101
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Sun T, Gilani SM, Podany P, Harigopal M, Zhong M, Wang H. Cytomorphologic features of SMARCA4-deficient non-small cell lung carcinoma and correlation with immunohistochemical and molecular features. Cancer Cytopathol 2022; 130:620-629. [PMID: 35468657 DOI: 10.1002/cncy.22581] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2021] [Revised: 02/19/2022] [Accepted: 03/22/2022] [Indexed: 11/08/2022]
Abstract
BACKGROUND SMARCA4/BRG1-deficient tumors and those that have loss of SMARCA/BRG1 have been described as various aggressive carcinomas and sarcomas, including a subset of non-small cell lung carcinoma (NSCLC). Cytomorphologic features of NSCLCs are yet to be described. The objective of this study was to evaluate the cytomorphologic features, immunohistochemical profile, and molecular profile of SMARCA4/BRG1-deficient NSCLC (SMARCA4-dNSCLC). METHODS The authors retrospectively searched for cases with SMARCA4/BRG1 functional loss alterations, which were identified in molecular studies and further confirmed by immunocytochemistry, and they reviewed the cytomorphologic features. Tumors with BRG1 loss were also stained with an extensive antibody panel. Molecular profiling and clinical information of the identified cases were scrutinized. RESULTS In total, 12 cytopathology cases from different anatomic sites were included. All cases showed variable expression of cytokeratin irrespective of type. One-half of cases had glandular features, followed by squamoid features, and poorly differentiated features. The most common cytologic features included sheets or papillary architecture, round or oval cell shapes, nuclear enlargement, moderate-to-marked pleomorphism, and coarse chromatin. Two cases with poorly differentiated cytomorphology had a predominance of single cells, scant cytoplasm, and macronucleoli. Variable expression of epithelial markers was noted in all cases. TP53 was the most frequently co-mutated gene in SMARCA4-dNSLCs. CONCLUSIONS This study demonstrates that SMARCA4-dNSCLCs can have a wide spectrum of cytomorphologic features, ranging from a relatively well differentiated adenocarcinoma to a poorly differentiated/undifferentiated carcinoma, with the majority of cases exhibiting some high-grade features, such as mitosis, apoptosis, necrosis, and marked pleomorphism.
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Affiliation(s)
- Tong Sun
- Department of Pathology, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Syed M Gilani
- Department of Pathology, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Peter Podany
- Department of Pathology, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Malini Harigopal
- Department of Pathology, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Minghao Zhong
- Department of Pathology, Yale University School of Medicine, New Haven, Connecticut, USA
| | - He Wang
- Department of Pathology, Yale University School of Medicine, New Haven, Connecticut, USA
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102
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Bonefas KM, Iwase S. Soma-to-germline transformation in chromatin-linked neurodevelopmental disorders? FEBS J 2022; 289:2301-2317. [PMID: 34514717 PMCID: PMC8918023 DOI: 10.1111/febs.16196] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 08/16/2021] [Accepted: 09/10/2021] [Indexed: 01/22/2023]
Abstract
Mutations in numerous chromatin regulators cause neurodevelopmental disorders (NDDs) with unknown mechanisms. Understandably, most research has focused on how chromatin regulators control gene expression that is directly relevant to brain development and function, such as synaptic genes. However, some NDD models surprisingly show ectopic expression of germline genes in the brain. These germline genes are usually expressed only in the primordial germ cells, testis, and ovaries for germ cell development and sexual reproduction. Such ectopic germline gene expression has been reported in several NDDs, including immunodeficiency, centromeric instability, facial anomalies syndrome 1; Kleefstra syndrome 1; MeCP2 duplication syndrome; and mental retardation, X-linked syndromic, Claes-Jensen type. The responsible genes, DNMT3B, G9A/GLP, MECP2, and KDM5C, all encode chromatin regulators for gene silencing. These mutations may therefore lead to germline gene derepression and, in turn, a severe identity crisis of brain cells-potentially interfering with normal brain development. Thus, the ectopic expression of germline genes is a unique hallmark defining this NDD subset and further implicates the importance of germline gene silencing during brain development. The functional impact of germline gene expression on brain development, however, remains undetermined. This perspective article explores how this apparent soma-to-germline transformation arises and how it may interfere with neurodevelopment through genomic instability and impaired sensory cilium formation. Furthermore, we also discuss how to test these hypotheses experimentally to ultimately determine the contribution of ectopic germline transcripts to chromatin-linked NDDs.
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Affiliation(s)
- Katherine M. Bonefas
- Department of Human Genetics, Michigan Medicine, University of Michigan, Ann Arbor, MI 48109,The University of Michigan Neuroscience Graduate Program,Corresponding authors: Please address correspondence to: , and
| | - Shigeki Iwase
- Department of Human Genetics, Michigan Medicine, University of Michigan, Ann Arbor, MI 48109,The University of Michigan Neuroscience Graduate Program,Corresponding authors: Please address correspondence to: , and
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Taylor-Papadimitriou J, Burchell JM. Histone Methylases and Demethylases Regulating Antagonistic Methyl Marks: Changes Occurring in Cancer. Cells 2022; 11:cells11071113. [PMID: 35406676 PMCID: PMC8997813 DOI: 10.3390/cells11071113] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2022] [Revised: 03/17/2022] [Accepted: 03/22/2022] [Indexed: 02/06/2023] Open
Abstract
Epigenetic regulation of gene expression is crucial to the determination of cell fate in development and differentiation, and the Polycomb (PcG) and Trithorax (TrxG) groups of proteins, acting antagonistically as complexes, play a major role in this regulation. Although originally identified in Drosophila, these complexes are conserved in evolution and the components are well defined in mammals. Each complex contains a protein with methylase activity (KMT), which can add methyl groups to a specific lysine in histone tails, histone 3 lysine 27 (H3K27), by PcG complexes, and H3K4 and H3K36 by TrxG complexes, creating transcriptionally repressive or active marks, respectively. Histone demethylases (KDMs), identified later, added a new dimension to histone methylation, and mutations or changes in levels of expression are seen in both methylases and demethylases and in components of the PcG and TrX complexes across a range of cancers. In this review, we focus on both methylases and demethylases governing the methylation state of the suppressive and active marks and consider their action and interaction in normal tissues and in cancer. A picture is emerging which indicates that the changes which occur in cancer during methylation of histone lysines can lead to repression of genes, including tumour suppressor genes, or to the activation of oncogenes. Methylases or demethylases, which are themselves tumour suppressors, are highly mutated. Novel targets for cancer therapy have been identified and a methylase (KMT6A/EZH2), which produces the repressive H3K27me3 mark, and a demethylase (KDM1A/LSD1), which demethylates the active H3K4me2 mark, are now under clinical evaluation.
