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Aldawood N, Almustafa S, Alwasel S, Aldahmash W, Ben Bacha A, Alamri A, Alanazi M, Harrath AH. Involvement of Autophagy and Oxidative Stress-Mediated DNA Hypomethylation in Transgenerational Nephrotoxicity Induced in Rats by the Mycotoxin Fumonisin B1. Toxins (Basel) 2023; 15:663. [PMID: 37999527 PMCID: PMC10674455 DOI: 10.3390/toxins15110663] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2023] [Revised: 11/12/2023] [Accepted: 11/14/2023] [Indexed: 11/25/2023] Open
Abstract
Fumonisin B1 (FB1), a mycotoxin produced by Fusarium verticillioides, is one of the most common pollutants in natural foods and agricultural crops. It can cause chronic and severe health issues in humans and animals. The aim of this study was to evaluate the transgenerational effects of FB1 exposure on the structure and function of the kidneys in offspring. Virgin female Wistar rats were randomly divided into three groups: group one (control) received sterile water, and groups two and three were intragastrically administered low (20 mg/kg) and high (50 mg/kg) doses of FB1, respectively, from day 6 of pregnancy until delivery. Our results showed that exposure to either dose of FB1 caused histopathological changes, such as atrophy, hypercellularity, hemorrhage, calcification, and a decrease in the glomerular diameter, in both the first and second generations. The levels of the antioxidant markers glutathione, glutathione S-transferase, and catalase significantly decreased, while malondialdehyde levels increased. Moreover, autophagy was induced, as immunofluorescence analysis revealed that LC-3 protein expression was significantly increased in both generations after exposure to either dose of FB1. However, a significant decrease in methyltransferase (DNMT3) protein expression was observed in the first generation in both treatment groups (20 mg/kg and 50 mg/kg), indicating a decrease in DNA methylation as a result of early-life exposure to FB1. Interestingly, global hypomethylation was also observed in the second generation in both treatment groups despite the fact that the mothers of these rats were not exposed to FB1. Thus, early-life exposure to FB1 induced nephrotoxicity in offspring of the first and second generations. The mechanisms of action underlying this transgenerational effect may include oxidative stress, autophagy, and DNA hypomethylation.
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Affiliation(s)
- Nouf Aldawood
- Department of Biology, College of Science, Princess Nourah bint Abdulrahman University, Riyadh 11671, Saudi Arabia;
| | - Sarah Almustafa
- Department of Zoology, College of Sciences, King Saud University, Riyadh 11451, Saudi Arabia (S.A.); (W.A.)
| | - Saleh Alwasel
- Department of Zoology, College of Sciences, King Saud University, Riyadh 11451, Saudi Arabia (S.A.); (W.A.)
| | - Waleed Aldahmash
- Department of Zoology, College of Sciences, King Saud University, Riyadh 11451, Saudi Arabia (S.A.); (W.A.)
| | - Abir Ben Bacha
- Department of Biochemistry, College of Sciences, King Saud University, Riyadh 11671, Saudi Arabia;
| | - Abdullah Alamri
- Genome Research Chair, Department of Biochemistry, College of Sciences, King Saud University, Riyadh 11495, Saudi Arabia; (A.A.); (M.A.)
| | - Mohammad Alanazi
- Genome Research Chair, Department of Biochemistry, College of Sciences, King Saud University, Riyadh 11495, Saudi Arabia; (A.A.); (M.A.)
| | - Abdel Halim Harrath
- Department of Zoology, College of Sciences, King Saud University, Riyadh 11451, Saudi Arabia (S.A.); (W.A.)
