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Hajdú G, Szathmári C, Sőti C. Modeling Host-Pathogen Interactions in C. elegans: Lessons Learned from Pseudomonas aeruginosa Infection. Int J Mol Sci 2024; 25:7034. [PMID: 39000143 PMCID: PMC11241598 DOI: 10.3390/ijms25137034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2024] [Revised: 06/17/2024] [Accepted: 06/22/2024] [Indexed: 07/16/2024] Open
Abstract
Infections, such as that by the multiresistant opportunistic bacterial pathogen Pseudomonas aeruginosa, may pose a serious health risk, especially on vulnerable patient populations. The nematode Caenorhabditis elegans provides a simple organismal model to investigate both pathogenic mechanisms and the emerging role of innate immunity in host protection. Here, we review the virulence and infection strategies of P. aeruginosa and host defenses of C. elegans. We summarize the recognition mechanisms of patterns of pathogenesis, including novel pathogen-associated molecular patterns and surveillance immunity of translation, mitochondria, and lysosome-related organelles. We also review the regulation of antimicrobial and behavioral defenses by the worm's neuroendocrine system. We focus on how discoveries in this rich field align with well-characterized evolutionary conserved protective pathways, as well as on potential crossovers to human pathogenesis and innate immune responses.
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Affiliation(s)
- Gábor Hajdú
- Department of Molecular Biology, Semmelweis University, 1094 Budapest, Hungary
| | - Csenge Szathmári
- Department of Molecular Biology, Semmelweis University, 1094 Budapest, Hungary
| | - Csaba Sőti
- Department of Molecular Biology, Semmelweis University, 1094 Budapest, Hungary
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2
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Feng D, Qu L, Powell-Coffman JA. Whole genome profiling of short-term hypoxia induced genes and identification of HIF-1 binding sites provide insights into HIF-1 function in Caenorhabditis elegans. PLoS One 2024; 19:e0295094. [PMID: 38743782 PMCID: PMC11093353 DOI: 10.1371/journal.pone.0295094] [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: 11/13/2023] [Accepted: 04/23/2024] [Indexed: 05/16/2024] Open
Abstract
Oxygen is essential to all the aerobic organisms. However, during normal development, disease and homeostasis, organisms are often challenged by hypoxia (oxygen deprivation). Hypoxia-inducible transcription factors (HIFs) are master regulators of hypoxia response and are evolutionarily conserved in metazoans. The homolog of HIF in the genetic model organism C. elegans is HIF-1. In this study, we aimed to understand short-term hypoxia response to identify HIF-1 downstream genes and identify HIF-1 direct targets in C. elegans. The central research questions were: (1) which genes are differentially expressed in response to short-term hypoxia? (2) Which of these changes in gene expression are dependent upon HIF-1 function? (3) Are any of these hif-1-dependent genes essential to survival in hypoxia? (4) Which genes are the direct targets of HIF-1? We combine whole genome gene expression analyses and chromatin immunoprecipitation sequencing (ChIP-seq) experiments to address these questions. In agreement with other published studies, we report that HIF-1-dependent hypoxia-responsive genes are involved in metabolism and stress response. Some HIF-1-dependent hypoxia-responsive genes like efk-1 and phy-2 dramatically impact survival in hypoxic conditions. Genes regulated by HIF-1 and hypoxia overlap with genes responsive to hydrogen sulfide, also overlap with genes regulated by DAF-16. The genomic regions that co-immunoprecipitate with HIF-1 are strongly enriched for genes involved in stress response. Further, some of these potential HIF-1 direct targets are differentially expressed under short-term hypoxia or are differentially regulated by mutations that enhance HIF-1 activity.
