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Torres-Velarde JM, Allen KN, Salvador-Pascual A, Leija RG, Luong D, Moreno-Santillán DD, Ensminger DC, Vázquez-Medina JP. Peroxiredoxin 6 suppresses ferroptosis in lung endothelial cells. Free Radic Biol Med 2024; 218:82-93. [PMID: 38579937 PMCID: PMC11177496 DOI: 10.1016/j.freeradbiomed.2024.04.208] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/28/2024] [Revised: 03/26/2024] [Accepted: 04/02/2024] [Indexed: 04/07/2024]
Abstract
Peroxiredoxin 6 (Prdx6) repairs peroxidized membranes by reducing oxidized phospholipids, and by replacing oxidized sn-2 fatty acyl groups through hydrolysis/reacylation by its phospholipase A2 (aiPLA2) and lysophosphatidylcholine acyltransferase activities. Prdx6 is highly expressed in the lung, and intact lungs and cells null for Prdx6 or with single-point mutations that inactivate either Prdx6-peroxidase or aiPLA2 activity alone exhibit decreased viability, increased lipid peroxidation, and incomplete repair when exposed to paraquat, hyperoxia, or organic peroxides. Ferroptosis is form of cell death driven by the accumulation of phospholipid hydroperoxides. We studied the role of Prdx6 as a ferroptosis suppressor in the lung. We first compared the expression Prdx6 and glutathione peroxidase 4 (GPx4) and visualized Prdx6 and GPx4 within the lung. Lung Prdx6 mRNA levels were five times higher than GPx4 levels. Both Prdx6 and GPx4 localized to epithelial and endothelial cells. Prdx6 knockout or knockdown sensitized lung endothelial cells to erastin-induced ferroptosis. Cells with genetic inactivation of either aiPLA2 or Prdx6-peroxidase were more sensitive to ferroptosis than WT cells, but less sensitive than KO cells. We then conducted RNA-seq analyses in Prdx6-depleted cells to further explore how the loss of Prdx6 sensitizes lung endothelial cells to ferroptosis. Prdx6 KD upregulated transcriptional signatures associated with selenoamino acid metabolism and mitochondrial function. Accordingly, Prdx6 deficiency blunted mitochondrial function and increased GPx4 abundance whereas GPx4 KD had the opposite effect on Prdx6. Moreover, we detected Prdx6 and GPx4 interactions in intact cells, suggesting that both enzymes cooperate to suppress lipid peroxidation. Notably, Prdx6-depleted cells remained sensitive to erastin-induced ferroptosis despite the compensatory increase in GPx4. These results show that Prdx6 suppresses ferroptosis in lung endothelial cells and that both aiPLA2 and Prdx6-peroxidase contribute to this effect. These results also show that Prdx6 supports mitochondrial function and modulates several coordinated cytoprotective pathways in the pulmonary endothelium.