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104
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Janssen SM, Lorincz MC. Interplay between chromatin marks in development and disease. Nat Rev Genet 2022; 23:137-153. [PMID: 34608297 DOI: 10.1038/s41576-021-00416-x] [Citation(s) in RCA: 52] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/23/2021] [Indexed: 02/07/2023]
Abstract
DNA methylation (DNAme) and histone post-translational modifications (PTMs) have important roles in transcriptional regulation. Although many reports have characterized the functions of such chromatin marks in isolation, recent genome-wide studies reveal surprisingly complex interactions between them. Here, we focus on the interplay between DNAme and methylation of specific lysine residues on the histone H3 tail. We describe the impact of genetic perturbation of the relevant methyltransferases in the mouse on the landscape of chromatin marks as well as the transcriptome. In addition, we discuss the specific neurodevelopmental growth syndromes and cancers resulting from pathogenic mutations in the human orthologues of these genes. Integrating these observations underscores the fundamental importance of crosstalk between DNA and histone H3 methylation in development and disease.
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Affiliation(s)
- Sanne M Janssen
- Department of Medical Genetics, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Matthew C Lorincz
- Department of Medical Genetics, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada.
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105
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Sun C, Zhang X, Ruzycki PA, Chen S. Essential Functions of MLL1 and MLL2 in Retinal Development and Cone Cell Maintenance. Front Cell Dev Biol 2022; 10:829536. [PMID: 35223853 PMCID: PMC8864151 DOI: 10.3389/fcell.2022.829536] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2021] [Accepted: 01/25/2022] [Indexed: 11/23/2022] Open
Abstract
MLL1 (KMT2A) and MLL2 (KMT2B) are homologous members of the mixed-lineage leukemia (MLL) family of histone methyltransferases involved in epigenomic transcriptional regulation. Their sequence variants have been associated with neurological and psychological disorders, but little is known about their roles and mechanism of action in CNS development. Using mouse retina as a model, we previously reported MLL1’s role in retinal neurogenesis and horizontal cell maintenance. Here we determine roles of MLL2 and MLL1/MLL2 together in retinal development using conditional knockout (CKO) mice. Deleting Mll2 from Chx10+ retinal progenitors resulted in a similar phenotype as Mll1 CKO, but removal of both alleles produced much more severe deficits than each single CKO: 1-month double CKO mutants displayed null light responses in electroretinogram; thin retinal layers, including shorter photoreceptor outer segments with impaired phototransduction gene expression; and reduced numbers of M-cones, horizontal and amacrine neurons, followed by fast retinal degeneration. Despite moderately reduced progenitor cell proliferation at P0, the neurogenic capacity was largely maintained in double CKO mutants. However, upregulated apoptosis and reactive gliosis were detected during postnatal retinal development. Finally, the removal of both MLLs in fated rods produced a normal phenotype, but the CKO in M-cones impaired M-cone function and survival, indicating both cell non-autonomous and autonomous mechanisms. Altogether, our results suggest that MLL1/MLL2 play redundant roles in maintaining specific retinal neurons after cell fate specification and are essential for establishing functional neural networks.
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Affiliation(s)
- Chi Sun
- Department of Ophthalmology and Visual Sciences, St. Louis, MO, United States
| | - Xiaodong Zhang
- Department of Ophthalmology and Visual Sciences, St. Louis, MO, United States
| | - Philip A. Ruzycki
- Department of Ophthalmology and Visual Sciences, St. Louis, MO, United States
| | - Shiming Chen
- Department of Ophthalmology and Visual Sciences, St. Louis, MO, United States
- Department of Developmental Biology, Washington University, St. Louis, MO, United States
- *Correspondence: Shiming Chen,
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106
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Parreno V, Martinez AM, Cavalli G. Mechanisms of Polycomb group protein function in cancer. Cell Res 2022; 32:231-253. [PMID: 35046519 PMCID: PMC8888700 DOI: 10.1038/s41422-021-00606-6] [Citation(s) in RCA: 50] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Accepted: 12/10/2021] [Indexed: 02/01/2023] Open
Abstract
AbstractCancer arises from a multitude of disorders resulting in loss of differentiation and a stem cell-like phenotype characterized by uncontrolled growth. Polycomb Group (PcG) proteins are members of multiprotein complexes that are highly conserved throughout evolution. Historically, they have been described as essential for maintaining epigenetic cellular memory by locking homeotic genes in a transcriptionally repressed state. What was initially thought to be a function restricted to a few target genes, subsequently turned out to be of much broader relevance, since the main role of PcG complexes is to ensure a dynamically choregraphed spatio-temporal regulation of their numerous target genes during development. Their ability to modify chromatin landscapes and refine the expression of master genes controlling major switches in cellular decisions under physiological conditions is often misregulated in tumors. Surprisingly, their functional implication in the initiation and progression of cancer may be either dependent on Polycomb complexes, or specific for a subunit that acts independently of other PcG members. In this review, we describe how misregulated Polycomb proteins play a pleiotropic role in cancer by altering a broad spectrum of biological processes such as the proliferation-differentiation balance, metabolism and the immune response, all of which are crucial in tumor progression. We also illustrate how interfering with PcG functions can provide a powerful strategy to counter tumor progression.
