1
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Mahlke MA, Lumerman L, Ly P, Nechemia-Arbely Y. Epigenetic centromere identity is precisely maintained through DNA replication but is uniquely specified among human cells. Life Sci Alliance 2023; 6:e202201807. [PMID: 36596606 PMCID: PMC9811134 DOI: 10.26508/lsa.202201807] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Revised: 12/21/2022] [Accepted: 12/22/2022] [Indexed: 01/05/2023] Open
Abstract
Centromere identity is defined and maintained epigenetically by the presence of the histone variant CENP-A. How centromeric CENP-A position is specified and precisely maintained through DNA replication is not fully understood. The recently released Telomere-to-Telomere (T2T) genome assembly containing the first complete human centromere sequences provides a new resource for examining CENP-A position. Mapping CENP-A position in clones of the same cell line to the T2T assembly identified highly similar CENP-A position after multiple cell divisions. In contrast, centromeric CENP-A epialleles were evident at several centromeres of different human cell lines, demonstrating the location of CENP-A enrichment and the site of kinetochore recruitment vary among human cells. Across the cell cycle, CENP-A molecules deposited in G1 phase are maintained in their precise position through DNA replication. Thus, despite CENP-A dilution during DNA replication, CENP-A is precisely reloaded onto the same sequences within the daughter centromeres, maintaining unique centromere identity among human cells.
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Affiliation(s)
- Megan A Mahlke
- UPMC Hillman Cancer Center, Pittsburgh, PA, USA
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Lior Lumerman
- UPMC Hillman Cancer Center, Pittsburgh, PA, USA
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Peter Ly
- Department of Pathology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Yael Nechemia-Arbely
- UPMC Hillman Cancer Center, Pittsburgh, PA, USA
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA, USA
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2
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Shoshani O, Brunner SF, Yaeger R, Ly P, Nechemia-Arbely Y, Kim DH, Fang R, Castillon GA, Yu M, Li JSZ, Sun Y, Ellisman MH, Ren B, Campbell PJ, Cleveland DW. Chromothripsis drives the evolution of gene amplification in cancer. Nature 2020; 591:137-141. [PMID: 33361815 PMCID: PMC7933129 DOI: 10.1038/s41586-020-03064-z] [Citation(s) in RCA: 182] [Impact Index Per Article: 45.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2018] [Accepted: 11/26/2020] [Indexed: 12/15/2022]
Abstract
Focal chromosomal amplification is an important route to generating cancer through mediating over-expression of oncogenes1–3 or to developing cancer therapy resistance by increasing expression of a gene whose action diminishes efficacy of an anti-cancer drug. Here we used whole-genome sequencing of clonal isolates developing chemotherapeutic resistance to identify chromothripsis as a major driver of extrachromosomal DNA (ecDNA) amplification into circular double minutes (DMs) through PARP- and DNA-PKcs-dependent mechanisms. Longitudinal analyses revealed that DMs undergo continuing structural evolution to promote increased drug tolerance through additional chromothriptic events. In-situ Hi-C sequencing is used to demonstrate that DMs preferentially tether near chromosome ends where they re-integrate when DNA damage is present. Intrachromosomal amplifications formed initially under low-level drug selection undergo continuing breakage-fusion-bridge cycles, generating >100 megabase-long amplicons that we show become trapped within interphase bridges and then shattered, producing micronuclei that mediate DM formation. Similar genome rearrangement profiles linked to localized gene amplification are identified in human cancers with acquired drug resistance or with oncogene amplifications. We propose that chromothripsis is a primary mechanism accelerating genomic DNA amplification and which enables rapid acquisition of tolerance to altered growth conditions.
