1
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Lee HK, Willi M, Liu C, Hennighausen L. Cell-specific and shared regulatory elements control a multigene locus active in mammary and salivary glands. Nat Commun 2023; 14:4992. [PMID: 37591874 PMCID: PMC10435465 DOI: 10.1038/s41467-023-40712-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Accepted: 08/08/2023] [Indexed: 08/19/2023] Open
Abstract
Regulation of high-density loci harboring genes with different cell-specificities remains a puzzle. Here we investigate a locus that evolved through gene duplication and contains eight genes and 20 candidate regulatory elements, including one super-enhancer. Casein genes (Csn1s1, Csn2, Csn1s2a, Csn1s2b, Csn3) are expressed in mammary glands, induced 10,000-fold during pregnancy and account for 50% of mRNAs during lactation, Prr27 and Fdcsp are salivary-specific and Odam has dual specificity. We probed the function of 12 candidate regulatory elements, individually and in combination, in the mouse genome. The super-enhancer is essential for the expression of Csn3, Csn1s2b, Odam and Fdcsp but largely dispensable for Csn1s1, Csn2 and Csn1s2a. Csn3 activation also requires its own local enhancer. Synergism between local enhancers and cytokine-responsive promoter elements facilitates activation of Csn2 during pregnancy. Our work identifies the regulatory complexity of a multigene locus with an ancestral super-enhancer active in mammary and salivary tissue and local enhancers and promoter elements unique to mammary tissue.
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Affiliation(s)
- Hye Kyung Lee
- Section of Genetics and Physiology, Laboratory of Cellular and Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, US National Institutes of Health, Bethesda, Maryland, 20892, USA.
| | - Michaela Willi
- Section of Genetics and Physiology, Laboratory of Cellular and Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, US National Institutes of Health, Bethesda, Maryland, 20892, USA
| | - Chengyu Liu
- Transgenic Core, National Heart, Lung, and Blood Institute, US National Institutes of Health, Bethesda, Maryland, 20892, USA
| | - Lothar Hennighausen
- Section of Genetics and Physiology, Laboratory of Cellular and Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, US National Institutes of Health, Bethesda, Maryland, 20892, USA.
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2
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Evaluation of the α-casein (CSN1S1) locus as a potential target for a site-specific transgene integration. Sci Rep 2022; 12:7983. [PMID: 35568783 PMCID: PMC9107462 DOI: 10.1038/s41598-022-12071-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2021] [Accepted: 04/29/2022] [Indexed: 11/25/2022] Open
Abstract
Transgenic animals are an important tool in biotechnology, including the production of recombinant proteins in the milk. Traditionally, expression constructs are based on hybrid vectors bearing mammary gland specific regulatory elements from the α-casein (Csn1s1), β-casein (Csn2), whey acidic protein (WAP), or β-lactoglobulin (BLG) genes. Overexpression from the randomly integrated vectors typically provides high levels of expression, but has drawbacks due to unpredictable genome localization. CRISPR-Cas9 targeted transgene integration into the endogenous casein locus could alleviate the need for extensive animal screening to achieve high and reproducible expression levels. We decided to evaluate such a “precise” integration approach, placing the human granulocyte–macrophage colony-stimulating factor (hGMCSF) gene under control of the mouse endogenous alpha-S1-casein (Csn1s1) promoter. We designed two types of transgene integrations: a knock-in in the second exon of the Csn1s1 (INS-GM) and a full-size Csn1s1 replacement with hGMCSF (REP-GM) which was never tested before. The INS-GM approach demonstrated low transgene expression and milk protein levels (0.4% of Csn2 transcripts; 2–11 µg/ml hGMCSF). This was probably caused by the absence of the 3’-polyadenylation signal in the hGMCSF transgene. REP-GM animals displayed high transgene expression, reaching and slightly exceeding the level of the endogenous Csn1s1 (30–40% of Csn2 transcripts), but yielded less hGMCSF protein than expected (0.2–0.5 mg/ml vs 25 mg/ml of Csn1s1), indicating that translation of the protein is not optimal. Homozygous inserts leading to the Csn1s1 knock-out did not have any long standing effects on the animals’ health. Thus, in our experimental design, site-specific transgene integration into the casein locus did not provide any significant advantage over the overexpression approach.
