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Guo CC, Xu HE, Ma X. ARID3a from the ARID family: structure, role in autoimmune diseases and drug discovery. Acta Pharmacol Sin 2023; 44:2139-2150. [PMID: 37488425 PMCID: PMC10618457 DOI: 10.1038/s41401-023-01134-2] [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: 03/13/2023] [Accepted: 07/09/2023] [Indexed: 07/26/2023] Open
Abstract
The AT-rich interaction domain (ARID) family of DNA-binding proteins is a group of transcription factors and chromatin regulators with a highly conserved ARID domain that recognizes specific AT-rich DNA sequences. Dysfunction of ARID family members has been implicated in various human diseases including cancers and intellectual disability. Among them, ARID3a has gained increasing attention due to its potential involvement in autoimmunity. In this article we provide an overview of the ARID family, focusing on the structure and biological functions of ARID3a. It explores the role of ARID3a in autoreactive B cells and its contribution to autoimmune diseases such as systemic lupus erythematosus and primary biliary cholangitis. Furthermore, we also discuss the potential for drug discovery targeting ARID3a and present a plan for future research in this field.
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Affiliation(s)
- Cheng-Cen Guo
- Department of Gastroenterology and Hepatology, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai Institute of Digestive Disease, Shanghai, 200001, China.
| | - H Eric Xu
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China.
- University of Chinese Academy of Sciences, Beijing, 100049, China.
- School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210, China.
| | - Xiong Ma
- Department of Gastroenterology and Hepatology, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai Institute of Digestive Disease, Shanghai, 200001, China.
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2
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Martin OA, Thomas M, Marquet M, Bruzeau C, Garot A, Brousse M, Bender S, Carrion C, Choi JE, Vuong BQ, Gearhart PJ, Maul RW, Le Noir S, Pinaud E. The IgH Eµ-MAR regions promote UNG-dependent error-prone repair to optimize somatic hypermutation. Front Immunol 2023; 14:1030813. [PMID: 36865553 PMCID: PMC9971809 DOI: 10.3389/fimmu.2023.1030813] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Accepted: 01/13/2023] [Indexed: 02/16/2023] Open
Abstract
Intoduction Two scaffold/matrix attachment regions (5'- and 3'-MARsEµ ) flank the intronic core enhancer (cEµ) within the immunoglobulin heavy chain locus (IgH). Besides their conservation in mice and humans, the physiological role of MARsEµ is still unclear and their involvement in somatic hypermutation (SHM) has never been deeply evaluated. Methods Our study analyzed SHM and its transcriptional control in a mouse model devoid of MARsEµ , further combined to relevant models deficient for base excision repair and mismatch repair. Results We observed an inverted substitution pattern in of MARsEµ -deficient animals: SHM being decreased upstream from cEµ and increased downstream of it. Strikingly, the SHM defect induced by MARsEµ -deletion was accompanied by an increase of sense transcription of the IgH V region, excluding a direct transcription-coupled effect. Interestingly, by breeding to DNA repair-deficient backgrounds, we showed that the SHM defect, observed upstream from cEµ in this model, was not due to a decrease in AID deamination but rather the consequence of a defect in base excision repair-associated unfaithful repair process. Discussion Our study pointed out an unexpected "fence" function of MARsEµ regions in limiting the error-prone repair machinery to the variable region of Ig gene loci.
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Affiliation(s)
- Ophélie A Martin
- Laboratoire Contrôle de la Réponse Immune B et des Lymphoproliférations (CRIBL), Université de Limoges, CNRS Unité Mixte de Recherche 7276, Inserm Unité 1262, Limoges, France
| | - Morgane Thomas
- Laboratoire Contrôle de la Réponse Immune B et des Lymphoproliférations (CRIBL), Université de Limoges, CNRS Unité Mixte de Recherche 7276, Inserm Unité 1262, Limoges, France
| | - Marie Marquet
- Laboratoire Contrôle de la Réponse Immune B et des Lymphoproliférations (CRIBL), Université de Limoges, CNRS Unité Mixte de Recherche 7276, Inserm Unité 1262, Limoges, France
| | - Charlotte Bruzeau
- Laboratoire Contrôle de la Réponse Immune B et des Lymphoproliférations (CRIBL), Université de Limoges, CNRS Unité Mixte de Recherche 7276, Inserm Unité 1262, Limoges, France
| | - Armand Garot
- Laboratoire Contrôle de la Réponse Immune B et des Lymphoproliférations (CRIBL), Université de Limoges, CNRS Unité Mixte de Recherche 7276, Inserm Unité 1262, Limoges, France
| | - Mylène Brousse
- Laboratoire Contrôle de la Réponse Immune B et des Lymphoproliférations (CRIBL), Université de Limoges, CNRS Unité Mixte de Recherche 7276, Inserm Unité 1262, Limoges, France
| | - Sébastien Bender
- Laboratoire Contrôle de la Réponse Immune B et des Lymphoproliférations (CRIBL), Université de Limoges, CNRS Unité Mixte de Recherche 7276, Inserm Unité 1262, Limoges, France.,Centre Hospitalier Universitaire Dupuytren, Service d'Immunopathologie, Limoges, France
| | - Claire Carrion
- Laboratoire Contrôle de la Réponse Immune B et des Lymphoproliférations (CRIBL), Université de Limoges, CNRS Unité Mixte de Recherche 7276, Inserm Unité 1262, Limoges, France
| | - Jee Eun Choi
- The Graduate Center, The City University of New York, New York, NY, United States
| | - Bao Q Vuong
- The Graduate Center, The City University of New York, New York, NY, United States
| | - Patricia J Gearhart
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, National Institutes of Health, Baltimore, MD, United States
| | - Robert W Maul
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, National Institutes of Health, Baltimore, MD, United States
| | - Sandrine Le Noir
- Laboratoire Contrôle de la Réponse Immune B et des Lymphoproliférations (CRIBL), Université de Limoges, CNRS Unité Mixte de Recherche 7276, Inserm Unité 1262, Limoges, France
| | - Eric Pinaud
- Laboratoire Contrôle de la Réponse Immune B et des Lymphoproliférations (CRIBL), Université de Limoges, CNRS Unité Mixte de Recherche 7276, Inserm Unité 1262, Limoges, France
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Babu S, Takeuchi Y, Masai I. Banp regulates DNA damage response and chromosome segregation during the cell cycle in zebrafish retina. eLife 2022; 11:74611. [PMID: 35942692 PMCID: PMC9363121 DOI: 10.7554/elife.74611] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Accepted: 07/05/2022] [Indexed: 11/25/2022] Open
Abstract
