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Sartsanga C, Phengchat R, Wako T, Fukui K, Ohmido N. Localization and quantitative distribution of a chromatin structural protein Topoisomerase II on plant chromosome using HVTEM and UHVTEM. Micron 2024; 179:103596. [PMID: 38359615 DOI: 10.1016/j.micron.2024.103596] [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: 08/28/2023] [Revised: 01/29/2024] [Accepted: 01/29/2024] [Indexed: 02/17/2024]
Abstract
Topoisomerase II (TopoII) is an essential structural protein of the metaphase chromosome. It maintains the axial compaction of chromosomes during metaphase. It is localized at the axial region of chromosomes and accumulates at the centromeric region in metaphase chromosomes. However, little is known about TopoII localization and distribution in plant chromosomes, except for several publications. We used high voltage transmission electron microscopy (HVTEM) and ultra-high voltage transmission electron microscopy (UHVTEM) in conjunction with immunogold labeling and visualization techniques to detect TopoII and investigate its localization, alignment, and density on the barley chromosome at 1.4 nm scale. We found that HVTEM and UHVTEM combined with immunogold labeling is suitable for the detection of structural proteins, including a single molecule of TopoII. This is because the average size of the gold particles for TopoII visualization after silver enhancement is 8.9 ± 3.9 nm, which is well detected. We found that 31,005 TopoII molecules are distributed along the barley chromosomes in an unspecific pattern at the chromosome arms and accumulate specifically at the nucleolus organizer regions (NORs) and centromeric region. The TopoII density were 1.32-fold, 1.58-fold, and 1.36-fold at the terminal region, at the NORs, and the centromeric region, respectively. The findings of TopoII localization in this study support the multiple reported functions of TopoII in the barley metaphase chromosome.
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Affiliation(s)
- Channarong Sartsanga
- Graduate School of Human Development and Environment, Kobe University, Tsurukabuto 3-11, Nada-ku, 657-8501, Kobe, Japan
| | - Rinyaporn Phengchat
- Nanotechnology Research Centre, National Research of Council, 11421 Saskatchewan Drive, T6G 2M9 Edmonton, Alberta, Canada
| | - Toshiyuki Wako
- Institute of Crop Sciences, National Agriculture and Food Research Organization, 2-1-1 Kannondai, Tsukuba, Ibaraki 305-8518, Japan
| | - Kiichi Fukui
- Graduate School of Pharmaceutical Sciences, Osaka University, Yamadaoka 1-6, Suita, Osaka 565-0871, Japan
| | - Nobuko Ohmido
- Graduate School of Human Development and Environment, Kobe University, Tsurukabuto 3-11, Nada-ku, 657-8501, Kobe, Japan.
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Lee S, Jun YW, Linares GR, Butler B, Yuva-Adyemir Y, Moore J, Krishnan G, Ruiz-Juarez B, Santana M, Pons M, Silverman N, Weng Z, Ichida JK, Gao FB. Downregulation of Hsp90 and the antimicrobial peptide Mtk suppresses poly(GR)-induced neurotoxicity in C9ORF72-ALS/FTD. Neuron 2023; 111:1381-1390.e6. [PMID: 36931278 PMCID: PMC10264157 DOI: 10.1016/j.neuron.2023.02.029] [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] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Revised: 01/22/2023] [Accepted: 02/16/2023] [Indexed: 03/18/2023]
Abstract
GGGGCC repeat expansion in the C9ORF72 gene is the most common genetic cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). Repeat RNAs can be translated into dipeptide repeat proteins, including poly(GR), whose mechanisms of action remain largely unknown. In an RNA-seq analysis of poly(GR) toxicity in Drosophila, we found that several antimicrobial peptide genes, such as metchnikowin (Mtk), and heat shock protein (Hsp) genes are activated. Mtk knockdown in the fly eye or in all neurons suppresses poly(GR) neurotoxicity. These findings suggest a cell-autonomous role of Mtk in neurodegeneration. Hsp90 knockdown partially rescues both poly(GR) toxicity in flies and neurodegeneration in C9ORF72 motor neurons derived from induced pluripotent stem cells (iPSCs). Topoisomerase II (TopoII) regulates poly(GR)-induced upregulation of Hsp90 and Mtk. TopoII knockdown also suppresses poly(GR) toxicity in Drosophila and improves survival of C9ORF72 iPSC-derived motor neurons. These results suggest potential novel therapeutic targets for C9ORF72-ALS/FTD.