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Affiliation(s)
| | - Kaitlin N Allen
- Department of Integrative Biology, University of California, Berkeley, USA
| | | | - Roberto G Leija
- Department of Integrative Biology, University of California, Berkeley, USA
| | - Diamond Luong
- Department of Integrative Biology, University of California, Berkeley, USA
| | | | - David C Ensminger
- Department of Integrative Biology, University of California, Berkeley, USA
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2
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Rahaman H, Herojit K, Singh LR, Haobam R, Fisher AB. Structural and Functional Diversity of the Peroxiredoxin 6 Enzyme Family. Antioxid Redox Signal 2024; 40:759-775. [PMID: 37463006 DOI: 10.1089/ars.2023.0287] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 09/14/2023]
Abstract
Significance: Peroxiredoxins (Prdxs) with a single peroxidative cysteine (CP) in a conserved motif PXXX(T/S)XXCP within its thioredoxin fold, have been classified as the peroxiredoxin 6 (Prdx6 ) family. All Prdxs can reduce H2O2 and short chain hydroperoxides while Prdx6 in addition, can reduce phospholipid hydroperoxides (PLOOH) due to its ability to interact with peroxidized phospholipid substrate. The single CP of Prdx6 uses various external electron donors including glutathione thioredoxin, and ascorbic acid for resolution of its peroxidized state and, therefore, its peroxidase activity. Prdx6 proteins also exhibit Ca2+-independent phospholipase A2 (PLA2), lysophosphatidylcholine acyltransferase (LPCAT), and chaperone activities that depend on cellular localization and the oxidation and oligomerisation states of the protein. Thus, Prdx6 is a "moonlighting" enzyme. Recent Advance: Physiologically, Prdx6s have been reported to play an important role in protection against oxidative stress, repair of peroxidized cell membranes, mammalian lung surfactant turnover, activation of some NADPH oxidases, the regulation of seed germination in plants, as an indicator of cellular levels of reactive O2 species through Nrf-Klf9 activation, and possibly in male fertility, regulation of cell death through ferroptosis, cancer metastasis, and oxidative stress-related signalling pathways. Critical Issues: This review outlines Prdx6 enzyme unique structural features and explores its wide range of physiological functions. Yet, existing structural data falls short of fully revealing all of human Prdx6 multifunctional roles. Further endeavour is required to bridge this gap in its understanding. Although there are wide variations in both the structure and function of Prdx6 family members in various organisms, all Prdx6 proteins show the unique a long C-terminal extension that is also seen in Prdx1, but not in other Prdxs. Future Directions: As research data continues to accumulate, the potential for detailed insights into the role of C-terminal of Prdx6 in its oligomerisation and activities. There is a need for thorough exploration of structural characteristics of the various biological functions. Additionally, uncovering the interacting partners of Prdx6 and understanding its involvement in signalling pathways will significantly contribute to a more profound comprehension of its role.
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Affiliation(s)
- Hamidur Rahaman
- Department of Biotechnology, Manipur University, Imphal, India
| | - Khundrakpam Herojit
- Department of Biotechnology, Manipur University, Imphal, India
- Department of Biotechnology, Mangolnganbi College, Ningthoukhong, India
| | | | - Reena Haobam
- Department of Biotechnology, Manipur University, Imphal, India
| | - Aron B Fisher
- Institute for Environmental Medicine, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, USA
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Henriquez-Olguin C, Meneses-Valdes R, Kritsiligkou P, Fuentes-Lemus E. From workout to molecular switches: How does skeletal muscle produce, sense, and transduce subcellular redox signals? Free Radic Biol Med 2023; 209:355-365. [PMID: 37923089 DOI: 10.1016/j.freeradbiomed.2023.10.404] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/22/2023] [Revised: 10/16/2023] [Accepted: 10/23/2023] [Indexed: 11/07/2023]
Abstract
Skeletal muscle is crucial for maintaining human health and overall quality of life. Acute exercise introduces a multifaceted intracellular stress, with numerous post-translational modifications believed to underpin the health benefits of sustained exercise training. Reactive oxygen species (ROS) are posited to serve as second messengers, triggering cytoprotective adaptations such as the upregulation of enzymatic scavenger systems. However, a significant knowledge gap exists between the generation of oxidants in muscle and the exact mechanisms driving muscle adaptations. This review delves into the current research on subcellular redox biochemistry and its role in the physiological adaptations to exercise. We propose that the subcellular regulation of specific redox modifications is key to ensuring specificity in the intracellular response.
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Affiliation(s)
- Carlos Henriquez-Olguin
- The August Krogh Section of Molecular Physiology, Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, 2100, Denmark; Exercise Science Laboratory, Faculty of Medicine, Universidad Finis Terrae, Av. Pedro de Valdivia 1509, Santiago, Chile.