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Affiliation(s)
- Ofer Shoshani
- Ludwig Cancer Research, University of California at San Diego, La Jolla, CA, USA.,Department of Cellular and Molecular Medicine, University of California at San Diego, La Jolla, CA, USA
| | | | - Rona Yaeger
- Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Peter Ly
- Ludwig Cancer Research, University of California at San Diego, La Jolla, CA, USA.,Department of Cellular and Molecular Medicine, University of California at San Diego, La Jolla, CA, USA.,Department of Pathology, University of Texas Southwestern Medical Center, Dallas, TX, USA.,Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Yael Nechemia-Arbely
- Ludwig Cancer Research, University of California at San Diego, La Jolla, CA, USA.,Department of Cellular and Molecular Medicine, University of California at San Diego, La Jolla, CA, USA.,Hillman Cancer Center, University of Pittsburgh, Pittsburgh, PA, USA.,Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Dong Hyun Kim
- Ludwig Cancer Research, University of California at San Diego, La Jolla, CA, USA.,Department of Cellular and Molecular Medicine, University of California at San Diego, La Jolla, CA, USA
| | - Rongxin Fang
- Ludwig Cancer Research, University of California at San Diego, La Jolla, CA, USA.,Department of Cellular and Molecular Medicine, University of California at San Diego, La Jolla, CA, USA
| | - Guillaume A Castillon
- National Center for Microscopy and Imaging Research (NCMIR), University of California at San Diego, La Jolla, CA, USA
| | - Miao Yu
- Ludwig Cancer Research, University of California at San Diego, La Jolla, CA, USA.,Department of Cellular and Molecular Medicine, University of California at San Diego, La Jolla, CA, USA
| | - Julia S Z Li
- Ludwig Cancer Research, University of California at San Diego, La Jolla, CA, USA.,Department of Cellular and Molecular Medicine, University of California at San Diego, La Jolla, CA, USA
| | - Ying Sun
- Department of Pediatrics, University of California at San Diego, La Jolla, CA, USA
| | - Mark H Ellisman
- National Center for Microscopy and Imaging Research (NCMIR), University of California at San Diego, La Jolla, CA, USA.,Department of Neurosciences, University of California at San Diego, La Jolla, CA, USA.,Department of Bioengineering, University of California at San Diego, La Jolla, CA, USA
| | - Bing Ren
- Ludwig Cancer Research, University of California at San Diego, La Jolla, CA, USA.,Department of Cellular and Molecular Medicine, University of California at San Diego, La Jolla, CA, USA
| | - Peter J Campbell
- Wellcome Sanger Institute, Hinxton, UK. .,Department of Haematology, University of Cambridge, Cambridge, UK.
| | - Don W Cleveland
- Ludwig Cancer Research, University of California at San Diego, La Jolla, CA, USA. .,Department of Cellular and Molecular Medicine, University of California at San Diego, La Jolla, CA, USA.
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3
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Mahlke MA, Nechemia-Arbely Y. Guarding the Genome: CENP-A-Chromatin in Health and Cancer. Genes (Basel) 2020; 11:genes11070810. [PMID: 32708729 PMCID: PMC7397030 DOI: 10.3390/genes11070810] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [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: 06/19/2020] [Revised: 07/10/2020] [Accepted: 07/15/2020] [Indexed: 02/07/2023] Open
Abstract
Faithful chromosome segregation is essential for the maintenance of genomic integrity and requires functional centromeres. Centromeres are epigenetically defined by the histone H3 variant, centromere protein A (CENP-A). Here we highlight current knowledge regarding CENP-A-containing chromatin structure, specification of centromere identity, regulation of CENP-A deposition and possible contribution to cancer formation and/or progression. CENP-A overexpression is common among many cancers and predicts poor prognosis. Overexpression of CENP-A increases rates of CENP-A deposition ectopically at sites of high histone turnover, occluding CCCTC-binding factor (CTCF) binding. Ectopic CENP-A deposition leads to mitotic defects, centromere dysfunction and chromosomal instability (CIN), a hallmark of cancer. CENP-A overexpression is often accompanied by overexpression of its chaperone Holliday Junction Recognition Protein (HJURP), leading to epigenetic addiction in which increased levels of HJURP and CENP-A become necessary to support rapidly dividing p53 deficient cancer cells. Alterations in CENP-A posttranslational modifications are also linked to chromosome segregation errors and CIN. Collectively, CENP-A is pivotal to genomic stability through centromere maintenance, perturbation of which can lead to tumorigenesis.
