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  1. Article ; Online: An Update on Nucleolar Stress: The Transcriptional Control of Autophagy.

    Pfister, Astrid S

    Cells

    2023  Volume 12, Issue 16

    Abstract: Nucleolar stress reflects a misfunction of the nucleolus caused by a failure in ribosome biogenesis and defective nucleolar architecture. Various causes have been reported, most commonly mutation of ribosomal proteins and ribosome processing factors, as ... ...

    Abstract Nucleolar stress reflects a misfunction of the nucleolus caused by a failure in ribosome biogenesis and defective nucleolar architecture. Various causes have been reported, most commonly mutation of ribosomal proteins and ribosome processing factors, as well as interference with these processes by intracellular or ectopic stress, such as RNA polymerase I inhibition, ROS, UV and others. The nucleolus represents the place for ribosome biogenesis and serves as a crucial hub in the cellular stress response. It has been shown to stimulate multiple downstream consequences, interfering with cell growth and survival. Nucleolar stress induction is most classically known to stimulate p53-dependent cell cycle arrest and apoptosis. Nucleolar stress represents a friend and enemy at the same time: From a pathophysiological perspective, inactivation of the nucleolar function by mutation or stress conditions is connected to multiple diseases, such as neurodegeneration, cancer and ribosomopathy syndromes. However, triggering the nucleolar stress response via specific chemotherapeutics, which interfere with nucleolar function, has beneficial effects for anti-cancer therapy. Interestingly, since the nucleolar stress response also triggers p53-independent mechanisms, it possesses the potential to specifically target p53-mutated tumors, which reflects the most common aberration in human cancer. More recent data have shown that the nucleolar stress response can activate autophagy and diverse signaling cascades that might allow initial pro-survival mechanisms. Nevertheless, it depends on the situation whether the cells undergo autophagy-mediated apoptosis or survive, as seen for autophagy-dependent drug resistance of chemotherapy-exposed tumor cells. Given the relatively young age of the research field, precise mechanisms that underly the involvement of autophagy in nucleolar stress are still under investigation. This review gives an update on the emerging contribution of nucleolar stress in the regulation of autophagy at a transcriptional level. It also appears that in autophagy p53-dependent as well as -independent responses are induced. Those could be exploited in future therapies against diseases connected to nucleolar stress.
    MeSH term(s) Humans ; Tumor Suppressor Protein p53/genetics ; Cell Nucleolus ; Autophagy/genetics ; Gene Expression Regulation ; Autophagic Cell Death
    Chemical Substances Tumor Suppressor Protein p53
    Language English
    Publishing date 2023-08-15
    Publishing country Switzerland
    Document type Journal Article ; Review
    ZDB-ID 2661518-6
    ISSN 2073-4409 ; 2073-4409
    ISSN (online) 2073-4409
    ISSN 2073-4409
    DOI 10.3390/cells12162071
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article: Emerging Role of the Nucleolar Stress Response in Autophagy.

    Pfister, Astrid S

    Frontiers in cellular neuroscience

    2019  Volume 13, Page(s) 156

    Abstract: Autophagy represents a conserved self-digestion program, which allows regulated degradation of cellular material. Autophagy is activated by cellular stress, serum starvation and nutrient deprivation. Several autophagic pathways have been uncovered, which ...