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3
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Smirnov AV, Shnaider TА, Korablev AN, Yunusova AM, Serova IA, Battulin NR. A hypomorphic mutation in the mouse Csn1s1 gene generated by CRISPR/Cas9 pronuclear microinjection. Vavilovskii Zhurnal Genet Selektsii 2021; 25:331-336. [PMID: 34901729 PMCID: PMC8627868 DOI: 10.18699/vj21.036] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Revised: 01/28/2021] [Accepted: 02/08/2021] [Indexed: 11/19/2022] Open
Abstract
Caseins are major milk proteins that have an evolutionarily conserved role in nutrition. Sequence variations in the
casein genes affect milk composition in livestock species. Regulatory elements of the casein genes could be used to direct
the expression of desired transgenes into the milk of transgenic animals. Dozens of casein alleles have been identified for
goats, cows, sheep, camels and horses, and these sequence variants are associated with altered gene expression and milk
protein content. Most of the known mutations affecting casein genes’ expression are located in the promoter and 3’-untranslated regions. We performed pronuclear microinjections with Cas9 mRNA and sgRNA against the first coding exon of
the mouse Csn1s1 gene to introduce random mutations in the α-casein (Csn1s1) signal peptide sequence at the beginning
of the mouse gene. Sanger sequencing of the founder mice identified 40 mutations. As expected, mutations clustered
around the sgRNA cut site (3 bp from PAM). Most of the mutations represented small deletions (1–10 bp), but we detected
several larger deletions as well (100–300 bp). Functionally most mutations led to gene knockout due to a frameshift or a
start codon loss. Some of the mutations represented in-frame indels in the first coding exon. Of these, we describe a novel
hypomorphic Csn1s1 (Csn1s1c.4-5insTCC) allele. We measured Csn1s1 protein levels and confirmed that the mutation has a
negative effect on milk composition, which shows a 50 % reduction in gene expression and a 40–80 % decrease in Csn1s1
protein amount, compared to the wild-type allele. We assumed that mutation affected transcript stability or splicing by an
unknown mechanism. This mutation can potentially serve as a genetic marker for low Csn1s1 expression.
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Affiliation(s)
- A V Smirnov
- Institute of Cytology and Genetics of the Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia
| | - T А Shnaider
- Institute of Cytology and Genetics of the Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia
| | - A N Korablev
- Institute of Cytology and Genetics of the Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia
| | - A M Yunusova
- Institute of Cytology and Genetics of the Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia
| | - I A Serova
- Institute of Cytology and Genetics of the Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia
| | - N R Battulin
- Institute of Cytology and Genetics of the Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia Novosibirsk State University, Novosibirsk, Russia
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4
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Kang J, Kim YW, Park S, Kang Y, Kim A. Multiple CTCF sites cooperate with each other to maintain a TAD for enhancer-promoter interaction in the β-globin locus. FASEB J 2021; 35:e21768. [PMID: 34245617 DOI: 10.1096/fj.202100105rr] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Revised: 06/11/2021] [Accepted: 06/15/2021] [Indexed: 01/01/2023]
Abstract
Insulators are cis-regulatory elements that block enhancer activity and prevent heterochromatin spreading. The binding of CCCTC-binding factor (CTCF) protein is essential for insulators to play the roles in a chromatin context. The β-globin locus, consisting of multiple genes and enhancers, is flanked by two insulators 3'HS1 and HS5. However, it has been reported that the absence of these insulators did not affect the β-globin transcription. To explain the unexpected finding, we have deleted a CTCF motif at 3'HS1 or HS5 in the human β-globin locus and analyzed chromatin interactions around the locus. It was found that a topologically associating domain (TAD) containing the β-globin locus is maintained by neighboring CTCF sites in the CTCF motif-deleted loci. The additional deletions of neighboring CTCF motifs disrupted the β-globin TAD, resulting in decrease of the β-globin transcription. Chromatin interactions of the β-globin enhancers with gene promoter were weakened in the multiple CTCF motifs-deleted loci, even though the enhancers have still active chromatin features such as histone H3K27ac and histone H3 depletion. Genome-wide analysis using public CTCF ChIA-PET and ChIP-seq data showed that chromatin domains possessing multiple CTCF binding sites tend to contain super-enhancers like the β-globin enhancers. Taken together, our results show that multiple CTCF sites surrounding the β-globin locus cooperate with each other to maintain a TAD. The β-globin TAD appears to provide a compact spatial environment that enables enhancers to interact with promoter.
