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MacDonald KM, Khan S, Lin B, Hurren R, Schimmer AD, Kislinger T, Harding SM. The proteomic landscape of genotoxic stress-induced micronuclei. Mol Cell 2024; 84:1377-1391.e6. [PMID: 38423013 DOI: 10.1016/j.molcel.2024.02.001] [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] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2023] [Revised: 12/20/2023] [Accepted: 02/05/2024] [Indexed: 03/02/2024]
Abstract
Micronuclei (MN) are induced by various genotoxic stressors and amass nuclear- and cytoplasmic-resident proteins, priming the cell for MN-driven signaling cascades. Here, we measured the proteome of micronuclear, cytoplasmic, and nuclear fractions from human cells exposed to a panel of six genotoxins, comprehensively profiling their MN protein landscape. We find that MN assemble a proteome distinct from both surrounding cytoplasm and parental nuclei, depleted of spliceosome and DNA damage repair components while enriched for a subset of the replisome. We show that the depletion of splicing machinery within transcriptionally active MN contributes to intra-MN DNA damage, a known precursor to chromothripsis. The presence of transcription machinery in MN is stress-dependent, causing a contextual induction of MN DNA damage through spliceosome deficiency. This dataset represents a unique resource detailing the global proteome of MN, guiding mechanistic studies of MN generation and MN-associated outcomes of genotoxic stress.
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Affiliation(s)
- Kate M MacDonald
- Department of Medical Biophysics, University of Toronto, Toronto, ON M5G 1L7, Canada
| | - Shahbaz Khan
- Princess Margaret Cancer Center, University Health Network, Toronto, ON M5G 2C4, Canada
| | - Brian Lin
- Department of Medical Biophysics, University of Toronto, Toronto, ON M5G 1L7, Canada
| | - Rose Hurren
- Princess Margaret Cancer Center, University Health Network, Toronto, ON M5G 2C4, Canada
| | - Aaron D Schimmer
- Department of Medical Biophysics, University of Toronto, Toronto, ON M5G 1L7, Canada; Princess Margaret Cancer Center, University Health Network, Toronto, ON M5G 2C4, Canada
| | - Thomas Kislinger
- Department of Medical Biophysics, University of Toronto, Toronto, ON M5G 1L7, Canada; Princess Margaret Cancer Center, University Health Network, Toronto, ON M5G 2C4, Canada
| | - Shane M Harding
- Department of Medical Biophysics, University of Toronto, Toronto, ON M5G 1L7, Canada; Princess Margaret Cancer Center, University Health Network, Toronto, ON M5G 2C4, Canada; Department of Radiation Oncology and Immunology, University of Toronto, Toronto, ON M5T 1P5, Canada.
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MacDonald KM, Nicholson-Puthenveedu S, Tageldein MM, Khasnis S, Arrowsmith CH, Harding SM. Antecedent chromatin organization determines cGAS recruitment to ruptured micronuclei. Nat Commun 2023; 14:556. [PMID: 36732527 PMCID: PMC9894866 DOI: 10.1038/s41467-023-36195-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Accepted: 01/17/2023] [Indexed: 02/04/2023] Open
Abstract
Micronuclei (MN) are cytosolic bodies that sequester acentric fragments or mis-segregated chromosomes from the primary nucleus. Spontaneous rupture of the MN envelope allows recognition by the viral receptor cyclic GMP-AMP synthase (cGAS), initiating interferon signaling downstream of DNA damage. Here, we demonstrate that MN rupture is permissive but not sufficient for cGAS localization. Chromatin characteristics such as histone 3, lysine 79 dimethylation (H3K79me2) are present in the nucleus before DNA damage, retained in ruptured MN, and regulate cGAS recruitment. cGAS is further responsive to dynamic intra-MN processes occurring prior to rupture, including transcription. MN chromatin tethering via the nucleosome acidic patch is necessary for cGAS-dependent interferon signaling. Our data suggest that both damage-antecedent nuclear chromatin status and MN-contained chromatin organizational changes dictate cGAS recruitment and the magnitude of the cGAS-driven interferon cascade. Our work defines MN as integrative signaling hubs for the cellular response to genotoxic stress.
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Affiliation(s)
- Kate M MacDonald
- Department of Medical Biophysics, University of Toronto, Toronto, ON, Canada
| | | | - Maha M Tageldein
- Department of Medical Biophysics, University of Toronto, Toronto, ON, Canada
| | - Sarika Khasnis
- Princess Margaret Cancer Center, University Health Network, Toronto, ON, Canada
| | - Cheryl H Arrowsmith
- Department of Medical Biophysics, University of Toronto, Toronto, ON, Canada
- Princess Margaret Cancer Center, University Health Network, Toronto, ON, Canada
- Structural Genomics Consortium, University of Toronto, Toronto, ON, Canada
| | - Shane M Harding
- Department of Medical Biophysics, University of Toronto, Toronto, ON, Canada.