    Abstract Autophagy represents a conserved self-digestion program, which allows regulated degradation of cellular material. Autophagy is activated by cellular stress, serum starvation and nutrient deprivation. Several autophagic pathways have been uncovered, which either non-selectively or selectively target the cellular cargo for lysosomal degradation. Autophagy engages the coordinated action of various key regulators involved in the steps of autophagosome formation, cargo targeting and lysosomal fusion. While non-selective (macro)autophagy is required for removal of bulk material or recycling of nutrients, selective autophagy mediates specific targeting of damaged organelles or protein aggregates. By proper action of the autophagic machinery, cellular homeostasis is maintained. In contrast, failure of this fundamental process is accompanied by severe pathophysiological conditions. Hallmarks of neuropathological disorders are for instance accumulated, mis-folded protein aggregates and damaged mitochondria. The nucleolus has been recognized as central hub in the cellular stress response. It represents a sub-nuclear organelle essential for ribosome biogenesis and also functions as stress sensor by mediating cell cycle arrest or apoptosis. Thus, proper nucleolar function is mandatory for cell growth and survival. Here, I highlight the emerging role of nucleolar factors in the regulation of autophagy. Moreover, I discuss the nucleolar stress response as a novel signaling pathway in the context of autophagy, health and disease.
    Language English
    Publishing date 2019-04-30
    Publishing country Switzerland
    Document type Journal Article ; Review
    ZDB-ID 2452963-1
    ISSN 1662-5102
    ISSN 1662-5102
    DOI 10.3389/fncel.2019.00156
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  3. Article ; Online: Correction: The Wnt target protein Peter Pan defines a novel p53-independent nucleolar stress-response pathway.

    Pfister, Astrid S / Keil, Marina / Kühl, Michael

    The Journal of biological chemistry

    2022  Volume 299, Issue 1, Page(s) 102808

    Language English
    Publishing date 2022-12-23
    Publishing country United States
    Document type Published Erratum
    ZDB-ID 2997-x
    ISSN 1083-351X ; 0021-9258
    ISSN (online) 1083-351X
    ISSN 0021-9258
    DOI 10.1016/j.jbc.2022.102808
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  4. Article: Nucleolar Stress Functions Upstream to Stimulate Expression of Autophagy Regulators.

    Dannheisig, David P / Schimansky, Anna / Donow, Cornelia / Pfister, Astrid S

    Cancers

    2021  Volume 13, Issue 24

    Abstract: Ribosome biogenesis is essential for protein synthesis, cell growth and survival. The process takes places in nucleoli and is orchestrated by various proteins, among them RNA polymerases I-III as well as ribosome biogenesis factors. Perturbation of ... ...

    Abstract Ribosome biogenesis is essential for protein synthesis, cell growth and survival. The process takes places in nucleoli and is orchestrated by various proteins, among them RNA polymerases I-III as well as ribosome biogenesis factors. Perturbation of ribosome biogenesis activates the nucleolar stress response, which classically triggers cell cycle arrest and apoptosis. Nucleolar stress is utilized in modern anti-cancer therapies, however, also contributes to the development of various pathologies, including cancer. Growing evidence suggests that nucleolar stress stimulates compensatory cascades, for instance bulk autophagy. However, underlying mechanisms are poorly understood. Here we demonstrate that induction of nucleolar stress activates expression of key autophagic regulators such as
    Language English
    Publishing date 2021-12-10
    Publishing country Switzerland
    Document type Journal Article
    ZDB-ID 2527080-1
    ISSN 2072-6694
    ISSN 2072-6694
    DOI 10.3390/cancers13246220
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  5. Article ; Online: Of Wnts and Ribosomes.

    Pfister, Astrid S / Kühl, Michael

    Progress in molecular biology and translational science

    2017  Volume 153, Page(s) 131–155

    Abstract: Wnt proteins are secreted glycoproteins that activate different intracellular signal transduction pathways. They regulate cell proliferation and are required for proper embryonic development. Misregulation of Wnt signaling can result in various diseases ... ...