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Epsilon-Globin HBE1 Enhances Radiotherapy Resistance by Down-Regulating BCL11A in Colorectal Cancer Cells. Cancers (Basel) 2019; 11:cancers11040498. [PMID: 30965648 PMCID: PMC6521047 DOI: 10.3390/cancers11040498] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2019] [Revised: 03/27/2019] [Accepted: 04/02/2019] [Indexed: 12/28/2022] Open
Abstract
Resistance to radiotherapy is considered an important obstacle in the treatment of colorectal cancer. However, the mechanisms that enable tumor cells to tolerate the effects of radiation remain unclear. Moreover, radiotherapy causes accumulated mutations in transcription factors, which can lead to changes in gene expression and radiosensitivity. This phenomenon reduces the effectiveness of radiation therapy towards cancer cells. In the present study, radiation-resistant (RR) cancer cells were established by sequential radiation exposure, and hemoglobin subunit epsilon 1 (HBE1) was identified as a candidate radiation resistance-associated protein based on RNA-sequencing analysis. Then, compared to radiosensitive (RS) cell lines, the overexpression of HBE1 in RR cell lines was used to measure various forms of radiation-induced cellular damage. Consequently, HBE1-overexpressing cell lines were found to exhibit decreased radiation-induced intracellular reactive oxygen species (ROS) production and cell mortality. Conversely, HBE1 deficiency in RR cell lines increased intracellular ROS production, G2/M arrest, and apoptosis, and decreased clonogenic survival rate. These effects were reversed by the ROS scavenger N-acetyl cysteine. Moreover, HBE1 overexpression was found to attenuate radiation-induced endoplasmic reticulum stress and apoptosis via an inositol-requiring enzyme 1(IRE1)-Jun amino-terminal kinase (JNK) signaling pathway. In addition, increased HBE1 expression induced by γ-irradiation in RS cells attenuated expression of the transcriptional regulator BCL11A, whereas its depletion in RR cells increased BCL11A expression. Collectively, these observations indicate that the expression of HBE1 during radiotherapy might potentiate the survival of radiation-exposed colorectal cancer cells.
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Maroofi N, Azarkeivan A, Banihashemi S, Mohammadparast S, Aghajanirefah A, Banan M. An enhancer haplotype may influence BCL11A expression levels and the response to hydroxyurea in β-thalassemia patients. Pharmacogenomics 2017. [PMID: 28639471 DOI: 10.2217/pgs-2017-0019] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
AIM To identify the BCL11A intron-2 enhancer linkage disequilibrium (LD) block, harboring two previously identified SNPs, associating with the hydroxyurea response in β-thalassemia patients and the functional significance of this region. MATERIALS & METHODS Several neighboring SNPs were genotyped in our cohort. The associating LD block was identified, and its function studied in K562 erythroid cells via CRISPR/Cas9 genome editing. RESULTS A haplotype harboring three tag SNPs correlated significantly with the HU-response and BCL11A transcript levels in the patients' reticulocytes. Two deletions encompassing this LD block significantly reduced BCL11A transcript levels in K562 cells. CONCLUSION Our data suggest an essential role for this LD block in BCL11A expression levels and the response to hydroxyurea in β-thalassemia patients.
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Affiliation(s)
- Nahal Maroofi
- Genetics Research Center, University of Social Welfare & Rehabilitation Sciences, Tehran, Iran
| | - Azita Azarkeivan
- Pediatric Hematology Oncology, Blood Transfusion Research Center, High Institute for Research & Education in Transfusion Medicine, Thalassemia Clinic, Tehran, Iran
| | - Soosan Banihashemi
- Genetics Research Center, University of Social Welfare & Rehabilitation Sciences, Tehran, Iran
| | - Saeid Mohammadparast
- Genetics Research Center, University of Social Welfare & Rehabilitation Sciences, Tehran, Iran
| | - Ali Aghajanirefah
- Genetics Research Center, University of Social Welfare & Rehabilitation Sciences, Tehran, Iran.,Laboratory Medicine, UCSF School of Medicine, San Francisco, CA 94115, USA
| | - Mehdi Banan
- Genetics Research Center, University of Social Welfare & Rehabilitation Sciences, Tehran, Iran
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Lee WS, McColl B, Maksimovic J, Vadolas J. Epigenetic interplay at the β-globin locus. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2017; 1860:393-404. [DOI: 10.1016/j.bbagrm.2017.01.014] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2016] [Revised: 01/28/2017] [Accepted: 01/30/2017] [Indexed: 02/02/2023]
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Desai MA, Webb HD, Sinanan LM, Scarsdale JN, Walavalkar NM, Ginder GD, Williams DC. An intrinsically disordered region of methyl-CpG binding domain protein 2 (MBD2) recruits the histone deacetylase core of the NuRD complex. Nucleic Acids Res 2015; 43:3100-13. [PMID: 25753662 PMCID: PMC4381075 DOI: 10.1093/nar/gkv168] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2014] [Revised: 02/13/2015] [Accepted: 02/20/2015] [Indexed: 12/20/2022] Open
Abstract
The MBD2-NuRD (Nucleosome Remodeling and Deacetylase) complex is an epigenetic reader of DNA methylation that regulates genes involved in normal development and neoplastic diseases. To delineate the architecture and functional interactions of the MBD2-NuRD complex, we previously solved the structures of MBD2 bound to methylated DNA and a coiled-coil interaction between MBD2 and p66α that recruits the CHD4 nucleosome remodeling protein to the complex. The work presented here identifies novel structural and functional features of a previously uncharacterized domain of MBD2 (MBD2IDR). Biophysical analyses show that the MBD2IDR is an intrinsically disordered region (IDR). However, despite this inherent disorder, MBD2IDR increases the overall binding affinity of MBD2 for methylated DNA. MBD2IDR also recruits the histone deacetylase core components (RbAp48, HDAC2 and MTA2) of NuRD through a critical contact region requiring two contiguous amino acid residues, Arg(286) and Leu(287). Mutating these residues abrogates interaction of MBD2 with the histone deacetylase core and impairs the ability of MBD2 to repress the methylated tumor suppressor gene PRSS8 in MDA-MB-435 breast cancer cells. These findings expand our knowledge of the multi-dimensional interactions of the MBD2-NuRD complex that govern its function.