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Affiliation(s)
- Dingxia Feng
- Department of Genetics, Development and Cell Biology, Iowa State University, Ames, Iowa, United States of America
| | - Long Qu
- Department of Statistics, Iowa State University, Ames, Iowa, United States of America
| | - Jo Anne Powell-Coffman
- Department of Genetics, Development and Cell Biology, Iowa State University, Ames, Iowa, United States of America
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3
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Feng D, Qu L, Powell-Coffman JA. Transcriptome analyses describe the consequences of persistent HIF-1 over-activation in Caenorhabditis elegans. PLoS One 2024; 19:e0295093. [PMID: 38517909 PMCID: PMC10959373 DOI: 10.1371/journal.pone.0295093] [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: 11/13/2023] [Accepted: 02/20/2024] [Indexed: 03/24/2024] Open
Abstract
Metazoan animals rely on oxygen for survival, but during normal development and homeostasis, animals are often challenged by hypoxia (low oxygen). In metazoans, many of the critical hypoxia responses are mediated by the evolutionarily conserved hypoxia-inducible transcription factors (HIFs). The stability and activity of HIF complexes are strictly regulated. In the model organism C. elegans, HIF-1 stability and activity are negatively regulated by VHL-1, EGL-9, RHY-1 and SWAN-1. Importantly, C. elegans mutants carrying strong loss-of-function mutations in these genes are viable, and this provides opportunities to interrogate the molecular consequences of persistent HIF-1 over-activation. We find that the genome-wide gene expression patterns are compellingly similar in these mutants, supporting models in which RHY-1, VHL-1 and EGL-9 function in common pathway(s) to regulate HIF-1 activity. These studies illuminate the diversified biological roles played by HIF-1, including metabolism and stress response. Genes regulated by persistent HIF-1 over-activation overlap with genes responsive to pathogens, and they overlap with genes regulated by DAF-16. As crucial stress regulators, HIF-1 and DAF-16 converge on key stress-responsive genes and function synergistically to enable hypoxia survival.
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Affiliation(s)
- Dingxia Feng
- Department of Genetics, Development and Cell Biology, Iowa State University, Ames, Iowa, United States of America
| | - Long Qu
- Department of Statistics, Iowa State University, Ames, Iowa, United States of America
| | - Jo Anne Powell-Coffman
- Department of Genetics, Development and Cell Biology, Iowa State University, Ames, Iowa, United States of America
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4
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Feng D, Qu L. Transcriptome analyses describe the consequences of persistent HIF-1 over-activation in Caenorhabditis elegans. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.15.567311. [PMID: 38014086 PMCID: PMC10680707 DOI: 10.1101/2023.11.15.567311] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2023]
Abstract
Metazoan animals rely on oxygen for survival, but during normal development and homeostasis, animals are often challenged by hypoxia (low oxygen). In metazoans, many of the critical hypoxia responses are mediated by the evolutionarily conserved hypoxia-inducible transcription factors (HIFs). The stability and activity of HIF complexes are strictly regulated. In the model organism C. elegans, HIF-1 stability and activity are negatively regulated by VHL-1, EGL-9, RHY-1 and SWAN-1. Importantly, C. elegans mutants carrying strong loss-of-function mutations in these genes are viable, and this provides opportunities to interrogate the molecular consequences of persistent HIF-1 over-activation. We find that the genome-wide gene expression patterns are compellingly similar in these mutants, supporting models in which RHY-1, SWAN-1 and EGL-9 function in common pathway(s) to regulate HIF-1 activity. These studies illuminate the diversified biological roles played by HIF-1, including metabolism, hypoxia and other stress responses, reproduction and development. Genes regulated by persistent HIF-1 over-activation overlap with genes responsive to pathogens, and they overlap with genes regulated by DAF-16. As crucial stress regulators, HIF-1 and DAF-16 converge on key stress-responsive genes and function synergistically to enable hypoxia survival.
