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Madrazo N, Khattar Z, Powers ET, Rosarda JD, Wiseman RL. Mapping stress-responsive signaling pathways induced by mitochondrial proteostasis perturbations. Mol Biol Cell 2024; 35:ar74. [PMID: 38536439 PMCID: PMC11151107 DOI: 10.1091/mbc.e24-01-0041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2024] [Revised: 03/12/2024] [Accepted: 03/22/2024] [Indexed: 04/09/2024] Open
Abstract
Imbalances in mitochondrial proteostasis are associated with pathologic mitochondrial dysfunction implicated in etiologically diverse diseases. This has led to considerable interest in defining the mechanisms responsible for regulating mitochondria in response to mitochondrial stress. Numerous stress-responsive signaling pathways have been suggested to regulate mitochondria in response to proteotoxic stress. These include the integrated stress response (ISR), the heat shock response (HSR), and the oxidative stress response (OSR). Here, we define the stress signaling pathways activated in response to chronic mitochondrial proteostasis perturbations by monitoring the expression of sets of genes regulated downstream of each of these signaling pathways in published Perturb-seq datasets from K562 cells CRISPRi-depleted of mitochondrial proteostasis factors. Interestingly, we find that the ISR is preferentially activated in response to chronic, genetically-induced mitochondrial proteostasis stress, with no other pathway showing significant activation. Further, we demonstrate that CRISPRi depletion of other mitochondria-localized proteins similarly shows preferential activation of the ISR relative to other stress-responsive signaling pathways. These results both establish our gene set profiling approach as a viable strategy to probe stress responsive signaling pathways induced by perturbations to specific organelles and identify the ISR as the predominant stress-responsive signaling pathway activated in response to chronic disruption of mitochondrial proteostasis.
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Affiliation(s)
- Nicole Madrazo
- Department of Molecular and Cellular Biology, Scripps Research, La Jolla, CA 92037
| | - Zinia Khattar
- Department of Molecular and Cellular Biology, Scripps Research, La Jolla, CA 92037
- Del Norte High School, San Diego, CA 92127
| | - Evan T. Powers
- Department of Chemistry, Scripps Research, La Jolla, CA 92037
| | - Jessica D. Rosarda
- Department of Anatomy, Physiology, and Genetics, Uniformed Services University of the Health Sciences, Bethesda, MD 20814
| | - R. Luke Wiseman
- Department of Molecular and Cellular Biology, Scripps Research, La Jolla, CA 92037
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2
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Ryoo HD. The integrated stress response in metabolic adaptation. J Biol Chem 2024; 300:107151. [PMID: 38462161 PMCID: PMC10998230 DOI: 10.1016/j.jbc.2024.107151] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2023] [Revised: 02/28/2024] [Accepted: 03/03/2024] [Indexed: 03/12/2024] Open
Abstract
The integrated stress response (ISR) refers to signaling pathways initiated by stress-activated eIF2α kinases. Distinct eIF2α kinases respond to different stress signals, including amino acid deprivation and mitochondrial stress. Such stress-induced eIF2α phosphorylation attenuates general mRNA translation and, at the same time, stimulates the preferential translation of specific downstream factors to orchestrate an adaptive gene expression program. In recent years, there have been significant new advances in our understanding of ISR during metabolic stress adaptation. Here, I discuss those advances, reviewing among others the ISR activation mechanisms in response to amino acid deprivation and mitochondrial stress. In addition, I review how ISR regulates the amino acid metabolic pathways and how changes in the ISR impact the physiology and pathology of various disease models.
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Affiliation(s)
- Hyung Don Ryoo
- Department of Cell Biology, New York University Grossman School of Medicine, New York, New York, USA.