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Affiliation(s)
- Jin Kang
- Department of Molecular Biology, College of Natural Sciences, Pusan National University, Busan, Korea
| | - Yea Woon Kim
- Department of Molecular Biology, College of Natural Sciences, Pusan National University, Busan, Korea
| | - Seongwon Park
- Department of Molecular Biology, College of Natural Sciences, Pusan National University, Busan, Korea
| | - Yujin Kang
- Department of Molecular Biology, College of Natural Sciences, Pusan National University, Busan, Korea
| | - AeRi Kim
- Department of Molecular Biology, College of Natural Sciences, Pusan National University, Busan, Korea
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5
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Li D, San M, Zhang J, Yang A, Xie W, Chen Y, Lu X, Zhang Y, Zhao M, Feng X, Zheng Y. Oxytocin receptor induces mammary tumorigenesis through prolactin/p-STAT5 pathway. Cell Death Dis 2021; 12:588. [PMID: 34099636 PMCID: PMC8184747 DOI: 10.1038/s41419-021-03849-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2020] [Revised: 05/19/2021] [Accepted: 05/20/2021] [Indexed: 12/30/2022]
Abstract
Oxytocin receptor (OXTR) is involved in social behaviors, thermoregulation, and milk ejection, yet little is known about its role in breast cancer. To investigate the role of OXTR in mammary gland development and tumorigenesis, a transgenic mouse model of OXTR overexpression (++Oxtr) was used. Overexpression of OXTR-induced progressive mammary hyperplasia, unexpected milk production, and tumorigenesis in females. OXTR-induced mammary tumors showed ERBB2 upregulation and mixed histological subtypes with predomination of papillary and medullary carcinomas. OXTR overexpression led to an activation of prolactin (PRL)/p-STAT5 pathway and created a microenvironment that promotes mammary-specific tumorigenesis. PRL inhibitor bromocriptine (Br) could mitigate OXTR-driven mammary tumor growth. The study demonstrates Oxtr is an oncogene and a potential drug target for HER2-type breast cancer.
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Affiliation(s)
- Dan Li
- Transgenic Research Center, Northeast Normal University, Changchun, Jilin, 130024, China.,The Precise Medicine Center, Department of Basic Medicine, Shenyang Medical College, Shenyang, Liaoning, 110034, China
| | - Mingjun San
- Transgenic Research Center, Northeast Normal University, Changchun, Jilin, 130024, China
| | - Jing Zhang
- Transgenic Research Center, Northeast Normal University, Changchun, Jilin, 130024, China
| | - Anlan Yang
- Transgenic Research Center, Northeast Normal University, Changchun, Jilin, 130024, China
| | - Wanhua Xie
- The Precise Medicine Center, Department of Basic Medicine, Shenyang Medical College, Shenyang, Liaoning, 110034, China
| | - Yang Chen
- Transgenic Research Center, Northeast Normal University, Changchun, Jilin, 130024, China.,School of Life Sciences, Xuzhou Medical University, Xuzhou, Jiangsu, 221004, China
| | - Xiaodan Lu
- Transgenic Research Center, Northeast Normal University, Changchun, Jilin, 130024, China
| | - Yuntao Zhang
- Transgenic Research Center, Northeast Normal University, Changchun, Jilin, 130024, China
| | - Mingyue Zhao
- Transgenic Research Center, Northeast Normal University, Changchun, Jilin, 130024, China
| | - Xuechao Feng
- Transgenic Research Center, Northeast Normal University, Changchun, Jilin, 130024, China.
| | - Yaowu Zheng
- Transgenic Research Center, Northeast Normal University, Changchun, Jilin, 130024, China. .,Institute of Biomedical Sciences, Shanxi University, Taiyuan, Shanxi, 030006, China.