Btg3-associated nuclear protein (Banp) was originally identified as a nuclear matrix-associated region (MAR)-binding protein and it functions as a tumor suppressor. At the molecular level, Banp regulates transcription of metabolic genes via a CGCG-containing motif called the Banp motif. However, its physiological roles in embryonic development are unknown. Here, we report that Banp is indispensable for the DNA damage response and chromosome segregation during mitosis. Zebrafish banp mutants show mitotic cell accumulation and apoptosis in developing retina. We found that DNA replication stress and tp53-dependent DNA damage responses were activated to induce apoptosis in banp mutants, suggesting that Banp is required for regulation of DNA replication and DNA damage repair. Furthermore, consistent with mitotic cell accumulation, chromosome segregation was not smoothly processed from prometaphase to anaphase in banp morphants, leading to a prolonged M-phase. Our RNA- and ATAC-sequencing identified 31 candidates for direct Banp target genes that carry the Banp motif. Interestingly, a DNA replication fork regulator, wrnip1, and two chromosome segregation regulators, cenpt and ncapg, are included in this list. Thus, Banp directly regulates transcription of wrnip1 for recovery from DNA replication stress, and cenpt and ncapg for chromosome segregation during mitosis. Our findings provide the first in vivo evidence that Banp is required for cell-cycle progression and cell survival by regulating DNA damage responses and chromosome segregation during mitosis. In order for a cell to divide, it must progress through a series of carefully controlled steps known as the cell cycle. First, the cell replicates its DNA and both copies get segregated to opposite ends. The cell then splits into two and each new cell receives a copy of the duplicated genetic material. If any of the stages in the cell cycle become disrupted or mis-regulated this can lead to uncontrolled divisions that may result in cancer. Researchers have often used a structure within the eye known as the retina to study the cell cycle in zebrafish and other animals as cells in the retina rapidly divide in a highly controlled manner. A protein called Banp is known to help stop tumors from growing in humans and mice, but its normal role in the body, particularly the cell cycle, has remained unclear. To investigate, Babu et al. studied the retina of mutant zebrafish that were unable to make the Banp protein. The experiments revealed that two stress responses indicating DNA damage or defects in copying DNA were active in the retinal cells of the mutant zebrafish. This suggested that Banp allows cell to progress through the cell cycle by repairing any DNA damage that may arise during replication. Banp does this by activating the gene for another protein called Wrnip1. Babu et al. also found that Banp helps segregate the two copies of DNA during cell division by promoting the activation of two other proteins called Cenpt and Ncapg. Further experiments identified 31 genes that were directly regulated by Banp. These findings demonstrate that Banp is required for zebrafish cells to be able to accurately copy their DNA and divide in to two new cells. In the future, the work of Babu et al. will provide a useful resource to investigate how tumors grow and spread around the body, and may contribute to the development of new treatments for cancer.
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Affiliation(s)
- Swathy Babu
- Developmental Neurobiology Unit, Okinawa Institute of Science and Technology Graduate University, Onna, Japan
| | - Yuki Takeuchi
- Developmental Neurobiology Unit, Okinawa Institute of Science and Technology Graduate University, Onna, Japan
| | - Ichiro Masai
- Developmental Neurobiology Unit, Okinawa Institute of Science and Technology Graduate University, Onna, Japan
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SATB family chromatin organizers as master regulators of tumor progression. Oncogene 2018; 38:1989-2004. [PMID: 30413763 DOI: 10.1038/s41388-018-0541-4] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Revised: 08/30/2018] [Accepted: 09/02/2018] [Indexed: 02/07/2023]
Abstract
SATB (Special AT-rich binding protein) family proteins have emerged as key regulators that integrate higher-order chromatin organization with the regulation of gene expression. Studies over the past decade have elucidated the specific roles of SATB1 and SATB2, two closely related members of this family, in cancer progression. SATB family chromatin organizers play diverse and important roles in regulating the dynamic equilibrium of apoptosis, cell invasion, metastasis, proliferation, angiogenesis, and immune modulation. This review highlights cellular and molecular events governed by SATB1 influencing the structural organization of chromatin and interacting with several co-activators and co-repressors of transcription towards tumor progression. SATB1 expression across tumor cell types generates cellular and molecular heterogeneity culminating in tumor relapse and metastasis. SATB1 exhibits dynamic expression within intratumoral cell types regulated by the tumor microenvironment, which culminates towards tumor progression. Recent studies suggested that cell-specific expression of SATB1 across tumor recruited dendritic cells (DC), cytotoxic T lymphocytes (CTL), T regulatory cells (Tregs) and tumor epithelial cells along with tumor microenvironment act as primary determinants of tumor progression and tumor inflammation. In contrast, SATB2 is differentially expressed in an array of cancer types and is involved in tumorigenesis. Survival analysis for patients across an array of cancer types correlated with expression of SATB family chromatin organizers suggested tissue-specific expression of SATB1 and SATB2 contributing to disease prognosis. In this context, it is pertinent to understand molecular players, cellular pathways, genetic and epigenetic mechanisms governed by cell types within tumors regulated by SATB proteins. We propose that patient survival analysis based on the expression profile of SATB chromatin organizers would facilitate their unequivocal establishment as prognostic markers and therapeutic targets for cancer therapy.
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Chen QY, Costa M. Oncogenic and tumor suppressive roles of special AT-rich sequence-binding protein. J Carcinog 2018; 17:2. [PMID: 30123095 PMCID: PMC6071479 DOI: 10.4103/jcar.jcar_8_17] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2017] [Accepted: 12/28/2017] [Indexed: 12/28/2022] Open
Abstract
In recent years, research efforts have been centered on the functional roles of special AT-rich sequence-binding protein (SATB2) in cancer development. Existing studies differ in the types of tumor tissues and cell lines used, resulting in mixed results, which hinder the clear understanding of whether SATB2 acts as a tumor suppressor or promoter. Literature search for this review consisted of a basic search on PubMed using keywords "SATB2" and "special AT-rich sequence-binding protein 2." Each article was then selected for further examination based on relevance of the title. In consideration to possible missing data from a primary PubMed search, after coding for relevant information, articles listed in the references section were filtered for further review. The current literature suggests that SATB2 can act both as a tumor suppressor and as a promoter since it can be regulated by multiple factors and is able to target different downstream genes in various types of cancer cell lines as well as tissues. Future studies should focus on its contradictory roles in different types of tumors. This paper provides a comprehensive review of currently available research on the role of SATB2 in different cancer cells and tissues and may provide some insight into the contradictory roles of SATB2 in cancer development.
