of their genomes. One such frequency matrix is represented by a robust singular value decomposition. For each singular value, the negative and positive ends of the sorted motif eigenvector correspond to the dual ends of the sorted gene eigenvector, respectively, comprising a dual eigen-module defined by cis-regulatory element frequencies (CREF). The CREF eigen-modules at levels 1, 2, 3, and 6 are highly conserved across humans, chimpanzees, and orangutans. The key biological processes embedded in the top three CREF eigen-modules are reproduction versus embryogenesis, fetal maturation versus immune system, and stress responses versus mitosis. Although the divergence at the nucleotide level between the chimpanzee and human genome was small, their cis-element frequency matrices crossed a singularity point, at which the fourth and fifth singular values were identical. The CREF eigen-modules corresponding to the fourth and fifth singular values were reorganized along the evolution from apes to human. Interestingly, the fourth sorted gene eigenvector encodes the phenotypes unique to human such as long-term memory, language development, and social behavior. The number of motifs present on Alu elements increases substantially at the fourth level. The motif analysis together with the cases of human-specific Alu insertions suggests that mutations related to Alu elements play a critical role in the evolution of the human-phenotypic gene eigenvector.
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Affiliation(s)
- Liang Li
- National Center of Mathematics and Interdisciplinary Sciences, Academy of Mathematics and Systems Science, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences
| | - Sheng Zhang
- National Center of Mathematics and Interdisciplinary Sciences, Academy of Mathematics and Systems Science, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences
| | - Lei M Li
- National Center of Mathematics and Interdisciplinary Sciences, Academy of Mathematics and Systems Science, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences
- Center for Excellence in Animal Evolution and Genetics, Chinese Academy of Sciences, Kunming, China
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5
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Ye W, Chen R, Chen X, Huang B, Lin R, Xie X, Chen J, Jiang J, Deng Y, Wen J. AhR regulates the expression of human cytochrome P450 1A1 (CYP1A1) by recruiting Sp1. FEBS J 2019; 286:4215-4231. [PMID: 31199573 DOI: 10.1111/febs.14956] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Revised: 04/09/2019] [Accepted: 06/11/2019] [Indexed: 12/28/2022]
Abstract
Cytochrome P450 1A1 (CYP1A1) is abundant in the kidney, liver, and intestine and is involved in the phase I metabolism of numerous endogenous and exogenous compounds. Therefore, exploring the regulatory mechanism of its basal expression in humans is particularly important to understand the bioactivation of several procarcinogens to their carcinogenic derivatives. Site-specific mutagenesis and deletion of the transcription factor binding site determined the core cis-acting elements in the human CYP1A1 proximal and distal promoter regions. The proximal promoter region [overlapping xenobiotic-responsive element (XRE) and GC box sequences] determined the basal expression of CYP1A1. In human hepatocellular carcinoma cells (HepG2) with aryl hydrocarbon receptor (AhR) or specificity protein 1 (Sp1) knockdown, we confirmed that AhR and Sp1 are involved in basal CYP1A1 expression. In HepG2 cells overexpressing either AhR or Sp1, AhR determined the proximal transactivation of basal CYP1A1 expression. Via DNA affinity precipitation assays and ChIP, we found that AhR bound to the promoter and recruited Sp1 to transactivate CYP1A1 expression. The coordinated interaction between Sp1 and AhR was identified to be DNA mediated. Our work revealed a basal regulatory mechanism of an interesting human gene by which AhR interacts with Sp1 through DNA and recruits Sp1 to regulate basal CYP1A1 expression.
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Affiliation(s)
- Wenchu Ye
- Guangdong Provincial Key Laboratory of Protein Function and Regulation in Agricultural Organisms, College of Life Sciences, South China Agricultural University Guangzhou, Guangzhou, Guangdong, 510642, China
- Key Laboratory of Zoonosis of Ministry of Agriculture and Rural Affairs, South China Agricultural University, Guangzhou, Guangdong, 510642, China
| | - Ruohong Chen
- Guangdong Provincial Key Laboratory of Protein Function and Regulation in Agricultural Organisms, College of Life Sciences, South China Agricultural University Guangzhou, Guangzhou, Guangdong, 510642, China
- Key Laboratory of Zoonosis of Ministry of Agriculture and Rural Affairs, South China Agricultural University, Guangzhou, Guangdong, 510642, China
| | - Xiaoxuan Chen
- Guangdong Provincial Key Laboratory of Protein Function and Regulation in Agricultural Organisms, College of Life Sciences, South China Agricultural University Guangzhou, Guangzhou, Guangdong, 510642, China
- Key Laboratory of Zoonosis of Ministry of Agriculture and Rural Affairs, South China Agricultural University, Guangzhou, Guangdong, 510642, China
| | - Boyan Huang
- Guangdong Provincial Key Laboratory of Protein Function and Regulation in Agricultural Organisms, College of Life Sciences, South China Agricultural University Guangzhou, Guangzhou, Guangdong, 510642, China
- Key Laboratory of Zoonosis of Ministry of Agriculture and Rural Affairs, South China Agricultural University, Guangzhou, Guangdong, 510642, China
| | - Ruqin Lin
- Guangdong Provincial Key Laboratory of Protein Function and Regulation in Agricultural Organisms, College of Life Sciences, South China Agricultural University Guangzhou, Guangzhou, Guangdong, 510642, China
- Key Laboratory of Zoonosis of Ministry of Agriculture and Rural Affairs, South China Agricultural University, Guangzhou, Guangdong, 510642, China
| | - Xuan Xie
- Guangdong Provincial Key Laboratory of Protein Function and Regulation in Agricultural Organisms, College of Life Sciences, South China Agricultural University Guangzhou, Guangzhou, Guangdong, 510642, China
- Key Laboratory of Zoonosis of Ministry of Agriculture and Rural Affairs, South China Agricultural University, Guangzhou, Guangdong, 510642, China
| | - Jiongjie Chen
- Guangdong Provincial Key Laboratory of Protein Function and Regulation in Agricultural Organisms, College of Life Sciences, South China Agricultural University Guangzhou, Guangzhou, Guangdong, 510642, China
- Key Laboratory of Zoonosis of Ministry of Agriculture and Rural Affairs, South China Agricultural University, Guangzhou, Guangdong, 510642, China
| | - Jun Jiang
- Guangdong Provincial Key Laboratory of Protein Function and Regulation in Agricultural Organisms, College of Life Sciences, South China Agricultural University Guangzhou, Guangzhou, Guangdong, 510642, China
- Key Laboratory of Zoonosis of Ministry of Agriculture and Rural Affairs, South China Agricultural University, Guangzhou, Guangdong, 510642, China
| | - Yiqun Deng
- Guangdong Provincial Key Laboratory of Protein Function and Regulation in Agricultural Organisms, College of Life Sciences, South China Agricultural University Guangzhou, Guangzhou, Guangdong, 510642, China
- Key Laboratory of Zoonosis of Ministry of Agriculture and Rural Affairs, South China Agricultural University, Guangzhou, Guangdong, 510642, China
| | - Jikai Wen
- Guangdong Provincial Key Laboratory of Protein Function and Regulation in Agricultural Organisms, College of Life Sciences, South China Agricultural University Guangzhou, Guangzhou, Guangdong, 510642, China
- Key Laboratory of Zoonosis of Ministry of Agriculture and Rural Affairs, South China Agricultural University, Guangzhou, Guangdong, 510642, China
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Herholz M, Cepeda E, Baumann L, Kukat A, Hermeling J, Maciej S, Szczepanowska K, Pavlenko V, Frommolt P, Trifunovic A. KLF-1 orchestrates a xenobiotic detoxification program essential for longevity of mitochondrial mutants. Nat Commun 2019; 10:3323. [PMID: 31346165 PMCID: PMC6658563 DOI: 10.1038/s41467-019-11275-w] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2018] [Accepted: 06/28/2019] [Indexed: 12/29/2022] Open
Abstract
Most manipulations that extend lifespan also increase resistance to various stress factors and environmental cues in a range of animals from yeast to mammals. However, the underlying molecular mechanisms regulating stress resistance during aging are still largely unknown. Here we identify Krüppel-like factor 1 (KLF-1) as a mediator of a cytoprotective response that dictates longevity induced by reduced mitochondrial function. A redox-regulated KLF-1 activation and transfer to the nucleus coincides with the peak of somatic mitochondrial biogenesis that occurs around a transition from larval stage L3 to D1. We further show that KLF-1 activates genes involved in the xenobiotic detoxification programme and identified cytochrome P450 oxidases, the KLF-1 main effectors, as longevity-assurance factors of mitochondrial mutants. Collectively, these findings underline the importance of the xenobiotic detoxification in the mitohormetic, longevity assurance pathway and identify KLF-1 as a central factor in orchestrating this response.
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Affiliation(s)
- Marija Herholz
- Cologne Excellence Cluster on Cellular Stress Responses in Ageing-Associated Diseases (CECAD) and Institute for Mitochondrial Diseases and Ageing, Medical Faculty, University of Cologne, D-50931, Cologne, Germany
| | - Estela Cepeda
- Cologne Excellence Cluster on Cellular Stress Responses in Ageing-Associated Diseases (CECAD) and Institute for Mitochondrial Diseases and Ageing, Medical Faculty, University of Cologne, D-50931, Cologne, Germany
| | - Linda Baumann
- Cologne Excellence Cluster on Cellular Stress Responses in Ageing-Associated Diseases (CECAD) and Institute for Mitochondrial Diseases and Ageing, Medical Faculty, University of Cologne, D-50931, Cologne, Germany
| | - Alexandra Kukat
- Cologne Excellence Cluster on Cellular Stress Responses in Ageing-Associated Diseases (CECAD) and Institute for Mitochondrial Diseases and Ageing, Medical Faculty, University of Cologne, D-50931, Cologne, Germany
| | - Johannes Hermeling
- Cologne Excellence Cluster on Cellular Stress Responses in Ageing-Associated Diseases (CECAD) and Institute for Mitochondrial Diseases and Ageing, Medical Faculty, University of Cologne, D-50931, Cologne, Germany
| | - Sarah Maciej
- Cologne Excellence Cluster on Cellular Stress Responses in Ageing-Associated Diseases (CECAD) and Institute for Mitochondrial Diseases and Ageing, Medical Faculty, University of Cologne, D-50931, Cologne, Germany
| | - Karolina Szczepanowska
- Cologne Excellence Cluster on Cellular Stress Responses in Ageing-Associated Diseases (CECAD) and Institute for Mitochondrial Diseases and Ageing, Medical Faculty, University of Cologne, D-50931, Cologne, Germany
| | - Victor Pavlenko
- Cologne Excellence Cluster on Cellular Stress Responses in Ageing-Associated Diseases (CECAD) and Institute for Mitochondrial Diseases and Ageing, Medical Faculty, University of Cologne, D-50931, Cologne, Germany
| | - Peter Frommolt
- Cologne Excellence Cluster on Cellular Stress Responses in Ageing-Associated Diseases (CECAD) and Institute for Mitochondrial Diseases and Ageing, Medical Faculty, University of Cologne, D-50931, Cologne, Germany
| | - Aleksandra Trifunovic
- Cologne Excellence Cluster on Cellular Stress Responses in Ageing-Associated Diseases (CECAD) and Institute for Mitochondrial Diseases and Ageing, Medical Faculty, University of Cologne, D-50931, Cologne, Germany. .,Center for Molecular Medicine Cologne (CMMC), D-50931, Cologne, Germany.