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107
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Deshpande N, Jordan R, Henderson Pozzi M, Bryk M. Histone 3 lysine 4 monomethylation supports activation of transcription in S. cerevisiae during nutrient stress. Curr Genet 2022; 68:181-194. [PMID: 35041077 PMCID: PMC8976815 DOI: 10.1007/s00294-022-01226-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2021] [Revised: 12/17/2021] [Accepted: 12/31/2021] [Indexed: 12/11/2022]
Abstract
Mono-methylation of the fourth lysine on the N-terminal tail of histone H3 was found to support the induction of RNA polymerase II transcription in S. cerevisiae during nutrient stress. In S. cerevisiae, the mono-, di- and tri-methylation of lysine 4 on histone H3 (H3K4) is catalyzed by the protein methyltransferase, Set1. The three distinct methyl marks on H3K4 act in discrete ways to regulate transcription. Nucleosomes enriched with tri-methylated H3K4 are usually associated with active transcription whereas di-methylated H3K4 is associated with gene repression. Mono-methylated H3K4 has been shown to repress gene expression in S. cerevisiae and is detected at enhancers and promoters in eukaryotes. S. cerevisiae set1Δ mutants unable to methylate H3K4 exhibit growth defects during histidine starvation. The growth defects are rescued by either a wild-type allele of SET1 or partial-function alleles of set1, including a mutant that predominantly generates H3K4me1 and not H3K4me3. Rescue of the growth defect is associated with induction of the HIS3 gene. Growth defects observed when set1Δ cultures were starved for isoleucine and valine were also rescued by wild-type SET1 or partial-function set1 alleles. The results show that H3K4me1, in the absence of H3K4me3, supports transcription of the HIS3 gene and expression of one or more of the genes required for biosynthesis of isoleucine and valine during nutrient stress. Set1-like methyltransferases are evolutionarily conserved, and research has linked their functions to developmental gene regulation and several cancers in higher eukaryotes. Identification of mechanisms of H3K4me1-mediated activation of transcription in budding yeast will provide insight into gene regulation in all eukaryotes.
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Affiliation(s)
- Neha Deshpande
- Department of Biochemistry and Biophysics, Texas A&M University, 2128 TAMU, College Station, TX, 77843, USA
| | - Rachel Jordan
- Department of Biochemistry and Biophysics, Texas A&M University, 2128 TAMU, College Station, TX, 77843, USA
- iBio, 8800 HSC Blvd, Bryan, TX, 77807, USA
| | - Michelle Henderson Pozzi
- Department of Biochemistry and Biophysics, Texas A&M University, 2128 TAMU, College Station, TX, 77843, USA
| | - Mary Bryk
- Department of Biochemistry and Biophysics, Texas A&M University, 2128 TAMU, College Station, TX, 77843, USA.
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108
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Zug R. Developmental disorders caused by haploinsufficiency of transcriptional regulators: a perspective based on cell fate determination. Biol Open 2022; 11:bio058896. [PMID: 35089335 PMCID: PMC8801891 DOI: 10.1242/bio.058896] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Many human birth defects and neurodevelopmental disorders are caused by loss-of-function mutations in a single copy of transcription factor (TF) and chromatin regulator genes. Although this dosage sensitivity has long been known, how and why haploinsufficiency (HI) of transcriptional regulators leads to developmental disorders (DDs) is unclear. Here I propose the hypothesis that such DDs result from defects in cell fate determination that are based on disrupted bistability in the underlying gene regulatory network (GRN). Bistability, a crucial systems biology concept to model binary choices such as cell fate decisions, requires both positive feedback and ultrasensitivity, the latter often achieved through TF cooperativity. The hypothesis explains why dosage sensitivity of transcriptional regulators is an inherent property of fate decisions, and why disruption of either positive feedback or cooperativity in the underlying GRN is sufficient to cause disease. I present empirical and theoretical evidence in support of this hypothesis and discuss several issues for which it increases our understanding of disease, such as incomplete penetrance. The proposed framework provides a mechanistic, systems-level explanation of HI of transcriptional regulators, thus unifying existing theories, and offers new insights into outstanding issues of human disease. This article has an associated Future Leader to Watch interview with the author of the paper.