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Affiliation(s)
- Qiao Yi Chen
- Department of Environmental Medicine, New York University School of Medicine, NY, USA
| | - Max Costa
- Department of Environmental Medicine, New York University School of Medicine, NY, USA
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Wu G, Xu R, Zhang P, Xiao T, Fu Y, Zhang Y, Du Y, Ye J, Cheng J, Jiang H. Estrogen regulates stemness and senescence of bone marrow stromal cells to prevent osteoporosis via ERβ-SATB2 pathway. J Cell Physiol 2017; 233:4194-4204. [PMID: 29030963 DOI: 10.1002/jcp.26233] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2017] [Accepted: 09/29/2017] [Indexed: 12/22/2022]
Abstract
Decline of pluripotency in bone marrow stromal cells (BMSCs) associated with estrogen deficiency leads to a bone formation defect in osteoporosis. Special AT-rich sequence binding protein 2 (SATB2) is crucial for maintaining stemness and osteogenic differentiation of BMSCs. However, whether SATB2 is involved in estrogen-deficiency associated-osteoporosis is largely unknown. In this study, we found that estrogen mediated pluripotency and senescence of BMSCs, primarily through estrogen receptor beta (ERβ). BMSCs from the OVX rats displayed increased senescence and weaker SATB2 expression, stemness, and osteogenic differentiation, while estrogen could rescue these phenotypes. Inhibition of ERβ or ERα confirmed that SATB2 was associated with ERβ in estrogen-mediated pluripotency and senescence of BMSCs. Furthermore, estrogen mediated the upregulation of SATB2 through the induction of ERβ binding to estrogen response elements (ERE) located at -488 of the SATB2 gene. SATB2 overexpression alleviated senescence and enhanced stemness and osteogenic differentiation of OVX-BMSCs. SATB2-modified BMSCs transplantation could prevent trabecular bone loss in an ovariectomized rat model. Collectively, our study revealed the role of SATB2 in stemness, senescence, and osteogenesis of OVX-BMSCs. These results indicate that estrogen prevents osteoporosis by promoting stemness and osteogenesis, and inhibiting senescence of BMSCs through an ERβ-SATB2 pathway. Therefore, SATB2 is a novel anti-osteoporosis target gene.
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Affiliation(s)
- Geng Wu
- Department of Stomatology, The First People's Hospital of Lianyungang City, Lianyungang, China
| | - Rongyao Xu
- Jiangsu Key Laboratory of Oral Diseases, Nanjing Medical University, Nanjing, Jiangsu, China
| | - Ping Zhang
- Jiangsu Key Laboratory of Oral Diseases, Nanjing Medical University, Nanjing, Jiangsu, China.,Department of Oral and Maxillofacial Surgery, Affiliated Hospital of Stomatology, Nanjing Medical University, Nanjing, Jiangsu, China
| | - Tao Xiao
- Jiangsu Key Laboratory of Oral Diseases, Nanjing Medical University, Nanjing, Jiangsu, China
| | - Yu Fu
- Jiangsu Key Laboratory of Oral Diseases, Nanjing Medical University, Nanjing, Jiangsu, China.,Department of Oral and Maxillofacial Surgery, Affiliated Hospital of Stomatology, Nanjing Medical University, Nanjing, Jiangsu, China
| | - Yuchao Zhang
- Jiangsu Key Laboratory of Oral Diseases, Nanjing Medical University, Nanjing, Jiangsu, China.,Department of Oral and Maxillofacial Surgery, Affiliated Hospital of Stomatology, Nanjing Medical University, Nanjing, Jiangsu, China
| | - Yifei Du
- Jiangsu Key Laboratory of Oral Diseases, Nanjing Medical University, Nanjing, Jiangsu, China.,Department of Oral and Maxillofacial Surgery, Affiliated Hospital of Stomatology, Nanjing Medical University, Nanjing, Jiangsu, China
| | - Jinhai Ye
- Jiangsu Key Laboratory of Oral Diseases, Nanjing Medical University, Nanjing, Jiangsu, China.,Department of Oral and Maxillofacial Surgery, Affiliated Hospital of Stomatology, Nanjing Medical University, Nanjing, Jiangsu, China
| | - Jie Cheng
- Jiangsu Key Laboratory of Oral Diseases, Nanjing Medical University, Nanjing, Jiangsu, China.,Department of Oral and Maxillofacial Surgery, Affiliated Hospital of Stomatology, Nanjing Medical University, Nanjing, Jiangsu, China
| | - Hongbing Jiang
- Jiangsu Key Laboratory of Oral Diseases, Nanjing Medical University, Nanjing, Jiangsu, China.,Department of Oral and Maxillofacial Surgery, Affiliated Hospital of Stomatology, Nanjing Medical University, Nanjing, Jiangsu, China
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Nechanitzky R, Dávila A, Savarese F, Fietze S, Grosschedl R. Satb1 and Satb2 Are Dispensable for X Chromosome Inactivation in Mice. Dev Cell 2012; 23:866-71. [DOI: 10.1016/j.devcel.2012.09.018] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Zhang J, Tu Q, Grosschedl R, Kim MS, Griffin T, Drissi H, Yang P, Chen J. Roles of SATB2 in osteogenic differentiation and bone regeneration. Tissue Eng Part A 2011; 17:1767-76. [PMID: 21385070 DOI: 10.1089/ten.tea.2010.0503] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Expressed in branchial arches and osteoblast-lineage cells, special AT-rich sequence-binding protein (SATB2) is responsible for preventing craniofacial abnormalities and defects in osteoblast function. In this study, we transduced SATB2 into murine adult stem cells, and found that SATB2 significantly increased expression levels of bone matrix proteins, osteogenic transcription factors, and a potent angiogenic factor, vascular endothelial growth factor. Using an osterix (Osx) promoter-luciferase construct and calvarial cells isolated from runt-related transcription factor 2 (Runx2)-deficient mice, we found that SATB2 upregulates Osx expression independent of Runx2, but synergistically enhances the regulatory effect of Runx2 on Osx promoter. We then transplanted SATB2-overexpressing adult stem cells genetically double-labeled with bone sialoprotein (BSP) promoter-driven luciferase and β-actin promoter-driven enhanced green fluorescent protein into mandibular bone defects. We identified increased luciferase-positive cells in SATB2-overexpressing groups, indicating more transplanted cells undergoing osteogenic differentiation. New bone formation was consequently accelerated in SATB2 groups. In conclusion, SATB2 acts as a potent transcription factor to enhance osteoblastogenesis and promote bone regeneration. The application of SATB2 in bone tissue engineering gives rise to a higher bone forming capacity as a result of multiple-level amplification of regulatory activity.
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Affiliation(s)
- Jin Zhang
- Division of Oral Biology, Department of General Dentistry, Tufts University School of Dental Medicine, Boston, Massachusetts 02111, USA
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Yao X, Nie H, Rojas IC, Harriss JV, Maika SD, Gottlieb PD, Rathbun G, Tucker PW. The L2a element is a mouse CD8 silencer that interacts with MAR-binding proteins SATB1 and CDP. Mol Immunol 2010; 48:153-63. [PMID: 20884053 DOI: 10.1016/j.molimm.2010.08.014] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2010] [Revised: 07/29/2010] [Accepted: 08/24/2010] [Indexed: 02/07/2023]
Abstract
Previous transgenic-reporter and targeted-deletion studies indicate that the subset-specific expression of CD8αβ heterodimers is controlled by multiple enhancer activities, since no silencer elements had been found within the locus. We have identified such a silencer as L2a, a previously characterized ∼ 220 bp nuclear matrix associating region (MAR) located ∼ 4.5 kb upstream of CD8α. L2a transgenes driven by the E8(I) enhancer showed no reporter expression in thymic subsets or T cells in splenic, inguinal and mesenteric lymph node peripheral T cells. Deletion of L2a resulted in significant reporter de-repression, even in the CD4(+)CD8(+) double positive (DP) thymocyte population. L2a contains binding sites for two MAR-interacting proteins, SATB1 and CDP. We found that that binding of these factors was markedly influenced by the content and spacing of L2a sub-motifs (L and S) and that SATB1 binds preferentially to the L motif both in vitro and in vivo. A small fraction of the transgenic CD8 single positive (SP) thymocytes and peripheral CD8(+) T cells bypassed L2a-silencing to give rise to variegated expression of the transgenic reporter. Crossing the L2a-containing transgene onto a SATB1 knockdown background enhanced variegated expression, suggesting that SATB1 is critical in overcoming L2a-silenced transcription.