- Princess Margaret Cancer Center, University Health Network, Toronto, ON, Canada.
- Departments of Radiation Oncology and Immunology, University of Toronto, Toronto, ON, Canada.
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MacDonald KM, Benguerfi S, Harding SM. Alerting the immune system to DNA damage: micronuclei as mediators. Essays Biochem 2020; 64:753-764. [PMID: 32844183 PMCID: PMC7588664 DOI: 10.1042/ebc20200016] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2020] [Revised: 08/01/2020] [Accepted: 08/13/2020] [Indexed: 12/18/2022]
Abstract
Healthy cells experience thousands of DNA lesions per day during normal cellular metabolism, and ionizing radiation and chemotherapeutic drugs rely on DNA damage to kill cancer cells. In response to such lesions, the DNA damage response (DDR) activates cell-cycle checkpoints, initiates DNA repair mechanisms, or promotes the clearance of irreparable cells. Work over the past decade has revealed broader influences of the DDR, involving inflammatory gene expression following unresolved DNA damage, and immune surveillance of damaged or mutated cells. Subcellular structures called micronuclei, containing broken fragments of DNA or whole chromosomes that have been isolated away from the rest of the genome, are now recognized as one mediator of DDR-associated immune recognition. Micronuclei can initiate pro-inflammatory signaling cascades, or massively degrade to invoke distinct forms of genomic instability. In this mini-review, we aim to provide an overview of the current evidence linking the DDR to activation of the immune response through micronuclei formation, identifying key areas of interest, open questions, and emerging implications.
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Affiliation(s)
- Kate M MacDonald
- Department of Medical Biophysics, University of Toronto, Toronto, ON, Canada
| | - Soraya Benguerfi
- Princess Margaret Cancer Center, University Health Network, Toronto, ON, Canada
| | - Shane M Harding
- Department of Medical Biophysics, University of Toronto, Toronto, ON, Canada
- Princess Margaret Cancer Center, University Health Network, Toronto, ON, Canada
- Department of Radiation Oncology and Immunology, University of Toronto, Toronto, ON, Canada
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Abstract
This study was undertaken to evaluate the relationship between maternal serum alpha-fetoprotein (MSAFP) levels and oesophageal atresia (OA). OA occurred in 16 fetuses of mothers who had an MSAFP test in the study interval. The multiple of the median (MOM) value for MSAFP averaged 1.54 +/- 0.65 (range 0.5-2.9 MOM), which was significantly higher than the value seen in controls. The median MOM was 1.35. Using a cut-off of 2.5 MOM, the sensitivity of MSAFP for detecting OA was 19 per cent. Although OA should be considered in the differential diagnosis of an elevated MSAFP level, MSAFP cannot be considered an appropriate screening test for OA given the low sensitivity.
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Affiliation(s)
- B N Chodirker
- Department of Human Genetics, University of Manitoba, Winnipeg, Canada
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Chodirker BN, Erdile LB, MacDonald KM, Harman CR, Cheang MS, Evans JA. MSAFP levels in aboriginal Canadian women. Can J Public Health 1994; 85:424-6. [PMID: 7534622] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Maternal serum alpha-fetoprotein (MSAFP) levels in 529 non-diabetic aboriginal Canadian women were compared with levels in 13,285 non-diabetic non-aboriginal women. A woman was considered to be aboriginal if she was listed on the Indian Register of Canada. After controlling for the gestational age on the date at which the sample was drawn and maternal weight, MSAFP levels appeared to be approximately 4 to 5% higher in aboriginal women. The possible implications of this finding on an MSAFP screening program are discussed.
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Affiliation(s)
- B N Chodirker
- Department of Human Genetics, University of Manitoba, Winnipeg
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Albar H, MacDonald KM, Harman CR, Evans JA, Chodirker BN. Elevated MSAFP levels and congenital heart defects: lack of an association. Am J Med Genet 1994; 49:337-40. [PMID: 7516120 DOI: 10.1002/ajmg.1320490319] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
This study was undertaken to evaluate the relationship between elevated maternal serum alpha fetoprotein (MSAFP) levels and congenital heart defects. Thirty-two infants with isolated major congenital heart defects and whose mothers had had MSAFP screening were identified. In only one case was the MSAFP greater than 2.3 multiples of the median. A review of our experience with women with elevated MSAFP levels did not document a higher rate of congenital heart malformations than would be expected based on estimated frequencies in the general population.
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Affiliation(s)
- H Albar
- Department of Human Genetics, University of Manitoba, Winnipeg, Canada
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