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Affiliation(s)
- Roman Zug
- Department of Biology, Lund University, 22362 Lund, Sweden
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109
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Smith JJ, Xiao Y, Parsan N, Medwig-Kinney TN, Martinez MAQ, Moore FEQ, Palmisano NJ, Kohrman AQ, Chandhok Delos Reyes M, Adikes RC, Liu S, Bracht SA, Zhang W, Wen K, Kratsios P, Matus DQ. The SWI/SNF chromatin remodeling assemblies BAF and PBAF differentially regulate cell cycle exit and cellular invasion in vivo. PLoS Genet 2022; 18:e1009981. [PMID: 34982771 PMCID: PMC8759636 DOI: 10.1371/journal.pgen.1009981] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2021] [Revised: 01/14/2022] [Accepted: 12/07/2021] [Indexed: 12/15/2022] Open
Abstract
Chromatin remodelers such as the SWI/SNF complex coordinate metazoan development through broad regulation of chromatin accessibility and transcription, ensuring normal cell cycle control and cellular differentiation in a lineage-specific and temporally restricted manner. Mutations in genes encoding the structural subunits of chromatin, such as histone subunits, and chromatin regulating factors are associated with a variety of disease mechanisms including cancer metastasis, in which cancer co-opts cellular invasion programs functioning in healthy cells during development. Here we utilize Caenorhabditis elegans anchor cell (AC) invasion as an in vivo model to identify the suite of chromatin agents and chromatin regulating factors that promote cellular invasiveness. We demonstrate that the SWI/SNF ATP-dependent chromatin remodeling complex is a critical regulator of AC invasion, with pleiotropic effects on both G0 cell cycle arrest and activation of invasive machinery. Using targeted protein degradation and enhanced RNA interference (RNAi) vectors, we show that SWI/SNF contributes to AC invasion in a dose-dependent fashion, with lower levels of activity in the AC corresponding to aberrant cell cycle entry and increased loss of invasion. Our data specifically implicate the SWI/SNF BAF assembly in the regulation of the G0 cell cycle arrest in the AC, whereas the SWI/SNF PBAF assembly promotes AC invasion via cell cycle-independent mechanisms, including attachment to the basement membrane (BM) and activation of the pro-invasive fos-1/FOS gene. Together these findings demonstrate that the SWI/SNF complex is necessary for two essential components of AC invasion: arresting cell cycle progression and remodeling the BM. The work here provides valuable single-cell mechanistic insight into how the SWI/SNF assemblies differentially contribute to cellular invasion and how SWI/SNF subunit-specific disruptions may contribute to tumorigeneses and cancer metastasis. Cellular invasion is required for animal development and homeostasis. Inappropriate activation of invasion however can result in cancer metastasis. Invasion programs are orchestrated by complex gene regulatory networks (GRN) that function in a coordinated fashion to turn on and off pro-invasive genes. While the core of GRNs are DNA binding transcription factors, they require aid from chromatin remodelers to access the genome. To identify the suite of pro-invasive chromatin remodelers, we paired high resolution imaging with RNA interference to individually knockdown 269 chromatin factors, identifying the evolutionarily conserved SWItching defective/Sucrose Non-Fermenting (SWI/SNF) ATP-dependent chromatin remodeling complex as a new regulator of Caenorhabditis elegans anchor cell (AC) invasion. Using a combination of CRISPR/Cas9 genome engineering and targeted protein degradation we demonstrate that the core SWI/SNF complex functions in a dose-dependent manner to control invasion. Further, we determine that the accessory SWI/SNF complexes, BAF and PBAF, contribute to invasion via distinctive mechanisms: BAF is required to prevent inappropriate proliferation while PBAF promotes AC attachment and remodeling of the basement membrane. Together, our data provide insights into how the SWI/SNF complex, which is mutated in many human cancers, can function in a dose-dependent fashion to regulate switching from invasive to proliferative fates.
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Affiliation(s)
- Jayson J. Smith
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, New York, United States of America
| | - Yutong Xiao
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, New York, United States of America
| | - Nithin Parsan
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, New York, United States of America
- Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
| | - Taylor N. Medwig-Kinney
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, New York, United States of America
| | - Michael A. Q. Martinez
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, New York, United States of America
| | - Frances E. Q. Moore
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, New York, United States of America
| | - Nicholas J. Palmisano
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, New York, United States of America
| | - Abraham Q. Kohrman
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, New York, United States of America
- Department of Molecular Biology, Princeton University, Princeton, New Jersey, United States of America
| | - Mana Chandhok Delos Reyes
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, New York, United States of America
| | - Rebecca C. Adikes
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, New York, United States of America
- Biology Department, Siena College, Loudonville, New York, United States of America
| | - Simeiyun Liu
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, New York, United States of America
- Molecular, Cellular and Developmental Biology, University of California Santa Cruz, Santa Cruz, California, United States of America
| | - Sydney A. Bracht
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, New York, United States of America
- Department of Cell Biology, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Wan Zhang
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, New York, United States of America
| | - Kailong Wen
- The Grossman Institute for Neuroscience, Quantitative Biology, and Human Behavior, University of Chicago, Chicago, Illinois, United States of America
- Department of Neurobiology, University of Chicago, Chicago, Illinois, United States of America
| | - Paschalis Kratsios
- The Grossman Institute for Neuroscience, Quantitative Biology, and Human Behavior, University of Chicago, Chicago, Illinois, United States of America
- Department of Neurobiology, University of Chicago, Chicago, Illinois, United States of America
| | - David Q. Matus
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, New York, United States of America
- * E-mail:
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Alterations of Chromatin Regulators in the Pathogenesis of Urinary Bladder Urothelial Carcinoma. Cancers (Basel) 2021; 13:cancers13236040. [PMID: 34885146 PMCID: PMC8656749 DOI: 10.3390/cancers13236040] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2021] [Revised: 11/29/2021] [Accepted: 11/29/2021] [Indexed: 12/14/2022] Open
Abstract
Simple Summary Urinary bladder cancer is one of the ten major cancers worldwide, with higher incidences in males, in smokers, and in highly industrialized countries. New therapies beyond cytotoxic chemotherapy are urgently needed to improve treatment of these tumors. A better understanding of the mechanisms underlying their development may help in this regard. Recently, it was discovered that a group of proteins regulating the state of chromatin and thus gene expression is exceptionally and frequently affected by gene mutations in bladder cancers. Altered function of these mutated chromatin regulators must therefore be fundamental in their development, but how and why is poorly understood. Here we review the current knowledge on changes in chromatin regulators and discuss their possible consequences for bladder cancer development and options for new therapies. Abstract Urothelial carcinoma (UC) is the most frequent histological type of cancer in the urinary bladder. Genomic changes in UC activate MAPK and PI3K/AKT signal transduction pathways, which increase cell proliferation and survival, interfere with cell cycle and checkpoint control, and prevent senescence. A more recently discovered additional category of genetic changes in UC affects chromatin regulators, including histone-modifying enzymes (KMT2C, KMT2D, KDM6A, EZH2), transcription cofactors (CREBBP, EP300), and components of the chromatin remodeling complex SWI/SNF (ARID1A, SMARCA4). It is not yet well understood how these changes contribute to the development and progression of UC. Therefore, we review here the emerging knowledge on genomic and gene expression alterations of chromatin regulators and their consequences for cell differentiation, cellular plasticity, and clonal expansion during UC pathogenesis. Our analysis identifies additional relevant chromatin regulators and suggests a model for urothelial carcinogenesis as a basis for further mechanistic studies and targeted therapy development.