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Affiliation(s)
- Xin Yao
- Section of Molecular Genetics and Microbiology, Institute for Cellular and Molecular Biology, University of Texas at Austin, 1 University Station A5000, Austin, TX 78721-0162, USA
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Patani N, Jiang W, Mansel R, Newbold R, Mokbel K. The mRNA expression of SATB1 and SATB2 in human breast cancer. Cancer Cell Int 2009; 9:18. [PMID: 19642980 PMCID: PMC2731048 DOI: 10.1186/1475-2867-9-18] [Citation(s) in RCA: 78] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2009] [Accepted: 07/30/2009] [Indexed: 02/08/2023] Open
Abstract
BACKGROUND SATB1 is a nuclear protein that has been recently reported to be a 'genome organizer' which delineates specific epigenetic modifications at target gene loci, directly up-regulating metastasis-associated genes while down-regulating tumor-suppressor genes. In this study, the level of mRNA expression of SATB1 and SATB2 were assessed in normal and malignant breast tissue in a cohort of women with breast cancer and correlated to conventional clinico-pathological parameters. MATERIALS AND METHODS Breast cancer tissues (n = 115) and normal background tissues (n = 31) were collected immediately after excision during surgery. Following RNA extraction, reverse transcription was carried out and transcript levels were determined using real-time quantitative PCR and normalized against beta-actin expression. Transcript levels within the breast cancer specimens were compared to the normal background tissues and analyzed against TNM stage, nodal involvement, tumour grade and clinical outcome over a 10 year follow-up period. RESULTS The levels of SATB1 were higher in malignant compared with normal breast tissue (p = 0.0167). SATB1 expression increased with increasing TNM stage (TNM1 vs. TNM2 p = 0.0264), increasing tumour grade (grade1 vs. grade 3 p = 0.017; grade 2 vs. grade 3 p = 0.0437; grade 1 vs. grade 2&3 p = 0.021) and Nottingham Prognostic Index (NPI) (NPI-1 vs. NPI-3 p = 0.0614; NPI-2 vs. NPI-3 p = 0.0495). Transcript levels were associated with oestrogen receptor (ER) positivity (ER(-) vs. ER(+) p = 0.046). SABT1 expression was also significantly correlated with downstream regulated genes IL-4 and MAF-1 (Pearson's correlation coefficient r = 0.21 and r = 0.162) and SATB2 (r = 0.506). After a median follow up of 10 years, there was a trend for higher SATB1 expression to be associated with shorter overall survival (OS). Higher levels of SATB2 were also found in malignant compared to background tissue (p = 0.049). SATB2 expression increased with increasing tumour grade (grade 1 vs. grade 3 p = 0.035). SATB2 was associated with ER positivity (ER(-) vs. ER(+) p = 0.0283) within ductal carcinomas. Higher transcript levels showed a significant association with poorer OS (p = 0.0433). CONCLUSION SATB1 mRNA expression is significantly associated with poor prognostic parameters in breast cancer, including increasing tumour grade, TNM stage and NPI. SATB2 mRNA expression is significantly associated with increasing tumour grade and poorer OS. These results are consistent with the notion that SATB1 acts as a 'master genome organizer' in human breast carcinogenesis.
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Affiliation(s)
- Neill Patani
- Department of Breast Surgery, St. George's University of London, London, UK
- The London Breast Institute, The Princess Grace Hospital, London, UK
| | - Wen Jiang
- Metastasis and Angiogenesis Research Group, University Department of Surgery, Cardiff University, Cardiff, UK
| | - Robert Mansel
- Metastasis and Angiogenesis Research Group, University Department of Surgery, Cardiff University, Cardiff, UK
| | - Robert Newbold
- The Brunel Institute of Cancer Genetics and Pharmacogenomics, London, UK
| | - Kefah Mokbel
- Department of Breast Surgery, St. George's University of London, London, UK
- The London Breast Institute, The Princess Grace Hospital, London, UK
- The Brunel Institute of Cancer Genetics and Pharmacogenomics, London, UK
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Lin D, Ippolito GC, Zong RT, Bryant J, Koslovsky J, Tucker P. Bright/ARID3A contributes to chromatin accessibility of the immunoglobulin heavy chain enhancer. Mol Cancer 2007; 6:23. [PMID: 17386101 PMCID: PMC1852116 DOI: 10.1186/1476-4598-6-23] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2007] [Accepted: 03/26/2007] [Indexed: 01/27/2023] Open
Abstract
Bright/ARID3A is a nuclear matrix-associated transcription factor that stimulates immunoglobulin heavy chain (IgH) expression and Cyclin E1/E2F-dependent cell cycle progression. Bright positively activates IgH transcriptional initiation by binding to ATC-rich P sites within nuclear matrix attachment regions (MARs) flanking the IgH intronic enhancer (Eμ). Over-expression of Bright in cultured B cells was shown to correlate with DNase hypersensitivity of Eμ. We report here further efforts to analyze Bright-mediated Eμ enhancer activation within the physiological constraints of chromatin. A system was established in which VH promoter-driven in vitro transcription on chromatin- reconstituted templates was responsive to Eμ. Bright assisted in blocking the general repression caused by nucleosome assembly but was incapable of stimulating transcription from prebound nucleosome arrays. In vitro transcriptional derepression by Bright was enhanced on templates in which Eμ is flanked by MARs and was inhibited by competition with high affinity Bright binding (P2) sites. DNase hypersensitivity of chromatin-reconstituted Eμ was increased when prepackaged with B cell nuclear extract supplemented with Bright. These results identify Bright as a contributor to accessibility of the IgH enhancer.
