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Campbell AE, Oliva J, Yates MP, Zhong JW, Shadle SC, Snider L, Singh N, Tai S, Hiramuki Y, Tawil R, van der Maarel SM, Tapscott SJ, Sverdrup FM. BET bromodomain inhibitors and agonists of the beta-2 adrenergic receptor identified in screens for compounds that inhibit DUX4 expression in FSHD muscle cells. Skelet Muscle 2017; 7:16. [PMID: 28870238 PMCID: PMC5584331 DOI: 10.1186/s13395-017-0134-x] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2017] [Accepted: 08/14/2017] [Indexed: 11/24/2022] Open
Abstract
Background Facioscapulohumeral dystrophy (FSHD) is a progressive muscle disease caused by mutations that lead to epigenetic derepression and inappropriate transcription of the double homeobox 4 (DUX4) gene in skeletal muscle. Drugs that enhance the repression of DUX4 and prevent its expression in skeletal muscle cells therefore represent candidate therapies for FSHD. Methods We screened an aggregated chemical library enriched for compounds with epigenetic activities and the Pharmakon 1600 library composed of compounds that have reached clinical testing to identify molecules that decrease DUX4 expression as monitored by the levels of DUX4 target genes in FSHD patient-derived skeletal muscle cell cultures. Results Our screens identified several classes of molecules that include inhibitors of the bromodomain and extra-terminal (BET) family of proteins and agonists of the beta-2 adrenergic receptor. Further studies showed that compounds from these two classes suppress the expression of DUX4 messenger RNA (mRNA) by blocking the activity of bromodomain-containing protein 4 (BRD4) or by increasing cyclic adenosine monophosphate (cAMP) levels, respectively. Conclusions These data uncover pathways involved in the regulation of DUX4 expression in somatic cells, provide potential candidate classes of compounds for FSHD therapeutic development, and create an important opportunity for mechanistic studies that may uncover additional therapeutic targets. Electronic supplementary material The online version of this article (doi:10.1186/s13395-017-0134-x) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Amy E Campbell
- Human Biology Division, Fred Hutchinson Cancer Research Center, Seattle, WA, 98109, USA
| | - Jonathan Oliva
- Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University, Saint Louis, MO, 63104, USA
| | - Matthew P Yates
- Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University, Saint Louis, MO, 63104, USA
| | - Jun Wen Zhong
- Human Biology Division, Fred Hutchinson Cancer Research Center, Seattle, WA, 98109, USA
| | - Sean C Shadle
- Human Biology Division, Fred Hutchinson Cancer Research Center, Seattle, WA, 98109, USA.,Molecular and Cellular Biology Program, University of Washington, Seattle, WA, 98105, USA
| | - Lauren Snider
- Human Biology Division, Fred Hutchinson Cancer Research Center, Seattle, WA, 98109, USA
| | - Nikita Singh
- Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University, Saint Louis, MO, 63104, USA
| | - Shannon Tai
- Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University, Saint Louis, MO, 63104, USA
| | - Yosuke Hiramuki
- Human Biology Division, Fred Hutchinson Cancer Research Center, Seattle, WA, 98109, USA
| | - Rabi Tawil
- Department of Neurology, University of Rochester Medical Center, Rochester, NY, 14642, USA
| | - Silvère M van der Maarel
- Department of Human Genetics, Leiden University Medical Center, 2333 ZA, Leiden, The Netherlands
| | - Stephen J Tapscott
- Human Biology Division, Fred Hutchinson Cancer Research Center, Seattle, WA, 98109, USA. .,Department of Neurology, University of Washington, Seattle, WA, 98105, USA.
| | - Francis M Sverdrup
- Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University, Saint Louis, MO, 63104, USA.