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Affiliation(s)
- Dingxia Feng
- Department of Genetics, Development and Cell Biology, Iowa State University, Ames, Iowa, United States of America
| | - Long Qu
- Department of Statistics, Iowa State University, Ames, Iowa, United States of America
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5
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Wang B, Pandey T, Long Y, Delgado-Rodriguez SE, Daugherty MD, Ma DK. Co-opted genes of algal origin protect C. elegans against cyanogenic toxins. Curr Biol 2022; 32:4941-4948.e3. [PMID: 36223775 PMCID: PMC9691542 DOI: 10.1016/j.cub.2022.09.041] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2022] [Revised: 08/31/2022] [Accepted: 09/21/2022] [Indexed: 11/06/2022]
Abstract
Amygdalin is a cyanogenic glycoside enriched in the tissues of many edible plants, including seeds of stone fruits such as cherry (Prunus avium), peach (Prunus persica), and apple (Malus domestica). These plants biosynthesize amygdalin in defense against herbivore animals, as amygdalin generates poisonous cyanide upon plant tissue destruction.1,2,3,4 Poisonous to many animals, amygdalin-derived cyanide is detoxified by potent enzymes commonly found in bacteria and plants but not most animals.5 Here we show that the nematode C. elegans can detoxify amygdalin by a genetic pathway comprising cysl-1, egl-9, hif-1, and cysl-2. A screen of a natural product library for hypoxia-independent regulators of HIF-1 identifies amygdalin as a potent activator of cysl-2, a HIF-1 transcriptional target that encodes a cyanide detoxification enzyme in C. elegans. As a cysl-2 paralog similarly essential for amygdalin resistance, cysl-1 encodes a protein homologous to cysteine biosynthetic enzymes in bacteria and plants but functionally co-opted in C. elegans. We identify exclusively HIF-activating egl-9 mutations in a cysl-1 suppressor screen and show that cysl-1 confers amygdalin resistance by regulating HIF-1-dependent cysl-2 transcription to protect against amygdalin toxicity. Phylogenetic analysis indicates that cysl-1 and cysl-2 were likely acquired from green algae through horizontal gene transfer (HGT) and functionally co-opted in protection against amygdalin. Since acquisition, these two genes evolved division of labor in a cellular circuit to detect and detoxify cyanide. Thus, algae-to-nematode HGT and subsequent gene function co-option events may facilitate host survival and adaptation to adverse environmental stresses and biogenic toxins.
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Affiliation(s)
- Bingying Wang
- Cardiovascular Research Institute and Department of Physiology, University of California, San Francisco, San Francisco, CA, USA
| | - Taruna Pandey
- Cardiovascular Research Institute and Department of Physiology, University of California, San Francisco, San Francisco, CA, USA
| | - Yong Long
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
| | | | - Matthew D Daugherty
- Department of Molecular Biology, University of California, San Diego, San Diego, CA, USA.
| | - Dengke K Ma
- Cardiovascular Research Institute and Department of Physiology, University of California, San Francisco, San Francisco, CA, USA; Innovative Genomics Institute, University of California, Berkeley, Berkeley, CA, USA.
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6
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Vora M, Pyonteck SM, Popovitchenko T, Matlack TL, Prashar A, Kane NS, Favate J, Shah P, Rongo C. The hypoxia response pathway promotes PEP carboxykinase and gluconeogenesis in C. elegans. Nat Commun 2022; 13:6168. [PMID: 36257965 PMCID: PMC9579151 DOI: 10.1038/s41467-022-33849-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Accepted: 10/05/2022] [Indexed: 12/31/2022] Open
Abstract
Actively dividing cells, including some cancers, rely on aerobic glycolysis rather than oxidative phosphorylation to generate energy, a phenomenon termed the Warburg effect. Constitutive activation of the Hypoxia Inducible Factor (HIF-1), a transcription factor known for mediating an adaptive response to oxygen deprivation (hypoxia), is a hallmark of the Warburg effect. HIF-1 is thought to promote glycolysis and suppress oxidative phosphorylation. Here, we instead show that HIF-1 can promote gluconeogenesis. Using a multiomics approach, we reveal the genomic, transcriptomic, and metabolomic landscapes regulated by constitutively active HIF-1 in C. elegans. We use RNA-seq and ChIP-seq under aerobic conditions to analyze mutants lacking EGL-9, a key negative regulator of HIF-1. We integrate these approaches to identify over two hundred genes directly and functionally upregulated by HIF-1, including the PEP carboxykinase PCK-1, a rate-limiting mediator of gluconeogenesis. This activation of PCK-1 by HIF-1 promotes survival in response to both oxidative and hypoxic stress. Our work identifies functional direct targets of HIF-1 in vivo, comprehensively describing the metabolome induced by HIF-1 activation in an organism.