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7
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Choi H, Ryu KY, Roh J. Krüppel-like factor 4 plays a role in the luteal transition in steroidogenesis by downregulating Cyp19A1 expression. Am J Physiol Endocrinol Metab 2019; 316:E1071-E1080. [PMID: 30939050 DOI: 10.1152/ajpendo.00238.2018] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
The transition from granulosa cell (GC) to luteal cell involves a change from estrogen production to predominantly progesterone production. We analyzed the role of Krüppel-like factor 4 (Klf4), a transcriptional repressor used to generate pluripotent cells, in that transition. After luteinizing hormone (LH)/human chorionic gonadotropin treatment of preovulatory follicles, a major but transient increase in Klf4 transcript levels was detected. Therefore, we enquired whether Klf4 is involved in the rapid decline of aromatase, the key estrogen-producing enzyme, using preovulatory GCs obtained from pregnant mare serum gonadotropin-primed immature rat ovaries. Cyp19A1 expression in GCs transfected with FLAG-Klf4 or Klf4-specific siRNA was analyzed by real-time PCR and immunofluorescence staining. Cyp19A1 decreased when Klf4 was overexpressed, and Cyp19A1 and estradiol biosynthesis increased when Klf4 was knocked down. The mechanism by which Klf4 regulates Cyp19A1 expression was investigated using Cyp19A1 promoter-luciferase reporter assays and chromatin immunoprecipitation assays. The results revealed that the steroidogenic factor-1 (SF1)-binding motif, but not the specificity protein 1 (Sp1) binding element or the CACCC motif, was required for Klf4-mediated repression of Cyp19A1 promoter activity. Here we showed that Klf4 suppressed endogenous Cyp19A1 transcript and protein production, and this resulted from direct binding of Klf4 to the SF1 recognition motif in the Cyp19A1 promoter. These findings suggest that Klf4 is a physiologic regulator of Cyp19A1 expression in response to the LH surge in preovulatory GCs and that it has an essential role in the luteal transition in steroidogenesis.
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Affiliation(s)
- Hyeonhae Choi
- Laboratory of Reproductive Endocrinology, Department of Anatomy and Cell Biology, College of Medicine, Hanyang University , Seoul , South Korea
| | - Ki-Young Ryu
- Department of Obstetrics and Gynecology, College of Medicine, Hanyang University , Seoul , South Korea
| | - Jaesook Roh
- Laboratory of Reproductive Endocrinology, Department of Anatomy and Cell Biology, College of Medicine, Hanyang University , Seoul , South Korea
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Xie X, Jiang J, Ye W, Chen R, Deng Y, Wen J. Sp1, Instead of AhR, Regulates the Basal Transcription of Porcine CYP1A1 at the Proximal Promoter. Front Pharmacol 2018; 9:927. [PMID: 30174605 PMCID: PMC6107784 DOI: 10.3389/fphar.2018.00927] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2018] [Accepted: 07/30/2018] [Indexed: 12/31/2022] Open
Abstract
Pigs are commonly used as an animal model to evaluate the toxic effects of exogenous compounds. Cytochrome P450 1A1 (CYP1A1) metabolizes numerous exogenous compounds and is abundantly expressed in the liver, kidneys, and intestines. The high amino acid similarity between human and porcine CYP1A1 indicates that they probably have the same metabolic characteristics. Therefore, understanding the regulatory mechanism of CYP1A1 expression in pigs is particularly important for predicting the toxicology and metabolic kinetics of exogenous chemicals. Currently, the transcriptional regulation of porcine CYP1A1 has rarely been studied, especially regarding basal transcription. In this study, we first confirmed that the key regulatory elements of porcine CYP1A1 basal transactivation are in the proximal promoter region using promoter truncation analysis via a dual luciferase assay in a porcine kidney cell line LLC-PK1. Two overlapping cis-elements, the xenobiotic response element (XRE) and GC box, in this proximal region potentially play key roles in the basal transactivation of porcine CYP1A1. Furthermore, using electrophoretic mobility shift assay and chromatin immunoprecipitation, the GC box binding protein Sp1 was confirmed to bind to the proximal promoter of porcine CYP1A1, instead of AhR, the XRE binding protein. In LLC-PK1 cells, by knocking down either Sp1 or AhR, the expression of porcine CYP1A1 at the mRNA level and protein level was significantly downregulated, suggesting both proteins are important for porcine CYP1A1 expression. However, promoter activity analysis in LLC-PK1 cells treated with an AhR agonist and antagonist confirmed that AhR does not participate in the basal regulation of porcine CYP1A1 at the proximal promoter. In conclusion, our study revealed that the proximal promoter is the key regulatory region for porcine CYP1A1 basal expression. Although AhR plays an important role in the transactivation of porcine CYP1A1 expression, the key determinant transcription factor for its basal transactivation is Sp1 at the proximal promoter of porcine CYP1A1.
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Affiliation(s)
- Xuan Xie
- Guangdong Provincial Key Laboratory of Protein Function and Regulation in Agricultural Organisms, College of Life Sciences, South China Agricultural University, Guangzhou, China.,Key Laboratory of Zoonosis of Ministry of Agriculture and Rural Affairs, South China Agricultural University, Guangzhou, China
| | - Jun Jiang
- Guangdong Provincial Key Laboratory of Protein Function and Regulation in Agricultural Organisms, College of Life Sciences, South China Agricultural University, Guangzhou, China.,Key Laboratory of Zoonosis of Ministry of Agriculture and Rural Affairs, South China Agricultural University, Guangzhou, China
| | - Wenchu Ye
- Guangdong Provincial Key Laboratory of Protein Function and Regulation in Agricultural Organisms, College of Life Sciences, South China Agricultural University, Guangzhou, China.,Key Laboratory of Zoonosis of Ministry of Agriculture and Rural Affairs, South China Agricultural University, Guangzhou, China
| | - Ruohong Chen
- Guangdong Provincial Key Laboratory of Protein Function and Regulation in Agricultural Organisms, College of Life Sciences, South China Agricultural University, Guangzhou, China.,Key Laboratory of Zoonosis of Ministry of Agriculture and Rural Affairs, South China Agricultural University, Guangzhou, China
| | - Yiqun Deng
- Guangdong Provincial Key Laboratory of Protein Function and Regulation in Agricultural Organisms, College of Life Sciences, South China Agricultural University, Guangzhou, China.,Key Laboratory of Zoonosis of Ministry of Agriculture and Rural Affairs, South China Agricultural University, Guangzhou, China
| | - Jikai Wen
- Guangdong Provincial Key Laboratory of Protein Function and Regulation in Agricultural Organisms, College of Life Sciences, South China Agricultural University, Guangzhou, China.,Key Laboratory of Zoonosis of Ministry of Agriculture and Rural Affairs, South China Agricultural University, Guangzhou, China
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9
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Regulation of Human Cytochrome P4501A1 (hCYP1A1): A Plausible Target for Chemoprevention? BIOMED RESEARCH INTERNATIONAL 2016; 2016:5341081. [PMID: 28105425 PMCID: PMC5220472 DOI: 10.1155/2016/5341081] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/05/2016] [Revised: 11/09/2016] [Accepted: 11/13/2016] [Indexed: 12/13/2022]
Abstract
Human cytochrome P450 1A1 (hCYP1A1) has been an object of study due to its role in precarcinogen metabolism; for this reason it is relevant to know more in depth the mechanisms that rule out its expression and activity, which make this enzyme a target for the development of novel chemiopreventive agents. The aim of this work is to review the origin, regulation, and structural and functional characteristics of CYP1A1 letting us understand its role in the bioactivation of precarcinogen and the consequences of its modulation in other physiological processes, as well as guide us in the study of this important protein.
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10
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Hashimoto H, Wang D, Steves AN, Jin P, Blumenthal RM, Zhang X, Cheng X. Distinctive Klf4 mutants determine preference for DNA methylation status. Nucleic Acids Res 2016; 44:10177-10185. [PMID: 27596594 PMCID: PMC5137437 DOI: 10.1093/nar/gkw774] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2016] [Revised: 08/22/2016] [Accepted: 08/23/2016] [Indexed: 01/06/2023] Open
Abstract
Reprogramming of mammalian genome methylation is critically important but poorly understood. Klf4, a transcription factor directing reprogramming, contains a DNA binding domain with three consecutive C2H2 zinc fingers. Klf4 recognizes CpG or TpG within a specific sequence. Mouse Klf4 DNA binding domain has roughly equal affinity for methylated CpG or TpG, and slightly lower affinity for unmodified CpG. The structural basis for this key preference is unclear, though the side chain of Glu446 is known to contact the methyl group of 5-methylcytosine (5mC) or thymine (5-methyluracil). We examined the role of Glu446 by mutagenesis. Substituting Glu446 with aspartate (E446D) resulted in preference for unmodified cytosine, due to decreased affinity for 5mC. In contrast, substituting Glu446 with proline (E446P) increased affinity for 5mC by two orders of magnitude. Structural analysis revealed hydrophobic interaction between the proline's aliphatic cyclic structure and the 5-methyl group of the pyrimidine (5mC or T). As in wild-type Klf4 (E446), the proline at position 446 does not interact directly with either the 5mC N4 nitrogen or the thymine O4 oxygen. In contrast, the unmethylated cytosine's exocyclic N4 amino group (NH2) and its ring carbon C5 atom hydrogen bond directly with the aspartate carboxylate of the E446D variant. Both of these interactions would provide a preference for cytosine over thymine, and the latter one could explain the E446D preference for unmethylated cytosine. Finally, we evaluated the ability of these Klf4 mutants to regulate transcription of methylated and unmethylated promoters in a luciferase reporter assay.