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3
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Ahlstedt BA, Ganji R, Mukkavalli S, Paulo JA, Gygi SP, Raman M. UBXN1 maintains ER proteostasis and represses UPR activation by modulating translation. EMBO Rep 2024; 25:672-703. [PMID: 38177917 PMCID: PMC10897191 DOI: 10.1038/s44319-023-00027-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2023] [Revised: 11/24/2023] [Accepted: 11/30/2023] [Indexed: 01/06/2024] Open
Abstract
ER protein homeostasis (proteostasis) is essential for proper folding and maturation of proteins in the secretory pathway. Loss of ER proteostasis can lead to the accumulation of misfolded or aberrant proteins in the ER and triggers the unfolded protein response (UPR). In this study, we find that the p97 adaptor UBXN1 is an important negative regulator of the UPR. Loss of UBXN1 sensitizes cells to ER stress and activates the UPR. This leads to widespread upregulation of the ER stress transcriptional program. Using comparative, quantitative proteomics we show that deletion of UBXN1 results in a significant enrichment of proteins involved in ER-quality control processes including those involved in protein folding and import. Notably, we find that loss of UBXN1 does not perturb p97-dependent ER-associated degradation (ERAD). Our studies indicate that loss of UBXN1 increases translation in both resting and ER-stressed cells. Surprisingly, this process is independent of p97 function. Taken together, our studies have identified a new role for UBXN1 in repressing translation and maintaining ER proteostasis in a p97 independent manner.
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Affiliation(s)
- Brittany A Ahlstedt
- Department of Developmental Molecular and Chemical Biology, Tufts University School of Medicine, Boston, MA, USA
- ALPCA diagnostics, Salem, NH, USA
| | - Rakesh Ganji
- Department of Developmental Molecular and Chemical Biology, Tufts University School of Medicine, Boston, MA, USA
| | - Sirisha Mukkavalli
- Department of Developmental Molecular and Chemical Biology, Tufts University School of Medicine, Boston, MA, USA
- Dana Farber Cancer Research Institute, Boston, MA, USA
| | - Joao A Paulo
- Department of Cell Biology Harvard Medical School, Boston, MA, USA
| | - Steve P Gygi
- Department of Cell Biology Harvard Medical School, Boston, MA, USA
| | - Malavika Raman
- Department of Developmental Molecular and Chemical Biology, Tufts University School of Medicine, Boston, MA, USA.
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4
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Madrazo N, Khattar Z, Powers ET, Rosarda JD, Wiseman RL. Mapping Stress-Responsive Signaling Pathways Induced by Mitochondrial Proteostasis Perturbations. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.30.577830. [PMID: 38352575 PMCID: PMC10862789 DOI: 10.1101/2024.01.30.577830] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/23/2024]
Abstract
Imbalances in mitochondrial proteostasis are associated with pathologic mitochondrial dysfunction implicated in etiologically-diverse diseases. This has led to considerable interest in defining the biological mechanisms responsible for regulating mitochondria in response to mitochondrial stress. Numerous stress responsive signaling pathways have been suggested to regulate mitochondria in response to proteotoxic stress, including the integrated stress response (ISR), the heat shock response (HSR), and the oxidative stress response (OSR). Here, we define the specific stress signaling pathways activated in response to mitochondrial proteostasis stress by monitoring the expression of sets of genes regulated downstream of each of these signaling pathways in published Perturb-seq datasets from K562 cells CRISPRi-depleted of individual mitochondrial proteostasis factors. Interestingly, we find that the ISR is preferentially activated in response to mitochondrial proteostasis stress, with no other pathway showing significant activation. Further expanding this study, we show that broad depletion of mitochondria-localized proteins similarly shows preferential activation of the ISR relative to other stress-responsive signaling pathways. These results both establish our gene set profiling approach as a viable strategy to probe stress responsive signaling pathways induced by perturbations to specific organelles and identify the ISR as the predominant stress-responsive signaling pathway activated in response to mitochondrial proteostasis disruption.