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6
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Redundant and non-redundant cytokine-activated enhancers control Csn1s2b expression in the lactating mouse mammary gland. Nat Commun 2021; 12:2239. [PMID: 33854063 PMCID: PMC8047016 DOI: 10.1038/s41467-021-22500-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Accepted: 03/16/2021] [Indexed: 12/27/2022] Open
Abstract
Enhancers are transcription factor platforms that synergize with promoters to control gene expression. Here, we investigate enhancers that activate gene expression several hundred-fold exclusively in the lactating mouse mammary gland. Using ChIP-seq for activating histone marks and transcription factors, we identify two candidate enhancers and one super-enhancer in the Csn1s2b locus. Through experimental mouse genetics, we dissect the lactation-specific distal enhancer bound by the mammary-enriched transcription factors STAT5 and NFIB and the glucocorticoid receptor. While deletions of canonical binding motifs for NFIB and STAT5, individually or combined, have a limited biological impact, a non-canonical STAT5 site is essential for enhancer activity during lactation. In contrast, the intronic enhancer contributes to gene expression only in late pregnancy and early lactation, possibly by interacting with the distal enhancer. A downstream super-enhancer, which physically interacts with the distal enhancer, is required for the functional establishment of the Csn1s2b promoter and gene activation. Lastly, NFIB binding in the promoter region fine-tunes Csn1s2b expression. Our study provides comprehensive insight into the anatomy and biology of regulatory elements that employ the JAK/STAT signaling pathway and preferentially activate gene expression during lactation. Enhancers and promoters work together to actively regulate gene expression affecting several biological processes. Here, the authors provide molecular insights into the regulation of enhancers and super-enhancers in the Csn1s2b locus during lactation.
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7
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Chai P, Yu J, Jia R, Wen X, Ding T, Zhang X, Ni H, Jia R, Ge S, Zhang H, Fan X. Generation of onco-enhancer enhances chromosomal remodeling and accelerates tumorigenesis. Nucleic Acids Res 2020; 48:12135-12150. [PMID: 33196849 PMCID: PMC7708045 DOI: 10.1093/nar/gkaa1051] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2020] [Revised: 10/16/2020] [Accepted: 10/22/2020] [Indexed: 01/09/2023] Open
Abstract
Chromatin remodeling impacts the structural neighborhoods and regulates gene expression. However, the role of enhancer-guided chromatin remodeling in the gene regulation remains unclear. Here, using RNA-seq and ChIP-seq, we identified for the first time that neurotensin (NTS) serves as a key oncogene in uveal melanoma and that CTCF interacts with the upstream enhancer of NTS and orchestrates an 800 kb chromosomal loop between the promoter and enhancer. Intriguingly, this novel CTCF-guided chromatin loop was ubiquitous in a cohort of tumor patients. In addition, a disruption in this chromosomal interaction prevented the histone acetyltransferase EP300 from embedding in the promoter of NTS and resulted in NTS silencing. Most importantly, in vitro and in vivo experiments showed that the ability of tumor formation was significantly suppressed via deletion of the enhancer by CRISPR-Cas9. These studies delineate a novel onco-enhancer guided epigenetic mechanism and provide a promising therapeutic concept for disease therapy.