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Affiliation(s)
| | - Dongxue Wang
- Department of Biochemistry, Emory University, Atlanta, GA 30322, USA
| | - Alyse N Steves
- Genetics and Molecular Biology Graduate Program, Laney Graduate School, Emory University, Atlanta, GA 30322, USA
| | - Peng Jin
- Department of Human Genetics, Emory University, Atlanta, GA 30322, USA
| | - Robert M Blumenthal
- Department of Medical Microbiology & Immunology and Program in Bioinformatics, The University of Toledo College of Medicine & Life Sciences, Toledo, Ohio 43614, USA
| | - Xing Zhang
- Department of Biochemistry, Emory University, Atlanta, GA 30322, USA
| | - Xiaodong Cheng
- Department of Biochemistry, Emory University, Atlanta, GA 30322, USA .,Genetics and Molecular Biology Graduate Program, Laney Graduate School, Emory University, Atlanta, GA 30322, USA
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11
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Park CS, Shen Y, Lewis A, Lacorazza HD. Role of the reprogramming factor KLF4 in blood formation. J Leukoc Biol 2016; 99:673-85. [DOI: 10.1189/jlb.1ru1215-539r] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2015] [Accepted: 01/22/2016] [Indexed: 12/31/2022] Open
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12
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He ZX, Chen XW, Zhou ZW, Zhou SF. Impact of physiological, pathological and environmental factors on the expression and activity of human cytochrome P450 2D6 and implications in precision medicine. Drug Metab Rev 2015; 47:470-519. [PMID: 26574146 DOI: 10.3109/03602532.2015.1101131] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
With only 1.3-4.3% in total hepatic CYP content, human CYP2D6 can metabolize more than 160 drugs. It is a highly polymorphic enzyme and subject to marked inhibition by a number of drugs, causing a large interindividual variability in drug clearance and drug response and drug-drug interactions. The expression and activity of CYP2D6 are regulated by a number of physiological, pathological and environmental factors at transcriptional, post-transcriptional, translational and epigenetic levels. DNA hypermethylation and histone modifications can repress the expression of CYP2D6. Hepatocyte nuclear factor-4α binds to a directly repeated element in the promoter of CYP2D6 and thus regulates the expression of CYP2D6. Small heterodimer partner represses hepatocyte nuclear factor-4α-mediated transactivation of CYP2D6. GW4064, a farnesoid X receptor agonist, decreases hepatic CYP2D6 expression and activity while increasing small heterodimer partner expression and its recruitment to the CYP2D6 promoter. The genotypes are key determinants of interindividual variability in CYP2D6 expression and activity. Recent genome-wide association studies have identified a large number of genes that can regulate CYP2D6. Pregnancy induces CYP2D6 via unknown mechanisms. Renal or liver diseases, smoking and alcohol use have minor to moderate effects only on CYP2D6 activity. Unlike CYP1 and 3 and other CYP2 members, CYP2D6 is resistant to typical inducers such as rifampin, phenobarbital and dexamethasone. Post-translational modifications such as phosphorylation of CYP2D6 Ser135 have been observed, but the functional impact is unknown. Further functional and validation studies are needed to clarify the role of nuclear receptors, epigenetic factors and other factors in the regulation of CYP2D6.
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Affiliation(s)
- Zhi-Xu He
- a Guizhou Provincial Key Laboratory for Regenerative Medicine, Stem Cell and Tissue Engineering Research Center & Sino-US Joint Laboratory for Medical Sciences, Guizhou Medical University , Guiyang , Guizhou , China
| | - Xiao-Wu Chen
- b Department of General Surgery , The First People's Hospital of Shunde, Southern Medical University , Shunde , Foshan , Guangdong , China , and
| | - Zhi-Wei Zhou
- c Department of Pharmaceutical Science , College of Pharmacy, University of South Florida , Tampa , FL , USA
| | - Shu-Feng Zhou
- a Guizhou Provincial Key Laboratory for Regenerative Medicine, Stem Cell and Tissue Engineering Research Center & Sino-US Joint Laboratory for Medical Sciences, Guizhou Medical University , Guiyang , Guizhou , China .,c Department of Pharmaceutical Science , College of Pharmacy, University of South Florida , Tampa , FL , USA
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13
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Jackson DP, Joshi AD, Elferink CJ. Ah Receptor Pathway Intricacies; Signaling Through Diverse Protein Partners and DNA-Motifs. Toxicol Res (Camb) 2015; 4:1143-1158. [PMID: 26783425 PMCID: PMC4714567 DOI: 10.1039/c4tx00236a] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
The Ah receptor is a transcription factor that modulates gene expression via interactions with multiple protein partners; these are reviewed, including the novel NC-XRE pathway involving KLF6.
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14
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Abstract
The discovery of the Klotho (KL) gene, which was originally identified as a putative aging-suppressor gene, has generated tremendous interest and has advanced understanding of the aging process. In mice, the overexpression of the KL gene extends the life span, whereas mutations to the KL gene shorten the life span. The human KL gene encodes the α-Klotho protein, which is a multifunctional protein that regulates the metabolism of phosphate, calcium, and vitamin D. α-Klotho also may function as a hormone, although the α-Klotho receptor(s) has not been found. Point mutations of the KL gene in humans are associated with hypertension and kidney disease, which suggests that α-Klotho may be essential to the maintenance of normal renal function. Three α-Klotho protein types with potentially different functions have been identified: a full-length transmembrane α-Klotho, a truncated soluble α-Klotho, and a secreted α-Klotho. Recent evidence suggests that α-Klotho suppresses the insulin and Wnt signaling pathways, inhibits oxidative stress, and regulates phosphatase and calcium absorption. In this review, we provide an update on recent advances in the understanding of the molecular, genetic, biochemical, and physiological properties of the KL gene. Specifically, this review focuses on the structure of the KL gene and the factors that regulate KL gene transcription, the key sites in the regulation of α-Klotho enzyme activity, the α-Klotho signaling pathways, and the molecular mechanisms that underlie α-Klotho function. This current understanding of the molecular biology of the α-Klotho protein may offer new insights into its function and role in aging.
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Affiliation(s)
- Yuechi Xu
- Department of Physiology, College of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104
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15
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Martínez-Armenta M, Díaz de León-Guerrero S, Catalán A, Alvarez-Arellano L, Uribe RM, Subramaniam M, Charli JL, Pérez-Martínez L. TGFβ2 regulates hypothalamic Trh expression through the TGFβ inducible early gene-1 (TIEG1) during fetal development. Mol Cell Endocrinol 2015; 400:129-39. [PMID: 25448845 PMCID: PMC4415168 DOI: 10.1016/j.mce.2014.10.021] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/27/2014] [Revised: 09/01/2014] [Accepted: 10/27/2014] [Indexed: 01/05/2023]
Abstract
The hypothalamus regulates the homeostasis of the organism by controlling hormone secretion from the pituitary. The molecular mechanisms that regulate the differentiation of the hypothalamic thyrotropin-releasing hormone (TRH) phenotype are poorly understood. We have previously shown that Klf10 or TGFβ inducible early gene-1 (TIEG1) is enriched in fetal hypothalamic TRH neurons. Here, we show that expression of TGFβ isoforms (1-3) and both TGFβ receptors (TβRI and II) occurs in the hypothalamus concomitantly with the establishment of TRH neurons during late embryonic development. TGFβ2 induces Trh expression via a TIEG1 dependent mechanism. TIEG1 regulates Trh expression through an evolutionary conserved GC rich sequence on the Trh promoter. Finally, in mice deficient in TIEG1, Trh expression is lower than in wild type animals at embryonic day 17. These results indicate that TGFβ signaling, through the upregulation of TIEG1, plays an important role in the establishment of Trh expression in the embryonic hypothalamus.
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MESH Headings
- Animals
- DNA-Binding Proteins/deficiency
- DNA-Binding Proteins/genetics
- Embryo, Mammalian
- Fetus
- Gene Expression Regulation, Developmental
- Hypothalamus/cytology
- Hypothalamus/growth & development
- Hypothalamus/metabolism
- Immunohistochemistry
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Neurons/cytology
- Neurons/metabolism
- Primary Cell Culture
- Promoter Regions, Genetic
- Protein Serine-Threonine Kinases/genetics
- Protein Serine-Threonine Kinases/metabolism
- Rats
- Rats, Wistar
- Receptor, Transforming Growth Factor-beta Type I
- Receptor, Transforming Growth Factor-beta Type II
- Receptors, Transforming Growth Factor beta/genetics
- Receptors, Transforming Growth Factor beta/metabolism
- Signal Transduction
- Thyrotropin-Releasing Hormone/genetics
- Thyrotropin-Releasing Hormone/metabolism
- Transcription Factors/deficiency
- Transcription Factors/genetics
- Transforming Growth Factor beta1/genetics
- Transforming Growth Factor beta1/metabolism
- Transforming Growth Factor beta2/genetics
- Transforming Growth Factor beta2/metabolism
- Transforming Growth Factor beta3/genetics
- Transforming Growth Factor beta3/metabolism
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Affiliation(s)
- Miriam Martínez-Armenta
- Laboratorio de Neuroinmunobiología, Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnología, Universidad Nacional Autónoma de México (UNAM), Cuernavaca, Morelos, Mexico
| | - Sol Díaz de León-Guerrero
- Laboratorio de Neuroinmunobiología, Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnología, Universidad Nacional Autónoma de México (UNAM), Cuernavaca, Morelos, Mexico
| | - Ana Catalán
- Laboratorio de Neuroinmunobiología, Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnología, Universidad Nacional Autónoma de México (UNAM), Cuernavaca, Morelos, Mexico
| | - Lourdes Alvarez-Arellano
- Laboratorio de Neuroinmunobiología, Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnología, Universidad Nacional Autónoma de México (UNAM), Cuernavaca, Morelos, Mexico
| | - Rosa Maria Uribe
- Departamento de Genética y Fisiología Molecular, Instituto de Biotecnología, UNAM, Cuernavaca, Morelos, Mexico
| | | | - Jean-Louis Charli
- Departamento de Genética y Fisiología Molecular, Instituto de Biotecnología, UNAM, Cuernavaca, Morelos, Mexico
| | - Leonor Pérez-Martínez
- Laboratorio de Neuroinmunobiología, Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnología, Universidad Nacional Autónoma de México (UNAM), Cuernavaca, Morelos, Mexico.
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16
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Vincent R, Sanyal A. Recent Advances in Understanding of NASH: MicroRNAs as Both Biochemical Markers and Players. CURRENT PATHOBIOLOGY REPORTS 2014; 2:109-115. [PMID: 25574453 DOI: 10.1007/s40139-014-0049-8] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Nonalcoholic fatty liver disease (NAFLD) and nonalcoholic steatohepatis (NASH) are becoming the dominant liver diseases in the US and Western World. Extensive work is being done to diagnose, understand, and explore the pathogenesis of these multivariable complex diseases. Recently a new avenue of biologic regulation is being explored. MicroRNAs are non-coding RNAs that modulate the expression of multiple genes and have been implicated in multiple diseases. Recently there is a growing body of evidence supporting a significant role of microRNAs in NAFLD pathogenesis and progression to NASH, and hinting at their use as targets, biomarkers and potential therapeutic tools. This review is designed to highlight some of the recent work on a few of the key microRNAs involved in the pathogenesis of NAFLD and NASH.