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Affiliation(s)
- Megan A. Mahlke
- UPMC Hillman Cancer Center, Pittsburgh, PA 15213, USA;
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | - Yael Nechemia-Arbely
- UPMC Hillman Cancer Center, Pittsburgh, PA 15213, USA;
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA 15261, USA
- Correspondence: ; Tel.: +1-412-623-3228; Fax: +1-412-623-7828
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4
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Barra V, Logsdon GA, Scelfo A, Hoffmann S, Hervé S, Aslanian A, Nechemia-Arbely Y, Cleveland DW, Black BE, Fachinetti D. Phosphorylation of CENP-A on serine 7 does not control centromere function. Nat Commun 2019; 10:175. [PMID: 30635586 PMCID: PMC6329807 DOI: 10.1038/s41467-018-08073-1] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Accepted: 12/12/2018] [Indexed: 01/16/2023] Open
Abstract
CENP-A is the histone H3 variant necessary to specify the location of all eukaryotic centromeres via its CENP-A targeting domain and either one of its terminal regions. In humans, several post-translational modifications occur on CENP-A, but their role in centromere function remains controversial. One of these modifications of CENP-A, phosphorylation on serine 7, has been proposed to control centromere assembly and function. Here, using gene targeting at both endogenous CENP-A alleles and gene replacement in human cells, we demonstrate that a CENP-A variant that cannot be phosphorylated at serine 7 maintains correct CENP-C recruitment, faithful chromosome segregation and long-term cell viability. Thus, we conclude that phosphorylation of CENP-A on serine 7 is dispensable to maintain correct centromere dynamics and function.
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Affiliation(s)
- Viviana Barra
- Institut Curie, PSL Research University, CNRS, UMR 144, 26 rue d'Ulm, 75005, Paris, France.,Department of Genetic Stability and Oncogenesis, Institut Gustave Roussy, CNRS UMR8200, 94805, Villejuif, France
| | - Glennis A Logsdon
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA.,Graduate Program in Biochemistry and Molecular Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA.,Department of Genome Sciences, University of Washington School of Medicine, Seattle, WA, 98195, USA
| | - Andrea Scelfo
- Institut Curie, PSL Research University, CNRS, UMR 144, 26 rue d'Ulm, 75005, Paris, France
| | - Sebastian Hoffmann
- Institut Curie, PSL Research University, CNRS, UMR 144, 26 rue d'Ulm, 75005, Paris, France
| | - Solène Hervé
- Institut Curie, PSL Research University, CNRS, UMR 144, 26 rue d'Ulm, 75005, Paris, France
| | - Aaron Aslanian
- Department of Chemical Physiology, The Scripps Research Institute, La Jolla, CA, 92037, USA
| | - Yael Nechemia-Arbely
- Ludwig Institute for Cancer Research and Department of Cellular and Molecular Medicine, University of California at San Diego, La Jolla, CA, 92093, USA.,Department of Pharmacology and Chemical Biology, University of Pittsburgh Cancer Institute, School of Medicine, University of Pittsburgh, Pittsburgh, PA, 15213, USA
| | - Don W Cleveland
- Ludwig Institute for Cancer Research and Department of Cellular and Molecular Medicine, University of California at San Diego, La Jolla, CA, 92093, USA
| | - Ben E Black
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA.,Graduate Program in Biochemistry and Molecular Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Daniele Fachinetti
- Institut Curie, PSL Research University, CNRS, UMR 144, 26 rue d'Ulm, 75005, Paris, France.
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5
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Hoffmann S, Dumont M, Barra V, Ly P, Nechemia-Arbely Y, McMahon MA, Hervé S, Cleveland DW, Fachinetti D. CENP-A Is Dispensable for Mitotic Centromere Function after Initial Centromere/Kinetochore Assembly. Cell Rep 2017; 17:2394-2404. [PMID: 27880912 DOI: 10.1016/j.celrep.2016.10.084] [Citation(s) in RCA: 70] [Impact Index Per Article: 10.0] [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: 05/05/2016] [Revised: 09/22/2016] [Accepted: 10/25/2016] [Indexed: 12/19/2022] Open
Abstract
Human centromeres are defined by chromatin containing the histone H3 variant CENP-A assembled onto repetitive alphoid DNA sequences. By inducing rapid, complete degradation of endogenous CENP-A, we now demonstrate that once the first steps of centromere assembly have been completed in G1/S, continued CENP-A binding is not required for maintaining kinetochore attachment to centromeres or for centromere function in the next mitosis. Degradation of CENP-A prior to kinetochore assembly is found to block deposition of CENP-C and CENP-N, but not CENP-T, thereby producing defective kinetochores and failure of chromosome segregation. Without the continuing presence of CENP-A, CENP-B binding to alphoid DNA sequences becomes essential to preserve anchoring of CENP-C and the kinetochore to each centromere. Thus, there is a reciprocal interdependency of CENP-A chromatin and the underlying repetitive centromere DNA sequences bound by CENP-B in the maintenance of human chromosome segregation.