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Affiliation(s)
- Peiwei Chai
- Department of Ophthalmology, Shanghai Key Laboratory of Orbital Diseases and Ocular Oncology, Ninth People's Hospital, Shanghai JiaoTong University School of Medicine, Shanghai, P. R. China
| | - Jie Yu
- Department of Ophthalmology, Shanghai Key Laboratory of Orbital Diseases and Ocular Oncology, Ninth People's Hospital, Shanghai JiaoTong University School of Medicine, Shanghai, P. R. China
| | - Ruobing Jia
- Department of Ophthalmology, Shanghai Key Laboratory of Orbital Diseases and Ocular Oncology, Ninth People's Hospital, Shanghai JiaoTong University School of Medicine, Shanghai, P. R. China
| | - Xuyang Wen
- Department of Ophthalmology, Shanghai Key Laboratory of Orbital Diseases and Ocular Oncology, Ninth People's Hospital, Shanghai JiaoTong University School of Medicine, Shanghai, P. R. China
| | - Tianyi Ding
- Institute for Regenerative Medicine, Shanghai East Hospital, School of Life Science and Technology, Tongji University, Shanghai, P. R. China.,Frontier Science Research Center for Stem Cells, Tongji University, Shanghai, 200092, P. R. China
| | - Xiaoyu Zhang
- Institute for Regenerative Medicine, Shanghai East Hospital, School of Life Science and Technology, Tongji University, Shanghai, P. R. China.,Frontier Science Research Center for Stem Cells, Tongji University, Shanghai, 200092, P. R. China
| | - Hongyan Ni
- Department of Ophthalmology, Shanghai Key Laboratory of Orbital Diseases and Ocular Oncology, Ninth People's Hospital, Shanghai JiaoTong University School of Medicine, Shanghai, P. R. China
| | - Renbing Jia
- Department of Ophthalmology, Shanghai Key Laboratory of Orbital Diseases and Ocular Oncology, Ninth People's Hospital, Shanghai JiaoTong University School of Medicine, Shanghai, P. R. China
| | - Shengfang Ge
- Department of Ophthalmology, Shanghai Key Laboratory of Orbital Diseases and Ocular Oncology, Ninth People's Hospital, Shanghai JiaoTong University School of Medicine, Shanghai, P. R. China
| | - He Zhang
- Institute for Regenerative Medicine, Shanghai East Hospital, School of Life Science and Technology, Tongji University, Shanghai, P. R. China.,Frontier Science Research Center for Stem Cells, Tongji University, Shanghai, 200092, P. R. China
| | - Xianqun Fan
- Department of Ophthalmology, Shanghai Key Laboratory of Orbital Diseases and Ocular Oncology, Ninth People's Hospital, Shanghai JiaoTong University School of Medicine, Shanghai, P. R. China
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8
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N-terminal domain of the architectural protein CTCF has similar structural organization and ability to self-association in bilaterian organisms. Sci Rep 2020; 10:2677. [PMID: 32060375 PMCID: PMC7021899 DOI: 10.1038/s41598-020-59459-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Accepted: 01/24/2020] [Indexed: 12/12/2022] Open
Abstract
CTCF is the main architectural protein found in most of the examined bilaterian organisms. The cluster of the C2H2 zinc-finger domains involved in recognition of long DNA-binding motif is only part of the protein that is evolutionarily conserved, while the N-terminal domain (NTD) has different sequences. Here, we performed biophysical characterization of CTCF NTDs from various species representing all major phylogenetic clades of higher metazoans. With the exception of Drosophilides, the N-terminal domains of CTCFs show an unstructured organization and absence of folded regions in vitro. In contrast, NTDs of Drosophila melanogaster and virilis CTCFs contain unstructured folded regions that form tetramers and dimers correspondingly in vitro. Unexpectedly, most NTDs are able to self-associate in the yeast two-hybrid and co-immunoprecipitation assays. These results suggest that NTDs of CTCFs might contribute to the organization of CTCF-mediated long-distance interactions and chromosomal architecture.
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9
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Pellacani D, Tan S, Lefort S, Eaves CJ. Transcriptional regulation of normal human mammary cell heterogeneity and its perturbation in breast cancer. EMBO J 2019; 38:e100330. [PMID: 31304632 PMCID: PMC6627240 DOI: 10.15252/embj.2018100330] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Revised: 10/22/2018] [Accepted: 11/08/2018] [Indexed: 12/18/2022] Open
Abstract
The mammary gland in adult women consists of biologically distinct cell types that differ in their surface phenotypes. Isolation and molecular characterization of these subpopulations of mammary cells have provided extensive insights into their different transcriptional programs and regulation. This information is now serving as a baseline for interpreting the heterogeneous features of human breast cancers. Examination of breast cancer mutational profiles further indicates that most have undergone a complex evolutionary process even before being detected. The consequent intra-tumoral as well as inter-tumoral heterogeneity of these cancers thus poses major challenges to deriving information from early and hence likely pervasive changes in potential therapeutic interest. Recently described reproducible and efficient methods for generating human breast cancers de novo in immunodeficient mice transplanted with genetically altered primary cells now offer a promising alternative to investigate initial stages of human breast cancer development. In this review, we summarize current knowledge about key transcriptional regulatory processes operative in these partially characterized subpopulations of normal human mammary cells and effects of disrupting these processes in experimentally produced human breast cancers.