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Affiliation(s)
- Danjuan Lin
- Section of Molecular Genetics and Microbiology and Institute of Cell and Molecular Biology, University of Texas at Austin, Austin, Texas, USA
| | - Gregory C Ippolito
- Section of Molecular Genetics and Microbiology and Institute of Cell and Molecular Biology, University of Texas at Austin, Austin, Texas, USA
| | - Rui-Ting Zong
- Section of Molecular Genetics and Microbiology and Institute of Cell and Molecular Biology, University of Texas at Austin, Austin, Texas, USA
| | - James Bryant
- Section of Molecular Genetics and Microbiology and Institute of Cell and Molecular Biology, University of Texas at Austin, Austin, Texas, USA
| | - Janet Koslovsky
- Section of Molecular Genetics and Microbiology and Institute of Cell and Molecular Biology, University of Texas at Austin, Austin, Texas, USA
| | - Philip Tucker
- Section of Molecular Genetics and Microbiology and Institute of Cell and Molecular Biology, University of Texas at Austin, Austin, Texas, USA
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Inlay MA, Lin T, Gao HH, Xu Y. Critical roles of the immunoglobulin intronic enhancers in maintaining the sequential rearrangement of IgH and Igk loci. ACTA ACUST UNITED AC 2006; 203:1721-32. [PMID: 16785310 PMCID: PMC2118354 DOI: 10.1084/jem.20052310] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
V(D)J recombination of immunoglobulin (Ig) heavy (IgH) and light chain genes occurs sequentially in the pro– and pre–B cells. To identify cis-elements that dictate this order of rearrangement, we replaced the endogenous matrix attachment region/Igk intronic enhancer (MiEκ) with its heavy chain counterpart (Eμ) in mice. This replacement, denoted EμR, substantially increases the accessibility of both Vκ and Jκ loci to V(D)J recombinase in pro–B cells and induces Igk rearrangement in these cells. However, EμR does not support Igk rearrangement in pre–B cells. Similar to that in MiEκ−/− pre–B cells, the accessibility of Vκ segments to V(D)J recombinase is considerably reduced in EμR pre–B cells when compared with wild-type pre–B cells. Therefore, Eμ and MiEκ play developmental stage-specific roles in maintaining the sequential rearrangement of IgH and Igk loci by promoting the accessibility of V, D, and J loci to the V(D)J recombinase.
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Affiliation(s)
- Matthew A Inlay
- Section of Molecular Biology, Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093, USA
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13
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Ishihara SL, Morohashi KI. A boundary for histone acetylation allows distinct expression patterns of the Ad4BP/SF-1 and GCNF loci in adrenal cortex cells. Biochem Biophys Res Commun 2005; 329:554-62. [PMID: 15737622 DOI: 10.1016/j.bbrc.2005.02.011] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2005] [Indexed: 01/21/2023]
Abstract
Ad4BP/SF-1 is a nuclear receptor whose expression is restricted to tissues involved in steroid hormone synthesis such as the adrenal cortex and gonads. Recent sequence data analysis has shown that the Ad4BP/SF-1 gene is located only 13kb downstream of the last exon of the neighboring GCNF gene that is expressed in some neurons and gonadal germ cells. Despite the close proximity of the two genes, regulatory elements from one do not interfere with the transcription of the neighboring gene, resulting in distinct expression patterns of Ad4BP/SF-1 and GCNF. This observation has led to the prediction that an insulator element must exist between the two loci to establish independent transcription units. We performed DNase I hypersensitivity assays on the adrenal cortex cell line, Y-1, to test for the existence of an insulator. Three hypersensitive sites were identified in the region spanning 2.1kb between the last exon of GCNF and the first exon of Ad4BP/SF-1. The most upstream site contains a binding site for CTCF, a known insulator protein, while the other sites are predicted to associate with the nuclear matrix. Chromatin immunoprecipitation analysis using anti-acetylated histone H3 and H4 antibodies showed a discontinuous pattern of histone H3 and H4 acetylation upstream of these sites. Our data suggest that the chromatin architecture specialized by CTCF and the nuclear matrix contribute to the distinct pattern of transcriptional regulation of these genes.
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Affiliation(s)
- Satoru L Ishihara
- Division for Sex Differentiation, National Institute for Basic Biology, National Institutes of Natural Sciences, Higashiyama 5-1, Myoudaiji-cho, Okazaki 444-8787, Japan
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14
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Nie H, Maika SD, Tucker PW, Gottlieb PD. A Role for SATB1, a Nuclear Matrix Association Region-Binding Protein, in the Development of CD8SP Thymocytes and Peripheral T Lymphocytes. THE JOURNAL OF IMMUNOLOGY 2005; 174:4745-52. [PMID: 15814699 DOI: 10.4049/jimmunol.174.8.4745] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Studies have suggested that binding of the SATB1 protein to L2a, a matrix association region located 4.5 kb 5' to the mouse CD8alpha gene, positively affects CD8 expression in T cells. Therefore, experiments were performed to determine the effect on T cell development of reduced expression of SATB1. Because homozygous SATB1-null mice do not survive to adulthood due to non-thymus autonomous defects, mice were produced that were homozygous for a T cell-specific SATB1-antisense transgene and heterozygous for a SATB1-null allele. Thymic SATB1 protein was reduced significantly in these mice, and the major cellular phenotype observed was a significant reduction in the percentage of CD8SP T cells in thymus, spleen, and lymph nodes. Mice were smaller than wild type but generally healthy, and besides a general reduction in cellularity and a slight increase in surface CD3 expression on CD8SP thymocytes, the composition of the thymus was similar to wild type. The reduction in thymic SATB1 does not lead to the variegated expression of CD8-negative single positive thymocytes seen upon deletion of several regulatory elements and suggested by others to reflect failure to activate the CD8 locus. Thus, the present results point to an essential role for SATB1 late in the development and maturation of CD8SP T cells.
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Affiliation(s)
- Hui Nie
- Section of Molecular Genetics and Microbiology and Institute for Cellular and Molecular Biology, University of Texas, Austin, TX 78712, USA
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15
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Dobreva G, Dambacher J, Grosschedl R. SUMO modification of a novel MAR-binding protein, SATB2, modulates immunoglobulin mu gene expression. Genes Dev 2004; 17:3048-61. [PMID: 14701874 PMCID: PMC305257 DOI: 10.1101/gad.1153003] [Citation(s) in RCA: 206] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Nuclear matrix attachment regions (MARs) are regulatory DNA sequences that are important for higher-order chromatin organization, long-range enhancer function, and extension of chromatin modifications. Here we characterize a novel cell type-specific MAR-binding protein, SATB2, which binds to the MARs of the endogenous immunoglobulin micro locus in pre-B cells and enhances gene expression. We found that SATB2 differs from the closely related thymocyte-specific protein SATB1 by modifications of two lysines with the small ubiquitive related modifier (SUMO), which are augmented specifically by the SUMO E3 ligase PIAS1. Mutations of the SUMO conjugation sites of SATB2 enhance its activation potential and association with endogenous MARs in vivo, whereas N-terminal fusions with SUMO1 or SUMO3 decrease SATB2-mediated gene activation. Sumoylation is also involved in targeting SATB2 to the nuclear periphery, raising the possibility that this reversible modification of a MAR-binding protein may contribute to the modulation of subnuclear DNA localization.
