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Kong X, Nguyen NV, Li Y, Sakr JS, Williams K, Sharifi S, Chau J, Bayrakci A, Mizuno S, Takahashi S, Kiyono T, Tawil R, Mortazavi A, Yokomori K. Engineered FSHD mutations results in D4Z4 heterochromatin disruption and feedforward DUX4 network activation. iScience 2024; 27:109357. [PMID: 38510139 PMCID: PMC10951985 DOI: 10.1016/j.isci.2024.109357] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2023] [Revised: 09/20/2023] [Accepted: 02/23/2024] [Indexed: 03/22/2024] Open
Abstract
Facioscapulohumeral dystrophy (FSHD) is linked to contraction of D4Z4 repeats on chromosome 4q with SMCHD1 mutations acting as a disease modifier. D4Z4 heterochromatin disruption and abnormal upregulation of the transcription factor DUX4, encoded in the D4Z4 repeat, are the hallmarks of FSHD. However, defining the precise effect of D4Z4 contraction has been difficult because D4Z4 repeats are primate-specific and DUX4 expression is very rare in highly heterogeneous patient myocytes. We generated isogenic mutant cell lines harboring D4Z4 and/or SMCHD1 mutations in a healthy human skeletal myoblast line. We found that the mutations affect D4Z4 heterochromatin differently, and that SMCHD1 mutation or disruption of DNA methylation stabilizes otherwise variegated DUX4 target activation in D4Z4 contraction mutant cells, demonstrating the critical role of modifiers. Our study revealed amplification of the DUX4 signal through downstream targets, H3.X/Y and LEUTX. Our results provide important insights into how rare DUX4 expression leads to FSHD pathogenesis.
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Affiliation(s)
- Xiangduo Kong
- Department of Biological Chemistry, School of Medicine, University of California, Irvine, Irvine, CA, USA
| | - Nam Viet Nguyen
- Department of Biological Chemistry, School of Medicine, University of California, Irvine, Irvine, CA, USA
| | - Yumeng Li
- Department of Biological Chemistry, School of Medicine, University of California, Irvine, Irvine, CA, USA
| | - Jasmine Shaaban Sakr
- Department of Development and Cell Biology, School of Biological Sciences, University of California, Irvine, Irvine, CA, USA
| | - Kate Williams
- Department of Development and Cell Biology, School of Biological Sciences, University of California, Irvine, Irvine, CA, USA
| | - Sheila Sharifi
- Department of Biological Chemistry, School of Medicine, University of California, Irvine, Irvine, CA, USA
| | - Jonathan Chau
- Department of Biological Chemistry, School of Medicine, University of California, Irvine, Irvine, CA, USA
| | - Altay Bayrakci
- Department of Biological Chemistry, School of Medicine, University of California, Irvine, Irvine, CA, USA
| | - Seiya Mizuno
- Laboratory Animal Resource Center in Transborder Medical Research Center, University of Tsukuba, Tsukuba, Ibaraki, Japan
| | - Satoru Takahashi
- Laboratory Animal Resource Center in Transborder Medical Research Center, University of Tsukuba, Tsukuba, Ibaraki, Japan
- Department of Anatomy and Embryology, Faculty of Medicine, University of Tsukuba, Tsukuba, Ibaraki 305-8577, Japan
| | - Tohru Kiyono
- Exploratory Oncology Research and Clinical Trial Center, National Cancer Center, Kashiwa, Chiba, Japan
| | - Rabi Tawil
- Neuromuscular Disease Unit, Department of Neurology, University of Rochester Medical Center, Rochester, NY, USA
| | - Ali Mortazavi
- Department of Development and Cell Biology, School of Biological Sciences, University of California, Irvine, Irvine, CA, USA
| | - Kyoko Yokomori
- Department of Biological Chemistry, School of Medicine, University of California, Irvine, Irvine, CA, USA
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