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Affiliation(s)
- Davide Pellacani
- Terry Fox LaboratoryBritish Columbia Cancer AgencyVancouverBCCanada
| | - Susanna Tan
- Terry Fox LaboratoryBritish Columbia Cancer AgencyVancouverBCCanada
| | - Sylvain Lefort
- Terry Fox LaboratoryBritish Columbia Cancer AgencyVancouverBCCanada
| | - Connie J Eaves
- Terry Fox LaboratoryBritish Columbia Cancer AgencyVancouverBCCanada
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10
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Shin HY, Hennighausen L, Yoo KH. STAT5-Driven Enhancers Tightly Control Temporal Expression of Mammary-Specific Genes. J Mammary Gland Biol Neoplasia 2019; 24:61-71. [PMID: 30328555 DOI: 10.1007/s10911-018-9418-y] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/19/2018] [Accepted: 10/12/2018] [Indexed: 12/24/2022] Open
Abstract
The de novo formation of milk-secreting mammary epithelium during pregnancy is regulated by prolactin through activation of the transcription factor STAT5, which stimulates the expression of several hundred mammary-specific genes. In addition to its key role in activating gene expression in mammary tissue, STAT5, which is ubiquitously expressed in most cell types, implements T cell-specific programs controlled by interleukins. However, the mechanisms by which STAT5 controls cell-specific genetic programs activated by distinct cytokines remain relatively unknown. Integration of data from genome-wide surveys of chromatin markers and transcription factor binding at regulatory elements may shed light on the mechanisms that drive cell-specific programs. Here, we have illustrated how STAT5 controls cell-specific gene expression through its concentration and an auto-regulatory enhancer supporting its high levels in mammary tissue. The unique genomic features of STAT5-driven enhancers or super-enhancers that regulate mammary-specific genes and their dynamic remodeling in response to pregnancy hormone levels are described. We have further provided biological evidence supporting the in vivo function of a STAT5-driven super-enhancer with the aid of CRISPR/Cas9 genome editing. Finally, we discuss how the functions of mammary-specific super-enhancers are confined by the zinc finger protein, CTCF, to allow exclusive activation of mammary-specific genes without affecting common neighboring genes. This review comprehensively summarizes the molecular pathways underlying differential control of cell-specific gene sets by STAT5 and provides novel insights into STAT5-dependent mammary physiology.
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Affiliation(s)
- Ha Youn Shin
- Department of Biomedical Science and Engineering, Konkuk University, Seoul, 05029, Republic of Korea
| | - Lothar Hennighausen
- Laboratory of Genetics and Physiology, National Institutes of Diabetes, Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, 20892, USA
- BK21 PLUS Project, Sookmyung Women's University, Seoul, 04310, Republic of Korea
| | - Kyung Hyun Yoo
- Department of Biological Sciences, Sookmyung Women's University, Seoul, 04310, Republic of Korea.
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11
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Yoo KH, Hennighausen L, Shin HY. Dissecting Tissue-Specific Super-Enhancers by Integrating Genome-Wide Analyses and CRISPR/Cas9 Genome Editing. J Mammary Gland Biol Neoplasia 2019; 24:47-59. [PMID: 30291498 DOI: 10.1007/s10911-018-9417-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Accepted: 10/01/2018] [Indexed: 12/17/2022] Open
Abstract
Recent advances in genome-wide sequencing technologies have provided researchers with unprecedented opportunities to discover the genomic structures of gene regulatory units in living organisms. In particular, the integration of ChIP-seq, RNA-seq, and DNase-seq techniques has facilitated the mapping of a new class of regulatory elements. These elements, called super-enhancers, can regulate cell-type-specific gene sets and even fine-tune gene expression regulation in response to external stimuli, and have become a hot topic in genome biology. However, there is scant genetic evidence demonstrating their unique biological relevance and the mechanisms underlying these biological functions. In this review, we describe a robust genome-wide strategy for mapping cell-type-specific enhancers or super-enhancers in the mammary genome. In this strategy, genome-wide screening of active enhancer clusters that are co-occupied by mammary-enriched transcription factors, co-factors, and active enhancer marks is used to identify bona fide mammary tissue-specific super-enhancers. The in vivo function of these super-enhancers and their associated regulatory elements may then be investigated in various ways using the advanced CRISPR/Cas9 genome-editing technology. Based on our experience targeting various mammary genomic sites using CRISPR/Cas9 in mice, we comprehensively discuss the molecular consequences of the different targeting methods, such as the number of gRNAs and the dependence on their simultaneous or sequential injections. We also mention the considerations that are essential for obtaining accurate results and shed light on recent progress that has been made in developing modified CRISPR/Cas9 genome-editing techniques. In the future, the coupling of advanced genome-wide sequencing and genome-editing technologies could provide new insights into the complex genetic regulatory networks involved in mammary-gland development.