| | - Roberto Meneses-Valdes
- The August Krogh Section of Molecular Physiology, Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, 2100, Denmark
| | | | - Eduardo Fuentes-Lemus
- Department of Biomedical Sciences, Panum Institute, Blegdamsvej 3, University of Copenhagen, Copenhagen, 2200, Denmark
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4
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Garavaglia ML, Bodega F, Porta C, Milzani A, Sironi C, Dalle-Donne I. Molecular Impact of Conventional and Electronic Cigarettes on Pulmonary Surfactant. Int J Mol Sci 2023; 24:11702. [PMID: 37511463 PMCID: PMC10380520 DOI: 10.3390/ijms241411702] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Revised: 07/11/2023] [Accepted: 07/15/2023] [Indexed: 07/30/2023] Open
Abstract
The alveolar epithelium is covered by a non-cellular layer consisting of an aqueous hypophase topped by pulmonary surfactant, a lipo-protein mixture with surface-active properties. Exposure to cigarette smoke (CS) affects lung physiology and is linked to the development of several diseases. The macroscopic effects of CS are determined by several types of cell and molecular dysfunction, which, among other consequences, lead to surfactant alterations. The purpose of this review is to summarize the published studies aimed at uncovering the effects of CS on both the lipid and protein constituents of surfactant, discussing the molecular mechanisms involved in surfactant homeostasis that are altered by CS. Although surfactant homeostasis has been the topic of several studies and some molecular pathways can be deduced from an analysis of the literature, it remains evident that many aspects of the mechanisms of action of CS on surfactant homeostasis deserve further investigation.
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Affiliation(s)
| | - Francesca Bodega
- Dipartimento di Fisiopatologia Medico-Chirurgica e dei Trapianti, Università degli Studi di Milano, 20133 Milan, Italy
| | - Cristina Porta
- Dipartimento di Fisiopatologia Medico-Chirurgica e dei Trapianti, Università degli Studi di Milano, 20133 Milan, Italy
| | - Aldo Milzani
- Dipartimento di Bioscienze, Università degli Studi di Milano, 20133 Milan, Italy
| | - Chiara Sironi
- Dipartimento di Fisiopatologia Medico-Chirurgica e dei Trapianti, Università degli Studi di Milano, 20133 Milan, Italy
| | - Isabella Dalle-Donne
- Dipartimento di Bioscienze, Università degli Studi di Milano, 20133 Milan, Italy
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5
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Anti-Oxidant and Pro-Oxidant Effects of Peroxiredoxin 6: A Potential Target in Respiratory Diseases. Cells 2023; 12:cells12010181. [PMID: 36611974 PMCID: PMC9818991 DOI: 10.3390/cells12010181] [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: 11/30/2022] [Revised: 12/26/2022] [Accepted: 12/30/2022] [Indexed: 01/03/2023] Open
Abstract
Peroxiredoxin 6 (PRDX6) is widely distributed in several organs, especially the lungs. The role of PRDX6 in oxidative stress is controversial and even contradictory, as indicated by research conducted over the past 20 years. PRDX6 has anti-oxidant or pro-oxidant effects on oxidative stress in different diseases. It can even exhibit both anti-oxidant and pro-oxidant effects in the same disease. These findings are attributed to the fact that PRDX6 is a multifunctional enzyme. The peroxidase and phospholipase A2 activity of PRDX6 is closely related to its anti-oxidant and pro-oxidant effects, which leads to the conflicting regulatory effects of PRDX6 on oxidative stress in respiratory diseases. Moreover, PRDX6 interacts with multiple redox signaling pathways to interfere with cell proliferation and apoptosis. PRDX6 has become a new target in respiratory disease research due to its important regulatory role in oxidative stress. In this paper, the role of PRDX6 in oxidative stress in respiratory diseases and the research progress in targeting PRDX6 are reviewed.