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Haynes P, Kernan K, Zhou SL, Miller DG. Expression patterns of FSHD-causing DUX4 and myogenic transcription factors PAX3 and PAX7 are spatially distinct in differentiating human stem cell cultures. Skelet Muscle 2017. [PMID: 28637492 PMCID: PMC5480156 DOI: 10.1186/s13395-017-0130-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Background Facioscapulohumeral muscular dystrophy (FSHD) is most commonly inherited in an autosomal dominant pattern and caused by the abnormal expression of DUX4 in skeletal muscle. The DUX4 transcription factor has DNA binding domains similar to several paired class homeotic transcription factors, but only myogenic factors PAX3 and PAX7 rescue cell viability when co-expressed with DUX4 in mouse myoblasts. This observation suggests competition for DNA binding sites in satellite cells might limit muscle repair and may be one aspect of DUX4-associated myotoxicity. The competition hypothesis requires that DUX4 and PAX3/7 be expressed in the same cells at some point during development or in adult tissues. We modeled myogenesis using human isogenic iPS and ES cells and examined expression patterns of DUX4, PAX3, and PAX7 to determine if conditions that promote PAX3 and PAX7 expression in cell culture also promote DUX4 expression in the same cells. Methods Isogenic iPSCs were generated from human fibroblasts of two FSHD-affected individuals with somatic mosaicism. Clones containing the shortened FSHD-causing D4Z4 array or the long non-pathogenic array were isolated from the same individuals. We also examined myogenesis in commercially available hES cell lines derived from FSHD-affected and non-affected embryos. DUX4, PAX3, and PAX7 messenger RNAs (mRNAs) were quantified during a 40-day differentiation protocol, and antibodies were used to identify cell types in different stages of differentiation to determine if DUX4 and PAX3 or PAX7 are present in the same cells. Results Human iPS and ES cells differentiated into skeletal myocytes as evidenced by Titin positive multinucleated fibers appearing toward the end of a 40-day differentiation protocol. PAX3 and PAX7 were expressed at similar times during differentiation, and DUX4 positive nuclei were seen at terminal stages of differentiation in cells containing the short D4Z4 arrays. Nuclei that expressed both DUX4 and PAX3, or DUX4 and PAX7 were not observed after examining immunostained nuclei at five different time points during myogenic differentiation of pluripotent cells. Conclusions We conclude that DUX4, PAX3, and PAX7 have distinct expression patterns during myogenic differentiation of stem cells. Our findings are consistent with the hypothesis that muscle damage in FSHD is due to DUX4-mediated toxicity causing destruction of terminally differentiated myofibers. While these studies examine DUX4, PAX3, and PAX7 expression patterns during stem cell myogenesis, they should not be generalized to tissue repair in adult muscle tissue. Electronic supplementary material The online version of this article (doi:10.1186/s13395-017-0130-1) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Premi Haynes
- Division of Genetic Medicine, Department of Pediatrics, University of Washington, Campus Box 358056, 850 Republican Street, Room N416, Seattle, WA, 98109, USA
| | - Kelly Kernan
- Division of Genetic Medicine, Department of Pediatrics, University of Washington, Campus Box 358056, 850 Republican Street, Room N416, Seattle, WA, 98109, USA
| | - Suk-Lin Zhou
- Division of Genetic Medicine, Department of Pediatrics, University of Washington, Campus Box 358056, 850 Republican Street, Room N416, Seattle, WA, 98109, USA
| | - Daniel G Miller
- Division of Genetic Medicine, Department of Pediatrics, University of Washington, Campus Box 358056, 850 Republican Street, Room N416, Seattle, WA, 98109, USA.
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DUX4-induced dsRNA and MYC mRNA stabilization activate apoptotic pathways in human cell models of facioscapulohumeral dystrophy. PLoS Genet 2017; 13:e1006658. [PMID: 28273136 PMCID: PMC5362247 DOI: 10.1371/journal.pgen.1006658] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2016] [Revised: 03/22/2017] [Accepted: 02/26/2017] [Indexed: 12/19/2022] Open
Abstract
Facioscapulohumeral dystrophy (FSHD) is caused by the mis-expression of DUX4 in skeletal muscle cells. DUX4 is a transcription factor that activates genes normally associated with stem cell biology and its mis-expression in FSHD cells results in apoptosis. To identify genes and pathways necessary for DUX4-mediated apoptosis, we performed an siRNA screen in an RD rhabdomyosarcoma cell line with an inducible DUX4 transgene. Our screen identified components of the MYC-mediated apoptotic pathway and the double-stranded RNA (dsRNA) innate immune response pathway as mediators of DUX4-induced apoptosis. Further investigation revealed that DUX4 expression led to increased MYC mRNA, accumulation of nuclear dsRNA foci, and activation of the dsRNA response pathway in both RD cells and human myoblasts. Nuclear dsRNA foci were associated with aggregation of the exon junction complex component EIF4A3. The elevation of MYC mRNA, dsRNA accumulation, and EIF4A3 nuclear aggregates in FSHD muscle cells suggest that these processes might contribute to FSHD pathophysiology. Facioscapulohumeral dystrophy (FSHD) is a common form of muscular dystrophy which is currently untreatable. It is caused by the inappropriate expression in skeletal muscle of the gene DUX4 that encodes a transcription factor normally expressed in some stem cells. When DUX4 is expressed in cultured human or mouse skeletal muscle cells, it activates a program of cell death. Knowing the molecular basis for the cell death induced by DUX4 is important to determine the mechanism of muscle damage in FSHD. We used a molecular screening approach to identify genes and pathways necessary for DUX4 to induce the cell death program. We found that DUX4 activated a known MYC-induced cell death pathway, at least in part through stabilization of MYC mRNA. We also found that DUX4 expression led to an accumulation of double stranded RNAs (dsRNAs) that induced a cell death pathway evolved to protect against viral infections. This dsRNA accumulation was accompanied by aggregation of the EIF4A3 protein, a factor involved in mRNA surveillance and decay, which may provide a partial mechanism for how DUX4 can inhibit RNA quality control pathways in cells. Because FSHD muscle cells have increased MYC mRNA, dsRNA accumulation, and EIF4A3 nuclear aggregates, we conclude that these processes might contribute to FSHD pathophysiology.