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Affiliation(s)
- Sebastian Hoffmann
- Institut Curie, PSL Research University, CNRS, UMR 144, 26 rue d'Ulm, F-75005, Paris, France
| | - Marie Dumont
- Institut Curie, PSL Research University, CNRS, UMR 144, 26 rue d'Ulm, F-75005, Paris, France
| | - Viviana Barra
- Institut Curie, PSL Research University, CNRS, UMR 144, 26 rue d'Ulm, F-75005, Paris, France
| | - Peter Ly
- Ludwig Institute for Cancer Research, University of California at San Diego, La Jolla, CA 92093, USA; Department of Cellular and Molecular Medicine, University of California at San Diego, La Jolla, CA 92093, USA
| | - Yael Nechemia-Arbely
- Ludwig Institute for Cancer Research, University of California at San Diego, La Jolla, CA 92093, USA; Department of Cellular and Molecular Medicine, University of California at San Diego, La Jolla, CA 92093, USA
| | - Moira A McMahon
- Ludwig Institute for Cancer Research, University of California at San Diego, La Jolla, CA 92093, USA; Department of Cellular and Molecular Medicine, University of California at San Diego, La Jolla, CA 92093, USA
| | - Solène Hervé
- Institut Curie, PSL Research University, CNRS, UMR 144, 26 rue d'Ulm, F-75005, Paris, France
| | - Don W Cleveland
- Ludwig Institute for Cancer Research, University of California at San Diego, La Jolla, CA 92093, USA; Department of Cellular and Molecular Medicine, University of California at San Diego, La Jolla, CA 92093, USA.
| | - Daniele Fachinetti
- Institut Curie, PSL Research University, CNRS, UMR 144, 26 rue d'Ulm, F-75005, Paris, France.
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6
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Lanton T, Shriki A, Nechemia-Arbely Y, Abramovitch R, Levkovitch O, Adar R, Rosenberg N, Paldor M, Goldenberg D, Sonnenblick A, Peled A, Rose-John S, Galun E, Axelrod JH. Interleukin 6-dependent genomic instability heralds accelerated carcinogenesis following liver regeneration on a background of chronic hepatitis. Hepatology 2017; 65:1600-1611. [PMID: 28027584 DOI: 10.1002/hep.29004] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/12/2016] [Revised: 11/23/2016] [Accepted: 12/11/2016] [Indexed: 01/05/2023]
Abstract
UNLABELLED Liver cancer, which typically develops on a background of chronic liver inflammation, is now the second leading cause of cancer mortality worldwide. For patients with liver cancer, surgical resection is a principal treatment modality that offers a chance of prolonged survival. However, tumor recurrence after resection, the mechanisms of which remain obscure, markedly limits the long-term survival of these patients. We have shown that partial hepatectomy in multidrug resistance 2 knockout (Mdr2-/- ) mice, a model of chronic inflammation-associated liver cancer, significantly accelerates hepatocarcinogenesis. Here, we explore the postsurgical mechanisms that drive accelerated hepatocarcinogenesis in Mdr2-/- mice by perioperative pharmacological inhibition of interleukin-6 (IL6), which is a crucial liver regeneration priming cytokine. We demonstrate that inhibition of IL6 signaling dramatically impedes tumorigenesis following partial hepatectomy without compromising survival or liver mass recovery. IL6 blockade significantly inhibited hepatocyte cell cycle progression while promoting a hypertrophic regenerative response, without increasing apoptosis. Mdr2-/- mice contain hepatocytes with a notable persistent DNA damage response (γH2AX, 53BP1) due to chronic inflammation. We show that liver regeneration in this microenvironment leads to a striking increase in hepatocytes bearing micronuclei, a marker of genomic instability, which is suppressed by IL6 blockade. CONCLUSION Our findings indicate that genomic instability derived during the IL6-mediated liver regenerative response within a milieu of chronic inflammation links partial hepatectomy to accelerated hepatocarcinogenesis; this suggests a new therapeutic approach through the usage of an anti-IL6 treatment to extend the tumor-free survival of patients undergoing surgical resection. (Hepatology 2017;65:1600-1611).