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Affiliation(s)
- Mehul Vora
- The Waksman Institute, Rutgers The State University of New Jersey, Piscataway, NJ, 08854, USA
| | - Stephanie M Pyonteck
- The Waksman Institute, Rutgers The State University of New Jersey, Piscataway, NJ, 08854, USA
| | - Tatiana Popovitchenko
- The Waksman Institute, Rutgers The State University of New Jersey, Piscataway, NJ, 08854, USA
| | - Tarmie L Matlack
- The Waksman Institute, Rutgers The State University of New Jersey, Piscataway, NJ, 08854, USA
| | - Aparna Prashar
- The Department of Genetics, Rutgers The State University of New Jersey, Piscataway, NJ, 08854, USA
| | - Nanci S Kane
- The Waksman Institute, Rutgers The State University of New Jersey, Piscataway, NJ, 08854, USA
| | - John Favate
- The Department of Genetics, Rutgers The State University of New Jersey, Piscataway, NJ, 08854, USA
| | - Premal Shah
- The Department of Genetics, Rutgers The State University of New Jersey, Piscataway, NJ, 08854, USA
| | - Christopher Rongo
- The Waksman Institute, Rutgers The State University of New Jersey, Piscataway, NJ, 08854, USA. .,The Department of Genetics, Rutgers The State University of New Jersey, Piscataway, NJ, 08854, USA.
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7
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Mack HID, Kremer J, Albertini E, Mack EKM, Jansen-Dürr P. Regulation of fatty acid desaturase- and immunity gene-expression by mbk-1/DYRK1A in Caenorhabditis elegans. BMC Genomics 2022; 23:25. [PMID: 34983389 PMCID: PMC8729107 DOI: 10.1186/s12864-021-08176-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Accepted: 11/08/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND In the nematode Caenorhabditis elegans, longevity in response to germline ablation, but not in response to reduced insulin/IGF1-like signaling, is strongly dependent on the conserved protein kinase minibrain-related kinase 1 (MBK-1). In humans, the MBK-1 ortholog DYRK1A is associated with a variety of disorders, most prominently with neurological defects observed in Down syndrome. To better understand mbk-1's physiological roles and their dependence on genetic background, we analyzed the influence of mbk-1 loss on the transcriptomes of wildtype and long-lived, germline-deficient or insulin-receptor defective, C. elegans strains by RNA-sequencing. RESULTS mbk-1 loss elicited global changes in transcription that were less pronounced in insulin-receptor mutant than in germline-deficient or wildtype C. elegans. Irrespective of genetic background, mbk-1 regulated genes were enriched for functions in biological processes related to organic acid metabolism and pathogen defense. qPCR-studies confirmed mbk-1 dependent induction of all three C. elegans Δ9-fatty acid desaturases, fat-5, fat-6 and fat-7, in wildtype, germline-deficient and insulin-receptor mutant strains. Conversely, mbk-1 dependent expression patterns of selected pathogen resistance genes, including asp-12, dod-24 and drd-50, differed across the genetic backgrounds examined. Finally, cth-1 and cysl-2, two genes which connect pathogen resistance to the metabolism of the gaseous messenger and lifespan regulator hydrogen sulfide (H2S), were commonly suppressed by mbk-1 loss only in wildtype and germline-deficient, but not in insulin-receptor mutant C. elegans. CONCLUSION Our work reveals previously unknown roles of C. elegans mbk-1 in the regulation of fatty acid desaturase- and H2S metabolic-genes. These roles are only partially dependent on genetic background. Considering the particular importance of fatty acid desaturation and H2S for longevity of germline-deficient C. elegans, we propose that these processes at least in part account for the previous observation that mbk-1 preferentially regulates lifespan in these worms.
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Affiliation(s)
- Hildegard I D Mack
- Institute for Biomedical Aging Research, University of Innsbruck, Rennweg 10, 6020, Innsbruck, Austria.
| | - Jennifer Kremer
- Department of Hematology, Oncology and Immunology, Philipps-University Marburg, and University Hospital Giessen and Marburg, Baldingerstrasse, 35032, Marburg, Germany
| | - Eva Albertini
- Institute for Biomedical Aging Research, University of Innsbruck, Rennweg 10, 6020, Innsbruck, Austria
| | - Elisabeth K M Mack
- Department of Hematology, Oncology and Immunology, Philipps-University Marburg, and University Hospital Giessen and Marburg, Baldingerstrasse, 35032, Marburg, Germany
| | - Pidder Jansen-Dürr
- Institute for Biomedical Aging Research, University of Innsbruck, Rennweg 10, 6020, Innsbruck, Austria.