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111
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Rajan A, Ostgaard CM, Lee CY. Regulation of Neural Stem Cell Competency and Commitment during Indirect Neurogenesis. Int J Mol Sci 2021; 22:12871. [PMID: 34884676 PMCID: PMC8657492 DOI: 10.3390/ijms222312871] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2021] [Revised: 11/24/2021] [Accepted: 11/24/2021] [Indexed: 11/29/2022] Open
Abstract
Indirect neurogenesis, during which neural stem cells generate neurons through intermediate progenitors, drives the evolution of lissencephalic brains to gyrencephalic brains. The mechanisms that specify intermediate progenitor identity and that regulate stem cell competency to generate intermediate progenitors remain poorly understood despite their roles in indirect neurogenesis. Well-characterized lineage hierarchy and available powerful genetic tools for manipulating gene functions make fruit fly neural stem cell (neuroblast) lineages an excellent in vivo paradigm for investigating the mechanisms that regulate neurogenesis. Type II neuroblasts in fly larval brains repeatedly undergo asymmetric divisions to generate intermediate neural progenitors (INPs) that undergo limited proliferation to increase the number of neurons generated per stem cell division. Here, we review key regulatory genes and the mechanisms by which they promote the specification and generation of INPs, safeguarding the indirect generation of neurons during fly larval brain neurogenesis. Homologs of these regulators of INPs have been shown to play important roles in regulating brain development in vertebrates. Insight into the precise regulation of intermediate progenitors will likely improve our understanding of the control of indirect neurogenesis during brain development and brain evolution.
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Affiliation(s)
- Arjun Rajan
- Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA; (A.R.); (C.M.O.)
| | - Cyrina M. Ostgaard
- Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA; (A.R.); (C.M.O.)
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Cheng-Yu Lee
- Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA; (A.R.); (C.M.O.)
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
- Division of Genetic Medicine, Department of Internal Medicine and Comprehensive Cancer Center, University of Michigan Medical School, Ann Arbor, MI 48109, USA
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112
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Kleinschmidt RA, Lyon LM, Smith SL, Rittenberry J, Lawless KM, Acosta AA, Donze D. Genetic screen for suppressors of increased silencing in rpd3 mutants in Saccharomyces cerevisiae identifies a potential role for H3K4 methylation. G3 GENES|GENOMES|GENETICS 2021; 11:6371869. [PMID: 34534290 PMCID: PMC8527511 DOI: 10.1093/g3journal/jkab309] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/20/2021] [Accepted: 08/27/2021] [Indexed: 11/24/2022]
Abstract
Several studies have identified the paradoxical phenotype of increased heterochromatic gene silencing at specific loci that results from deletion or mutation of the histone deacetylase (HDAC) gene RPD3. To further understand this phenomenon, we conducted a genetic screen for suppressors of this extended silencing phenotype at the HMR locus in Saccharomyces cerevisiae. Most of the mutations that suppressed extended HMR silencing in rpd3 mutants without completely abolishing silencing were identified in the histone H3 lysine 4 methylation (H3K4me) pathway, specifically in SET1, BRE1, and BRE2. These second-site mutations retained normal HMR silencing, therefore, appear to be specific for the rpd3Δ extended silencing phenotype. As an initial assessment of the role of H3K4 methylation in extended silencing, we rule out some of the known mechanisms of Set1p/H3K4me mediated gene repression by HST1, HOS2, and HST3 encoded HDACs. Interestingly, we demonstrate that the RNA Polymerase III complex remains bound and active at the HMR-tDNA in rpd3 mutants despite silencing extending beyond the normal barrier. We discuss these results as they relate to the interplay among different chromatin-modifying enzyme functions and the importance of further study of this enigmatic phenomenon.
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Affiliation(s)
| | - Laurie M Lyon
- Department of Biological Sciences, Louisiana State University, Baton Rouge, LA 70803, USA
| | - Samantha L Smith
- Department of Biological Sciences, Louisiana State University, Baton Rouge, LA 70803, USA
| | - Jonah Rittenberry
- Department of Biological Sciences, Louisiana State University, Baton Rouge, LA 70803, USA
| | - K Maeve Lawless
- Department of Biological Sciences, Louisiana State University, Baton Rouge, LA 70803, USA
| | - Anabelle A Acosta
- Department of Biological Sciences, Louisiana State University, Baton Rouge, LA 70803, USA
| | - David Donze
- Department of Biological Sciences, Louisiana State University, Baton Rouge, LA 70803, USA
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113
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Li X, Zhou J, Zhao W, Wen Q, Wang W, Peng H, Gao Y, Bouchonville KJ, Offer SM, Chan K, Wang Z, Li N, Gan H. Defining Proximity Proteomics of Histone Modifications by Antibody-mediated Protein A-APEX2 Labeling. GENOMICS PROTEOMICS & BIOINFORMATICS 2021; 20:87-100. [PMID: 34555496 PMCID: PMC9510856 DOI: 10.1016/j.gpb.2021.09.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/23/2021] [Revised: 09/08/2021] [Accepted: 09/10/2021] [Indexed: 12/02/2022]
Abstract
Proximity labeling catalyzed by promiscuous enzymes, such as APEX2, has emerged as a powerful approach to characterize multiprotein complexes and protein–protein interactions. However, current methods depend on the expression of exogenous fusion proteins and cannot be applied to identify proteins surrounding post-translationally modified proteins. To address this limitation, we developed a new method to label proximal proteins of interest by antibody-mediated protein A-ascorbate peroxidase 2 (pA-APEX2) labeling (AMAPEX). In this method, a modified protein is bound in situ by a specific antibody, which then tethers a pA-APEX2 fusion protein. Activation of APEX2 labels the nearby proteins with biotin; the biotinylated proteins are then purified using streptavidin beads and identified by mass spectrometry. We demonstrated the utility of this approach by profiling the proximal proteins of histone modifications including H3K27me3, H3K9me3, H3K4me3, H4K5ac, and H4K12ac, as well as verifying the co-localization of these identified proteins with bait proteins by published ChIP-seq analysis and nucleosome immunoprecipitation. Overall, AMAPEX is an efficient method to identify proteins that are proximal to modified histones.