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Affiliation(s)
- Robert Vincent
- Virginia Common Wealth University, Department of Hepatology and Gastroenterology. 1250 West Marshall Richmond VA, 23228
| | - Arun Sanyal
- Virginia Common Wealth University, Department of Hepatology and Gastroenterology. 1250 West Marshall Richmond VA, 23228
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17
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Kim JH, Kim K, Youn BU, Lee J, Kim I, Shin HI, Akiyama H, Choi Y, Kim N. Kruppel-like factor 4 attenuates osteoblast formation, function, and cross talk with osteoclasts. ACTA ACUST UNITED AC 2014; 204:1063-74. [PMID: 24616223 PMCID: PMC3998795 DOI: 10.1083/jcb.201308102] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
KLF4 controls bone homeostasis by negatively regulating both osteoclast and osteoblast differentiation. Osteoblasts not only control bone formation but also support osteoclast differentiation. Here we show the involvement of Kruppel-like factor 4 (KLF4) in the differentiation of osteoclasts and osteoblasts. KLF4 was down-regulated by 1α,25-dihydroxyvitamin D3 (1,25(OH)2D3) in osteoblasts. Overexpression of KLF4 in osteoblasts attenuated 1,25(OH)2D3-induced osteoclast differentiation in co-culture of mouse bone marrow cells and osteoblasts through the down-regulation of receptor activator of nuclear factor κB ligand (RANKL) expression. Direct binding of KLF4 to the RANKL promoter repressed 1,25(OH)2D3-induced RANKL expression by preventing vitamin D receptor from binding to the RANKL promoter region. In contrast, ectopic overexpression of KLF4 in osteoblasts attenuated osteoblast differentiation and mineralization. KLF4 interacted directly with Runx2 and inhibited the expression of its target genes. Moreover, mice with conditional knockout of KLF4 in osteoblasts showed markedly increased bone mass caused by enhanced bone formation despite increased osteoclast activity. Thus, our data suggest that KLF4 controls bone homeostasis by negatively regulating both osteoclast and osteoblast differentiation.
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Affiliation(s)
- Jung Ha Kim
- Department of Pharmacology, Medical Research Center for Gene Regulation and BK21 plus, Chonnam National University Medical School, Gwangju 501-746, Korea
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18
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Liu Y, Olanrewaju YO, Zheng Y, Hashimoto H, Blumenthal RM, Zhang X, Cheng X. Structural basis for Klf4 recognition of methylated DNA. Nucleic Acids Res 2014; 42:4859-67. [PMID: 24520114 PMCID: PMC4005678 DOI: 10.1093/nar/gku134] [Citation(s) in RCA: 72] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
Transcription factor Krüppel-like factor 4 (Klf4), one of the factors directing cellular reprogramming, recognizes the CpG dinucleotide (whether methylated or unmodified) within a specific G/C-rich sequence. The binding affinity of the mouse Klf4 DNA-binding domain for methylated DNA is only slightly stronger than that for an unmodified oligonucleotide. The structure of the C-terminal three Krüppel-like zinc fingers (ZnFs) of mouse Klf4, in complex with fully methylated DNA, was determined at 1.85 Å resolution. An arginine and a glutamate interact with the methyl group. By comparison with two other recently characterized structures of ZnF protein complexes with methylated DNA, we propose a common principle of recognition of methylated CpG by C2H2 ZnF proteins, which involves a spatially conserved Arg–Glu pair.
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Affiliation(s)
- Yiwei Liu
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA 30322, USA, New England Biolabs, 240 County Road, Ipswich, MA 01938, USA and Department of Medical Microbiology and Immunology and Program in Bioinformatics, The University of Toledo College of Medicine and Life Sciences, Toledo, OH 43614, USA
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19
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MiR-34a regulates apoptosis in liver cells by targeting the KLF4 gene. Cell Mol Biol Lett 2014; 19:52-64. [PMID: 24415058 PMCID: PMC6275989 DOI: 10.2478/s11658-013-0115-y] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2013] [Revised: 12/28/2013] [Indexed: 02/07/2023] Open
Abstract
MicroRNAs (miRNAs) regulate gene expression by inhibiting translation or targeting messenger RNA (mRNA) for degradation in a posttranscriptional fashion. In this study, we show that ectopic expression of miR-34a-5p reduces the mRNA and protein levels of Krüppel-like factor 4 (KLF4). We also demonstrate that miR-34a targets the 3′-untranslated mRNA region of KLF4 and show that overexpression of miR-34a induces a significant level of apoptosis in BNL CL.2 cells exposed to doxorubicin or 10 Gy X-ray. Our data suggest that the effects of miR-34a on apoptosis occur due to the downregulation of KLF4.
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20
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Vigneault F, Guérin SL. Regulation of gene expression: probing DNA–protein interactionsin vivoandin vitro. Expert Rev Proteomics 2014; 2:705-18. [PMID: 16209650 DOI: 10.1586/14789450.2.5.705] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Tremendous efforts have been put together over the last several years to complete the entire sequencing of the human genome. As we enter the proteomic era, when the major aim is understanding which gene encodes which protein, the time has also come to identify their precise function inside the astonishing signaling network required to accomplish all cellular functions. Understanding when, why and how a gene is expressed has now become a necessity toward identifying all the regulatory pathways that mediate cellular processes such as differentiation, migration, replication, DNA repair and apoptosis. Regulation of gene transcription is a process that is primarily under the influence of nuclear-located transcription factors. Consequently, identifying which protein activates or represses a specific gene is a prerequisite for understanding cell fate and function. The current state of, and recent advances in, transcriptional regulation approaches are reviewed here, with special emphasis on new technologies required when probing for DNA-protein interactions. This review explores different strategies aimed at identifying both the regulatory sequences of any given gene and the trans-acting regulatory factors that recognize these elements as their target sites in the nucleus. Ongoing developments in the fields of nanotechnology, RNA silencing and protein modeling toward the investigation of DNA-protein interactions and their relevance in the battle against cancer are discussed.
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Affiliation(s)
- Francois Vigneault
- Laboratoire d'Endocrinologie Moléculaire et Oncologique, Centre de recherche du CHUL (CHUQ), Sainte-Foy, Québec, G1V 4G2, Canada.
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21
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Wilson SR, Joshi AD, Elferink CJ. The tumor suppressor Kruppel-like factor 6 is a novel aryl hydrocarbon receptor DNA binding partner. J Pharmacol Exp Ther 2013; 345:419-29. [PMID: 23512538 DOI: 10.1124/jpet.113.203786] [Citation(s) in RCA: 96] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
The aryl hydrocarbon receptor (AhR) is a ligand-mediated basic helix-loop-helix transcription factor of the Per/Arnt/Sim family that regulates adaptive and toxic responses to a variety of chemical pollutants, including polycyclic aromatic hydrocarbons and halogenated aromatic hydrocarbons, most notably 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). Ligand activation leads to AhR nuclear translocation and binding to a xenobiotic response element (XRE) in association with the Arnt to regulate gene expression. Several recent genome-wide transcriptional studies identified numerous AhR target genes that lack the canonical XRE recognition site in the promoter regions. Characterization of one such target gene, the plasminogen activator inhibitor 1, identified a novel nonconsensus XRE (NC-XRE) that confers TCDD responsiveness independently of the Arnt protein. Studies reported here show that the NC-XRE is a recognition site for the AhR and a new binding partner, the Kruppel-like factor (KLF) family member KLF6. In vivo chromatin immunoprecipitations and in vitro DNA binding studies demonstrate that the AhR and KLF6 proteins form an obligatory heterodimer necessary for NC-XRE binding. Mutational analyses show that the protein-protein interactions involve the AhR C terminus and KLF6 N terminus, respectively. Moreover, NC-XRE binding depends on the 5' basic region in KLF6 rather than the previously characterized zinc finger DNA binding domain. Collectively, the results unmask a novel AhR signaling mechanism distinct from the canonical XRE-driven process that will enrich our future understanding of AhR biology.
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Affiliation(s)
- Shelly R Wilson
- Department of Pharmacology and Toxicology, University of Texas Medical Branch, 301 University Blvd., Galveston, TX, USA
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22
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Koopmansch B, Berx G, Foidart JM, Gilles C, Winkler R. Interplay between KLF4 and ZEB2/SIP1 in the regulation of E-cadherin expression. Biochem Biophys Res Commun 2013; 431:652-7. [DOI: 10.1016/j.bbrc.2013.01.070] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2013] [Accepted: 01/19/2013] [Indexed: 11/26/2022]
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23
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Pérez-Monter C, Martínez-Armenta M, Miquelajauregui A, Furlan-Magaril M, Varela-Echavarría A, Recillas-Targa F, May V, Charli JL, Pérez-Martínez L. The Krüppel-like factor 4 controls biosynthesis of thyrotropin-releasing hormone during hypothalamus development. Mol Cell Endocrinol 2011; 333:127-33. [PMID: 21182892 DOI: 10.1016/j.mce.2010.12.020] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/23/2010] [Revised: 12/10/2010] [Accepted: 12/13/2010] [Indexed: 01/16/2023]
Abstract
Embryonic neurogenesis is controlled by the activation of specific genetic programs. In the hypothalamus, neuronal thyrotropin-releasing hormone (TRH) populations control important physiological process, including energy homeostasis and autonomic function; however, the genetic program leading to the TRH expression is poorly understood. Here, we show that the Klf4 gene, encoding the transcription factor Krüppel-like factor 4 (Klf4), was expressed in the rat hypothalamus during development and regulated Trh expression. In rat fetal hypothalamic cells Klf4 regulated Trh promoter activity through CACCC and GC motifs present on the Trh gene promoter. Accordingly, hypothalamic Trh expression was down-regulated at embryonic day 15 in the Klf4(-/-) mice resulting in diminished bioactive peptide levels. Although at the neonatal stage the Trh transcript levels of the Klf4(-/-) mice were normal, the reduction in peptide levels persisted. Thus, our data indicate that Klf4 plays a key role in the maturation of TRH expression in hypothalamic neurons.
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Affiliation(s)
- Carlos Pérez-Monter
- Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos 62271, Mexico
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24
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Ilnytska O, Stütz AM, Park-York M, York DA, Ribnicky DM, Zuberi A, Cefalu WT, Argyropoulos G. Molecular mechanisms for activation of the agouti-related protein and stimulation of appetite. Diabetes 2011; 60:97-106. [PMID: 20980461 PMCID: PMC3012203 DOI: 10.2337/db10-0172] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
OBJECTIVE The agouti-related protein (Agrp) is a powerful orexigenic peptide, but little is known about its transcriptional regulation. The objective of this study was to determine molecular mechanisms for the activation of hypothalamic Agrp and identify compounds that stimulate appetite. RESEARCH DESIGN AND METHODS We used promoter analyses methods, hypothalamic cell culture and transfection, immunohistochemistry, luciferase-expressing transgenic mice, in vivo bioluminescence, anitisense RNA, mouse feeding studies, indirect calorimetry, real-time PCR, and Western blots. RESULTS We found that the Krüppel-like factor 4 (Klf4) is a potent activator of Agrp by binding to a specific CACCC-box in its minimal promoter. We also found that an extract of tarragon, termed PMI-5011, activated hypothalamic Klf4 and Agrp. In vivo, PMI-5011 increased Agrp promoter activity in luciferase-expressing transgenic mice, increased hypothalamic Klf4 and Agrp expression, increased hypothalamic Orexin and melanin-concentrating hormone, increased food intake, reduced circulating insulin and leptin levels, attenuated energy expenditure, and enhanced body weight but only when using a high-fat diet. CONCLUSIONS These data show that Klf4 augmented hypothalamic Agrp by binding to a specific CACCC-box onto its minimal promoter. In addition, the tarragon extract PMI-5011 activated Klf4 and orexigenic neuropeptides and reduced peripheral insulin and leptin levels leading to positive energy balance.