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Affiliation(s)
- Nicole Madrazo
- Department of Molecular and Cellular Biology, Scripps Research, La Jolla, CA 92037
- These authors contributed equally
| | - Zinia Khattar
- Department of Molecular and Cellular Biology, Scripps Research, La Jolla, CA 92037
- Del Norte High School, San Diego, CA 92127
- These authors contributed equally
| | - Evan T. Powers
- Department of Chemistry, Scripps Research, La Jolla, CA 92037
| | - Jessica D. Rosarda
- Department of Anatomy, Physiology, and Genetics, Uniformed Services University of the Health Sciences, Bethesda, MD 20814
| | - R. Luke Wiseman
- Department of Molecular and Cellular Biology, Scripps Research, La Jolla, CA 92037
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5
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Ronayne CT, Latorre-Muro P. Navigating the landscape of mitochondrial-ER communication in health and disease. Front Mol Biosci 2024; 11:1356500. [PMID: 38323074 PMCID: PMC10844478 DOI: 10.3389/fmolb.2024.1356500] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2023] [Accepted: 01/10/2024] [Indexed: 02/08/2024] Open
Abstract
Intracellular organelle communication enables the maintenance of tissue homeostasis and health through synchronized adaptive processes triggered by environmental cues. Mitochondrial-Endoplasmic Reticulum (ER) communication sustains cellular fitness by adjusting protein synthesis and degradation, and metabolite and protein trafficking through organelle membranes. Mitochondrial-ER communication is bidirectional and requires that the ER-components of the Integrated Stress Response signal to mitochondria upon activation and, likewise, mitochondria signal to the ER under conditions of metabolite and protein overload to maintain proper functionality and ensure cellular survival. Declines in the mitochondrial-ER communication occur upon ageing and correlate with the onset of a myriad of heterogeneous age-related diseases such as obesity, type 2 diabetes, cancer, or neurodegenerative pathologies. Thus, the exploration of the molecular mechanisms of mitochondrial-ER signaling and regulation will provide insights into the most fundamental cellular adaptive processes with important therapeutical opportunities. In this review, we will discuss the pathways and mechanisms of mitochondrial-ER communication at the mitochondrial-ER interface and their implications in health and disease.
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Affiliation(s)
- Conor T. Ronayne
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA, United States
- Department of Cell Biology, Harvard Medical School, Boston, MA, United States
| | - Pedro Latorre-Muro
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA, United States
- Department of Cell Biology, Harvard Medical School, Boston, MA, United States
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Zhang SX, Wang JJ, Starr CR, Lee EJ, Park KS, Zhylkibayev A, Medina A, Lin JH, Gorbatyuk M. The endoplasmic reticulum: Homeostasis and crosstalk in retinal health and disease. Prog Retin Eye Res 2024; 98:101231. [PMID: 38092262 PMCID: PMC11056313 DOI: 10.1016/j.preteyeres.2023.101231] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2023] [Revised: 12/05/2023] [Accepted: 12/06/2023] [Indexed: 12/19/2023]
Abstract
The endoplasmic reticulum (ER) is the largest intracellular organelle carrying out a broad range of important cellular functions including protein biosynthesis, folding, and trafficking, lipid and sterol biosynthesis, carbohydrate metabolism, and calcium storage and gated release. In addition, the ER makes close contact with multiple intracellular organelles such as mitochondria and the plasma membrane to actively regulate the biogenesis, remodeling, and function of these organelles. Therefore, maintaining a homeostatic and functional ER is critical for the survival and function of cells. This vital process is implemented through well-orchestrated signaling pathways of the unfolded protein response (UPR). The UPR is activated when misfolded or unfolded proteins accumulate in the ER, a condition known as ER stress, and functions to restore ER homeostasis thus promoting cell survival. However, prolonged activation or dysregulation of the UPR can lead to cell death and other detrimental events such as inflammation and oxidative stress; these processes are implicated in the pathogenesis of many human diseases including retinal disorders. In this review manuscript, we discuss the unique features of the ER and ER stress signaling in the retina and retinal neurons and describe recent advances in the research to uncover the role of ER stress signaling in neurodegenerative retinal diseases including age-related macular degeneration, inherited retinal degeneration, achromatopsia and cone diseases, and diabetic retinopathy. In some chapters, we highlight the complex interactions between the ER and other intracellular organelles focusing on mitochondria and illustrate how ER stress signaling regulates common cellular stress pathways such as autophagy. We also touch upon the integrated stress response in retinal degeneration and diabetic retinopathy. Finally, we provide an update on the current development of pharmacological agents targeting the UPR response and discuss some unresolved questions and knowledge gaps to be addressed by future research.