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Sharapov MG, Goncharov RG, Parfenyuk SB, Glushkova OV, Novoselov VI. The Role of Phospholipase Activity of Peroxiredoxin 6 in Its Transmembrane Transport and Protective Properties. Int J Mol Sci 2022; 23:ijms232315265. [PMID: 36499590 PMCID: PMC9738660 DOI: 10.3390/ijms232315265] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Revised: 11/24/2022] [Accepted: 12/01/2022] [Indexed: 12/12/2022] Open
Abstract
Peroxiredoxin 6 (Prdx6) is a multifunctional eukaryotic antioxidant enzyme. Mammalian Prdx6 possesses peroxidase activity against a wide range of organic and inorganic hydroperoxides, as well as exhibits phospholipase A2 (aiPLA2) activity, which plays an important role in the reduction of oxidized phospholipids and cell membrane remodeling. Exogenous Prdx6 has recently been shown to be able to penetrate inside the cell. We hypothesized that this entry may be due to the phospholipase activity of Prdx6. Experiments using exogenous Prdx6 in three cell lines (3T3, A549, RAW 264.7) demonstrated that it is the phospholipase activity that promotes its penetration into the cell. Overoxidation of Prdx6 led to a suppression of the peroxidase activity and a 3-to-4-fold growth of aiPLA2, which enhanced the efficiency of its transmembrane transport into the cells by up to 15 times. A mutant form of Prdx6-S32A with an inactivated phospholipase center turned out to be unable to enter the cells in both the reduced and oxidized state of the peroxidase active center. Previously, we have shown that exogenous Prdx6 has a significant radioprotective action. However, the role of phospholipase activity in the radioprotective effects of Prdx6 remained unstudied. Trials with the mutant Prdx6-S32A form, with the use of a total irradiation model in mice, showed a nearly 50% reduction of the radioprotective effect upon aiPLA2 loss. Such a significant decrease in the radioprotective action may be due to the inability of Prdx6-S32A to penetrate animal cells, which prevents its reduction by the natural intracellular reducing agent glutathione S-transferase (πGST) and lowers the efficiency of elimination of peroxides formed from the effect of ionizing radiation. Thus, phospholipase activity may play an important role in the reduction of oxidized Prdx6 and manifestation of its antioxidant properties.
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Chowhan RK, Hotumalani S, Rahaman H, Singh LR. pH induced conformational alteration in human peroxiredoxin 6 might be responsible for its resistance against lysosomal pH or high temperature. Sci Rep 2021; 11:9657. [PMID: 33958651 PMCID: PMC8102515 DOI: 10.1038/s41598-021-89093-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Accepted: 04/16/2021] [Indexed: 12/03/2022] Open
Abstract
Peroxiredoxin 6 (Prdx6), the ubiquitously expressed enzyme belonging to the family of peroxidases, namely, peroxiredoxins, exhibits a unique feature of functional compartmentalization within cells. Whereas, the enzyme localized in cytosol shows glutathione peroxidase activity, its lysosomal counterpart performs calcium independent phospholipase A2 (aiPLA2) activity. Like any true moonlighting protein, these two activities of Prdx6 are mutually exclusive of each other as a function of the pH of the cellular compartments. Differential substrate preference at different pH (i.e. peroxidised phospholipids at neutral pH and reduced phospholipids at acidic pH) is considered to be the reason for this behavior. To gain insight into the pH-induced structural–functional interplay we have systematically evaluated conformational variations, thermodynamic stability of the protein and quaternary state of the conformers at both pH 7.0 and 4.0. Our findings suggest that change in pH allows alterations in native states of Prdx6 at pH 7.0 and 4.0 such that the changes make the protein resistant to thermal denaturation at low pH.