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Affiliation(s)
- Kyung Hyun Yoo
- Department of Biological Sciences, Sookmyung Women's University, Seoul, 04310, Republic of Korea
| | - Lothar Hennighausen
- Laboratory of Genetics and Physiology, National Institutes of Diabetes, Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, 20892, USA
- BK21 Biological Science Visiting Professor, Sookmyung Women's University, Seoul, 04310, Republic of Korea
| | - Ha Youn Shin
- Department of Biomedical Science and Engineering, Konkuk University, Seoul, 05029, Republic of Korea.
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12
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The structural and functional roles of CTCF in the regulation of cell type-specific and human disease-associated super-enhancers. Genes Genomics 2018; 41:257-265. [PMID: 30456521 DOI: 10.1007/s13258-018-0768-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2018] [Accepted: 11/13/2018] [Indexed: 12/20/2022]
Abstract
BACKGROUND Super-enhancers play critical roles in cell-type specific gene controls and human disease progression. CCCTC-binding factor (CTCF), a transcriptional repressor that insulates the expression of neighboring genes and is involved in chromatin interactions, is frequently present in the boundary regions of or within super-enhancers. However, the structural and functional roles of CTCF in regulating super-enhancers remain elusive. OBJECTIVE To provide a comprehensive review describing the distinct chromatin features and functional roles of CTCF within super-enhancers. METHODS This review compares the various tools used to study the three-dimensional (3D) chromatin architecture of super-enhancers; summarizes the chromatin features of CTCF within cell-type specific super-enhancers and their in vivo biological activities, as determined by CRISPR/Cas9 genome editing; and describes the structural and functional activities of CTCF within human disease-associated super-enhancers. CONCLUSION This review provides fundamental insights into the regulatory mechanisms of super-enhancers and facilitates studies of tissue-specific developmental processes and human disease progression.
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13
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Shin HY. Targeting Super-Enhancers for Disease Treatment and Diagnosis. Mol Cells 2018; 41:506-514. [PMID: 29754476 PMCID: PMC6030247 DOI: 10.14348/molcells.2018.2297] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2017] [Revised: 04/06/2018] [Accepted: 04/12/2018] [Indexed: 01/05/2023] Open
Abstract
The transcriptional regulation of genes determines the fate of animal cell differentiation and subsequent organ development. With the recent progress in genome-wide technologies, the genomic landscapes of enhancers have been broadly explored in mammalian genomes, which led to the discovery of novel specific subsets of enhancers, termed super-enhancers. Super-enhancers are large clusters of enhancers covering the long region of regulatory DNA and are densely occupied by transcription factors, active histone marks, and co-activators. Accumulating evidence points to the critical role that super-enhancers play in cell type-specific development and differentiation, as well as in the development of various diseases. Here, I provide a comprehensive description of the optimal approach for identifying functional units of super-enhancers and their unique chromatin features in normal development and in diseases, including cancers. I also review the recent updated knowledge on novel approaches of targeting super-enhancers for the treatment of specific diseases, such as small-molecule inhibitors and potential gene therapy. This review will provide perspectives on using super-enhancers as biomarkers to develop novel disease diagnostic tools and establish new directions in clinical therapeutic strategies.