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Affiliation(s)
- Sarah X Zhang
- Department of Ophthalmology and Ross Eye Institute, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, State University of New York, Buffalo, NY, United States; Department of Biochemistry, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, State University of New York, Buffalo, NY, United States.
| | - Josh J Wang
- Department of Ophthalmology and Ross Eye Institute, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, State University of New York, Buffalo, NY, United States
| | - Christopher R Starr
- Department of Optometry and Vision Science, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Eun-Jin Lee
- Department of Ophthalmology and Byers Eye Institute, Stanford University, Stanford, CA, United States; VA Palo Alto Healthcare System, Palo Alto, CA, United States; Department of Pathology, Stanford University, Stanford, CA, United States
| | - Karen Sophia Park
- Department of Ophthalmology and Ross Eye Institute, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, State University of New York, Buffalo, NY, United States
| | - Assylbek Zhylkibayev
- Department of Optometry and Vision Science, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Andy Medina
- Department of Ophthalmology and Ross Eye Institute, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, State University of New York, Buffalo, NY, United States
| | - Jonathan H Lin
- Department of Ophthalmology and Byers Eye Institute, Stanford University, Stanford, CA, United States; VA Palo Alto Healthcare System, Palo Alto, CA, United States; Department of Pathology, Stanford University, Stanford, CA, United States
| | - Marina Gorbatyuk
- Department of Optometry and Vision Science, University of Alabama at Birmingham, Birmingham, AL, United States
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Perea V, Baron KR, Dolina V, Aviles G, Kim G, Rosarda JD, Guo X, Kampmann M, Wiseman RL. Pharmacologic activation of a compensatory integrated stress response kinase promotes mitochondrial remodeling in PERK-deficient cells. Cell Chem Biol 2023; 30:1571-1584.e5. [PMID: 37922906 PMCID: PMC10842031 DOI: 10.1016/j.chembiol.2023.10.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2023] [Revised: 08/21/2023] [Accepted: 10/10/2023] [Indexed: 11/07/2023]
Abstract
The integrated stress response (ISR) comprises the eIF2α kinases PERK, GCN2, HRI, and PKR, which induce translational and transcriptional signaling in response to diverse insults. Deficiencies in PERK signaling lead to mitochondrial dysfunction and contribute to the pathogenesis of numerous diseases. We define the potential for pharmacologic activation of compensatory eIF2α kinases to rescue ISR signaling and promote mitochondrial adaptation in PERK-deficient cells. We show that the HRI activator BtdCPU and GCN2 activator halofuginone promote ISR signaling and rescue ER stress sensitivity in PERK-deficient cells. However, BtdCPU induces mitochondrial depolarization, leading to mitochondrial fragmentation and activation of the OMA1-DELE1-HRI signaling axis. In contrast, halofuginone promotes mitochondrial elongation and adaptive mitochondrial respiration, mimicking regulation induced by PERK. This shows halofuginone can compensate for deficiencies in PERK signaling and promote adaptive mitochondrial remodeling, highlighting the potential for pharmacologic ISR activation to mitigate mitochondrial dysfunction and motivating the pursuit of highly selective ISR activators.
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Affiliation(s)
- Valerie Perea
- Department of Molecular and Cellular Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Kelsey R Baron
- Department of Molecular and Cellular Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Vivian Dolina
- Department of Molecular and Cellular Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Giovanni Aviles
- Department of Biophysics and Biochemistry and Institute for Neurodegenerative Diseases, UCSF, San Francisco, CA 94158, USA
| | - Grace Kim
- Department of Molecular and Cellular Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Jessica D Rosarda
- Department of Molecular and Cellular Biology, The Scripps Research Institute, La Jolla, CA 92037, USA; Department of Anatomy, Physiology, and Genetics, Uniformed Services University of the Health Sciences, Bethesda, MD 20814, USA
| | - Xiaoyan Guo
- Department of Biophysics and Biochemistry and Institute for Neurodegenerative Diseases, UCSF, San Francisco, CA 94158, USA; Department of Genetics and Genome Sciences, University of Connecticut Health, Farmington, CT 06030, USA
| | - Martin Kampmann
- Department of Biophysics and Biochemistry and Institute for Neurodegenerative Diseases, UCSF, San Francisco, CA 94158, USA
| | - R Luke Wiseman
- Department of Molecular and Cellular Biology, The Scripps Research Institute, La Jolla, CA 92037, USA.