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Affiliation(s)
- Olha Ilnytska
- Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, Louisiana
- Department of Biological Sciences, Rutgers University, Newark, New Jersey
| | - Adrian M. Stütz
- Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, Louisiana
- Department of Genome Biology, European Molecular Biology Laboratory, Heidelberg, Germany
| | | | - David A. York
- Center for Advanced Nutrition, Utah State University, Logan, Utah
| | - David M. Ribnicky
- Biotech Center, Cook College, Rutgers University, New Brunswick, New Jersey
| | - Aamir Zuberi
- Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, Louisiana
| | - William T. Cefalu
- Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, Louisiana
| | - George Argyropoulos
- Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, Louisiana
- Weis Center for Research, Geisinger Clinic, Danville, Pennsylvania
- Corresponding author: George Argyropoulos,
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25
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Krüppel-like factor KLF9 regulates PPARγ transactivation at the middle stage of adipogenesis. Cell Death Differ 2010; 18:315-27. [PMID: 20725087 DOI: 10.1038/cdd.2010.100] [Citation(s) in RCA: 99] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Krüppel-like factors (KLFs) as a family of zinc-finger transcription factors involve in the regulation of many physiological processes. In these studies, KLF9 was characterized for its role in adipogenesis. The expression of KLF9 was markedly upregulated during the middle stage of 3T3-L1 adipocyte differentiation, and inhibition of KLF9 by RNAi impaired adipogenesis. Using promoter deletion and mutation analysis, we identified two KLF9-binding sites within the 0.6-kb region of the PPARγ2 proximal promoter, indicating that KLF9 interacts with the PPARγ2 promoter. Furthermore, we found that KLF9 could synergistically activate PPARγ2 promoter by directly interacting with C/EBPα. In addition, overexpression of PPARγ2 rescued the impairment of adipocyte differentiation induced by KLF9 knockdown, which supports that PPARγ2 is a downstream target of KLF9. Collectively, our results indicate KLF9 as a key pro-adipogenic transcription factor through regulation of PPARγ2 expression with C/EBPα at the middle stage of adipogenesis.
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26
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Nurmemmedov E, Yengo RK, Ladomery MR, Thunnissen MMGM. Kinetic behaviour of WT 1's zinc finger domain in binding to the alpha-actinin-1 mRNA. Arch Biochem Biophys 2010; 497:21-7. [PMID: 20193655 DOI: 10.1016/j.abb.2010.02.013] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2009] [Revised: 02/23/2010] [Accepted: 02/24/2010] [Indexed: 12/13/2022]
Abstract
The zinc finger transcription factor Wilms tumour protein (WT 1) is known for its essential involvement in the development of the genitourinary system as well as of other organs and tissues. WT 1 is capable of selectively binding either DNA or mRNA targets. A KTS insertion due to alternative splicing between the zinc fingers 3 and 4 and an unconventional zinc finger 1 are the unique features that distinguish WT 1 from classical DNA-binding C(2)H(2)-type zinc finger proteins. The DNA binding characteristics of WT 1 are well studied. Due to lack of information about its native RNA targets, no extensive research has been directed at how WT 1 binds RNA. Using surface plasmon resonance, this study attempts to understand the binding behaviour of WT 1 zinc fingers with its recently reported and first putative mRNA target, ACT 34, whose stem-loop structure is believed to be critical for the interactions with WT 1. We have analysed the interactions of five WT 1 zinc finger truncations with wild-type ACT 34 and four variants. Our results indicate that WT 1 zinc fingers bind ACT 34 in a specific manner, and that this occurs as interplay of all four zinc fingers. We also report that a sensitive kinetic balance, which is equilibrated by both zinc finger 1 and KTS, regulates the interaction with ACT 34. The stem-loop and the flanking nucleotides are important elements for specific recognition by WT 1 zinc fingers.
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Affiliation(s)
- Elmar Nurmemmedov
- Molecular Biophysics, Chemical Center, Lund University, 221 00 Lund, Sweden.
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27
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Yakovlev A, Khafizova M, Abdullaev Z, Loukinov D, Kondratyev A. Epigenetic regulation of caspase-3 gene expression in rat brain development. Gene 2010; 450:103-8. [PMID: 19909801 DOI: 10.1016/j.gene.2009.10.008] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2009] [Revised: 10/30/2009] [Accepted: 10/30/2009] [Indexed: 01/27/2023]
Abstract
The expression levels of caspase-3, a major contributor to the execution of neuronal apoptosis, markedly decrease in the process of brain maturation. We have previously cloned the rat caspase-3 gene promoter and identified its essential regulatory elements. In the present study, we extended previous findings by examining transcriptional regulation of caspase-3 expression in the rat brain of two different ages, corresponding to the immature and mature brain. In particular, we determined that the rate of transcription initiation substantially declines during brain maturation. Furthermore, we established that mRNA levels of Ets1, Ets2, and Sp1 do not change in the brain with maturation, suggesting that these transcription factors do not contribute to age-dependent caspase-3 down-regulation. Hence, we examined a role of DNA methylation and histone modification in this process. Utilizing bisulfite DNA sequencing, we determined the presence of age-dependent differentially methylated fragments within the caspase-3 promoter region. Strikingly, differentially methylated CpG sites correspond to the predicted binding sites for a number of transcription factors that have been previously shown to be involved in neuronal development and differentiation. Moreover, using chromatin immunoprecipitation, we found that mature brains displayed significantly lower levels of histone 3 acetylated Lys14 and histone 4 acetylated Lys5, 8, 12, and 16. This observation is consistent with the decreased level of expression of caspase-3 in the mature brain. Together with our observation that histone deacetylase inhibitor, trichostatin A, increased the level of caspase-3 mRNA in cortical neurons in vitro, these results further indicate an important role of epigenetic factors in the regulation of caspase-3 gene expression.
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Affiliation(s)
- Alexander Yakovlev
- Department of Neuroscience, Georgetown University, Washington, DC 20057, USA
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Nandan MO, Yang VW. The role of Krüppel-like factors in the reprogramming of somatic cells to induced pluripotent stem cells. Histol Histopathol 2009; 24:1343-55. [PMID: 19688699 DOI: 10.14670/hh-24.1343] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
The potential for clinical application of pluripotent embryonic stem cells is immense but hampered by moral and ethical complications. Recent advances in the reprogramming of somatic cells by defined factors to a state that resemble embryonic stem cells have created tremendous excitement in the field. Four factors, Sox2, Oct4, Klf4 and c-Myc, when exogenously introduced into somatic cells, can lead to the formation of induced pluripotent stem (iPS) cells that have the capacity for self-renewal and differentiation into tissues of all three germ layers. In this review, we focus on the role of Krüppel-like factors (KLFs) in regulating somatic cell reprogramming. KLFs are zinc finger-containing transcription factors with diverse biological functions. We first provide an overview of the KLF family of regulatory proteins, paying special attention to the established biological and biochemical functions of KLF4 and KLF5. We then review the role of KLFs in somatic cell reprogramming and delineate the putative mechanism by which KLFs participates the establishment and self-renewal of iPS cells. Further research is likely to provide additional insight into the mechanisms of somatic cell reprogramming and refinement of the technique with which to generate clinically relevant iPS cells.
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Affiliation(s)
- Mandayam O Nandan
- Division of Digestive Diseases, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia, USA
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Huesca M, Lock LS, Khine AA, Viau S, Peralta R, Cukier IH, Jin H, Al-Qawasmeh RA, Lee Y, Wright J, Young A. A novel small molecule with potent anticancer activity inhibits cell growth by modulating intracellular labile zinc homeostasis. Mol Cancer Ther 2009; 8:2586-96. [PMID: 19755513 DOI: 10.1158/1535-7163.mct-08-1104] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
ML-133 is a novel small molecule with potent antiproliferative activity, as shown in cancer cell lines and in a human colon tumor xenograft model. ML-133 reduces the concentration of intracellular labile zinc in HT-29 colon cancer cells, leading to induction of the Krüppel-like factor 4 transcription factor. Krüppel-like factor 4 displaces the positive regulator SP1 from the cyclin D1 promoter, thereby negatively regulating the expression of cyclin D1 and promoting the G(1)-S phase arrest of cell proliferation. The antiproliferative and antitumor activity of ML-133 described in the present study suggests modulation of intracellular zinc homeostasis as a potential strategy for the treatment of several cancer types, and ML-133 represents a promising new class of antitumor agents that deserves further development.
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Affiliation(s)
- Mario Huesca
- Lorus Therapeutics Inc., Toronto, Ontario M9W 4Z7 Canada.
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30
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Kawanami D, Mahabeleshwar GH, Lin Z, Atkins GB, Hamik A, Haldar SM, Maemura K, Lamanna JC, Jain MK. Kruppel-like factor 2 inhibits hypoxia-inducible factor 1alpha expression and function in the endothelium. J Biol Chem 2009; 284:20522-30. [PMID: 19491109 DOI: 10.1074/jbc.m109.025346] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Hypoxia-inducible factor 1 (HIF-1) is a central regulator of the hypoxic response in many cell types. In endothelial cells, HIF-1 induces the expression of key proangiogenic factors to promote angiogenesis. Recent studies have identified Kruppel-like factor 2 (KLF2) as a potent inhibitor of angiogenesis. However, the role of KLF2 in regulating HIF-1 expression and function has not been evaluated. KLF2 expression was induced acutely by hypoxia in endothelial cells. Adenoviral overexpression of KLF2 inhibited hypoxia-induced expression of HIF-1alpha and its target genes such as interleukin 8, angiopoietin-2, and vascular endothelial growth factor in endothelial cells. Conversely, knockdown of KLF2 increased expression of HIF-1alpha and its targets. Furthermore, KLF2 inhibited hypoxia-induced endothelial tube formation, whereas endothelial cells from mice with haploinsufficiency of KLF2 showed increased tube formation in response to hypoxia. Consistent with this ex vivo observation, KLF2 heterozygous mice showed increased microvessel density in the brain. Mechanistically, KLF2 promoted HIF-1alpha degradation in a von Hippel-Lindau protein-independent but proteasome-dependent manner. Finally, KLF2 disrupted the interaction between HIF-1alpha and its chaperone Hsp90, suggesting that KLF2 promotes degradation of HIF-1alpha by affecting its folding and maturation. These observations identify KLF2 as a novel inhibitor of HIF-1alpha expression and function. Therefore, KLF2 may be a target for modulating the angiogenic response in disease states.