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8
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Feng D, Zhai Z, Shao Z, Zhang Y, Powell-Coffman JA. Crosstalk in oxygen homeostasis networks: SKN-1/NRF inhibits the HIF-1 hypoxia-inducible factor in Caenorhabditis elegans. PLoS One 2021; 16:e0249103. [PMID: 34242227 PMCID: PMC8270126 DOI: 10.1371/journal.pone.0249103] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Accepted: 06/24/2021] [Indexed: 11/30/2022] Open
Abstract
During development, homeostasis, and disease, organisms must balance responses that allow adaptation to low oxygen (hypoxia) with those that protect cells from oxidative stress. The evolutionarily conserved hypoxia-inducible factors are central to these processes, as they orchestrate transcriptional responses to oxygen deprivation. Here, we employ genetic strategies in C. elegans to identify stress-responsive genes and pathways that modulate the HIF-1 hypoxia-inducible factor and facilitate oxygen homeostasis. Through a genome-wide RNAi screen, we show that RNAi-mediated mitochondrial or proteasomal dysfunction increases the expression of hypoxia-responsive reporter Pnhr-57::GFP in C. elegans. Interestingly, only a subset of these effects requires hif-1. Of particular importance, we found that skn-1 RNAi increases the expression of hypoxia-responsive reporter Pnhr-57::GFP and elevates HIF-1 protein levels. The SKN-1/NRF transcription factor has been shown to promote oxidative stress resistance. We present evidence that the crosstalk between HIF-1 and SKN-1 is mediated by EGL-9, the prolyl hydroxylase that targets HIF-1 for oxygen-dependent degradation. Treatment that induces SKN-1, such as heat or gsk-3 RNAi, increases expression of a Pegl-9::GFP reporter, and this effect requires skn-1 function and a putative SKN-1 binding site in egl-9 regulatory sequences. Collectively, these data support a model in which SKN-1 promotes egl-9 transcription, thereby inhibiting HIF-1. We propose that this interaction enables animals to adapt quickly to changes in cellular oxygenation and to better survive accompanying oxidative stress.
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Affiliation(s)
- Dingxia Feng
- Department of Genetics, Development and Cell Biology, Iowa State University, Ames, Iowa, United States of America
| | - Zhiwei Zhai
- Department of Genetics, Development and Cell Biology, Iowa State University, Ames, Iowa, United States of America
| | - Zhiyong Shao
- Department of Genetics, Development and Cell Biology, Iowa State University, Ames, Iowa, United States of America
| | - Yi Zhang
- Department of Genetics, Development and Cell Biology, Iowa State University, Ames, Iowa, United States of America
| | - Jo Anne Powell-Coffman
- Department of Genetics, Development and Cell Biology, Iowa State University, Ames, Iowa, United States of America
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9
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Kruempel JCP, Miller HA, Schaller ML, Fretz A, Howington M, Sarker M, Huang S, Leiser SF. Hypoxic response regulators RHY-1 and EGL-9/PHD promote longevity through a VHL-1-independent transcriptional response. GeroScience 2020; 42:1621-1633. [PMID: 32399915 DOI: 10.1007/s11357-020-00194-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Accepted: 04/15/2020] [Indexed: 12/19/2022] Open
Abstract
HIF-1-mediated adaptation to changes in oxygen availability is a critical aspect of healthy physiology. HIF is regulated by a conserved mechanism whereby EGLN/PHD family members hydroxylate HIF in an oxygen-dependent manner, targeting it for ubiquitination by Von-Hippel-Lindau (VHL) family members, leading to its proteasomal degradation. The activity of the only C. elegans PHD family member, EGL-9, is also regulated by a hydrogen sulfide sensing cysteine-synthetase-like protein, CYSL-1, which is, in turn, regulated by RHY-1/acyltransferase. Over the last decade, multiple seminal studies have established a role for the hypoxic response in regulating longevity, with mutations in vhl-1 substantially extending C. elegans lifespan through a HIF-1-dependent mechanism. However, studies on other components of the hypoxic signaling pathway that similarly stabilize HIF-1 have shown more mixed results, suggesting that mutations in egl-9 and rhy-1 frequently fail to extend lifespan. Here, we show that egl-9 and rhy-1 mutants suppress the long-lived phenotype of vhl-1 mutants. We also show that RNAi of rhy-1 extends lifespan of wild-type worms while decreasing lifespan of vhl-1 mutant worms. We further identify VHL-1-independent gene expression changes mediated by EGL-9 and RHY-1 and find that a subset of these genes contributes to longevity regulation. The resulting data suggest that changes in HIF-1 activity derived by interactions with EGL-9 likely contribute greatly to its role in regulation of longevity.