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Affiliation(s)
- Megha A Desai
- Department of Human and Molecular Genetics and Massey Cancer Center, Virginia Commonwealth University, Richmond, VA 23298, USA
| | - Heather D Webb
- Department of Pathology and Massey Cancer Center, Virginia Commonwealth University, Richmond, VA 23298, USA
| | - Leander M Sinanan
- Department of Pathology and Laboratory Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - J Neel Scarsdale
- Institute of Structural Biology and Drug Design, Center for the Study of Biological Complexity, and Massey Cancer Center, Virginia Commonwealth University, Richmond, VA 23298, USA
| | - Ninad M Walavalkar
- Department of Pathology and Laboratory Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Gordon D Ginder
- Departments of Internal Medicine, Human and Molecular Genetics, and Microbiology and Immunology and Massey Cancer Center, Virginia Commonwealth University, Richmond, VA 23298, USA
| | - David C Williams
- Department of Pathology and Laboratory Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
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Xing H, Wang C, Wu H, Chen D, Li S, Xu S. Effects of atrazine and chlorpyrifos on DNA methylation in the brain and gonad of the common carp. Comp Biochem Physiol C Toxicol Pharmacol 2015; 168:11-9. [PMID: 25460047 DOI: 10.1016/j.cbpc.2014.11.002] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/23/2014] [Revised: 11/06/2014] [Accepted: 11/12/2014] [Indexed: 12/28/2022]
Abstract
DNA methylation is known to play an important role in the regulation of gene expression in animal. The purpose of the present study was to examine the effect of atrazine (ATR), chlorpyrifos (CPF) and combined ATR/CPF exposure on DNA methylation in the brain and gonad of common carp (Cyprinus carpio L.). The carp were sampled after a 40-d exposure to CPF and ATR, individually or in combination, followed by a 40-d recovery to measure the levels of global DNA methylation and the expression of methylation enzymes (DNA methyltransferases (DNMTs) and methylcytosine binding domain 2 (MBD2)) in the brain and gonad tissues. The results revealed that a significant global DNA hypomethylation in the common carp exposed to ATR, CPF and their mixture was observed compared to the control fish. The MBD2 mRNA expression was up-regulated in the brain and gonad of the common carp exposed to ATR, CPF and their mixture, in contrast, the DNMTs mRNA expression was down-regulated. The information regarding the effects of ATR and CPF on DNA methylation status generated in this study is important for pesticides toxicology evaluation. However, the effect of ATR and CPF on the methylation status of specific genes, as well as its detailed mechanism requires further investigation.
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Affiliation(s)
- Houjuan Xing
- College of Animal Science and Technology, Northeast Agricultural University, 59 Mucai Street, Harbin 150030, China; Animal Health Supervision Institute of Heilongjiang Province, 243 Haping Road, Xiangfang District, Harbin 150069, PR China
| | - Chao Wang
- College of Animal Science and Technology, Northeast Agricultural University, 59 Mucai Street, Harbin 150030, China
| | - Hongda Wu
- Institute of Animal Science, Academy of Agricultural Sciences of Heilongjiang Province, 368 Xuefu Road, Xiangfang District, Harbin 150086, PR China
| | - Dechun Chen
- College of Veterinary Medicine, Northeast Agricultural University, 59 Mucai Street, Harbin 150030, China
| | - Shu Li
- College of Animal Science and Technology, Northeast Agricultural University, 59 Mucai Street, Harbin 150030, China; College of Veterinary Medicine, Northeast Agricultural University, 59 Mucai Street, Harbin 150030, China.
| | - Shiwen Xu
- College of Veterinary Medicine, Northeast Agricultural University, 59 Mucai Street, Harbin 150030, China.