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Affiliation(s)
- Soojin Lee
- Department of Neurology, UMass Chan Medical School, Worcester, MA 01605, USA
| | - Yong-Woo Jun
- Department of Neurology, UMass Chan Medical School, Worcester, MA 01605, USA
| | - Gabriel R Linares
- Department of Stem Cell Biology and Regenerative Medicine, Eli and Edythe Broad Center for Regenerative Medicine and Stem Cell Research, University of Southern California, Los Angeles, CA, USA
| | - Brandon Butler
- Department of Stem Cell Biology and Regenerative Medicine, Eli and Edythe Broad Center for Regenerative Medicine and Stem Cell Research, University of Southern California, Los Angeles, CA, USA
| | - Yeliz Yuva-Adyemir
- Department of Neurology, UMass Chan Medical School, Worcester, MA 01605, USA
| | - Jill Moore
- Program in Bioinformatics and Integrative Biology, UMass Chan Medical School, Worcester, MA 01605, USA
| | - Gopinath Krishnan
- Department of Neurology, UMass Chan Medical School, Worcester, MA 01605, USA
| | - Bryan Ruiz-Juarez
- Department of Stem Cell Biology and Regenerative Medicine, Eli and Edythe Broad Center for Regenerative Medicine and Stem Cell Research, University of Southern California, Los Angeles, CA, USA
| | - Manuel Santana
- Department of Stem Cell Biology and Regenerative Medicine, Eli and Edythe Broad Center for Regenerative Medicine and Stem Cell Research, University of Southern California, Los Angeles, CA, USA
| | - Marine Pons
- Department of Neurology, UMass Chan Medical School, Worcester, MA 01605, USA
| | - Neal Silverman
- Division of Infectious Diseases and Immunology, Department of Medicine, UMass Chan Medical School, Worcester, MA 01605, USA
| | - Zhiping Weng
- Program in Bioinformatics and Integrative Biology, UMass Chan Medical School, Worcester, MA 01605, USA
| | - Justin K Ichida
- Department of Stem Cell Biology and Regenerative Medicine, Eli and Edythe Broad Center for Regenerative Medicine and Stem Cell Research, University of Southern California, Los Angeles, CA, USA
| | - Fen-Biao Gao
- Department of Neurology, UMass Chan Medical School, Worcester, MA 01605, USA.
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d'Alcontres MS, Palacios JA, Mejias D, Blasco MA. TopoIIα prevents telomere fragility and formation of ultra thin DNA bridges during mitosis through TRF1-dependent binding to telomeres. Cell Cycle 2014; 13:1463-81. [PMID: 24626180 PMCID: PMC4050144 DOI: 10.4161/cc.28419] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Telomeres are repetitive nucleoprotein structures at the ends of chromosomes. Like most genomic regions consisting of repetitive DNA, telomeres are fragile sites prone to replication fork stalling and generation of chromosomal instability. In particular, abrogation of the TRF1 telomere binding protein leads to stalled replication forks and aberrant telomere structures known as “multitelomeric signals”. Here, we report that TRF1 deficiency also leads to the formation of “ultra-fine bridges” (UFB) during mitosis, and to an increased time to complete mitosis mediated by the spindle assembly checkpoint proteins (SAC). We find that topoisomerase IIα (TopoIIα), an enzyme essential for resolution of DNA replication intermediates, binds telomeres in a TRF1-mediated manner. Indeed, similar to TRF1 abrogation, TopoIIα downregulation leads to telomere fragility and UFB, suggesting that these phenotypes are due to decreased TopoIIα at telomeres. We find that SAC proteins bind telomeres in vivo, and that this is disrupted upon TRF1 deletion. These findings suggest that TRF1 links TopoIIα and SAC proteins in a pathway that ensures correct telomere replication and mitotic segregation, unveiling how TRF1 protects from telomere fragility and mitotic defects.
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Affiliation(s)
- Martina Stagno d'Alcontres
- Telomeres and Telomerase Group; Molecular Oncology Programme; Spanish National Cancer Research Centre (CNIO); Madrid, Spain
| | - Jose Alejandro Palacios
- Telomeres and Telomerase Group; Molecular Oncology Programme; Spanish National Cancer Research Centre (CNIO); Madrid, Spain
| | - Diego Mejias
- Confocal Microscopy Unit; Biotechnology Programme; Spanish National Cancer Research Centre (CNIO); Madrid, Spain
| | - Maria A Blasco
- Telomeres and Telomerase Group; Molecular Oncology Programme; Spanish National Cancer Research Centre (CNIO); Madrid, Spain
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