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Affiliation(s)
- Xinran Li
- Shenzhen Key Laboratory of Synthetic Genomics, Guangdong Provincial Key Laboratory of Synthetic Genomics, CAS Key Laboratory of Quantitative Engineering Biology, Shenzhen Institute of Synthetic Biology, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China
| | - Jiaqi Zhou
- Shenzhen Key Laboratory of Synthetic Genomics, Guangdong Provincial Key Laboratory of Synthetic Genomics, CAS Key Laboratory of Quantitative Engineering Biology, Shenzhen Institute of Synthetic Biology, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China
| | - Wenjuan Zhao
- Shenzhen Key Laboratory of Synthetic Genomics, Guangdong Provincial Key Laboratory of Synthetic Genomics, CAS Key Laboratory of Quantitative Engineering Biology, Shenzhen Institute of Synthetic Biology, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China
| | - Qing Wen
- Shenzhen Key Laboratory of Synthetic Genomics, Guangdong Provincial Key Laboratory of Synthetic Genomics, CAS Key Laboratory of Quantitative Engineering Biology, Shenzhen Institute of Synthetic Biology, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China
| | - Weijie Wang
- Shenzhen Key Laboratory of Synthetic Genomics, Guangdong Provincial Key Laboratory of Synthetic Genomics, CAS Key Laboratory of Quantitative Engineering Biology, Shenzhen Institute of Synthetic Biology, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China
| | - Huipai Peng
- Shenzhen Key Laboratory of Synthetic Genomics, Guangdong Provincial Key Laboratory of Synthetic Genomics, CAS Key Laboratory of Quantitative Engineering Biology, Shenzhen Institute of Synthetic Biology, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China
| | - Yuan Gao
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA
| | - Kelly J Bouchonville
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Rochester, MN 55905, USA
| | - Steven M Offer
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Rochester, MN 55905, USA; Mayo Clinic College of Medicine, Rochester, MN 55905, USA; Mayo Clinic Cancer Center, Rochester, MN 55905, USA
| | - Kuiming Chan
- Department of Biomedical Sciences, City University of Hong Kong, Hong Kong Special Administrative Region 999077, China; Key Laboratory of Biochip Technology, Biotech and Health Centre, Shenzhen Research Institute of City University of Hong Kong, Shenzhen 518172, China
| | - Zhiquan Wang
- Mayo Clinic College of Medicine, Rochester, MN 55905, USA; Division of Hematology, Department of Medicine, Mayo Clinic, Rochester, MN 55905, USA.
| | - Nan Li
- Shenzhen Key Laboratory of Synthetic Genomics, Guangdong Provincial Key Laboratory of Synthetic Genomics, CAS Key Laboratory of Quantitative Engineering Biology, Shenzhen Institute of Synthetic Biology, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China.
| | - Haiyun Gan
- Shenzhen Key Laboratory of Synthetic Genomics, Guangdong Provincial Key Laboratory of Synthetic Genomics, CAS Key Laboratory of Quantitative Engineering Biology, Shenzhen Institute of Synthetic Biology, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China.
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114
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Tilly BC, Chalkley GE, van der Knaap JA, Moshkin YM, Kan TW, Dekkers DH, Demmers JA, Verrijzer CP. In vivo analysis reveals that ATP-hydrolysis couples remodeling to SWI/SNF release from chromatin. eLife 2021; 10:69424. [PMID: 34313222 PMCID: PMC8352592 DOI: 10.7554/elife.69424] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Accepted: 07/26/2021] [Indexed: 12/23/2022] Open
Abstract
ATP-dependent chromatin remodelers control the accessibility of genomic DNA through nucleosome mobilization. However, the dynamics of genome exploration by remodelers, and the role of ATP hydrolysis in this process remain unclear. We used live-cell imaging of Drosophila polytene nuclei to monitor Brahma (BRM) remodeler interactions with its chromosomal targets. In parallel, we measured local chromatin condensation and its effect on BRM association. Surprisingly, only a small portion of BRM is bound to chromatin at any given time. BRM binds decondensed chromatin but is excluded from condensed chromatin, limiting its genomic search space. BRM-chromatin interactions are highly dynamic, whereas histone-exchange is limited and much slower. Intriguingly, loss of ATP hydrolysis enhanced chromatin retention and clustering of BRM, which was associated with reduced histone turnover. Thus, ATP hydrolysis couples nucleosome remodeling to remodeler release, driving a continuous transient probing of the genome.