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Affiliation(s)
| | | | | | - Rinat Abramovitch
- Goldyne Savad Institute of Gene Therapy.,Magnetic Resonance Imaging/Magnetic Resonance Spectroscopy Laboratory, Human Biology Research Center
| | | | | | | | | | | | - Amir Sonnenblick
- Sharett Institute of Oncology, Hadassah Medical Center, Jerusalem, Israel
| | | | - Stefan Rose-John
- Institut für Biochemie, Christian-Albrechts-Universität zu Kiel, Kiel, Germany
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7
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Nechemia-Arbely Y, Fachinetti D, Miga KH, Sekulic N, Soni GV, Kim DH, Wong AK, Lee AY, Nguyen K, Dekker C, Ren B, Black BE, Cleveland DW. Human centromeric CENP-A chromatin is a homotypic, octameric nucleosome at all cell cycle points. J Cell Biol 2017; 216:607-621. [PMID: 28235947 PMCID: PMC5350519 DOI: 10.1083/jcb.201608083] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2016] [Revised: 11/18/2016] [Accepted: 01/17/2017] [Indexed: 12/11/2022] Open
Abstract
In this study, the authors use new reference models for 23 human centromeres and find that at all cell cycle phases centromeric CENP-A chromatin complexes are octameric nucleosomes with two molecules of CENP-A. This finding refutes previous models that have suggested that hemisomes may briefly transition to octameric nucleosomes. Chromatin assembled with centromere protein A (CENP-A) is the epigenetic mark of centromere identity. Using new reference models, we now identify sites of CENP-A and histone H3.1 binding within the megabase, α-satellite repeat–containing centromeres of 23 human chromosomes. The overwhelming majority (97%) of α-satellite DNA is found to be assembled with histone H3.1–containing nucleosomes with wrapped DNA termini. In both G1 and G2 cell cycle phases, the 2–4% of α-satellite assembled with CENP-A protects DNA lengths centered on 133 bp, consistent with octameric nucleosomes with DNA unwrapping at entry and exit. CENP-A chromatin is shown to contain equimolar amounts of CENP-A and histones H2A, H2B, and H4, with no H3. Solid-state nanopore analyses show it to be nucleosomal in size. Thus, in contrast to models for hemisomes that briefly transition to octameric nucleosomes at specific cell cycle points or heterotypic nucleosomes containing both CENP-A and histone H3, human CENP-A chromatin complexes are octameric nucleosomes with two molecules of CENP-A at all cell cycle phases.