    Abstract Wnt proteins are secreted glycoproteins that activate different intracellular signal transduction pathways. They regulate cell proliferation and are required for proper embryonic development. Misregulation of Wnt signaling can result in various diseases including cancer. In most circumstances, cell growth is essential for cell division and thus cell proliferation. Therefore, several reports have highlighted the key role of Wnt proteins for cell growth. Ribosomes represent the cellular protein synthesis machinery and cells need to be equipped with an appropriate number of ribosomes to allow cell growth. Recent findings suggest a role for Wnt proteins in regulating ribosome biogenesis and we here summarize these findings representing a previously unknown function of Wnt proteins. Understanding this role of Wnt signaling might open new avenues to slow down proliferation by drugs for instance in cancer therapy.
    MeSH term(s) Animals ; Cell Proliferation ; Humans ; Protein Biosynthesis ; Ribosomes/metabolism ; Wnt Proteins/metabolism ; Wnt Signaling Pathway
    Chemical Substances Wnt Proteins
    Language English
    Publishing date 2017-12-21
    Publishing country Netherlands
    Document type Journal Article ; Review
    ZDB-ID 2471995-X
    ISSN 1878-0814 ; 0079-6603 ; 1877-1173
    ISSN (online) 1878-0814
    ISSN 0079-6603 ; 1877-1173
    DOI 10.1016/bs.pmbts.2017.11.006
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  6. Article: The Wnt/β-Catenin Pathway is Activated as a Novel Nucleolar Stress Response

    Dannheisig, David P / Bächle, Jana / Tasic, Jasmin / Keil, Marina / Pfister, Astrid S

    Journal of molecular biology. 2021 Jan. 22, v. 433, no. 2

    2021  

    Abstract: Ribosomes are mandatory for growth and survival. The complex process of ribosome biogenesis is located in nucleoli and requires action of the RNA polymerases I–III, together with a multitude of processing factors involved in rRNA cleavage and maturation. ...

    Abstract Ribosomes are mandatory for growth and survival. The complex process of ribosome biogenesis is located in nucleoli and requires action of the RNA polymerases I–III, together with a multitude of processing factors involved in rRNA cleavage and maturation. Impaired ribosome biogenesis and loss of nucleolar integrity triggers nucleolar stress, which classically stabilizes the tumor suppressor p53 and induces cell cycle arrest and apoptosis. Nucleolar stress is implemented in modern anti-cancer therapies, however, also emerges as contributor to diverse pathological conditions. These include ribosomopathies, such as the Shwachman Bodian Diamond Syndrome (SBDS), which are not only characterized by nucleolar stress, but paradoxically also increased cancer incidence. Wnt signaling is tightly coupled to cell proliferation and is constitutively activated in various tumor types. In addition, the Wnt/β-Catenin pathway regulates ribosome formation. Here, we demonstrate that induction of nucleolar stress by different strategies stimulates the Wnt/β-Catenin pathway. We show that depletion of the key ribosomopathy factor SBDS, or the nucleolar factors Nucleophosmin (NPM), Pescadillo 1 (PES1) or Peter Pan (PPAN) by si RNA-mediated knockdown or CRISPR/Cas9 strategy activates Wnt/β-Catenin signaling in a β-Catenin-dependent manner and stabilizes β-Catenin in human cancer cells. Moreover, triggering nucleolar stress by the chemotherapeutic agents Actinomycin D or the RNA polymerase I inhibitor CX-5461 stimulates expression of Wnt/β-Catenin targets, which is followed by the p53 target CDKN1A (p21). As PPAN expression is induced by Wnt/β-Catenin signaling, our data establish a novel feedback mechanism and reveal that nucleolar stress over-activates the Wnt/β-Catenin pathway, which most likely serves as compensatory mechanism to sustain ribosome biogenesis.
    Keywords CRISPR-Cas systems ; DNA-directed RNA polymerase ; apoptosis ; biogenesis ; cell cycle checkpoints ; cell proliferation ; drug therapy ; humans ; molecular biology ; neoplasms ; ribosomes ; stress response
    Language English
    Dates of publication 2021-0122
    Publishing place Elsevier Ltd
    Document type Article
    Note NAL-AP-2-clean
    ZDB-ID 80229-3
    ISSN 1089-8638 ; 0022-2836
    ISSN (online) 1089-8638
    ISSN 0022-2836
    DOI 10.1016/j.jmb.2020.11.018
    Database NAL-Catalogue (AGRICOLA)

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  7. Article ; Online: The Wnt/β-Catenin Pathway is Activated as a Novel Nucleolar Stress Response.