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Affiliation(s)
- Ben C Tilly
- Department of Biochemistry, Rotterdam, Netherlands
| | | | | | | | | | - Dick Hw Dekkers
- Department of Biochemistry, Rotterdam, Netherlands.,Proteomics Center, Erasmus University Medical Center, Rotterdam, Netherlands
| | - Jeroen Aa Demmers
- Department of Biochemistry, Rotterdam, Netherlands.,Proteomics Center, Erasmus University Medical Center, Rotterdam, Netherlands
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115
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The MLL3/4 H3K4 methyltransferase complex in establishing an active enhancer landscape. Biochem Soc Trans 2021; 49:1041-1054. [PMID: 34156443 PMCID: PMC8286814 DOI: 10.1042/bst20191164] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Revised: 05/21/2021] [Accepted: 05/24/2021] [Indexed: 12/23/2022]
Abstract
Enhancers are cis-regulatory elements that play essential roles in tissue-specific gene expression during development. Enhancer function in the expression of developmental genes requires precise regulation, while deregulation of enhancer function could be the main cause of tissue-specific cancer development. MLL3/KMT2C and MLL4/KMT2D are two paralogous histone modifiers that belong to the SET1/MLL (also named COMPASS) family of lysine methyltransferases and play critical roles in enhancer-regulated gene activation. Importantly, large-scale DNA sequencing studies have revealed that they are amongst the most frequently mutated genes associated with human cancers. MLL3 and MLL4 form identical multi-protein complexes for modifying mono-methylation of histone H3 lysine 4 (H3K4) at enhancers, which together with the p300/CBP-mediated H3K27 acetylation can generate an active enhancer landscape for long-range target gene activation. Recent studies have provided a better understanding of the possible mechanisms underlying the roles of MLL3/MLL4 complexes in enhancer regulation. Moreover, accumulating studies offer new insights into our knowledge of the potential role of MLL3/MLL4 in cancer development. In this review, we summarize recent evidence on the molecular mechanisms of MLL3/MLL4 in the regulation of active enhancer landscape and long-range gene expression, and discuss their clinical implications in human cancers.
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116
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Heslop JA, Pournasr B, Liu JT, Duncan SA. GATA6 defines endoderm fate by controlling chromatin accessibility during differentiation of human-induced pluripotent stem cells. Cell Rep 2021; 35:109145. [PMID: 34010638 PMCID: PMC8202205 DOI: 10.1016/j.celrep.2021.109145] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Revised: 01/20/2021] [Accepted: 04/26/2021] [Indexed: 02/07/2023] Open
Abstract
In addition to driving specific gene expression profiles, transcriptional regulators are becoming increasingly recognized for their capacity to modulate chromatin structure. GATA6 is essential for the formation of definitive endoderm; however, the molecular basis defining the importance of GATA6 to endoderm commitment is poorly understood. The members of the GATA family of transcription factors have the capacity to bind and alter the accessibility of chromatin. Using pluripotent stem cells as a model of human development, we reveal that GATA6 is integral to the establishment of the endoderm enhancer network via the induction of chromatin accessibility and histone modifications. We additionally identify the chromatin-modifying complexes that interact with GATA6, defining the putative mechanisms by which GATA6 modulates chromatin architecture. The identified GATA6-dependent processes further our knowledge of the molecular mechanisms that underpin cell-fate decisions during formative development.
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Affiliation(s)
- James A Heslop
- Department of Regenerative Medicine and Cell Biology, Medical University of South Carolina, Charleston, SC, USA
| | - Behshad Pournasr
- Department of Regenerative Medicine and Cell Biology, Medical University of South Carolina, Charleston, SC, USA
| | - Jui-Tung Liu
- Department of Regenerative Medicine and Cell Biology, Medical University of South Carolina, Charleston, SC, USA
| | - Stephen A Duncan
- Department of Regenerative Medicine and Cell Biology, Medical University of South Carolina, Charleston, SC, USA.
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117
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The transcription factor code: a beacon for histone methyltransferase docking. Trends Cell Biol 2021; 31:792-800. [PMID: 34016504 DOI: 10.1016/j.tcb.2021.04.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Revised: 03/30/2021] [Accepted: 04/08/2021] [Indexed: 12/19/2022]
Abstract
Histone methylation is required for the establishment and maintenance of gene expression patterns that determine cellular identity, and its perturbation often leads to aberrant development and disease. Recruitment of histone methyltransferases (HMTs) to gene regulatory elements (GREs) of developmental genes is important for the correct activation and silencing of these genes, but the drivers of this recruitment are largely unknown. Here we propose that lineage-instructive transcription factors (Lin-TFs) act as general recruiters of HMT complexes to cell type-specific GREs through protein-protein interactions. We also postulate that the specificity of these interactions is dictated by Lin-TF post-translational modifications (PTMs), which act as a 'transcription factor code' that can determine the directionality of cell fate decisions during differentiation and development.
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118
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Quezada E, Cappelli C, Diaz I, Jury N, Wightman N, Brown RH, Montecino M, van Zundert B. BET bromodomain inhibitors PFI-1 and JQ1 are identified in an epigenetic compound screen to enhance C9ORF72 gene expression and shown to ameliorate C9ORF72-associated pathological and behavioral abnormalities in a C9ALS/FTD model. Clin Epigenetics 2021; 13:56. [PMID: 33726839 PMCID: PMC7962347 DOI: 10.1186/s13148-021-01039-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2020] [Accepted: 02/23/2021] [Indexed: 12/25/2022] Open
Abstract
BACKGROUND An intronic GGGGCC (G4C2) hexanucleotide repeat expansion (HRE) in the C9ORF72 gene is the most common cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD), referred to as C9ALS/FTD. No cure or effective treatment exist for C9ALS/FTD. Three major molecular mechanisms have emerged to explain C9ALS/FTD disease mechanisms: (1) C9ORF72 loss-of-function through haploinsufficiency, (2) dipeptide repeat (DPR) proteins mediated toxicity by the translation of the repeat RNAs, and more controversial, (3) RNA-mediated toxicity by bidirectional transcription of the repeats that form intranuclear RNA foci. Recent studies indicate a double-hit pathogenic mechanism in C9ALS/FTD, where reduced C9ORF72 protein levels lead to impaired clearance of toxic DPRs. Here we explored whether pharmacological compounds can revert these pathological hallmarks in vitro and cognitive impairment in a C9ALS/FTD mouse model (C9BAC). We specifically focused our study on small molecule inhibitors targeting chromatin-regulating proteins (epidrugs) with the goal of increasing C9ORF72 gene expression and reduce toxic DPRs. RESULTS We generated luciferase reporter cell lines containing 10 (control) or ≥ 90 (mutant) G4C2 HRE located between exon 1a and 1b of the human C9ORF72 gene. In a screen of 14 different epidrugs targeting bromodomains, chromodomains and histone-modifying enzymes, we found that several bromodomain and extra-terminal domain (BET) inhibitors (BETi), including PFI-1 and JQ1, increased luciferase reporter activity. Using primary cortical cultures from C9BAC mice, we further found that PFI-1 treatment increased the expression of V1-V3 transcripts of the human mutant C9ORF72 gene, reduced poly(GP)-DPR inclusions but enhanced intranuclear RNA foci. We also tested whether JQ1, an BETi previously shown to reach the mouse brain by intraperitoneal (i.p.) injection, can revert behavioral abnormalities in C9BAC mice. Interestingly, it was found that JQ1 administration (daily i.p. administration for 7 days) rescued hippocampal-dependent cognitive deficits in C9BAC mice. CONCLUSIONS Our findings place BET bromodomain inhibitors as a potential therapy for C9ALS/FTD by ameliorating C9ORF72-associated pathological and behavioral abnormalities. Our finding that PFI-1 increases accumulation of intranuclear RNA foci is in agreement with recent data in flies suggesting that nuclear RNA foci can be neuroprotective by sequestering repeat transcripts that result in toxic DPRs.