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Affiliation(s)
- Joseph C P Kruempel
- Molecular & Integrative Physiology Department, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Hillary A Miller
- Cellular and Molecular Biology Graduate Program, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Megan L Schaller
- Molecular & Integrative Physiology Department, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Abrielle Fretz
- Molecular & Integrative Physiology Department, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Marshall Howington
- Cellular and Molecular Biology Graduate Program, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Marjana Sarker
- Molecular & Integrative Physiology Department, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Shijiao Huang
- Molecular & Integrative Physiology Department, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Scott F Leiser
- Molecular & Integrative Physiology Department, University of Michigan, Ann Arbor, MI, 48109, USA. .,Department of Internal Medicine, University of Michigan, Ann Arbor, MI, 48109, USA.
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Abstract
Recent years have witnessed an emergence of interest in understanding metabolic changes associated with immune responses, termed immunometabolism. As oxygen is central to all aerobic metabolism, hypoxia is now recognized to contribute fundamentally to inflammatory and immune responses. Studies from a number of groups have implicated a prominent role for oxygen metabolism and hypoxia in innate immunity of healthy tissue (physiologic hypoxia) and during active inflammation (inflammatory hypoxia). This inflammatory hypoxia emanates from a combination of recruited inflammatory cells (e.g., neutrophils, eosinophils, and monocytes), high rates of oxidative metabolism, and the activation of multiple oxygen-consuming enzymes during inflammation. These localized shifts toward hypoxia have identified a prominent role for the transcription factor hypoxia-inducible factor (HIF) in the regulation of innate immunity. Such studies have provided new and enlightening insight into our basic understanding of immune mechanisms, and extensions of these findings have identified potential therapeutic targets. In this review, we summarize recent literature around the topic of innate immunity and mucosal hypoxia with a focus on transcriptional responses mediated by HIF.
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Affiliation(s)
- Sean P Colgan
- Department of Medicine, University of Colorado School of Medicine, Aurora, Colorado 80045, USA;
- Mucosal Inflammation Program, University of Colorado School of Medicine, Aurora, Colorado 80045, USA
| | - Glenn T Furuta
- Mucosal Inflammation Program, University of Colorado School of Medicine, Aurora, Colorado 80045, USA
- Department of Pediatrics, University of Colorado School of Medicine, Aurora, Colorado 80045, USA
| | - Cormac T Taylor
- UCD Conway Institute, Systems Biology Ireland and School of Medicine, University College Dublin, Belfield, Dublin 4, Ireland
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11
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Burton NO, Riccio C, Dallaire A, Price J, Jenkins B, Koulman A, Miska EA. Cysteine synthases CYSL-1 and CYSL-2 mediate C. elegans heritable adaptation to P. vranovensis infection. Nat Commun 2020; 11:1741. [PMID: 32269224 PMCID: PMC7142082 DOI: 10.1038/s41467-020-15555-8] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2019] [Accepted: 03/19/2020] [Indexed: 11/09/2022] Open
Abstract
Parental exposure to pathogens can prime offspring immunity in diverse organisms. The mechanisms by which this heritable priming occurs are largely unknown. Here we report that the soil bacteria Pseudomonas vranovensis is a natural pathogen of the nematode Caenorhabditis elegans and that parental exposure of animals to P. vranovensis promotes offspring resistance to infection. Furthermore, we demonstrate a multigenerational enhancement of progeny survival when three consecutive generations of animals are exposed to P. vranovensis. By investigating the mechanisms by which animals heritably adapt to P. vranovensis infection, we found that parental infection by P. vranovensis results in increased expression of the cysteine synthases cysl-1 and cysl-2 and the regulator of hypoxia inducible factor rhy-1 in progeny, and that these three genes are required for adaptation to P. vranovensis. These observations establish a CYSL-1, CYSL-2, and RHY-1 dependent mechanism by which animals heritably adapt to infection.