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Affiliation(s)
- Rimpy Kaur Chowhan
- Dr. B. R. Ambedkar Center for Biomedical Research, University of Delhi, Delhi, 110007, India
| | - Sunaina Hotumalani
- Dr. B. R. Ambedkar Center for Biomedical Research, University of Delhi, Delhi, 110007, India
| | - Hamidur Rahaman
- Department of Biotechnology, Manipur University, Imphal, 795003, India
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8
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Elko EA, Cunniff B, Seward DJ, Chia SB, Aboushousha R, van de Wetering C, van der Velden J, Manuel A, Shukla A, Heintz NH, Anathy V, van der Vliet A, Janssen-Heininger YMW. Peroxiredoxins and Beyond; Redox Systems Regulating Lung Physiology and Disease. Antioxid Redox Signal 2019; 31:1070-1091. [PMID: 30799628 PMCID: PMC6767868 DOI: 10.1089/ars.2019.7752] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Significance: The lung is a unique organ, as it is constantly exposed to air, and thus it requires a robust antioxidant defense system to prevent the potential damage from exposure to an array of environmental insults, including oxidants. The peroxiredoxin (PRDX) family plays an important role in scavenging peroxides and is critical to the cellular antioxidant defense system. Recent Advances: Exciting discoveries have been made to highlight the key features of PRDXs that regulate the redox tone. PRDXs do not act in isolation as they require the thioredoxin/thioredoxin reductase/NADPH, sulfiredoxin (SRXN1) redox system, and in some cases glutaredoxin/glutathione, for their reduction. Furthermore, the chaperone function of PRDXs, controlled by the oxidation state, demonstrates the versatility in redox regulation and control of cellular biology exerted by this class of proteins. Critical Issues: Despite the long-known observations that redox perturbations accompany a number of pulmonary diseases, surprisingly little is known about the role of PRDXs in the etiology of these diseases. In this perspective, we review the studies that have been conducted thus far to address the roles of PRDXs in lung disease, or experimental models used to study these diseases. Intriguing findings, such as the secretion of PRDXs and the formation of autoantibodies, raise a number of questions about the pathways that regulate secretion, redox status, and immune response to PRDXs. Future Directions: Further understanding of the mechanisms by which individual PRDXs control lung inflammation, injury, repair, chronic remodeling, and cancer, and the importance of PRDX oxidation state, configuration, and client proteins that govern these processes is needed.
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Affiliation(s)
- Evan A Elko
- Department of Pathology and Laboratory Medicine, Larner College of Medicine, University of Vermont, Burlington, Vermont
| | - Brian Cunniff
- Department of Pathology and Laboratory Medicine, Larner College of Medicine, University of Vermont, Burlington, Vermont
| | - David J Seward
- Department of Pathology and Laboratory Medicine, Larner College of Medicine, University of Vermont, Burlington, Vermont
| | - Shi Biao Chia
- Department of Pathology and Laboratory Medicine, Larner College of Medicine, University of Vermont, Burlington, Vermont
| | - Reem Aboushousha
- Department of Pathology and Laboratory Medicine, Larner College of Medicine, University of Vermont, Burlington, Vermont
| | - Cheryl van de Wetering
- Department of Pathology and Laboratory Medicine, Larner College of Medicine, University of Vermont, Burlington, Vermont
| | - Jos van der Velden
- Department of Pathology and Laboratory Medicine, Larner College of Medicine, University of Vermont, Burlington, Vermont
| | - Allison Manuel
- Department of Pathology and Laboratory Medicine, Larner College of Medicine, University of Vermont, Burlington, Vermont
| | - Arti Shukla
- Department of Pathology and Laboratory Medicine, Larner College of Medicine, University of Vermont, Burlington, Vermont
| | - Nicholas H Heintz
- Department of Pathology and Laboratory Medicine, Larner College of Medicine, University of Vermont, Burlington, Vermont
| | - Vikas Anathy
- Department of Pathology and Laboratory Medicine, Larner College of Medicine, University of Vermont, Burlington, Vermont
| | - Albert van der Vliet
- Department of Pathology and Laboratory Medicine, Larner College of Medicine, University of Vermont, Burlington, Vermont
| | - Yvonne M W Janssen-Heininger
- Department of Pathology and Laboratory Medicine, Larner College of Medicine, University of Vermont, Burlington, Vermont
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9
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Antioxidants Special Issue: Peroxiredoxin 6 as a Unique Member of the Peroxiredoxin Family. Antioxidants (Basel) 2019; 8:antiox8040107. [PMID: 31010116 PMCID: PMC6523856 DOI: 10.3390/antiox8040107] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Accepted: 04/17/2019] [Indexed: 12/15/2022] Open
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10
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Feinstein SI. Mouse Models of Genetically Altered Peroxiredoxin 6. Antioxidants (Basel) 2019; 8:E77. [PMID: 30934692 PMCID: PMC6523285 DOI: 10.3390/antiox8040077] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Revised: 03/07/2019] [Accepted: 03/20/2019] [Indexed: 01/07/2023] Open
Abstract
Peroxiredoxin 6 (Prdx6) has been shown to have three enzymatic activities: peroxidase, phospholipase A₂ (PLA₂) and acyl transferase. The peroxidase activity is unusual, as it is capable of reducing phospholipid hydroperoxides (as well as hydrogen peroxide and short chain organic peroxides). Knockout and overexpressing mice have been produced that demonstrate the effect that eliminating or overproducing Prdx6 has on the animals' physiology. In addition, mutations in various amino acids of Prdx6 have been identified that interfere with different enzymatic functions as well as protein transport. These mutations were originally characterized biochemically; subsequently, several knock-in mouse strains have been produced, each containing one mutation. These mice include the S32T knock-in that affects protein transport, the C47S knock-in that inactivates the peroxidase enzymatic activity, the D140A knock-in that inactivates the PLA₂ enzymatic activity and the H26A knock-in that inactivates the peroxidase and blocks binding to phospholipids. This review summarizes the properties of these mice based upon studies conducted with the knockout, overexpressing and knock-in mice and the effect of the genetic changes on the biochemistry and physiology of these mice. The availability of these mice is also briefly discussed.