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Affiliation(s)
- Yael Nechemia-Arbely
- Ludwig Institute for Cancer Research and Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093
| | - Daniele Fachinetti
- Ludwig Institute for Cancer Research and Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093
| | - Karen H Miga
- Center for Biomolecular Science and Engineering, University of California, Santa Cruz, Santa Cruz, CA 95064
| | - Nikolina Sekulic
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104
| | - Gautam V Soni
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, 2628 CJ Delft, Netherlands
| | - Dong Hyun Kim
- Ludwig Institute for Cancer Research and Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093
| | - Adeline K Wong
- Ludwig Institute for Cancer Research and Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093
| | - Ah Young Lee
- Ludwig Institute for Cancer Research and Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093
| | - Kristen Nguyen
- Ludwig Institute for Cancer Research and Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093
| | - Cees Dekker
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, 2628 CJ Delft, Netherlands
| | - Bing Ren
- Ludwig Institute for Cancer Research and Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093
| | - Ben E Black
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104
| | - Don W Cleveland
- Ludwig Institute for Cancer Research and Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093
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8
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Nechemia-Arbely Y, Khamaisi M, Rosenberger C, Koesters R, Shina A, Geva C, Shriki A, Klaus S, Rosen S, Rose-John S, Galun E, Axelrod JH, Heyman SN. In vivo evidence suggesting reciprocal renal hypoxia-inducible factor-1 upregulation and signal transducer and activator of transcription 3 activation in response to hypoxic and non-hypoxic stimuli. Clin Exp Pharmacol Physiol 2015; 40:262-72. [PMID: 23384058 DOI: 10.1111/1440-1681.12064] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2012] [Accepted: 01/31/2013] [Indexed: 01/05/2023]
Abstract
In vitro studies suggest that combined activation of hypoxia-inducible factor (HIF) and signal transducer and activator of transcription 3 (STAT3) promotes the hypoxia response. However, their interrelationship in vivo remains poorly defined. The present study investigated the possible relationship between HIF-1 upregulation and STAT3 activation in the rodent kidney in vivo. Activation of HIF-1 and STAT3 was analysed by immunohistochemical staining and western blot analysis in: (i) models of hypoxia-associated kidney injury induced by radiocontrast media or rhabdomyolysis; (ii) following activation of STAT3 by the interleukin (IL)-6-soluble IL-6 receptor complex; or (iii) following HIF-1α stabilization using hypoxic and non-hypoxic stimuli (mimosine, FG-4497, CO, CoCl(2)) and in targeted von Hippel-Lindau-knockout mice. Western blot analysis and immunostaining revealed marked induction of both transcription factors under all conditions tested, suggesting that in vivo STAT3 can trigger HIF and vice versa. Colocalization of HIF-1α and phosphorylated STAT3 was detected in some, but not all, renal cell types, suggesting that in some cells a paracrine mechanism may be responsible for the reciprocal activation of the two transcription factors. Nevertheless, in several cell types spatial concordance was observed under the majority of conditions tested, suggesting that HIF-1 and STAT3 may act as cotranscription factors. These in vivo studies suggest that, in response to renal hypoxic-stress, upregulation of HIF-1 and activation of STAT3 may be both reciprocal and cell type dependent.
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Affiliation(s)
- Yael Nechemia-Arbely
- Goldyne Savad Institute of Gene Therapy, Hadassah Hebrew University Hospital, Jerusalem, Israel, Israel
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9
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Nechemia-Arbely Y, Fachinetti D, Cleveland DW. Replicating centromeric chromatin: spatial and temporal control of CENP-A assembly. Exp Cell Res 2012; 318:1353-60. [PMID: 22561213 DOI: 10.1016/j.yexcr.2012.04.007] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2012] [Revised: 04/17/2012] [Accepted: 04/19/2012] [Indexed: 11/17/2022]
Abstract
The centromere is the fundamental unit for insuring chromosome inheritance. This complex region has a distinct type of chromatin in which histone H3 is replaced by a structurally different homologue identified in humans as CENP-A. In metazoans, specific DNA sequences are neither required nor sufficient for centromere identity. Rather, an epigenetic mark comprised of CENP-A containing chromatin is thought to be the major determinant of centromere identity. In this view, CENP-A deposition and chromatin assembly are fundamental processes for the maintenance of centromeric identity across mitotic and meiotic divisions. Several lines of evidence support CENP-A deposition in metazoans occurring at only one time in the cell cycle. Such cell cycle-dependent loading of CENP-A is found in divergent species from human to fission yeast, albeit with differences in the cell cycle point at which CENP-A is assembled. Cell cycle dependent CENP-A deposition requires multiple assembly factors for its deposition and maintenance. This review discusses the regulation of new CENP-A deposition and its relevance to centromere identity and inheritance.