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Affiliation(s)
- Daiji Kawanami
- University Hospitals Harrington-McLaughlin Heart & Vascular Institute and Case Cardiovascular Research Institute, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106, USA
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Abstract
Ghrelin, an endogenous ligand of the GH (growth hormone) secretagogue receptor, influences many metabolic processes including GH secretion, food intake, energy balance, insulin secretion and adipogenesis. Although ghrelin exhibits a variety of biological functions, the mechanism by which ghrelin expression is regulated is unknown. Ghrelin is expressed in the gastrointestinal tract, predominantly in the stomach, as is KLF4 (Krüppel-like factor 4). Therefore we investigated whether ghrelin expression is associated with KLF4, and found that the tissue distribution of ghrelin corresponded with that of KLF4. Furthermore, treatment with butyrate, an inducer of KLF4 expression, stimulated ghrelin expression, and fasting, which induces ghrelin expression, also increased KLF4 expression, suggesting that ghrelin expression is associated with KLF4. Then, we investigated the effects of KLF4 on the human ghrelin-promoter activity and identified a KLF4-responsive region in the promoter. KLF4 expression specifically stimulated human ghrelin-promoter activity in a dose-dependent manner in human gastric-cancer AGS cells. However, this effect was not seen in response to a mutant KLF4 construct. Transfection studies using mutant constructs containing 5'-deletions in the human ghrelin promoter revealed that the KLF4-responsive element is located between -1228 and -1105. Electrophoretic mobility shift assays using oligonucleotides containing -1165/-1146 revealed the binding of KLF4 to the human ghrelin promoter. Finally, deletion of the -1165/-1146 region abrogated KLF4-induced transactivation of the ghrelin promoter. Collectively, these results indicate that KLF4 positively regulates human ghrelin expression via binding to a KLF-responsive region in the promoter.
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Gaudreault M, Gingras ME, Lessard M, Leclerc S, Guérin SL. Electrophoretic mobility shift assays for the analysis of DNA-protein interactions. Methods Mol Biol 2009; 543:15-35. [PMID: 19378156 DOI: 10.1007/978-1-60327-015-1_2] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Electromobility shift assay is a simple, efficient, and rapid method for the study of specific DNA-protein interactions. It relies on the reduction in the electrophoretic mobility conferred to a DNA fragment by an interacting protein. The technique is suitable to qualitative, quantitative, and kinetic analyses. It can also be used to analyze conformational changes.
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Affiliation(s)
- Manon Gaudreault
- Oncology and Molecular Endocrinology Research Center, CHUL, Centre Hospitalier Universitaire de Québec and Laval University, 2705 Laurier Blvd, Québec, QC, Canada, G1V 4G2
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DiFeo A, Martignetti JA, Narla G. The role of KLF6 and its splice variants in cancer therapy. Drug Resist Updat 2008; 12:1-7. [PMID: 19097929 DOI: 10.1016/j.drup.2008.11.001] [Citation(s) in RCA: 106] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2008] [Revised: 11/03/2008] [Accepted: 11/04/2008] [Indexed: 12/21/2022]
Abstract
The Krüppel-like zinc finger transcription factor (KLF6) gene encodes a family of proteins generated through alternative splicing involved in the regulation of cancer development and progression. Alternative splicing of the KLF6 gene results in the production of at least four alternatively spliced isoforms, two of which are extensively discussed in this review. The full length form of the KLF6 gene is a tumor suppressor gene that is frequently inactivated by loss of heterozygozity (LOH), somatic mutation, and/or decreased expression in human cancer. While the exact mechanisms underlying KLF6's tumor suppressor roles are not completely known, a number of highly relevant, overlapping pathways have been described: transactivation of p21 in a p53-independent manner, reduction of cyclin D1/cdk4 complexes via interaction with cyclin D1, inhibition of c-Jun proto-oncoprotein activities, decreased VEGF expression, and induction of apoptosis. Kruppel-like factor 6 splice variant 1 (KLF6-SV1) is an oncogenic splice variant of the KLF6 tumor suppressor gene that is specifically overexpressed in a number of human cancers. Increased KLF6-SV1 expression is associated with poor prognosis in prostate, lung, and ovarian cancer. Furthermore, KLF6-SV1 has been shown to be biologically active, antagonizing the tumor suppressor function of KLF6 and promoting tumor growth and dissemination in both ovarian and prostate cancer models. In addition, a common germline polymorphism in the KLF6 gene associated with increased prostate cancer risk in a large multi-institutional study of 3411 men results in increased expression of KLF6-SV1. Furthermore, recent studies have demonstrated that targeted reduction of KLF6-SV1 results in the induction of spontaneous apoptosis in cell culture, synergizes with chemotherapeutic agents like cisplatin, and results in significant tumor regression in vivo. Combined, these data make the KLF6 gene family a compelling therapeutic target for both the treatment of localized as well as metastatic cancer.
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Affiliation(s)
- Analisa DiFeo
- Department of Genetics and Genomic Sciences, Mount Sinai School of Medicine, New York, NY 10029, USA
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34
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KLF5 enhances SREBP-1 action in androgen-dependent induction of fatty acid synthase in prostate cancer cells. Biochem J 2008; 417:313-22. [DOI: 10.1042/bj20080762] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
KLF5 (Krüppel-like factor 5) is a zinc-finger transcription factor that plays a critical role in the regulation of cellular signalling involved in cell proliferation, differentiation and oncogenesis. In the present study, we showed that KLF5 acts as a key regulator controlling the expression of FASN (fatty acid synthase) through an interaction with SREBP-1 (sterol-regulatory-element-binding protein-1) in the androgen-dependent LNCaP prostate cancer cell line. The mRNA level of KLF5 increased when cells were treated with a synthetic androgen, R1881. Furthermore, KLF5 bound to SREBP-1 and enhanced the SREBP-1-mediated increase in FASN promoter activity. The results also demonstrated that the expression of KLF5 in LNCaP prostate cancer cells enhanced FASN expression, whereas silencing of KLF5 by small interfering RNA down-regulated FASN expression. The proximal promoter region and the first intron of the FASN gene contain multiple CACCC elements that mediate the transcriptional regulation of the gene by KLF5. However, other lipogenic and cholesterogenic genes, such as those encoding acetyl-CoA carboxylase, ATP-citrate lyase, the LDL (low-density lipoprotein) receptor, HMG-CoA (3-hydroxy-3-methylglutaryl-CoA) synthase and HMG-CoA reductase are irresponsive to KLF5 expression, owing to the absence of CACCC elements in their promoter regions. Taken together, these results suggest that the FASN gene is activated by the synergistic action of KLF5 and SREBP-1, which was induced by androgen in androgen-dependent prostate cancer cells.
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35
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Involvement of CREM in CYP1A1 induction through ligand-independent activation pathway of aryl hydrocarbon receptor in HepG2 cells. Arch Biochem Biophys 2008; 478:26-35. [DOI: 10.1016/j.abb.2008.07.021] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2008] [Revised: 07/07/2008] [Accepted: 07/24/2008] [Indexed: 11/21/2022]
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36
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Okuda T, Nakayama KI. Identification and characterization of the human Gb3/CD77 synthase gene promoter. Glycobiology 2008; 18:1028-35. [PMID: 18757779 DOI: 10.1093/glycob/cwn082] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Hemolytic uremic syndrome (HUS) is triggered by verotoxin (VT) produced by the Escherichia coli O157 strain. Several studies have demonstrated that VT induces endothelial cell (EC) death via the VT receptor globotriaosylceramide (Gb3/CD77) leading to this symptom. Inflammatory mediators which are produced as a result of E. coli O157 infection, increase the expression level of Gb3 in EC. Therefore increased expression of Gb3 is considered as a progression step for HUS. The increased expression of Gb3 is due to the transcriptional upregulation of Gb3/CD77 synthase gene (Gb3S, also known as alpha1,4-galactosyltransferase gene), the mechanism of which still remains unknown. To understand the transcriptional machinery and to elucidate the onset mechanism of HUS, we cloned and characterized the human Gb3S promoter. A modified 5'-RACE was used to determine the transcriptional initiation site, which revealed the presence of a TATA-less GC-rich sequence in the proximal region. Promoter activity measured using a luciferase assay demonstrated that the GC-rich sequence is necessary for the basal transcriptional activity, and two silencer elements located 5'-upstream of this GC-rich region regulated the transcriptional level. Furthermore, we found that the GC-rich sequence contained three potential Sp1 binding sites and that all three Sp1 binding elements acted as positive regulators. Since Sp1 is an inducer of several genes in the presence of the inflammatory cytokines in EC, our results suggest that the transcriptional regulation of the Gb3S gene by Sp1 might affect the VT sensitivity of EC and HUS progression.
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Affiliation(s)
- Tetsuya Okuda
- Glycolipids Function Analysis Team, Health Technology Research Center, National institute of Advanced Industrial Science and Technology (AIST), 2217-14 Hayashi, Takamatsu, Kagawa 761-0395, Japan
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37
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Eaton SA, Funnell APW, Sue N, Nicholas H, Pearson RCM, Crossley M. A network of Krüppel-like Factors (Klfs). Klf8 is repressed by Klf3 and activated by Klf1 in vivo. J Biol Chem 2008; 283:26937-47. [PMID: 18687676 DOI: 10.1074/jbc.m804831200] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Transcription factors of the Sp/Klf (Krüppel-like factor) family regulate biological processes such as hematopoiesis, adipogenesis, and stem cell maintenance. Here we show that Bklf or Klf3 (Basic Krüppel-like factor) represses the Klf8 (Krüppel-like Factor 8) gene in vivo. Conversely, Eklf or Klf1 (Erythroid Krüppel-like factor) activates the Klf8 gene. Klf8 is driven by two promoters, both of which contain multiple CACCC sites. Klf3 can repress Klf1-mediated activation of both promoters. Chromatin immunoprecipitation experiments confirm that Klf3 occupies both Klf8 promoters in vivo. Interestingly, in Klf3 knock-out tissue Klf1 gains access, binds, and activates both Klf8 promoters. These results demonstrate direct competition between activating and repressing Klfs in vivo. Together with previous evidence that Klf1 directly activates the Klf3 gene, the results reveal an elaborate network of cross-talk within the Klf family. The recognition of cross-regulation and potential redundancy between Klf family members is critical to the interpretation of various Klf knock-out mice and the understanding of individual Klfs in particular contexts.