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Affiliation(s)
- Ha Youn Shin
- Department of Biomedical Science and Engineering, Konkuk University, Seoul 05029,
Korea
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14
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CRISPR-based strategies for studying regulatory elements and chromatin structure in mammalian gene control. Mamm Genome 2018; 29:205-228. [PMID: 29196861 PMCID: PMC9881389 DOI: 10.1007/s00335-017-9727-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2017] [Accepted: 11/27/2017] [Indexed: 01/31/2023]
Abstract
The development of high-throughput methods has enabled the genome-wide identification of putative regulatory elements in a wide variety of mammalian cells at an unprecedented resolution. Extensive genomic studies have revealed the important role of regulatory elements and genetic variation therein in disease formation and risk. In most cases, there is only correlative evidence for the roles of these elements and non-coding changes within these elements in pathogenesis. With the advent of genome- and epigenome-editing tools based on the CRISPR technology, it is now possible to test the functional relevance of the regulatory elements and alterations on a genomic scale. Here, we review the various CRISPR-based strategies that have been developed to functionally validate the candidate regulatory elements in mammals as well as the non-coding genetic variants found to be associated with human disease. We also discuss how these synthetic biology tools have helped to elucidate the role of three-dimensional nuclear architecture and higher-order chromatin organization in shaping functional genome and controlling gene expression.
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15
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Oudelaar AM, Hanssen LL, Hardison RC, Kassouf MT, Hughes JR, Higgs DR. Between form and function: the complexity of genome folding. Hum Mol Genet 2017; 26:R208-R215. [PMID: 28977451 PMCID: PMC5886466 DOI: 10.1093/hmg/ddx306] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2017] [Revised: 07/18/2017] [Accepted: 07/19/2017] [Indexed: 01/24/2023] Open
Abstract
It has been known for over a century that chromatin is not randomly distributed within the nucleus. However, the question of how DNA is folded and the influence of such folding on nuclear processes remain topics of intensive current research. A longstanding, unanswered question is whether nuclear organization is simply a reflection of nuclear processes such as transcription and replication, or whether chromatin is folded by independent mechanisms and this per se encodes function? Evidence is emerging that both may be true. Here, using the α-globin gene cluster as an illustrative model, we provide an overview of the most recent insights into the layers of genome organization across different scales and how this relates to gene activity.
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Affiliation(s)
- A. Marieke Oudelaar
- MRC Molecular Haematology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, OX3 9DS, UK
| | - Lars L.P. Hanssen
- MRC Molecular Haematology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, OX3 9DS, UK
| | - Ross C. Hardison
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, PA 16802, USA
| | - Mira T. Kassouf
- MRC Molecular Haematology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, OX3 9DS, UK
| | - Jim R. Hughes
- MRC Molecular Haematology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, OX3 9DS, UK
| | - Douglas R. Higgs
- MRC Molecular Haematology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, OX3 9DS, UK
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16
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Facultative CTCF sites moderate mammary super-enhancer activity and regulate juxtaposed gene in non-mammary cells. Nat Commun 2017; 8:16069. [PMID: 28714474 PMCID: PMC5520053 DOI: 10.1038/ncomms16069] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Accepted: 05/25/2017] [Indexed: 01/06/2023] Open
Abstract
Precise spatiotemporal gene regulation is paramount for the establishment and maintenance of cell-specific programmes. Although there is evidence that chromatin neighbourhoods, formed by the zinc-finger protein CTCF, can sequester enhancers and their target genes, there is limited in vivo evidence for CTCF demarcating super-enhancers and preventing cross talk between distinct regulatory elements. Here, we address these questions in the Wap locus with its mammary-specific super-enhancer separated by CTCF sites from widely expressed genes. Mutational analysis demonstrates that the Wap super-enhancer controls Ramp3, despite three separating CTCF sites. Their deletion in mice results in elevated expression of Ramp3 in mammary tissue through augmented promoter–enhancer interactions. Deletion of the distal CTCF-binding site results in loss of Ramp3 expression in non-mammary tissues. This suggests that CTCF sites are porous borders, allowing a super-enhancer to activate a secondary target. Likewise, CTCF sites shield a widely expressed gene from suppressive influences of a silent locus. Chromatin neighbourhoods, formed by CTCF, have been proposed to isolate enhancers and their target genes from other regulatory elements. Here, the authors provide evidence that while CTCF binding does regulates mammary-specific super-enhancers, CTCF sites are relatively porous borders.
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