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Affiliation(s)
- Gergana Dobreva
- Gene Center and Institute of Biochemistry, University of Munich, Munich 81377, Germany
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16
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Gombert WM, Farris SD, Rubio ED, Morey-Rosler KM, Schubach WH, Krumm A. The c-myc insulator element and matrix attachment regions define the c-myc chromosomal domain. Mol Cell Biol 2004; 23:9338-48. [PMID: 14645543 PMCID: PMC309672 DOI: 10.1128/mcb.23.24.9338-9348.2003] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Insulator elements and matrix attachment regions are essential for the organization of genetic information within the nucleus. By comparing the pattern of histone modifications at the mouse and human c-myc alleles, we identified an evolutionarily conserved boundary at which the c-myc transcription unit is separated from the flanking condensed chromatin enriched in lysine 9-methylated histone H3. This region harbors the c-myc insulator element (MINE), which contains at least two physically separable, functional activities: enhancer-blocking activity and barrier activity. The enhancer-blocking activity is mediated by CTCF. Chromatin immunoprecipitation assays demonstrate that CTCF is constitutively bound at the insulator and at the promoter region independent of the transcriptional status of c-myc. This result supports an architectural role of CTCF rather than a regulatory role in transcription. An additional higher-order nuclear organization of the c-myc locus is provided by matrix attachment regions (MARs) that define a domain larger than 160 kb. The MARs of the c-myc domain do not act to prevent the association of flanking regions with lysine 9-methylated histones, suggesting that they do not function as barrier elements.
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Affiliation(s)
- Wendy M Gombert
- Department of Radiation Oncology, University of Washington School of Medicine, Seattle, WA 98104, USA
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17
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Abstract
In the mammalian immune system, V(D)J rearrangement of immunoglobulin (Ig) and T-cell receptor (TCR) genes is regulated in a lineage- and stage-specific fashion. Because each of the seven loci capable of rearrangement utilizes the same recombination machinery, it is thought that V(D)J recombination of each antigen receptor locus is regulated through the differential accessibility of each locus to the V(D)J recombination machinery. Accumulating evidence indicates that chromatin remodeling mediated by DNA methylation and demethylation plays important roles in regulating V(D)J recombination and germline transcription through the Ig and TCR loci. DNA demethylation within the antigen receptor loci appears to be regulated by cis-elements also required for coordinated V(D)J recombination and germline transcription. In this paper, we critically examine the relationship between demethylation and V(D)J recombination as well as the mechanism to regulate DNA demethylation within the antigen receptor loci.
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Affiliation(s)
- Matthew Inlay
- Division of Biological Sciences, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0322, USA
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18
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Kaul R, Mukherjee S, Ahmed F, Bhat MK, Chhipa R, Galande S, Chattopadhyay S. Direct interaction with and activation of p53 by SMAR1 retards cell-cycle progression at G2/M phase and delays tumor growth in mice. Int J Cancer 2003; 103:606-15. [PMID: 12494467 DOI: 10.1002/ijc.10881] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
The tumor-suppressor p53 is a multifunctional protein mainly responsible for maintaining genomic integrity. p53 induces its tumor-suppressor activity by either causing cell-cycle arrest (G(1)/S or G(2)/M) or inducing cells to undergo apoptosis. This function of wild-type p53 as "guardian of the genome" is presumably achieved by forming molecular complexes with different DNA targets as well as by interacting with a number of cellular proteins, e.g., Mdm2, Gadd45, p21, 14-3-3sigma, Bax and Apaf-1. Upon activation, p53 activates p21, which in turn controls the cell cycle by regulating G(1) or G(2) checkpoints. Here, we report SMAR1 as one such p53-interacting protein that is involved in delaying tumor progression in vivo as well as in regulating the cell cycle. SMAR1 is a newly identified MARBP involved in chromatin-mediated gene regulation. The SMAR1 gene encodes at least 2 alternatively spliced variants: SMAR1(L) (the full-length form) and SMAR1(S) (the shorter form). We report that expression of SMAR1(S), but not of SMAR1(L), mRNA was decreased in most of the human cell lines examined, suggesting selective silencing of SMAR1(S). Overexpression of SMAR1(S) in mouse melanoma cells (B16F1) and their subsequent injection in C57BL/6 mice delays tumor growth. Exogenous SMAR1(S) causes significant retardation of B16F1 cells in the G(2)/M phase of the cell cycle compared to SMAR1(L). SMAR1(S) activates p53-mediated reporter gene expression in mouse melanoma cells, breast cancer cells (MCF-7) and p53 null cells (K562), followed by activation of its downstream effector, p21. We further demonstrate that SMAR1 physically interacts and colocalizes with p53. These data together suggest that SMAR1 is the only known MARBP that delays tumor progression via direct activation and interaction with tumor-suppressor p53.
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Affiliation(s)
- Ruchika Kaul
- National Center for Cell Science, Pune University Campus, Pune, India
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19
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Kioussis D, Ellmeier W. Chromatin and CD4, CD8A and CD8B gene expression during thymic differentiation. Nat Rev Immunol 2002; 2:909-19. [PMID: 12461564 DOI: 10.1038/nri952] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The regulation of gene expression during thymocyte development provides an ideal experimental system to study lineage-commitment processes. In particular, expression of the CD4, CD8A and CD8B genes seems to correlate well with the cell-fate decisions that are taken by thymocytes, and elucidating the molecular mechanisms that underlie the differential expression of these genes could reveal key events in differentiation processes. Here, we review examples of how gene cis elements (such as promoters, enhancers and locus control regions) and trans elements (such as transcription factors, chromatin-remodelling complexes and histone-modification enzymes) come together to orchestrate a finely tuned sequence of events that results in the complex pattern of CD4, CD8A and CD8B gene expression that is observed during thymocyte development.
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Affiliation(s)
- Dimitris Kioussis
- Division of Molecular Immunology, National Institute for Medical Research, The Ridgeway, London NW7 1AA, UK.
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20
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Liu ZM, George-Raizen JB, Li S, Meyers KC, Chang MY, Garrard WT. Chromatin structural analyses of the mouse Igkappa gene locus reveal new hypersensitive sites specifying a transcriptional silencer and enhancer. J Biol Chem 2002; 277:32640-9. [PMID: 12080064 DOI: 10.1074/jbc.m204065200] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
To identify new regulatory elements within the mouse Igkappa locus, we have mapped DNase I hypersensitive sites (HSs) in the chromatin of B cell lines arrested at different stages of differentiation. We have focused on two regions encompassing 50 kilobases suspected to contain new regulatory elements based on our previous high level expression results with yeast artificial chromosome-based mouse Igkappa transgenes. This approach has revealed a cluster of HSs within the 18-kilobase intervening sequence, which we cloned and sequenced in its entirety, between the Vkappa gene closest to the Jkappa region. These HSs exhibit pro/pre-B cell-specific transcriptional silencing of a Vkappa gene promoter in transient transfection assays. We also identified a plasmacytoma cell-specific HS in the far downstream region of the locus, which in analogous transient transfection assays proved to be a powerful transcriptional enhancer. Deletional analyses reveal that for each element multiple DNA segments cooperate to achieve either silencing or enhancement. The enhancer sequence is conserved in the human Igkappa gene locus, including NF-kappaB and E-box sites that are important for the activity. In summary, our results pinpoint the locations of presumptive regulatory elements for future knockout studies to define their functional roles in the native locus.