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Affiliation(s)
- Sheldon I Feinstein
- Institute for Environmental Medicine, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA.
- Peroxitech, Ltd., Philadelphia, PA 19104, USA.
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Non-Mammalian Prdx6 Enzymes (Proteins with 1-Cys Prdx Mechanism) Display PLA₂ Activity Similar to the Human Orthologue. Antioxidants (Basel) 2019; 8:antiox8030052. [PMID: 30832204 PMCID: PMC6466579 DOI: 10.3390/antiox8030052] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2019] [Revised: 02/20/2019] [Accepted: 02/22/2019] [Indexed: 12/31/2022] Open
Abstract
Mammalian peroxiredoxin class 6 (Prdx6) are bifunctional enzymes. Non-mammalian Prdx6 enzymes display Cys-based peroxidase activity, but to date their putative phospholipase A2 (PLA2 activities) has not been experimentally investigated. Initially, we observed that five non-mammalian Prdx6 enzymes (enzymes from Arabidopsis thaliana (AtPER1), Triticum aestivum (TaPER1), Pseudomonas aeruginosa (PaLsfA) and Aspergillus fumigatus (AfPrx1 and AfPrxC)) present features compatible with PLA2 activities in mammalian Prdx6 by amino acid sequences alignment and tertiary structure modeling. Employing unilamellar liposomes with tracer amounts of [3H]-1,2-Dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and thin layer chromatography, all the tested non-mammalian Prdx6 enzymes displayed PLA2 activities, with values ranging from 3.4 to 6.1 nmol/min/mg protein. It was previously shown that Thr177 phosphorylation of human Prdx6 increases its PLA2 activity, especially at neutral pH. Therefore, we investigated if human Erk2 kinase could also phosphorylate homologous Thr residues in non-mammalian Prdx6 proteins. We observed phosphorylation of the conserved Thr in three out of the five non-mammalian Prdx enzymes by mass spectrometry. In the case of the mitochondrial Prdx6 from A. fumigatus (AfPrxC), we also observed phosphorylation by western blot, and as a consequence, the PLA2 activity was increased in acidic and neutral conditions by the human Erk2 kinase treatment. The possible physiological meanings of these PLA2 activities described open new fields for future research.
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12
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Arevalo JA, Vázquez-Medina JP. The Role of Peroxiredoxin 6 in Cell Signaling. Antioxidants (Basel) 2018; 7:antiox7120172. [PMID: 30477202 PMCID: PMC6316032 DOI: 10.3390/antiox7120172] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2018] [Revised: 11/17/2018] [Accepted: 11/20/2018] [Indexed: 12/20/2022] Open
Abstract
Peroxiredoxin 6 (Prdx6, 1-cys peroxiredoxin) is a unique member of the peroxiredoxin family that, in contrast to other mammalian peroxiredoxins, lacks a resolving cysteine and uses glutathione and π glutathione S-transferase to complete its catalytic cycle. Prdx6 is also the only peroxiredoxin capable of reducing phospholipid hydroperoxides through its glutathione peroxidase (Gpx) activity. In addition to its peroxidase activity, Prdx6 expresses acidic calcium-independent phospholipase A2 (aiPLA2) and lysophosphatidylcholine acyl transferase (LPCAT) activities in separate catalytic sites. Prdx6 plays crucial roles in lung phospholipid metabolism, lipid peroxidation repair, and inflammatory signaling. Here, we review how the distinct activities of Prdx6 are regulated during physiological and pathological conditions, in addition to the role of Prdx6 in cellular signaling and disease.