    Dannheisig, David P / Bächle, Jana / Tasic, Jasmin / Keil, Marina / Pfister, Astrid S

    Journal of molecular biology

    2020  Volume 433, Issue 2, Page(s) 166719

    Abstract: Ribosomes are mandatory for growth and survival. The complex process of ribosome biogenesis is located in nucleoli and requires action of the RNA polymerases I-III, together with a multitude of processing factors involved in rRNA cleavage and maturation. ...

    Abstract Ribosomes are mandatory for growth and survival. The complex process of ribosome biogenesis is located in nucleoli and requires action of the RNA polymerases I-III, together with a multitude of processing factors involved in rRNA cleavage and maturation. Impaired ribosome biogenesis and loss of nucleolar integrity triggers nucleolar stress, which classically stabilizes the tumor suppressor p53 and induces cell cycle arrest and apoptosis. Nucleolar stress is implemented in modern anti-cancer therapies, however, also emerges as contributor to diverse pathological conditions. These include ribosomopathies, such as the Shwachman Bodian Diamond Syndrome (SBDS), which are not only characterized by nucleolar stress, but paradoxically also increased cancer incidence. Wnt signaling is tightly coupled to cell proliferation and is constitutively activated in various tumor types. In addition, the Wnt/β-Catenin pathway regulates ribosome formation. Here, we demonstrate that induction of nucleolar stress by different strategies stimulates the Wnt/β-Catenin pathway. We show that depletion of the key ribosomopathy factor SBDS, or the nucleolar factors Nucleophosmin (NPM), Pescadillo 1 (PES1) or Peter Pan (PPAN) by si RNA-mediated knockdown or CRISPR/Cas9 strategy activates Wnt/β-Catenin signaling in a β-Catenin-dependent manner and stabilizes β-Catenin in human cancer cells. Moreover, triggering nucleolar stress by the chemotherapeutic agents Actinomycin D or the RNA polymerase I inhibitor CX-5461 stimulates expression of Wnt/β-Catenin targets, which is followed by the p53 target CDKN1A (p21). As PPAN expression is induced by Wnt/β-Catenin signaling, our data establish a novel feedback mechanism and reveal that nucleolar stress over-activates the Wnt/β-Catenin pathway, which most likely serves as compensatory mechanism to sustain ribosome biogenesis.
    MeSH term(s) Cell Line ; Cell Nucleolus/genetics ; Cell Nucleolus/metabolism ; Gene Expression Regulation ; Gene Knockout Techniques ; Genes, Reporter ; Genotype ; Humans ; Mutation ; Nuclear Proteins/genetics ; Nuclear Proteins/metabolism ; Protein Binding ; Ribosomes/metabolism ; Stress, Physiological ; Tumor Suppressor Protein p53/genetics ; Tumor Suppressor Protein p53/metabolism ; Wnt Signaling Pathway ; beta Catenin/metabolism
    Chemical Substances Nuclear Proteins ; PPAN protein, human ; TP53 protein, human ; Tumor Suppressor Protein p53 ; beta Catenin
    Language English
    Publishing date 2020-11-20
    Publishing country England
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 80229-3
    ISSN 1089-8638 ; 0022-2836
    ISSN (online) 1089-8638
    ISSN 0022-2836
    DOI 10.1016/j.jmb.2020.11.018
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  8. Article ; Online: Loss of Peter Pan (PPAN) Affects Mitochondrial Homeostasis and Autophagic Flux.

    Dannheisig, David P / Beck, Eileen / Calzia, Enrico / Walther, Paul / Behrends, Christian / Pfister, Astrid S

    Cells

    2019  Volume 8, Issue 8

    Abstract: Nucleolar stress is a cellular response to inhibition of ribosome biogenesis or nucleolar disruption leading to cell cycle arrest and/or apoptosis. Emerging evidence points to a tight connection between nucleolar stress and autophagy as a mechanism ... ...