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Affiliation(s)
- Zhi-Mei Liu
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9148, USA
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21
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Goebel P, Montalbano A, Ayers N, Kompfner E, Dickinson L, Webb CF, Feeney AJ. High frequency of matrix attachment regions and cut-like protein x/CCAAT-displacement protein and B cell regulator of IgH transcription binding sites flanking Ig V region genes. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2002; 169:2477-87. [PMID: 12193717 DOI: 10.4049/jimmunol.169.5.2477] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
A major component in controlling V(D)J recombination is differential accessibility through localized changes in chromatin structure. Attachment of DNA to the nuclear matrix via matrix attachment region (MAR) sequences, and interaction with MAR-binding proteins have been shown to alter chromatin conformation, promote histone acetylation, and influence gene transcription. In this study, the flanking regions of several human and mouse Ig V(H) and Ig Vkappa genes were analyzed extensively for the presence of MARs by in vitro matrix-binding assay, and for interaction with the MAR-binding proteins cut-like protein x/CCAAT-displacement protein (Cux/CDP), B cell regulator of IgH transcription (Bright), and special AT-rich sequence-binding protein (SATB1) by EMSA. Cux/CDP and SATB1 are associated with repression, while Bright is an activator of Ig transcription. Binding sites were identified in the vicinity of all analyzed Ig V genes, and were also found flanking TCR Vbeta genes. We also show that the binding sites of the different factors do not always occur at MAR sequences. MAR sequences were also found within the Ig V loci at a much higher frequency than throughout the rest of the genome. Overall, the frequency and location of binding sites relative to the coding regions, and the strength of DNA-protein interaction showed much heterogeneity. Thus, variations in factor binding and MAR activity could potentially influence the extent of localized accessibility to V(D)J recombination and thus could play a role in unequal rearrangement of individual V genes. These sites could also contribute to effective transcription of Ig genes in mature and/or activated B cells, bringing both the promoter as well as the enhancer regions into close proximity at the nuclear matrix.
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Affiliation(s)
- Peter Goebel
- The Scripps Research Institute, La Jolla, CA 92037, USA
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22
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Kieffer LJ, Greally JM, Landres I, Nag S, Nakajima Y, Kohwi-Shigematsu T, Kavathas PB. Identification of a candidate regulatory region in the human CD8 gene complex by colocalization of DNase I hypersensitive sites and matrix attachment regions which bind SATB1 and GATA-3. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2002; 168:3915-22. [PMID: 11937547 DOI: 10.4049/jimmunol.168.8.3915] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
To locate elements regulating the human CD8 gene complex, we mapped nuclear matrix attachment regions (MARs) and DNase I hypersensitive (HS) sites over a 100-kb region that included the CD8B gene, the intergenic region, and the CD8A gene. MARs facilitate long-range chromatin remodeling required for enhancer activity and have been found closely linked to several lymphoid enhancers. Within the human CD8 gene complex, we identified six DNase HS clusters, four strong MARs, and several weaker MARs. Three of the strong MARs were closely linked to two tissue-specific DNase HS clusters (III and IV) at the 3' end of the CD8B gene. To further establish the importance of this region, we obtained 19 kb of sequence and screened for potential binding sites for the MAR-binding protein, SATB1, and for GATA-3, both of which are critical for T cell development. By gel shift analysis we identified two strong SATB1 binding sites, located 4.5 kb apart, in strong MARs. We also detected strong GATA-3 binding to an oligonucleotide containing two GATA-3 motifs located at an HS site in cluster IV. This clustering of DNase HS sites and MARs capable of binding SATB1 and GATA-3 at the 3' end of the CD8B gene suggests that this region is an epigenetic regulator of CD8 expression.
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Affiliation(s)
- Lynda J Kieffer
- Department of Laboratory Medicine and Department of Genetics and Section of Immunobiology, Yale University, New Haven, CT 06520, USA
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23
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Abstract
V(D)J recombination is of fundamental importance to the generation of diverse antigen receptor repertoires. We review our current understanding of the V(D)J recombination reaction and how it is regulated during lymphocyte development. We also discuss how defects in the mechanism or regulation of V(D)J recombination can lead to human disease.
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Affiliation(s)
- Craig H Bassing
- Howard Hughes Medical Institute, The Children's Hospital, The Center for Blood Research, Boston, MA 02115, USA
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24
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Abstract
Bright, or B cell regulator of immunoglobulin heavy chain transcription, is a B lymphocyte-specific protein first discovered for its ability to increase immunoglobulin transcription three- to sevenfold in antigen-activated B cells. It interacts with DNA through an ARID, or A/T-rich interaction domain, and is the only member of a previously undescribed family of DNA-binding proteins for which target genes have been identified. The mechanism(s) by which Bright facilitates transcription are unknown. Several proteins that associate with Bright may shed light upon its function. These include the nuclear matrix proteins sp100 and LYSp100B, and suggest that Bright may affect chromatin configuration and nuclear sublocalization. Furthermore, Bruton's tyrosine kinase is required for Bright binding activity, suggesting links between Bright, cell signaling cascades, and X-linked immunodeficiency disease.
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Affiliation(s)
- C F Webb
- Immunobiology and Cancer Program, Oklahoma Medical Research Foundation, Oklahoma City 73104, USA.
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25
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Sinclair AM, Lee JA, Goldstein A, Xing D, Liu S, Ju R, Tucker PW, Neufeld EJ, Scheuermann RH. Lymphoid apoptosis and myeloid hyperplasia in CCAAT displacement protein mutant mice. Blood 2001; 98:3658-67. [PMID: 11739170 DOI: 10.1182/blood.v98.13.3658] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
CCAAT displacement protein (cux/CDP) is an atypical homeodomain protein that represses expression of several developmentally regulated lymphoid and myeloid genes in vitro, including gp91-phox, immunoglobulin heavy chain, the T-cell receptor beta and gamma chains, and CD8. To determine how this activity affects cell development in vivo, a hypomorphic allele of cux/CDP was created by gene targeting. Homozygous mutant mice (cux/CDP(Delta HD/Delta HD)) demonstrated a partial neonatal lethality phenotype. Surviving animals suffered from a wasting disease, which usually resulted in death between 2 and 3 weeks of age. Analysis of T lymphopoiesis demonstrated that cux/CDP(Delta HD/Delta HD) mice had dramatically reduced thymic cellularity due to enhanced apoptosis, with a preferential loss of CD4(+)CD8(+) thymocytes. Ectopic CD25 expression was also observed in maturing thymocytes. B lymphopoiesis was also perturbed, with a 2- to 3-fold reduction in total bone marrow B-lineage cells and a preferential loss of cells in transition from pro-B/pre-BI to pre-BII stages due to enhanced apoptosis. These lymphoid abnormalities were independent of effects related to antigen receptor rearrangement. In contrast to the lymphoid demise, cux/CDP(Delta HD/Delta HD) mice demonstrated myeloid hyperplasia. Bone marrow reconstitution experiments identified that many of the hematopoietic defects were linked to microenvironmental effects, suggesting that underexpression of survival factors or overexpression of death-inducing factors accounted for the phenotypes observed. Tumor necrosis factor (TNF) levels were elevated in several tissues, especially thymus, suggesting that TNF may be a target gene for cux/CDP-mediated repression. These data suggest that cux/CDP regulates normal hematopoiesis, in part, by modulating the levels of survival and/or apoptosis factors expressed by the microenvironment.