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Wang C, Zhang Z, Yao H, Zhao F, Wang L, Wang X, Xing H, Xu S. Effects of atrazine and chlorpyrifos on DNA methylation in the liver, kidney and gill of the common carp (Cyprinus carpio L.). ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2014; 108:142-51. [PMID: 25062446 DOI: 10.1016/j.ecoenv.2014.06.011] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2014] [Revised: 06/08/2014] [Accepted: 06/09/2014] [Indexed: 05/28/2023]
Abstract
Pesticide exposure has repeatedly been associated with cancers, although the molecular mechanisms behind this association are largely undetermined. Abnormal DNA methylation plays a key role in the process of some disease. However, little was known about the effect of pesticides on DNA methylation in the common carp. In this study, we investigated the mRNA levels of DNA methyltransferases (DNMTs) and methyl-CpG-binding protein DNA-binding domain protein 2 (MBD2) as well as the DNA methylation levels in the liver, kidney and gill of the common carp (Cyprinus carpio L.) after 40-d exposure to atrazine (ATR) and chlorpyrifos (CPF) alone or in combination, and a 40-d recovery period. Juvenile common carp were exposed to various concentrations of ATR (at concentrations of 4.28, 42.8 and 428μg/L), CPF (1.16, 11.6 and 116μg/L), and an ATR/CPF mixture (at concentrations of 1.13, 11.3 and 113μg/L). The results revealed that the levels of genomic DNA methylation decreased in all tissues after 40d of exposure to ATR and CPF either individually or in combination. Moreover, the mRNA expression of DNMTs was down-regulated in all treatment groups. In contrast, the mRNA expression of MBD2 was up-regulated. These results demonstrated that long-term exposure to ATR, CPF and ATR/CPF mixtures could disrupt genomic DNA. It might imply that DNA methylation is involved in the toxicity caused by ATR and CPF in the common carp.
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Affiliation(s)
- Chao Wang
- Department of Veterinary Medicine, Northeast Agricultural University, Harbin 150030, PR China
| | - Ziwei Zhang
- Department of Veterinary Medicine, Northeast Agricultural University, Harbin 150030, PR China
| | - Haidong Yao
- Department of Veterinary Medicine, Northeast Agricultural University, Harbin 150030, PR China
| | - Fuqing Zhao
- Department of Veterinary Medicine, Northeast Agricultural University, Harbin 150030, PR China
| | - Liangliang Wang
- Department of Veterinary Medicine, Northeast Agricultural University, Harbin 150030, PR China
| | - Xiaolong Wang
- Center of conservation medicine & ecological safety, Northeast Forestry University, Harbin, 150040, PR China.
| | - Houjuan Xing
- Animal Health Supervision Institute of Heilongjiang Province, Harbin 150069, PR China.
| | - Shiwen Xu
- Department of Veterinary Medicine, Northeast Agricultural University, Harbin 150030, PR China.
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Chang KH, Fang X, Wang H, Huang A, Cao H, Yang Y, Bonig H, Stamatoyannopoulos JA, Papayannopoulou T. Epigenetic modifications and chromosome conformations of the beta globin locus throughout development. Stem Cell Rev Rep 2014; 9:397-407. [PMID: 22374078 DOI: 10.1007/s12015-012-9355-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Human embryonic stem cells provide an alternative to using human embryos for studying developmentally regulated gene expression. The co-expression of high levels of embryonic ε and fetal γ globin by the hESC-derived erythroblasts allows the interrogation of ε globin regulation at the transcriptional and epigenetic level which could only be attained previously by studying cell lines or transgenic mice. In this study, we compared the histone modifications across the β globin locus of the undifferentiated hESCs and hESC-, FL-, and mobilized PB CD34(+) cells-derived erythroblasts, which have distinct globin expression patterns corresponding to their developmental stages. We demonstrated that the histone codes employed by the β globin locus are conserved throughout development. Furthermore, in spite of the close proximity of the ε globin promoter, as compared to the β or γ globin promoter, with the LCR, a chromatin loop was also formed between the LCR and the active ε globin promoter, similar to the loop that forms between the β or γ globin promoters and the LCR, in contrary to the previously proposed tracking mechanism.