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Casa V, Runfola V, Micheloni S, Aziz A, Dilworth FJ, Gabellini D. Polycomb repressive complex 1 provides a molecular explanation for repeat copy number dependency in FSHD muscular dystrophy. Hum Mol Genet 2017; 26:753-767. [PMID: 28040729 PMCID: PMC5409123 DOI: 10.1093/hmg/ddw426] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2016] [Accepted: 12/15/2016] [Indexed: 11/13/2022] Open
Abstract
Repression of repetitive elements is crucial to preserve genome integrity and has been traditionally ascribed to constitutive heterochromatin pathways. FacioScapuloHumeral Muscular Dystrophy (FSHD), one of the most common myopathies, is characterized by a complex interplay of genetic and epigenetic events. The main FSHD form is linked to a reduced copy number of the D4Z4 macrosatellite repeat on 4q35, causing loss of silencing and aberrant expression of the D4Z4-embedded DUX4 gene leading to disease. By an unknown mechanism, D4Z4 copy-number correlates with FSHD phenotype. Here we show that the DUX4 proximal promoter (DUX4p) is sufficient to nucleate the enrichment of both constitutive and facultative heterochromatin components and to mediate a copy-number dependent gene silencing. We found that both the CpG/GC dense DNA content and the repetitive nature of DUX4p arrays are important for their repressive ability. We showed that DUX4p mediates a copy number-dependent Polycomb Repressive Complex 1 (PRC1) recruitment, which is responsible for the copy-number dependent gene repression. Overall, we directly link genetic and epigenetic defects in FSHD by proposing a novel molecular explanation for the copy number-dependency in FSHD pathogenesis, and offer insight into the molecular functions of repeats in chromatin regulation.
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Affiliation(s)
- Valentina Casa
- Gene Expression and Muscular Dystrophy Unit, Division of Regenerative Medicine, IRCCS San Raffaele Scientific Institute, Milan 20132, Italy.,Università Vita-Salute San Raffaele, Milan 20132, Italy
| | - Valeria Runfola
- Gene Expression and Muscular Dystrophy Unit, Division of Regenerative Medicine, IRCCS San Raffaele Scientific Institute, Milan 20132, Italy
| | - Stefano Micheloni
- Gene Expression and Muscular Dystrophy Unit, Division of Regenerative Medicine, IRCCS San Raffaele Scientific Institute, Milan 20132, Italy
| | - Arif Aziz
- The Sprott Center for Stem Cell Research, Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, ON K1Y 4E9, Canada
| | - F Jeffrey Dilworth
- The Sprott Center for Stem Cell Research, Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, ON K1Y 4E9, Canada
| | - Davide Gabellini
- Gene Expression and Muscular Dystrophy Unit, Division of Regenerative Medicine, IRCCS San Raffaele Scientific Institute, Milan 20132, Italy.,Dulbecco Telethon Institute, Milan 20132, Italy
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Castillo-Aguilera O, Depreux P, Halby L, Arimondo PB, Goossens L. DNA Methylation Targeting: The DNMT/HMT Crosstalk Challenge. Biomolecules 2017; 7:biom7010003. [PMID: 28067760 PMCID: PMC5372715 DOI: 10.3390/biom7010003] [Citation(s) in RCA: 84] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Revised: 12/08/2016] [Accepted: 12/12/2016] [Indexed: 12/22/2022] Open
Abstract
Chromatin can adopt a decondensed state linked to gene transcription (euchromatin) and a condensed state linked to transcriptional repression (heterochromatin). These states are controlled by epigenetic modulators that are active on either the DNA or the histones and are tightly associated to each other. Methylation of both DNA and histones is involved in either the activation or silencing of genes and their crosstalk. Since DNA/histone methylation patterns are altered in cancers, molecules that target these modifications are interesting therapeutic tools. We present herein a vast panel of DNA methyltransferase inhibitors classified according to their mechanism, as well as selected histone methyltransferase inhibitors sharing a common mode of action.
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Affiliation(s)
- Omar Castillo-Aguilera
- Univ. Lille, ICPAL, EA 7365-GRITA-Groupe de Recherche sur les formes Injectables et les Technologies Associées, 3 rue du Pr. Laguesse, F-59000 Lille, France.
| | - Patrick Depreux
- Univ. Lille, ICPAL, EA 7365-GRITA-Groupe de Recherche sur les formes Injectables et les Technologies Associées, 3 rue du Pr. Laguesse, F-59000 Lille, France.
| | - Ludovic Halby
- FRE3600 Epigenetic Targeting of Cancer, CNRS, 31035 Toulouse, France.
| | - Paola B Arimondo
- FRE3600 Epigenetic Targeting of Cancer, CNRS, 31035 Toulouse, France.
- Churchill College, Cambridge CB3 0DS, UK.
| | - Laurence Goossens
- Univ. Lille, ICPAL, EA 7365-GRITA-Groupe de Recherche sur les formes Injectables et les Technologies Associées, 3 rue du Pr. Laguesse, F-59000 Lille, France.
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