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8
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Boone M, Zappa F. Signaling plasticity in the integrated stress response. Front Cell Dev Biol 2023; 11:1271141. [PMID: 38143923 PMCID: PMC10740175 DOI: 10.3389/fcell.2023.1271141] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2023] [Accepted: 11/29/2023] [Indexed: 12/26/2023] Open
Abstract
The Integrated Stress Response (ISR) is an essential homeostatic signaling network that controls the cell's biosynthetic capacity. Four ISR sensor kinases detect multiple stressors and relay this information to downstream effectors by phosphorylating a common node: the alpha subunit of the eukaryotic initiation factor eIF2. As a result, general protein synthesis is repressed while select transcripts are preferentially translated, thus remodeling the proteome and transcriptome. Mounting evidence supports a view of the ISR as a dynamic signaling network with multiple modulators and feedback regulatory features that vary across cell and tissue types. Here, we discuss updated views on ISR sensor kinase mechanisms, how the subcellular localization of ISR components impacts signaling, and highlight ISR signaling differences across cells and tissues. Finally, we consider crosstalk between the ISR and other signaling pathways as a determinant of cell health.
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Perea V, Cole C, Lebeau J, Dolina V, Baron KR, Madhavan A, Kelly JW, Grotjahn DA, Wiseman RL. PERK signaling promotes mitochondrial elongation by remodeling membrane phosphatidic acid. EMBO J 2023; 42:e113908. [PMID: 37306086 PMCID: PMC10390871 DOI: 10.15252/embj.2023113908] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Revised: 05/05/2023] [Accepted: 05/12/2023] [Indexed: 06/13/2023] Open
Abstract
Endoplasmic reticulum (ER) stress and mitochondrial dysfunction are linked in the onset and pathogenesis of numerous diseases. This has led to considerable interest in defining the mechanisms responsible for regulating mitochondria during ER stress. The PERK signaling arm of the unfolded protein response (UPR) has emerged as a prominent ER stress-responsive signaling pathway that regulates diverse aspects of mitochondrial biology. Here, we show that PERK activity promotes adaptive remodeling of mitochondrial membrane phosphatidic acid (PA) to induce protective mitochondrial elongation during acute ER stress. We find that PERK activity is required for ER stress-dependent increases in both cellular PA and YME1L-dependent degradation of the intramitochondrial PA transporter PRELID1. These two processes lead to the accumulation of PA on the outer mitochondrial membrane where it can induce mitochondrial elongation by inhibiting mitochondrial fission. Our results establish a new role for PERK in the adaptive remodeling of mitochondrial phospholipids and demonstrate that PERK-dependent PA regulation adapts organellar shape in response to ER stress.
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Affiliation(s)
- Valerie Perea
- Department of Molecular MedicineScripps ResearchLa JollaCAUSA
| | | | - Justine Lebeau
- Department of Molecular MedicineScripps ResearchLa JollaCAUSA
| | - Vivian Dolina
- Department of Molecular MedicineScripps ResearchLa JollaCAUSA
| | - Kelsey R Baron
- Department of Molecular MedicineScripps ResearchLa JollaCAUSA
| | | | - Jeffery W Kelly
- Department of ChemistryScripps ResearchLa JollaCAUSA
- Skaggs Institute for Chemical BiologyScripps ResearchLa JollaCAUSA
| | - Danielle A Grotjahn
- Department of Integrative, Structural, and Computational BiologyScripps ResearchLa JollaCAUSA
| | - R Luke Wiseman
- Department of Molecular MedicineScripps ResearchLa JollaCAUSA
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