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Affiliation(s)
- Kai-Hsin Chang
- Department of Medicine, Division of Hematology, University of Washington, NE Pacific St, Box 357710, Seattle, WA 98195, USA
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Chang KH, Huang A, Han H, Jiang Y, Fang X, Song CZ, Padilla S, Wang H, Qu H, Stamatoyannopoulos J, Li Q, Papayannopoulou T. Transcriptional environment and chromatin architecture interplay dictates globin expression patterns of heterospecific hybrids derived from undifferentiated human embryonic stem cells or from their erythroid progeny. Exp Hematol 2013; 41:967-979.e6. [PMID: 23993951 PMCID: PMC3836866 DOI: 10.1016/j.exphem.2013.08.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2013] [Accepted: 08/20/2013] [Indexed: 11/21/2022]
Abstract
To explore the response of β globin locus with established chromatin domains upon their exposure to new transcriptional environments, we transferred the chromatin-packaged β globin locus of undifferentiated human embryonic stem cells (hESCs) or hESC-derived erythroblasts into an adult transcriptional environment. Distinct globin expression patterns were observed. In hESC-derived erythroblasts where both ε and γ globin were active and marked by similar chromatin modifications, ε globin was immediately silenced upon transfer, whereas γ globin continued to be expressed for months, implying that different transcriptional environments were required for their continuing expression. Whereas β globin was silent both in hESCs and in hESC-derived erythroblasts, β globin was only activated upon transfer from hESCs, but not in the presence of dominant γ globin transferred from hESC-derived erythroblasts, confirming the competing nature of γ versus β globin expression. With time, however, silencing of γ globin occurred in the adult transcriptional environment with concurrent activation of β-globin, accompanied by a drastic change in the epigenetic landscape of γ and β globin gene regions without apparent changes in the transcriptional environment. This switching process could be manipulated by overexpression or downregulation of certain transcription factors. Our studies provide important insights into the interplay between the transcription environment and existing chromatin domains, and we offer an experimental system to study the time-dependent human globin switching.
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Affiliation(s)
- Kai-Hsin Chang
- Department of Medicine, Division of Hematology, University of Washington, Seattle, WA, 98195, USA
| | - Andy Huang
- Department of Medicine, Division of Hematology, University of Washington, Seattle, WA, 98195, USA
| | - Hemei Han
- Department of Medicine, Division of Medical Genetics, University of Washington, Seattle, WA 98195, USA
| | - Yi Jiang
- Department of Medicine, Division of Hematology, University of Washington, Seattle, WA, 98195, USA
| | - Xiangdong Fang
- Department of Medicine, Division of Medical Genetics, University of Washington, Seattle, WA 98195, USA
- Laboratory of Disease Genomics and Individualized Medicine, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing 100029, China
| | - Chao-Zhong Song
- Department of Medicine, Division of Medical Genetics, University of Washington, Seattle, WA 98195, USA
| | - Steve Padilla
- Department of Medicine, Division of Hematology, University of Washington, Seattle, WA, 98195, USA
| | - Hao Wang
- Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA
| | - Hongzhu Qu
- Laboratory of Disease Genomics and Individualized Medicine, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing 100029, China
- Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA
| | | | - Qiliang Li
- Department of Medicine, Division of Medical Genetics, University of Washington, Seattle, WA 98195, USA
| | - Thalia Papayannopoulou
- Department of Medicine, Division of Hematology, University of Washington, Seattle, WA, 98195, USA
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Katsumura KR, DeVilbiss AW, Pope NJ, Johnson KD, Bresnick EH. Transcriptional mechanisms underlying hemoglobin synthesis. Cold Spring Harb Perspect Med 2013; 3:a015412. [PMID: 23838521 PMCID: PMC3753722 DOI: 10.1101/cshperspect.a015412] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The physiological switch in expression of the embryonic, fetal, and adult β-like globin genes has garnered enormous attention from investigators interested in transcriptional mechanisms and the molecular basis of hemoglobinopathies. These efforts have led to the discovery of cell type-specific transcription factors, unprecedented mechanisms of transcriptional coregulator function, genome biology principles, unique contributions of nuclear organization to transcription and cell function, and promising therapeutic targets. Given the vast literature accrued on this topic, this article will focus on the master regulator of erythroid cell development and function GATA-1, its associated proteins, and its frontline role in controlling hemoglobin synthesis. GATA-1 is a crucial regulator of genes encoding hemoglobin subunits and heme biosynthetic enzymes. GATA-1-dependent mechanisms constitute an essential regulatory core that nucleates additional mechanisms to achieve the physiological control of hemoglobin synthesis.