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Affiliation(s)
- Nicholas O Burton
- Centre for Trophoblast Research, Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, CB2 3EG, UK.
| | - Cristian Riccio
- Gurdon Institute, University of Cambridge, Cambridge, CB2 1QN, UK
- Wellcome Sanger Institute, Wellcome Genome Campus, Cambridge, CB10 1SA, UK
| | - Alexandra Dallaire
- Gurdon Institute, University of Cambridge, Cambridge, CB2 1QN, UK
- Department of Genetics, University of Cambridge, Downing Street, Cambridge, CB2 3EH, UK
| | - Jonathan Price
- Gurdon Institute, University of Cambridge, Cambridge, CB2 1QN, UK
- Department of Genetics, University of Cambridge, Downing Street, Cambridge, CB2 3EH, UK
| | - Benjamin Jenkins
- Metabolic Research Laboratories, University of Cambridge, Cambridge, CB2 0QQ, UK
| | - Albert Koulman
- Metabolic Research Laboratories, University of Cambridge, Cambridge, CB2 0QQ, UK
| | - Eric A Miska
- Gurdon Institute, University of Cambridge, Cambridge, CB2 1QN, UK
- Wellcome Sanger Institute, Wellcome Genome Campus, Cambridge, CB10 1SA, UK
- Department of Genetics, University of Cambridge, Downing Street, Cambridge, CB2 3EH, UK
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12
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Romanelli-Credrez L, Doitsidou M, Alkema MJ, Salinas G. HIF-1 Has a Central Role in Caenorhabditis elegans Organismal Response to Selenium. Front Genet 2020; 11:63. [PMID: 32161616 PMCID: PMC7052493 DOI: 10.3389/fgene.2020.00063] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2019] [Accepted: 01/17/2020] [Indexed: 11/13/2022] Open
Abstract
Selenium is a trace element for most organisms; its deficiency and excess are detrimental. Selenium beneficial effects are mainly due to the role of the 21st genetically encoded amino acid selenocysteine (Sec). Selenium also exerts Sec-independent beneficial effects. Its harmful effects are thought to be mainly due to non-specific incorporation in protein synthesis. Yet the selenium response in animals is poorly understood. In Caenorhabditis elegans, Sec is genetically incorporated into a single selenoprotein. Similar to mammals, a 20-fold excess of the optimal selenium requirement is harmful. Sodium selenite (Na2SeO3) excess causes development retardation, impaired growth, and neurodegeneration of motor neurons. To study the organismal response to selenium we performed a genetic screen for C. elegans mutants that are resistant to selenite. We isolated non-sense and missense egl-9/EGLN mutants that confer robust resistance to selenium. In contrast, hif-1/HIF null mutant was highly sensitive to selenium, establishing a role for this transcription factor in the selenium response. We showed that EGL-9 regulates HIF-1 activity through VHL-1, and identified CYSL-1 as a key sensor that transduces the selenium signal. Finally, we showed that the key enzymes involved in sulfide and sulfite stress (sulfide quinone oxidoreductase and sulfite oxidase) are not required for selenium resistance. In contrast, knockout strains in the persulfide dioxygenase ETHE-1 and the sulfurtransferase MPST-7 affect the organismal response to selenium. In sum, our results identified a transcriptional pathway as well as enzymes possibly involved in the organismal selenium response.