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Affiliation(s)
- Sally A Eaton
- School of Molecular and Microbial Biosciences, University of Sydney, Sydney, New South Wales 2006, Australia
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Lee SH, Jang MK, Lee OH, Kim OS, Kim YM, Yajima S, Lee YC, Mouradian MM. Transcriptional auto-regulation of the dopamine receptor regulating factor (DRRF) gene. Mol Cell Endocrinol 2008; 289:23-8. [PMID: 18472212 DOI: 10.1016/j.mce.2008.03.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/16/2007] [Revised: 03/21/2008] [Accepted: 03/26/2008] [Indexed: 10/22/2022]
Abstract
The murine dopamine receptor regulating factor (DRRF) gene is transcribed from a TATA-less promoter that has several putative Sp1 binding sites. The present investigation identifies functional transcription factors that modulate the expression of this gene. In the D2-dopamine receptor expressing NB41A3 cells, Sp1 potently activates transcription from the DRRF promoter in pCAT-DRRF-1153/+17, while DRRF itself effectively inhibits it. Sp1 also activates this promoter in pCAT-DRRF-310/+17. In competitive co-transfection experiments, DRRF represses the transcriptional activation induced by Sp1, while Sp1 de-represses the inhibitory effect of DRRF. Deletion of the 31 bp fragment between -1153 and -1122 decreased basal transcription down to about 60%. This fragment contains a functional AP1 binding site. In addition, deletion of the 129 bp region between -901 and -772 further decreased transcription. The latter region has a functional AP2 binding site. The present observations suggest that DRRF auto-regulates its own promoter by competing with Sp1 and that both AP1 and AP2 modulate expression of this gene.
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Affiliation(s)
- Sang-Hyeon Lee
- Department of Bioscience and Biotechnology, Silla University, San 1-1, Kwaebop-dong, Sasang-gu, Busan 617-736, Republic of Korea.
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Evans PM, Liu C. Roles of Krüpel-like factor 4 in normal homeostasis, cancer and stem cells. Acta Biochim Biophys Sin (Shanghai) 2008; 40:554-64. [PMID: 18604447 DOI: 10.1111/j.1745-7270.2008.00439.x] [Citation(s) in RCA: 155] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Krüpel-like factor 4 (KLF4) is a zinc finger-type transcription factor expressed in a variety of tissues, including the epithelium of the intestine and the skin, and it plays an important role in differentiation and cell cycle arrest. Depending on the gene targeted, KLF4 can both activate and repress transcription. Moreover, in certain cellular contexts, KLF4 can function as a tumor suppressor or an oncogene. Finally, KLF4 is important in reprogramming differentiated fibroblasts into inducible pluripotent stem cells, which highly resemble embryonic stem cells. This review summarizes what is known about the diverse functions of KLF4 as well as their molecular mechanisms.
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Affiliation(s)
- Paul M Evans
- Department of Biochemistry and Molecular Biology, Sealy Center for Cancer Cell Biology, University of Texas Medical Branch, Galveston, Texas 77555-1448, USA
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40
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Ghaleb AM, Yang VW. The Pathobiology of Krüppel-like Factors in Colorectal Cancer. CURRENT COLORECTAL CANCER REPORTS 2008; 4:59-64. [PMID: 18504508 DOI: 10.1007/s11888-008-0011-4] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/15/2023]
Abstract
The Krüppel-like factor (KLF) proteins are zinc finger-containing transcription factors that exert important functions in regulating diverse biologic processes such as growth, proliferation, differentiation, development, inflammation, and apoptosis. Many KLFs have also been shown to play significant roles in tumorigenesis of various organs and tissues. Three in particular-KLF4, KLF5, and KLF6-are often dysregulated in tumors of the gastrointestinal tract, including colorectal cancer. This article reviews the functions of these three KLFs in normal gastrointestinal biology and their pathobiologic roles in colorectal cancer.
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41
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Haarmann-Stemmann T, Bothe H, Kohli A, Sydlik U, Abel J, Fritsche E. Analysis of the Transcriptional Regulation and Molecular Function of the Aryl Hydrocarbon Receptor Repressor in Human Cell Lines. Drug Metab Dispos 2007; 35:2262-9. [PMID: 17890447 DOI: 10.1124/dmd.107.016253] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The aryl hydrocarbon receptor repressor (AhRR) is a member of the aryl hydrocarbon receptor (AhR) signaling cascade, which mediates dioxin toxicity and is involved in regulation of cell growth and differentiation. The AhRR was described as a feedback modulator, which counteracts AhR-dependent gene expression. We investigated the molecular mechanisms of transcriptional regulation of the human AhRR by cloning its regulatory DNA region located in intron I of the AhRR. By means of reporter gene analyses and generation of deletion variants, we identified a functional, 3-methylcholanthrene-sensitive xenobiotic response element (XRE) site. Chromatin immunoprecipitation analyses revealed that the AhRR binds to this XRE, displaying an autoregulatory loop of AhRR expression. In addition we show that an adjacent GC-box is of functional relevance for AhRR transcription, since blocking of this GC-box resulted in a decrease of constitutive and inducible AhRR gene activity. The differences in constitutive AhRR mRNA level observed in HepG2, primary fibroblast, and HeLa cells are directly correlated with CYP1A1 inducibility. We show that the nonresponsiveness of high AhRR-expressing cells toward AhR-agonists is associated with a constitutive binding of the AhRR to XRE sites of CYP1A1. Treatment with the histone deacetylase inhibitor sodium butyrate restored the responsiveness of CYP1A1 in these cell lines, due to the dissociation of AhRR from the XREs. Furthermore, transient AhRR mRNA silencing in untreated HeLa cells was accompanied by an increase of basal CYP1A1 expression, pointing to a constitutive role of the AhRR in regulation of CYP1A1. The functional relevance of the AhRR in high AhRR-expressing primary fibroblasts is discussed.
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Affiliation(s)
- Thomas Haarmann-Stemmann
- Molecular Toxicology, Institut für Umweltmedizinische Forschung, Auf'm Hennekamp 50, 40225, Düsseldorf, Germany
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Ghaleb AM, McConnell BB, Nandan MO, Katz JP, Kaestner KH, Yang VW. Haploinsufficiency of Krüppel-like factor 4 promotes adenomatous polyposis coli dependent intestinal tumorigenesis. Cancer Res 2007; 67:7147-54. [PMID: 17671182 PMCID: PMC2373271 DOI: 10.1158/0008-5472.can-07-1302] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The zinc finger transcription factor Krüppel-like factor 4 (KLF4) is frequently down-regulated in colorectal cancer. Previous studies showed that the expression of KLF4 was activated by the colorectal cancer tumor suppressor adenomatous polyposis coli (APC) and that KLF4 repressed the Wnt/beta-catenin pathway. Here, we examined whether KLF4 plays a role in modulating intestinal tumorigenesis by comparing the tumor burdens in mice heterozygous for the Apc(Min) allele (Apc(Min/+)) and those heterozygous for both the Apc(Min) and Klf4 alleles (Klf4(+/-)/Apc(Min/+)). Between 10 and 20 weeks of age, Klf4(+/-)/Apc(Min/+) mice developed, on average, 59% more intestinal adenomas than Apc(Min/+) mice (P < 0.0001). Immunohistochemical staining showed that Klf4 protein levels were lower in the normal-appearing intestinal tissues of Klf4(+/-)/Apc(Min/+) mice compared with wild-type, Klf4(+/-), or Apc(Min/+) mice. In contrast, the levels of beta-catenin and cyclin D1 were higher in the normal-appearing intestinal tissues of Klf4(+/-)/Apc(Min/+) mice compared with the other three genotypes. Klf4 levels were further decreased in adenomas from both Apc(Min/+) and Klf4(+/-)/Apc(Min/+) mice compared with their corresponding normal-appearing tissues. Reverse transcription-PCR showed an inverse correlation between adenoma size and Klf4 mRNA levels in both Klf4(+/-)/Apc(Min/+) and Apc(Min/+) mice. There was also a progressive loss of heterozygosity of the wild-type Apc allele in adenomas with increasing size from Klf4(+/-)/Apc(Min/+) and Apc(Min/+) mice. Results from this study show that KLF4 plays an important role in promoting the development of intestinal adenomas in the presence of Apc(Min) mutation.
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Affiliation(s)
- Amr M. Ghaleb
- Division of Digestive Diseases and Department of Medicine, Emory University School of Medicine, Atlanta, Georgia
| | - Beth B. McConnell
- Division of Digestive Diseases and Department of Medicine, Emory University School of Medicine, Atlanta, Georgia
| | - Mandayam O. Nandan
- Division of Digestive Diseases and Department of Medicine, Emory University School of Medicine, Atlanta, Georgia
| | - Jonathan P. Katz
- Division of Gastroenterology and Hepatology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania
| | - Klaus H. Kaestner
- Departments of Medicine and Genetics, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania
| | - Vincent W. Yang
- Division of Digestive Diseases and Department of Medicine, Emory University School of Medicine, Atlanta, Georgia
- Winship Cancer Institute, Emory University School of Medicine, Atlanta, Georgia
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43
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Hamik A, Lin Z, Kumar A, Balcells M, Sinha S, Katz J, Feinberg MW, Gerzsten RE, Edelman ER, Jain MK. Kruppel-like Factor 4 Regulates Endothelial Inflammation. J Biol Chem 2007; 282:13769-79. [PMID: 17339326 DOI: 10.1074/jbc.m700078200] [Citation(s) in RCA: 287] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The vascular endothelium plays a critical role in vascular homeostasis. Inflammatory cytokines and non-laminar blood flow induce endothelial dysfunction and confer a pro-adhesive and pro-thrombotic phenotype. Therefore, identification of factors that mediate the effects of these stimuli on endothelial function is of considerable interest. Kruppel-like factor 4 expression has been documented in endothelial cells, but a function has not been described. In this communication we describe the expression in vitro and in vivo of Kruppel-like factor 4 in human and mouse endothelial cells. Furthermore, we demonstrate that endothelial Kruppel-like factor 4 is induced by pro-inflammatory stimuli and shear stress. Overexpression of Kruppel-like factor 4 induces expression of multiple anti-inflammatory and anti-thrombotic factors including endothelial nitric-oxide synthase and thrombomodulin, whereas knockdown of Kruppellike factor 4 leads to enhancement of tumor necrosis factor alpha-induced vascular cell adhesion molecule-1 and tissue factor expression. The functional importance of Kruppel-like factor 4 is verified by demonstrating that Kruppel-like factor 4 expression markedly decreases inflammatory cell adhesion to the endothelial surface and prolongs clotting time under inflammatory states. Kruppel-like factor 4 differentially regulates the promoter activity of pro- and anti-inflammatory genes in a manner consistent with its anti-inflammatory function. These data implicate Kruppel-like factor 4 as a novel regulator of endothelial activation in response to pro-inflammatory stimuli.