    Abstract Nucleolar stress is a cellular response to inhibition of ribosome biogenesis or nucleolar disruption leading to cell cycle arrest and/or apoptosis. Emerging evidence points to a tight connection between nucleolar stress and autophagy as a mechanism underlying various diseases such as neurodegeneration and treatment of cancer. Peter Pan (PPAN) functions as a key regulator of ribosome biogenesis. We previously showed that human PPAN localizes to nucleoli and mitochondria and that PPAN knockdown triggers a p53-independent nucleolar stress response culminating in mitochondrial apoptosis. Here, we demonstrate a novel role of PPAN in the regulation of mitochondrial homeostasis and autophagy. Our present study characterizes PPAN as a factor required for maintaining mitochondrial integrity and respiration-coupled ATP production. PPAN interacts with cardiolipin, a lipid of the inner mitochondrial membrane. Down-regulation of PPAN enhances autophagic flux in cancer cells. PPAN knockdown promotes recruitment of the E3-ubiquitin ligase Parkin to damaged mitochondria. Moreover, we provide evidence that PPAN knockdown decreases mitochondrial mass in Parkin-expressing cells. In summary, our study uncovers that PPAN knockdown is linked to mitochondrial damage and stimulates autophagy.
    MeSH term(s) Apoptosis ; Cardiolipins/metabolism ; Gene Knockdown Techniques ; HEK293 Cells ; HeLa Cells ; Homeostasis ; Humans ; Mitochondria/metabolism ; Mitochondrial Membranes/metabolism ; Mitophagy/genetics ; Nuclear Proteins/genetics ; Nuclear Proteins/physiology ; Ubiquitin-Protein Ligases/metabolism
    Chemical Substances Cardiolipins ; Nuclear Proteins ; PPAN protein, human ; Ubiquitin-Protein Ligases (EC 2.3.2.27) ; parkin protein (EC 2.3.2.27)
    Language English
    Publishing date 2019-08-14
    Publishing country Switzerland
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 2661518-6
    ISSN 2073-4409 ; 2073-4409
    ISSN (online) 2073-4409
    ISSN 2073-4409
    DOI 10.3390/cells8080894
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  9. Article ; Online: Loss of Peter Pan protein is associated with cell cycle defects and apoptotic events.

    Keil, Marina / Meyer, Maria T / Dannheisig, David P / Maerz, Lars D / Philipp, Melanie / Pfister, Astrid S

    Biochimica et biophysica acta. Molecular cell research

    2019  Volume 1866, Issue 5, Page(s) 882–895

    Abstract: The nucleolus is a subnuclear compartment, which governs ribosome biogenesis. Moreover, it functions as hub in the stress response by orchestrating a variety of processes, such as regulation of cell cycle progression, senescence and apoptosis. Emerging ... ...