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Affiliation(s)
- Esteban Quezada
- Institute of Biomedical Sciences (ICB), Faculty of Medicine & Faculty of Life Sciences, Universidad Andres Bello, Santiago, Chile
| | - Claudio Cappelli
- Institute of Biomedical Sciences (ICB), Faculty of Medicine & Faculty of Life Sciences, Universidad Andres Bello, Santiago, Chile
| | - Iván Diaz
- Institute of Biomedical Sciences (ICB), Faculty of Medicine & Faculty of Life Sciences, Universidad Andres Bello, Santiago, Chile
| | - Nur Jury
- Institute of Biomedical Sciences (ICB), Faculty of Medicine & Faculty of Life Sciences, Universidad Andres Bello, Santiago, Chile
| | - Nicholas Wightman
- Department of Neurology, University of Massachusetts Medical School (UMMS), Worcester, MA, USA
| | - Robert H Brown
- Department of Neurology, University of Massachusetts Medical School (UMMS), Worcester, MA, USA
| | - Martín Montecino
- Institute of Biomedical Sciences (ICB), Faculty of Medicine & Faculty of Life Sciences, Universidad Andres Bello, Santiago, Chile.
- FONDAP Center for Genome Regulation, Santiago, Chile.
| | - Brigitte van Zundert
- Institute of Biomedical Sciences (ICB), Faculty of Medicine & Faculty of Life Sciences, Universidad Andres Bello, Santiago, Chile.
- Department of Neurology, University of Massachusetts Medical School (UMMS), Worcester, MA, USA.
- CARE Biomedical Research Center, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile.
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119
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Piunti A, Shilatifard A. The roles of Polycomb repressive complexes in mammalian development and cancer. Nat Rev Mol Cell Biol 2021; 22:326-345. [PMID: 33723438 DOI: 10.1038/s41580-021-00341-1] [Citation(s) in RCA: 191] [Impact Index Per Article: 63.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/22/2021] [Indexed: 12/14/2022]
Abstract
More than 80 years ago, the first Polycomb-related phenotype was identified in Drosophila melanogaster. Later, a group of diverse genes collectively called Polycomb group (PcG) genes were identified based on common mutant phenotypes. PcG proteins, which are well-conserved in animals, were originally characterized as negative regulators of gene transcription during development and subsequently shown to function in various biological processes; their deregulation is associated with diverse phenotypes in development and in disease, especially cancer. PcG proteins function on chromatin and can form two distinct complexes with different enzymatic activities: Polycomb repressive complex 1 (PRC1) is a histone ubiquitin ligase and PRC2 is a histone methyltransferase. Recent studies have revealed the existence of various mutually exclusive PRC1 and PRC2 variants. In this Review, we discuss new concepts concerning the biochemical and molecular functions of these new PcG complex variants, and how their epigenetic activities are involved in mammalian development and cancer.
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Affiliation(s)
- Andrea Piunti
- Simpson Querrey Institute for Epigenetics, Northwestern University Feinberg School of Medicine, Chicago, IL, USA.,Department of Biochemistry and Molecular Genetics, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - Ali Shilatifard
- Simpson Querrey Institute for Epigenetics, Northwestern University Feinberg School of Medicine, Chicago, IL, USA. .,Department of Biochemistry and Molecular Genetics, Northwestern University Feinberg School of Medicine, Chicago, IL, USA.
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120
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Kyrchanova O, Georgiev P. Mechanisms of Enhancer-Promoter Interactions in Higher Eukaryotes. Int J Mol Sci 2021; 22:ijms22020671. [PMID: 33445415 PMCID: PMC7828040 DOI: 10.3390/ijms22020671] [Citation(s) in RCA: 40] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Revised: 12/28/2020] [Accepted: 01/09/2021] [Indexed: 12/13/2022] Open
Abstract
In higher eukaryotes, enhancers determine the activation of developmental gene transcription in specific cell types and stages of embryogenesis. Enhancers transform the signals produced by various transcription factors within a given cell, activating the transcription of the targeted genes. Often, developmental genes can be associated with dozens of enhancers, some of which are located at large distances from the promoters that they regulate. Currently, the mechanisms underlying specific distance interactions between enhancers and promoters remain poorly understood. This review briefly describes the properties of enhancers and discusses the mechanisms of distance interactions and potential proteins involved in this process.
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