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Affiliation(s)
- Anne Hamik
- Cardiovascular Research Institute, Case Western Reserve University, Cleveland, Ohio 44106-7290, USA
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Funnell APW, Maloney CA, Thompson LJ, Keys J, Tallack M, Perkins AC, Crossley M. Erythroid Krüppel-like factor directly activates the basic Krüppel-like factor gene in erythroid cells. Mol Cell Biol 2007; 27:2777-90. [PMID: 17283065 PMCID: PMC1899893 DOI: 10.1128/mcb.01658-06] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
The Sp/Krüppel-like factor (Sp/Klf) family is comprised of around 25 zinc finger transcription factors that recognize CACCC boxes and GC-rich elements. We have investigated basic Krüppel-like factor (Bklf/Klf3) and show that in erythroid tissues its expression is highly dependent on another family member, erythroid Krüppel-like factor (Eklf/Klf1). We observe that Bklf mRNA is significantly reduced in erythroid tissues from Eklf-null murine embryos. We find that Bklf is driven primarily by two promoters, a ubiquitously active GC-rich upstream promoter, 1a, and an erythroid downstream promoter, 1b. Transcripts from the two promoters encode identical proteins. Interestingly, both the ubiquitous and the erythroid promoter are dependent on Eklf in erythroid cells. Eklf also activates both promoters in transient assays. Experiments utilizing an inducible form of Eklf demonstrate activation of the endogenous Bklf gene in the presence of an inhibitor of protein synthesis. The kinetics of activation are also consistent with Bklf being a direct Eklf target. Chromatin immunoprecipitation assays confirm that Eklf associates with both Bklf promoters. Eklf is typically an activator of transcription, whereas Bklf is noted as a repressor. Our results support the hypothesis that feedback cross-regulation occurs within the Sp/Klf family in vivo.
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Affiliation(s)
- Alister P W Funnell
- School of Molecular and Microbial Biosciences, G08, University of Sydney, Sydney, NSW 2006, Australia
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Kanai M, Wei D, Li Q, Jia Z, Ajani J, Le X, Yao J, Xie K. Loss of Krüppel-like factor 4 expression contributes to Sp1 overexpression and human gastric cancer development and progression. Clin Cancer Res 2007; 12:6395-402. [PMID: 17085651 DOI: 10.1158/1078-0432.ccr-06-1034] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
PURPOSE Increasing evidence indicates that the transcription factor, Sp1, regulates the expression of multiple genes involved in tumor development and progression. We have recently reported that Sp1 overexpression is directly correlated with the angiogenic potential of and poor prognosis for human gastric cancer. However, the underlying mechanisms that result in Sp1 overexpression remain unclear. EXPERIMENTAL DESIGN The expression of Sp1 and Krüppel-like factor 4 (KLF4), a potential tumor suppressor gene, in gastric cancer tissue was analyzed by immunohistochemistry and Western blot analysis. Alterations of Sp1 and KLF4 expression were achieved by gene transfer and verified by Northern and Western blot analyses. Furthermore, Sp1 promoter activity assay, electrophoretic mobility shift assay, and chromatin immunoprecipitation assay were done to identify the KLF4 binding sites on the Sp1 promoter. RESULTS Mutually exclusive expression of Sp1 and KLF4 was evident in gastric cancer and noncancerous tissue. Specifically, strong Sp1 expression but loss of KLF4 expression was found in cancer tissue, whereas the adjacent noncancerous tissue showed negative Sp1 expression but strong KLF4 expression. Enforced KLF4 expression repressed Sp1 expression at the promoter activity, mRNA, and protein levels. Moreover, a region within the proximal Sp1 promoter was identified to have overlapping KLF4- and Sp1-binding sites, to which KLF4 and Sp1 compete for binding. Sp1 positively regulated its own promoter, whereas KLF4 did the opposite. CONCLUSIONS Our data suggests that disruption of KLF4-mediated negative regulation contributes to the molecular events of Sp1 overexpression and to the development and progression of human gastric cancer.
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Affiliation(s)
- Masashi Kanai
- Department of Gastrointestinal Medical Oncology, The University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030, USA
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Niimi T, Hayashi Y, Sekiguchi K, Kitagawa Y. The Sp family of transcription factors regulates the human laminin alpha1 gene in JAR choriocarcinoma cells. ACTA ACUST UNITED AC 2006; 1759:573-9. [PMID: 17141338 DOI: 10.1016/j.bbaexp.2006.10.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2006] [Revised: 10/05/2006] [Accepted: 10/23/2006] [Indexed: 11/23/2022]
Abstract
Laminin-111 (alpha1beta1gamma1) is the major component of the embryonic and extra-embryonic basement membrane. The laminin alpha1 chain shows a restricted and developmentally regulated expression in basement membranes of distinct epithelial tissues while beta1 and gamma1 chains have a wide tissue distribution. To understand how human laminin alpha1 chain expression is controlled, we cloned and characterized the 5'-flanking region of the human laminin alpha1 (LAMA1) gene. Transfection studies using serially deleted promoter constructs and JAR choriocarcinoma cells revealed that the minimal promoter fragment resided in the +31 to -206 region, which contains a number of GC- and GT/A-rich motifs for the binding of the Sp family of transcription factors. Electrophoretic mobility shift assays and mutational analyses revealed that Sp1 and Sp3 bound specifically to these elements and are important for the promoter activity. Furthermore, we showed that Krüppel-like factors KLF4 and KLF6 also activate transcription of the human LAMA1 gene. Chromatin immunoprecipitation analysis demonstrated recruitment of these transcription factors to the promoter region. These results indicate that transcription of the human LAMA1 gene is controlled by a combination of the actions of Sp1/Sp3 and Krüppel-like factors, KLF4 and KLF6.
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Affiliation(s)
- Tomoaki Niimi
- Department of Bioengineering Sciences, Graduate School of Bioagricultural Sciences, Nagoya University, Chikusa, Nagoya 464-8601, Japan.
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Ghaleb AM, Katz JP, Kaestner KH, Du JX, Yang VW. Krüppel-like factor 4 exhibits antiapoptotic activity following gamma-radiation-induced DNA damage. Oncogene 2006; 26:2365-73. [PMID: 17016435 PMCID: PMC2230633 DOI: 10.1038/sj.onc.1210022] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
In response to gamma-radiation-induced DNA damage, organisms either activate cell cycle checkpoint and repair machinery or undergo apoptosis to eliminate damaged cells. Although previous studies indicated that the tumor suppressor p53 is critically involved in mediating both responses, how a cell decides which pathway to take is not well established. The zinc-finger-containing transcription factor, Krüppel-like factor 4 (KLF4), is a crucial mediator for the checkpoint functions of p53 after gamma-irradiation and does so by inhibiting the transition from the G(1) to S and G(2) to M phases of the cell cycle. Here, we determined the role of KLF4 in modulating the apoptotic response following gamma-irradiation. In three independent cell systems including colorectal cancer cells and mouse embryo fibroblasts in which expression of KLF4 could be manipulated, we observed that gamma-irradiated cells underwent apoptosis if KLF4 was absent. In the presence of KLF4, the degree of apoptosis was significantly reduced and cells resorted to checkpoint arrest. The mechanism by which KLF4 accomplished this antiapoptotic effect is by activating expression of the cell cycle arrest gene, p21(WAF1/CIP1), and by inhibiting the ability of p53 to transactivate expression of the proapoptotic gene, BAX. Results of our study illustrate an unexpected antiapoptotic function of KLF4, heretofore considered a tumor suppressor in colorectal cancer, and suggest that KLF4 may be an important determinant of cell fate following gamma-radiation-induced DNA damage.
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Affiliation(s)
- AM Ghaleb
- Division of Digestive Diseases, Department of Medicine, Emory University School of Medicine, Atlanta, GA, USA
| | - JP Katz
- Division of Gastroenterology, Department of Medicine, University of Pennsylvania School of Medicine, Philadelphia, PA, USA
| | - KH Kaestner
- Department of Genetics, University of Pennsylvania School of Medicine, Philadelphia, PA, USA
| | - JX Du
- Division of Digestive Diseases, Department of Medicine, Emory University School of Medicine, Atlanta, GA, USA
| | - VW Yang
- Division of Digestive Diseases, Department of Medicine, Emory University School of Medicine, Atlanta, GA, USA
- Department of Hematology and Oncology, Winship Cancer Institute, Emory University School of Medicine, Atlanta, GA, USA
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Blanchon L, Nores R, Gallot D, Marceau G, Borel V, Yang VW, Bocco JL, Lémery D, Panzetta-Dutari G, Sapin V. Activation of the human pregnancy-specific glycoprotein PSG-5 promoter by KLF4 and Sp1. Biochem Biophys Res Commun 2006; 343:745-53. [PMID: 16563348 DOI: 10.1016/j.bbrc.2006.03.032] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2006] [Accepted: 03/03/2006] [Indexed: 11/17/2022]
Abstract
Pregnancy-specific glycoproteins (PSGs) are major placental proteins thought to be essential for the maintenance of gestation. Little is known about the regulation of expression of the 11 genes encoding these proteins. It was previously demonstrated that Krüppel-like factor 6 (KLF6) and specific-protein 1 (Sp1) bind to conserved sequence within the PSG-5 gene promoter. Informatics analysis revealed the presence of one potential binding site for Krüppel-like factor 4 (KLF4), in the PSG-5 promoter, suggesting a potential transcriptional regulator role for KLF4. Using gene promoter-reporter transfections and X-ChIP assays, we demonstrated that KLF4 is an activator of the PSG-5 promoter by binding to a KLF consensus like binding which includes the Core Promoter Element region (-147/-140). Furthermore, we used previous data showing the binding of Sp1 transcription factor to a GT-box (-443/-437) and co-transfection assays with KLF4 and Sp1 to demonstrate the strong synergic activity of these two factors on the PSG-5 promoter.
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Affiliation(s)
- Loïc Blanchon
- INSERM U.384, Laboratoire de Biochimie, Faculté de Médecine, F-63000 Clermont-Ferrand, France
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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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van Vliet J, Crofts LA, Quinlan KGR, Czolij R, Perkins AC, Crossley M. Human KLF17 is a new member of the Sp/KLF family of transcription factors. Genomics 2006; 87:474-82. [PMID: 16460907 DOI: 10.1016/j.ygeno.2005.12.011] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2004] [Revised: 12/19/2005] [Accepted: 12/20/2005] [Indexed: 12/26/2022]
Abstract
The Sp/KLF transcription factors perform a variety of biological functions, but are related in that they bind GC-box and CACCC-box sequences in DNA via a highly conserved DNA-binding domain. A database homology search, using the zinc finger DNA-binding domain characteristic of the family, has identified human KLF17 as a new family member that is most closely related to KLFs 1-8 and 12. KLF17 appears to be the human orthologue of the previously reported mouse gene, zinc finger protein 393 (Zfp393), although it has diverged significantly. The DNA-binding domain is the most conserved region, suggesting that both the murine and the human forms recognize the same binding sites in DNA and may retain similar functions. We show that human KLF17 can bind G/C-rich sites via its zinc fingers and is able to activate transcription from CACCC-box elements. This is the first report of the DNA-binding characteristics and transactivation activity of human KLF17, which, together with the homology it displays to other KLF proteins, put it in the Sp/KLF family.
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Affiliation(s)
- Jane van Vliet
- School of Molecular and Microbial Biosciences, G08, University of Sydney, Sydney, NSW 2006, Australia
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