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Affiliation(s)
- Yael Nechemia-Arbely
- Ludwig Institute for Cancer Research, University of California, San Diego, La Jolla, CA 92093, USA
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10
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Nechemia-Arbely Y, Shriki A, Denz U, Drucker C, Scheller J, Raub J, Pappo O, Rose-John S, Galun E, Axelrod JH. Early hepatocyte DNA synthetic response posthepatectomy is modulated by IL-6 trans-signaling and PI3K/AKT activation. J Hepatol 2011; 54:922-9. [PMID: 21145830 DOI: 10.1016/j.jhep.2010.08.017] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/23/2009] [Revised: 07/05/2010] [Accepted: 08/03/2010] [Indexed: 12/26/2022]
Abstract
BACKGROUND & AIMS Interleukin-6 (IL-6) is a crucial factor in liver regeneration following partial hepatectomy (PH); however, the role of IL-6 and IL-6 trans-signaling in particular, in hepatocyte mitosis remains controversial. IL-6 trans-signaling relies upon the release of the soluble IL-6R (sIL-6R), which binds IL-6 to form an agonistic IL-6/sIL-6R complex. Herein we have examined the hypothesis that IL-6 trans-signaling plays a crucial and distinct role in liver regeneration following PH. METHODS The specific IL-6/sIL-6R antagonist, sgp130Fc, was expressed in mice and analyzed for its effect on hepatocyte mitosis following PH. Alternatively, we examined the effect of the IL-6/sIL-6R super-agonist, Hyper-IL-6, or IL-6 expressed either alone or in combination with hepatocyte growth factor (HGF) on hepatocyte mitosis in the absence of PH. RESULTS Following PH, the dramatic rise of circulating IL-6 levels is accompanied by a concurrent ∼2-fold increase in circulating sIL-6R levels. Ectopic expression of sgp130Fc reduced hepatocyte mitosis by about 40% at early times following PH, while substantially reducing AKT, but not STAT3, activation. But, ectopic Hyper-IL-6 expression in mice without PH was not mitogenic to hepatocytes in vivo. Rather, Hyper-IL-6, but not IL-6, markedly increased HGF-induced hepatocyte mitosis. This cooperative effect correlated with greater resistance of HIL-6 than IL-6 to HGF-mediated reduction of AKT activation, rather than changes in STAT3 or MAPK signaling, and was completely blocked by PI3K inhibition. CONCLUSIONS Following PH, IL-6/sIL-6R cooperates with growth factors, through a PI3K/AKT-dependent mechanism to promote entry of hepatocytes into the cell cycle.
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Affiliation(s)
- Yael Nechemia-Arbely
- The Goldyne Savad Institute of Gene Therapy, Hadassah University Hospital, Jerusalem, Israel
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Nechemia-Arbely Y, Barkan D, Pizov G, Shriki A, Rose-John S, Galun E, Axelrod JH. IL-6/IL-6R axis plays a critical role in acute kidney injury. J Am Soc Nephrol 2008; 19:1106-15. [PMID: 18337485 DOI: 10.1681/asn.2007070744] [Citation(s) in RCA: 258] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The response to tissue injury involves the coordination of inflammatory and repair processes. IL-6 expression correlates with the onset and severity of acute kidney injury (AKI), but its contribution to pathogenesis remains unclear. This study established a critical role for IL-6 in both the inflammatory response and the resolution of AKI. IL-6-deficient mice were resistant to HgCl2-induced AKI compared with wild-type mice. The accumulation of peritubular neutrophils was lower in IL-6-deficient mice than in wild-type mice, and neutrophil depletion before HgCl2 administration in wild-type mice significantly reduced AKI; these results demonstrate the critical role of IL-6 signaling in the injurious inflammatory process in AKI. Renal IL-6 expression and STAT3 activation in renal tubular epithelial cells significantly increased during the development of injury, suggesting active IL-6 signaling. Although a lack of renal IL-6 receptors (IL-6R) precludes the activation of classical signaling pathways, IL-6 can stimulate target cells together with a soluble form of the IL-6R (sIL-6R) in a process termed trans-signaling. During injury,serum sIL-6R levels increased three-fold, suggesting a possible role for IL-6 trans-signaling in AKI. Stimulation of IL-6 trans-signaling with an IL-6/sIL-6R fusion protein activated STAT3 in renal tubular epithelium and prevented AKI. IL-6/sIL-6R reduced lipid peroxidation after injury, suggesting that its protective effect may be largely mediated through amelioration of oxidative stress. In summary, IL-6 simultaneously promotes an injurious inflammatory response and, through a mechanism of trans-signaling, protects the kidney from further injury.
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