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DUX4 promotes transcription of FRG2 by directly activating its promoter in facioscapulohumeral muscular dystrophy
BACKGROUND: The most common form of facioscapulohumeral muscular dystrophy (FSHD) is caused by a genetic contraction of the polymorphic D4Z4 macrosatellite repeat array in the subtelomeric region of chromosome 4q. In some studies, genes centromeric to the D4Z4 repeat array have been reported to be o...
Autores principales: | , , , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
BioMed Central
2014
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4364343/ https://www.ncbi.nlm.nih.gov/pubmed/25789155 http://dx.doi.org/10.1186/2044-5040-4-19 |
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author | Thijssen, Peter E Balog, Judit Yao, Zizhen Pham, Tan Phát Tawil, Rabi Tapscott, Stephen J Van der Maarel, Silvère M |
author_facet | Thijssen, Peter E Balog, Judit Yao, Zizhen Pham, Tan Phát Tawil, Rabi Tapscott, Stephen J Van der Maarel, Silvère M |
author_sort | Thijssen, Peter E |
collection | PubMed |
description | BACKGROUND: The most common form of facioscapulohumeral muscular dystrophy (FSHD) is caused by a genetic contraction of the polymorphic D4Z4 macrosatellite repeat array in the subtelomeric region of chromosome 4q. In some studies, genes centromeric to the D4Z4 repeat array have been reported to be over-expressed in FSHD, including FRG1 and FRG2, presumably due to decreased long-distance repression by the shorter array through a mechanism similar to position-effect variegation. Differential regulation of FRG1 in FSHD has never been unequivocally proven, however, FRG2 has been reproducibly shown to be induced in primary FSHD-derived muscle cells when differentiated in vitro. The molecular function of FRG2 and a possible contribution to FSHD pathology remain unclear. Recent evidence has identified the mis-expression of DUX4, located within the D4Z4 repeat unit, in skeletal muscle as the cause of FSHD. DUX4 is a double homeobox transcription factor that has been shown to be toxic when expressed in muscle cells. METHODS: We used a combination of expression analysis by qRT/PCR and RNA sequencing to determine the transcriptional activation of FRG2 and DUX4. We examined this in both differentiating control and FSHD derived muscle cell cultures or DUX4 transduced control cell lines. Next, we used ChIP-seq analysis and luciferase reporter assays to determine the potential DUX4 transactivation effect on the FRG2 promoter. RESULTS: We show that DUX4 directly activates the expression of FRG2. Increased expression of FRG2 was observed following expression of DUX4 in myoblasts and fibroblasts derived from control individuals. Moreover, we identified DUX4 binding sites at the FRG2 promoter by chromatin immunoprecipitation followed by deep sequencing and confirmed the direct regulation of DUX4 on the FRG2 promoter by luciferase reporter assays. Activation of luciferase was dependent on both DUX4 expression and the presence of the DUX4 DNA binding motifs in the FRG2 promoter. CONCLUSION: We show that the FSHD-specific upregulation of FRG2 is a direct consequence of the activity of DUX4 protein rather than representing a regional de-repression secondary to fewer D4Z4 repeats. |
format | Online Article Text |
id | pubmed-4364343 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2014 |
publisher | BioMed Central |
record_format | MEDLINE/PubMed |
spelling | pubmed-43643432015-03-19 DUX4 promotes transcription of FRG2 by directly activating its promoter in facioscapulohumeral muscular dystrophy Thijssen, Peter E Balog, Judit Yao, Zizhen Pham, Tan Phát Tawil, Rabi Tapscott, Stephen J Van der Maarel, Silvère M Skelet Muscle Research BACKGROUND: The most common form of facioscapulohumeral muscular dystrophy (FSHD) is caused by a genetic contraction of the polymorphic D4Z4 macrosatellite repeat array in the subtelomeric region of chromosome 4q. In some studies, genes centromeric to the D4Z4 repeat array have been reported to be over-expressed in FSHD, including FRG1 and FRG2, presumably due to decreased long-distance repression by the shorter array through a mechanism similar to position-effect variegation. Differential regulation of FRG1 in FSHD has never been unequivocally proven, however, FRG2 has been reproducibly shown to be induced in primary FSHD-derived muscle cells when differentiated in vitro. The molecular function of FRG2 and a possible contribution to FSHD pathology remain unclear. Recent evidence has identified the mis-expression of DUX4, located within the D4Z4 repeat unit, in skeletal muscle as the cause of FSHD. DUX4 is a double homeobox transcription factor that has been shown to be toxic when expressed in muscle cells. METHODS: We used a combination of expression analysis by qRT/PCR and RNA sequencing to determine the transcriptional activation of FRG2 and DUX4. We examined this in both differentiating control and FSHD derived muscle cell cultures or DUX4 transduced control cell lines. Next, we used ChIP-seq analysis and luciferase reporter assays to determine the potential DUX4 transactivation effect on the FRG2 promoter. RESULTS: We show that DUX4 directly activates the expression of FRG2. Increased expression of FRG2 was observed following expression of DUX4 in myoblasts and fibroblasts derived from control individuals. Moreover, we identified DUX4 binding sites at the FRG2 promoter by chromatin immunoprecipitation followed by deep sequencing and confirmed the direct regulation of DUX4 on the FRG2 promoter by luciferase reporter assays. Activation of luciferase was dependent on both DUX4 expression and the presence of the DUX4 DNA binding motifs in the FRG2 promoter. CONCLUSION: We show that the FSHD-specific upregulation of FRG2 is a direct consequence of the activity of DUX4 protein rather than representing a regional de-repression secondary to fewer D4Z4 repeats. BioMed Central 2014-10-24 /pmc/articles/PMC4364343/ /pubmed/25789155 http://dx.doi.org/10.1186/2044-5040-4-19 Text en Copyright © 2014 Thijssen et al.; licensee BioMed Central Ltd. http://creativecommons.org/licenses/by/4.0 This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated. |
spellingShingle | Research Thijssen, Peter E Balog, Judit Yao, Zizhen Pham, Tan Phát Tawil, Rabi Tapscott, Stephen J Van der Maarel, Silvère M DUX4 promotes transcription of FRG2 by directly activating its promoter in facioscapulohumeral muscular dystrophy |
title | DUX4 promotes transcription of FRG2 by directly activating its promoter in facioscapulohumeral muscular dystrophy |
title_full | DUX4 promotes transcription of FRG2 by directly activating its promoter in facioscapulohumeral muscular dystrophy |
title_fullStr | DUX4 promotes transcription of FRG2 by directly activating its promoter in facioscapulohumeral muscular dystrophy |
title_full_unstemmed | DUX4 promotes transcription of FRG2 by directly activating its promoter in facioscapulohumeral muscular dystrophy |
title_short | DUX4 promotes transcription of FRG2 by directly activating its promoter in facioscapulohumeral muscular dystrophy |
title_sort | dux4 promotes transcription of frg2 by directly activating its promoter in facioscapulohumeral muscular dystrophy |
topic | Research |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4364343/ https://www.ncbi.nlm.nih.gov/pubmed/25789155 http://dx.doi.org/10.1186/2044-5040-4-19 |
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