    Abstract The nucleolus is a subnuclear compartment, which governs ribosome biogenesis. Moreover, it functions as hub in the stress response by orchestrating a variety of processes, such as regulation of cell cycle progression, senescence and apoptosis. Emerging evidence links the nucleolus also to the control of genomic stability and the development of human malignancies. Peter Pan (PPAN) is an essential ribosome biogenesis factor localized to nucleoli and mitochondria. We earlier showed that PPAN depletion triggers p53-independent nucleolar stress and apoptosis. In this study we investigated the precise localization of nucleolar PPAN during cell cycle and its function in cell cycle regulation. We show that PPAN knockdown impairs cell proliferation and induces G0/G1 as well as later G2/M cell cycle arrest in cancer cells. Although PPAN knockdown stabilizes the tumor suppressor p53 and induces CDKN1A/p21, the proliferation defects occur largely in a p53/p21-independent manner. We noticed a reduced number of knockdown cells entering cytokinesis and an elevation of binucleation. PPAN knockdown is also associated with increased H2A.X phosphorylation (γH2A.X) in cancer cells. We evaluated a potential signaling axis through the DNA damage response kinases ATM and ATR and alternatively apoptosis as a potent driver of γH2A.X. Interestingly, PPAN knockdown does not involve activation of ATM/ATR. Instead, γH2A.X is generated as a consequence of apoptosis induction in cancer cells. Strikingly, PPAN depletion in human fibroblasts did neither provoke apoptosis nor H2A.X phosphorylation, but recapitulated p53 stabilization. In summary, our data underline the notion that the PPAN-mediated, p53-independent nucleolar stress response has multiple facets.
    MeSH term(s) Apoptosis/genetics ; Ataxia Telangiectasia Mutated Proteins/genetics ; Ataxia Telangiectasia Mutated Proteins/metabolism ; Cell Nucleolus/genetics ; Cell Nucleolus/metabolism ; G2 Phase Cell Cycle Checkpoints/genetics ; HCT116 Cells ; HeLa Cells ; Histones/genetics ; Histones/metabolism ; Humans ; M Phase Cell Cycle Checkpoints/genetics ; Nuclear Proteins/genetics ; Nuclear Proteins/metabolism ; Signal Transduction/genetics ; Tumor Suppressor Protein p53/genetics ; Tumor Suppressor Protein p53/metabolism
    Chemical Substances H2AX protein, human ; Histones ; Nuclear Proteins ; PPAN protein, human ; TP53 protein, human ; Tumor Suppressor Protein p53 ; ATM protein, human (EC 2.7.11.1) ; ATR protein, human (EC 2.7.11.1) ; Ataxia Telangiectasia Mutated Proteins (EC 2.7.11.1)
    Language English
    Publishing date 2019-02-01
    Publishing country Netherlands
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 60-7
    ISSN 1879-2596 ; 1879-260X ; 1872-8006 ; 1879-2642 ; 1879-2618 ; 1879-2650 ; 0006-3002 ; 0005-2728 ; 0005-2736 ; 0304-4165 ; 0167-4838 ; 1388-1981 ; 0167-4889 ; 0167-4781 ; 0304-419X ; 1570-9639 ; 0925-4439 ; 1874-9399
    ISSN (online) 1879-2596 ; 1879-260X ; 1872-8006 ; 1879-2642 ; 1879-2618 ; 1879-2650
    ISSN 0006-3002 ; 0005-2728 ; 0005-2736 ; 0304-4165 ; 0167-4838 ; 1388-1981 ; 0167-4889 ; 0167-4781 ; 0304-419X ; 1570-9639 ; 0925-4439 ; 1874-9399
    DOI 10.1016/j.bbamcr.2019.01.010
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  10. Article: Identification of dynamic driver sets controlling phenotypical landscapes.

    Werle, Silke D / Ikonomi, Nensi / Schwab, Julian D / Kraus, Johann M / Weidner, Felix M / Rudolph, K Lenhard / Pfister, Astrid S / Schuler, Rainer / Kühl, Michael / Kestler, Hans A

    Computational and structural biotechnology journal

    2022  Volume 20, Page(s) 1603–1617

    Abstract: Controlling phenotypical landscapes is of vital interest to modern biology. This task becomes highly demanding because cellular decisions involve complex networks engaging in crosstalk interactions. Previous work on control theory indicates that small ... ...

    Abstract Controlling phenotypical landscapes is of vital interest to modern biology. This task becomes highly demanding because cellular decisions involve complex networks engaging in crosstalk interactions. Previous work on control theory indicates that small sets of compounds can control single phenotypes. However, a dynamic approach is missing to determine the drivers of the whole network dynamics. By analyzing 35 biologically motivated Boolean networks, we developed a method to identify small sets of compounds sufficient to decide on the entire phenotypical landscape. These compounds do not strictly prefer highly related compounds and show a smaller impact on the stability of the attractor landscape. The dynamic driver sets include many intervention targets and cellular reprogramming drivers in human networks. Finally, by using a new comprehensive model of colorectal cancer, we provide a complete workflow on how to implement our approach to shift from
    Language English
    Publishing date 2022-04-02
    Publishing country Netherlands
    Document type Journal Article
    ZDB-ID 2694435-2
    ISSN 2001-0370
    ISSN 2001-0370
    DOI 10.1016/j.csbj.2022.03.034
    Database MEDical Literature Analysis and Retrieval System OnLINE

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