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Affiliation(s)
- José A Arevalo
- Department of Integrative Biology, University of California, Berkeley, CA, 94705, USA.
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13
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Wahlig S, Lovatt M, Mehta JS. Functional role of peroxiredoxin 6 in the eye. Free Radic Biol Med 2018; 126:210-220. [PMID: 30120980 DOI: 10.1016/j.freeradbiomed.2018.08.017] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/01/2018] [Revised: 07/13/2018] [Accepted: 08/14/2018] [Indexed: 10/28/2022]
Abstract
Peroxiredoxin 6 (Prdx6) is the only mammalian 1-Cys member of the Prdx family, a group of enzymes which share the ability to reduce peroxides. In addition to its peroxidase function, Prdx6 also demonstrates phospholipase A2 and lysophosphatidylcholine acyl transferase (LPCAT) activities. These enzymatic activities play an important role in regenerating oxidized membrane phospholipids and maintaining an appropriate balance of intracellular reactive oxygen species. Development of clinical pathologies, including those within the eye, have been linked to dysregulation of Prdx6 function. Interplay between external stressors like exposure to UV light, transforming growth factor β (TGF-β), and hyperglycemia in conjunction with diminished Prdx6 levels and loss of redox balance is associated with cellular changes in a variety of ophthalmic pathologies including cataracts, glaucoma, and retinal degeneration. Many of these cellular abnormalities can be rescued through supplementation with exogenous Prdx6. Additionally, corneal endothelial cells have been found to express high levels of Prdx6 in the plasma membrane. These findings highlight the importance of Prdx6 as an essential regulator of oxidative stress in the eye.
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Affiliation(s)
- Stephen Wahlig
- Tissue Engineering and Stem Cell Group, Singapore Eye Research Institute (SERI), Singapore; Duke University School of Medicine, Durham, NC, USA
| | - Matthew Lovatt
- Tissue Engineering and Stem Cell Group, Singapore Eye Research Institute (SERI), Singapore
| | - Jodhbir S Mehta
- Tissue Engineering and Stem Cell Group, Singapore Eye Research Institute (SERI), Singapore; Singapore National Eye Center (SNEC), Singapore; Eye-ACP, Duke-NUS Graduate Medical School, Singapore.
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14
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Fisher AB. The phospholipase A 2 activity of peroxiredoxin 6. J Lipid Res 2018; 59:1132-1147. [PMID: 29716959 DOI: 10.1194/jlr.r082578] [Citation(s) in RCA: 77] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Revised: 04/30/2018] [Indexed: 12/21/2022] Open
Abstract
Peroxiredoxin 6 (Prdx6) is a Ca2+-independent intracellular phospholipase A2 (called aiPLA2) that is localized to cytosol, lysosomes, and lysosomal-related organelles. Activity is minimal at cytosolic pH but is increased significantly with enzyme phosphorylation, at acidic pH, and in the presence of oxidized phospholipid substrate; maximal activity with phosphorylated aiPLA2 is ∼2 µmol/min/mg protein. Prdx6 is a "moonlighting" protein that also expresses glutathione peroxidase and lysophosphatidylcholine acyl transferase activities. The catalytic site for aiPLA2 activity is an S32-H26-D140 triad; S32-H26 is also the phospholipid binding site. Activity is inhibited by a serine "protease" inhibitor (diethyl p-nitrophenyl phosphate), an analog of the PLA2 transition state [1-hexadecyl-3-(trifluoroethyl)-sn-glycero-2-phosphomethanol (MJ33)], and by two naturally occurring proteins (surfactant protein A and p67phox), but not by bromoenol lactone. aiPLA2 activity has important physiological roles in the turnover (synthesis and degradation) of lung surfactant phospholipids, in the repair of peroxidized cell membranes, and in the activation of NADPH oxidase type 2 (NOX2). The enzyme has been implicated in acute lung injury, carcinogenesis, neurodegenerative diseases, diabetes, male infertility, and sundry other conditions, although its specific roles have not been well defined. Protein mutations and animal models are now available to further investigate the roles of Prdx6-aiPLA2 activity in normal and pathological physiology.
