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Sun JH, Zhou L, Emerson DJ, Phyo SA, Titus KR, Gong W, Gilgenast TG, Beagan JA, Davidson BL, Tassone F, Phillips-Cremins JE. Disease-Associated Short Tandem Repeats Co-localize with Chromatin Domain Boundaries. Cell 2018; 175:224-238.e15. [PMID: 30173918 DOI: 10.1016/j.cell.2018.08.005] [Citation(s) in RCA: 124] [Impact Index Per Article: 20.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2018] [Revised: 06/11/2018] [Accepted: 08/02/2018] [Indexed: 01/15/2023]
Abstract
More than 25 inherited human disorders are caused by the unstable expansion of repetitive DNA sequences termed short tandem repeats (STRs). A fundamental unresolved question is why some STRs are susceptible to pathologic expansion, whereas thousands of repeat tracts across the human genome are relatively stable. Here, we discover that nearly all disease-associated STRs (daSTRs) are located at boundaries demarcating 3D chromatin domains. We identify a subset of boundaries with markedly higher CpG island density compared to the rest of the genome. daSTRs specifically localize to ultra-high-density CpG island boundaries, suggesting they might be hotspots for epigenetic misregulation or topological disruption linked to STR expansion. Fragile X syndrome patients exhibit severe boundary disruption in a manner that correlates with local loss of CTCF occupancy and the degree of FMR1 silencing. Our data uncover higher-order chromatin architecture as a new dimension in understanding repeat expansion disorders.
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Affiliation(s)
- James H Sun
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA 19104, USA; Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Linda Zhou
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA 19104, USA; Genomics and Computational Biology Program, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Daniel J Emerson
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Sai A Phyo
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA 19104, USA; Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Katelyn R Titus
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Wanfeng Gong
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Thomas G Gilgenast
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Jonathan A Beagan
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA 19104, USA; Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Beverly L Davidson
- The Raymond G. Perelman Center for Cellular and Molecular Therapeutics, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA; Department of Pathology and Laboratory Medicine, The University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Flora Tassone
- Biochemistry and Molecular Medicine, University of California-Davis, Sacramento, CA 95616, USA; MIND Institute, UC Davis, Sacramento, CA 95616, USA
| | - Jennifer E Phillips-Cremins
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA 19104, USA; Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; Department of Genetics, University of Pennsylvania, Philadelphia, PA 19104, USA.
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Abstract
Interleukin-8 (IL-8), originally discovered as the neutrophil chemoattractant and inducer of leukocyte-mediated inflammation, contributes to cancer progression through its induction of tumor cell proliferation, survival, and migration. IL-8 expression is increased in many types of advanced cancers, including ovarian cancer, and correlates with poor prognosis. Bortezomib (BZ) is the first FDA-approved proteasome inhibitor that has shown remarkable antitumor activity in multiple myeloma and other hematological malignancies. In solid tumors, including ovarian carcinoma, BZ has been less effective as a single agent; however, the mechanisms remain unknown. We have recently shown that in ovarian cancer cells, BZ greatly increases IL-8 expression, while expression of other NFκB-regulated cytokines, IL-6 and TNF, is unchanged. In this chapter, we describe a protocol that uses real-time qRT-PCR to quantitatively analyze mRNA levels of IL-8 and IL-6 in BZ-treated ovarian cancer cells. The protocol can be easily modified and used for analysis of other cytokines in different cell types.
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Affiliation(s)
- Bipradeb Singha
- Department of Biology, St. John's University, 8000 Utopia Parkway, Queens, NY, 11439, USA
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