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Affiliation(s)
- Koichi R Katsumura
- Department of Cell and Regenerative Biology, UW-Madison Blood Research Program, Wisconsin Institute for Medical Research, Carbone Cancer Center, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin 53705
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Abstract
An understanding of the human fetal to adult hemoglobin switch offers the potential to ameliorate β-type globin gene disorders such as sickle cell anemia and β-thalassemia through activation of the fetal γ-globin gene. Chromatin modifying complexes, including MBD2-NuRD and GATA-1/FOG-1/NuRD, play a role in γ-globin gene silencing, and Mi2β (CHD4) is a critical component of NuRD complexes. We observed that knockdown of Mi2β relieves γ-globin gene silencing in β-YAC transgenic murine chemical inducer of dimerization hematopoietic cells and in CD34(+) progenitor-derived human primary adult erythroid cells. We show that independent of MBD2-NuRD and GATA-1/FOG-1/NuRD, Mi2β binds directly to and positively regulates both the KLF1 and BCL11A genes, which encode transcription factors critical for γ-globin gene silencing during β-type globin gene switching. Remarkably, <50% knockdown of Mi2β is sufficient to significantly induce γ-globin gene expression without disrupting erythroid differentiation of primary human CD34(+) progenitors. These results indicate that Mi2β is a potential target for therapeutic induction of fetal hemoglobin.
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Abstract
Complex developmental processes such as hematopoiesis require a series of precise and coordinated changes in cellular identity to ensure blood homeostasis. Epigenetic mechanisms help drive changes in gene expression that accompany the transition from hematopoietic stem cells to terminally differentiated blood cells. Genome-wide profiling technologies now provide valuable glimpses of epigenetic changes that occur during normal hematopoiesis, and genetic mouse models developed to investigate the in vivo functions of chromatin-modifying enzymes clearly demonstrate significant roles for these enzymes during embryonic and adult hematopoiesis. Here, we will review the basic science aspects of chromatin modifications and the enzymes that add, remove, and interpret these epigenetic marks. This overview will provide a framework for understanding the roles that these molecules play during normal hematopoiesis. Moreover, many chromatin-modifying enzymes are involved in hematologic malignancies, underscoring the importance of establishing and maintaining appropriate chromatin modification patterns to normal hematology.
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MBD2 and multiple domains of CHD4 are required for transcriptional repression by Mi-2/NuRD complexes. Mol Cell Biol 2012; 32:5078-88. [PMID: 23071088 DOI: 10.1128/mcb.00819-12] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Mi-2/nucleosome remodeling and deacetylase (NuRD) chromatin remodeling complexes are important regulators of chromatin structure and DNA accessibility. We examined requirements for individual domains of chromodomain helicase DNA-binding protein 4 (CHD4), a core catalytic component of NuRD complexes, as well as the NuRD subunit methyl-binding domain protein 2 (MBD2) and methylated DNA, for NuRD function in the context of tissue-specific transcription. By itself, loss of NuRD activity is not sufficient for transcriptional activation. However, NuRD complexes greatly reduce activation of the B cell-specific mb-1 (Cd79a) gene by the transcription factors EBF1 and Pax5. Using our B cell model system, we determined that the two chromodomains and ATPase/helicase and C-terminal domains (CTD) of CHD4 are all necessary for repression of mb-1 promoters by NuRD. All of these domains except the CTD are required for efficient association of CHD4 with mb-1 promoter chromatin. Loss of MBD2 expression or of DNA methylation impaired association of CHD4 with mb-1 promoter chromatin and enhanced its transcription. We conclude that repressive functions of MBD2-containing NuRD complexes are dependent on cooperative interactions between the major domains of CHD4 with histones and DNA and on binding of methylated DNA by MBD2.
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