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Affiliation(s)
- Aron B Fisher
- Institute for Environmental Medicine of the Department of Physiology, University of Pennsylvania, Philadelphia, PA 19103
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15
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Fisher AB. Peroxiredoxin 6 in the repair of peroxidized cell membranes and cell signaling. Arch Biochem Biophys 2017; 617:68-83. [PMID: 27932289 PMCID: PMC5810417 DOI: 10.1016/j.abb.2016.12.003] [Citation(s) in RCA: 125] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2016] [Revised: 12/02/2016] [Accepted: 12/03/2016] [Indexed: 12/12/2022]
Abstract
Peroxiredoxin 6 represents a widely distributed group of peroxiredoxins that contain a single conserved cysteine in the protein monomer (1-cys Prdx). The cys when oxidized to the sulfenic form is reduced with glutathione (GSH) catalyzed by the π isoform of GSH-S-transferase. Three enzymatic activities of the protein have been described:1) peroxidase with H2O2, short chain hydroperoxides, and phospholipid hydroperoxides as substrates; 2) phospholipase A2 (PLA2); and 3) lysophosphatidylcholine acyl transferase (LPCAT). These activities have important physiological roles in antioxidant defense, turnover of cellular phospholipids, and the generation of superoxide anion via initiation of the signaling cascade for activation of NADPH oxidase (type 2). The ability of Prdx6 to reduce peroxidized cell membrane phospholipids (peroxidase activity) and also to replace the oxidized sn-2 fatty acyl group through hydrolysis/reacylation (PLA2 and LPCAT activities) provides a complete system for the repair of peroxidized cell membranes.
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Affiliation(s)
- Aron B Fisher
- Institute for Environmental Medicine of the Department of Physiology, University of Pennsylvania, 3620 Hamilton Walk, 1 John Morgan Building, Philadelphia, PA, United States.
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16
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Olmeda B, Martínez-Calle M, Pérez-Gil J. Pulmonary surfactant metabolism in the alveolar airspace: Biogenesis, extracellular conversions, recycling. Ann Anat 2016; 209:78-92. [PMID: 27773772 DOI: 10.1016/j.aanat.2016.09.008] [Citation(s) in RCA: 73] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Revised: 09/22/2016] [Accepted: 09/25/2016] [Indexed: 01/03/2023]
Abstract
Pulmonary surfactant is a lipid-protein complex that lines and stabilizes the respiratory interface in the alveoli, allowing for gas exchange during the breathing cycle. At the same time, surfactant constitutes the first line of lung defense against pathogens. This review presents an updated view on the processes involved in biogenesis and intracellular processing of newly synthesized and recycled surfactant components, as well as on the extracellular surfactant transformations before and after the formation of the surface active film at the air-water interface. Special attention is paid to the crucial regulation of surfactant homeostasis, because its disruption is associated with several lung pathologies.
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Affiliation(s)
- Bárbara Olmeda
- Department of Biochemistry, Faculty of Biology, and Research Institute "Hospital 12 de Octubre", Complutense University, 28040 Madrid, Spain
| | - Marta Martínez-Calle
- Department of Biochemistry, Faculty of Biology, and Research Institute "Hospital 12 de Octubre", Complutense University, 28040 Madrid, Spain
| | - Jesus Pérez-Gil
- Department of Biochemistry, Faculty of Biology, and Research Institute "Hospital 12 de Octubre", Complutense University, 28040 Madrid, Spain.
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