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Affiliation(s)
- A M Sinclair
- Department of Pathology and Laboratory of Molecular Pathology, University of Texas Southwestern Medical Center, Dallas, 75390-9072, USA
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26
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Krangel MS, McMurry MT, Hernandez-Munain C, Zhong XP, Carabana J. Accessibility control of T cell receptor gene rearrangement in developing thymocytes. The TCR alpha/delta locus. Immunol Res 2001; 22:127-35. [PMID: 11339350 DOI: 10.1385/ir:22:2-3:127] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The joining of T cell receptor (TCR) and immunoglobulin (Ig) gene segments through the process of V(D)J recombination occurs in a lineage-specific and developmental-stage-specific way during the early stages of lymphocyte development. Such developmental regulation is thought to be mediated through the control of gene segment accessibility to the recombinase. We have studied the regulation of V(D)J recombination at the TCR alpha/delta locus, because this locus provides a fascinating model in which distinct sets of gene segments are activated at different stages of T cell development. The transcriptional enhancers Edelta and Ealpha have been implicated as critical regulators that, in conjunction with other cis-acting elements, confer region-specific and developmental-stage-specific changes in gene segment accessibility within TCR alpha/delta locus chromatin. Current work suggests that they may do so by functioning as regional modulators of histone acetylation.
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Affiliation(s)
- M S Krangel
- Department of Immunology, Duke University Medical Center, Durham, NC 27710, USA.
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27
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Galande S, Dickinson LA, Mian IS, Sikorska M, Kohwi-Shigematsu T. SATB1 cleavage by caspase 6 disrupts PDZ domain-mediated dimerization, causing detachment from chromatin early in T-cell apoptosis. Mol Cell Biol 2001; 21:5591-604. [PMID: 11463840 PMCID: PMC87280 DOI: 10.1128/mcb.21.16.5591-5604.2001] [Citation(s) in RCA: 102] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
SATB1 is expressed primarily in thymocytes and orchestrates temporal and spatial expression of a large number of genes in the T-cell lineage. SATB1 binds to the bases of chromatin loop domains in vivo, recognizing a special DNA context with strong base-unpairing propensity. The majority of thymocytes are eliminated by apoptosis due to selection processes in the thymus. We investigated the fate of SATB1 during thymocyte and T-cell apoptosis. Here we show that SATB1 is specifically cleaved by a caspase 6-like protease at amino acid position 254 to produce a 65-kDa major fragment containing both a base-unpairing region (BUR)-binding domain and a homeodomain. We found that this cleavage separates the DNA-binding domains from amino acids 90 to 204, a region which we show to be a dimerization domain. The resulting SATB1 monomer loses its BUR-binding activity, despite containing both its DNA-binding domains, and rapidly dissociates from chromatin in vivo. We found this dimerization region to have sequence similarity to PDZ domains, which have been previously shown to be involved in signaling by conferring protein-protein interactions. SATB1 cleavage during Jurkat T-cell apoptosis induced by an anti-Fas antibody occurs concomitantly with the high-molecular-weight fragmentation of chromatin of ~50-kb fragments. Our results suggest that mechanisms of nuclear degradation early in apoptotic T cells involve efficient removal of SATB1 by disrupting its dimerization and cleavage of genomic DNA into loop domains to ensure rapid and efficient disassembly of higher-order chromatin structure.
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Affiliation(s)
- S Galande
- Department of Cell and Molecular Biology, Lawrence Berkeley National Laboratory, Berkeley, California, USA
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28
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Kaplan MH, Zong RT, Herrscher RF, Scheuermann RH, Tucker PW. Transcriptional activation by a matrix associating region-binding protein. contextual requirements for the function of bright. J Biol Chem 2001; 276:21325-30. [PMID: 11294836 DOI: 10.1074/jbc.m100836200] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Bright (B cell regulator of IgH transcription) is a B cell-specific, matrix associating region-binding protein that transactivates gene expression from the IgH intronic enhancer (E mu). We show here that Bright has multiple contextual requirements to function as a transcriptional activator. Bright cannot transactivate via out of context, concatenated binding sites. Transactivation is maximal on integrated substrates. Two of the three previously identified binding sites in E mu are required for full Bright transactivation. The Bright DNA binding domain defined a new family, which includes SWI1, a component of the SWI.SNF complex shown to have high mobility group-like DNA binding characteristics. Similar to one group of high mobility group box proteins, Bright distorts E mu binding site-containing DNA on binding, supporting the concept that it mediates E mu remodeling. Transfection studies further implicate Bright in facilitating spatially separated promoter-enhancer interactions in both transient and stable assays. Finally, we show that overexpression of Bright leads to enhanced DNase I sensitivity of the endogenous E mu matrix associating regions. These data further suggest that Bright may contribute to increased gene expression by remodeling the immunoglobulin locus during B cell development.
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Affiliation(s)
- M H Kaplan
- Institute for Molecular and Cellular Biology, University of Texas at Austin, Austin, Texas 78712-1075, USA
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29
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Chattopadhyay S, Kaul R, Charest A, Housman D, Chen J. SMAR1, a novel, alternatively spliced gene product, binds the Scaffold/Matrix-associated region at the T cell receptor beta locus. Genomics 2000; 68:93-6. [PMID: 10950932 DOI: 10.1006/geno.2000.6279] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Rearrangement and expression of the T cell receptor beta gene are critical events for early T lymphocyte development. To characterize cis-regulatory elements and their associated trans-factors that mediate these events, we have previously identified a nuclear matrix/scaffold-associated region, referred to as MARbeta, 400 bp upstream of the Ebeta enhancer. Electrophoretic mobility shift assay showed that two known MAR-binding proteins, SATB1 and Cux, bind MARbeta. In this article, we report the identification of a novel MAR-binding protein, named SMAR1, that also binds MARbeta. SMAR1 shares homology with SATB1 and Cux in the MAR-binding domain/Cut repeat and also with the tetramerization domain of a B cell-specific MAR-binding protein, Bright. The binding of GST-SMAR1 fusion protein to MARbeta is inhibited by the presence of an excess amount of MAR-containing DNA from the immunoglobulin kappa locus. Smar1 transcripts are most abundant in the thymus and are alternatively spliced. The smar1 gene maps to the distal portion of mouse chromosome 8 at a distance of 111.8 cM.
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Affiliation(s)
- S Chattopadhyay
- National Center for Cell Science, Ganeshkhind, Maharastra, Pune-411007, India
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