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Affiliation(s)
- Laura Romanelli-Credrez
- Laboratorio de Biología de Gusanos. Unidad Mixta, Departamento de Biociencias, Facultad de Química, Universidad de la República-Institut Pasteur de Montevideo, Montevideo, Uruguay
| | - Maria Doitsidou
- Centre for Discovery Brain Sciences (CDBS), University of Edinburgh, Edinburgh, United Kingdom
| | - Mark J Alkema
- Neurobiology Department, University of Massachusetts Medical School, Worcester, MA, United States
| | - Gustavo Salinas
- Laboratorio de Biología de Gusanos. Unidad Mixta, Departamento de Biociencias, Facultad de Química, Universidad de la República-Institut Pasteur de Montevideo, Montevideo, Uruguay
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Ruiz CE, Manuguerra S, Curcuraci E, Santulli A, Messina CM. Carbamazepine, cadmium chloride and polybrominated diphenyl ether-47, synergistically modulate the expression of antioxidants and cell cycle biomarkers, in the marine fish cell line SAF-1. MARINE ENVIRONMENTAL RESEARCH 2020; 154:104844. [PMID: 31784109 DOI: 10.1016/j.marenvres.2019.104844] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Revised: 11/08/2019] [Accepted: 11/20/2019] [Indexed: 06/10/2023]
Abstract
A wide range of contaminants, industrial by-products, plastics, and pharmaceutics belonging to various categories, have been found in sea water. Although these compounds are detected at concentrations that might be considered as sub-lethal, under certain conditions they could act synergistically producing unexpected effects in term of toxicity or perturbation of biochemical markers leading to standard pathway. In this study, the Sparus aurata fibroblast cell line SAF-1, was exposed to increasing concentrations of carbamazepine (CBZ), polybrominated diphenyl ether 47 (BDE-47) and cadmium chloride (CdCl2) until 72 h, to evaluate the cytotoxicity and the expression of genes related to antioxidant defense, cell cycle and energetic balance. In general, both vitality and gene expression were affected by the exposure to the different toxicants, in terms of antioxidant defense and cell cycle control, showing the most significant effects in cells exposed to the mixture of the three compounds, respect to the single compounds separately. The synergic effect of the compounds on the analyzed biomarkers, underlie the potential negative impact of the contaminants on health of marine organisms.
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Affiliation(s)
- Cristobal Espinosa Ruiz
- University of Palermo, Dept. of Earth and Sea Science DISTEM, Laboratory of Marine Biochemistry and Ecotoxicology, Via Barlotta 4, 91100, Trapani, Italy
| | - Simona Manuguerra
- University of Palermo, Dept. of Earth and Sea Science DISTEM, Laboratory of Marine Biochemistry and Ecotoxicology, Via Barlotta 4, 91100, Trapani, Italy
| | - Eleonora Curcuraci
- University of Palermo, Dept. of Earth and Sea Science DISTEM, Laboratory of Marine Biochemistry and Ecotoxicology, Via Barlotta 4, 91100, Trapani, Italy
| | - Andrea Santulli
- University of Palermo, Dept. of Earth and Sea Science DISTEM, Laboratory of Marine Biochemistry and Ecotoxicology, Via Barlotta 4, 91100, Trapani, Italy; Consorzio Universitario della Provincia di Trapani, Marine Biology Institute, Via Barlotta 4, 91100, Trapani, Italy
| | - Concetta M Messina
- University of Palermo, Dept. of Earth and Sea Science DISTEM, Laboratory of Marine Biochemistry and Ecotoxicology, Via Barlotta 4, 91100, Trapani, Italy.
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Glucose negatively affects Nrf2/SKN-1-mediated innate immunity in C. elegans. Aging (Albany NY) 2019; 10:3089-3103. [PMID: 30442878 PMCID: PMC6286829 DOI: 10.18632/aging.101610] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2018] [Accepted: 10/19/2018] [Indexed: 02/06/2023]
Abstract
High glucose levels negatively affect immune response. However, the underlying mechanisms are not well understood. Upon infection, the round worm C. elegans induces multiple gene transcription programs, including the Nrf2/SKN-1-mediated detoxification program, to activate the innate immunity. In this study, we find that high glucose conditions inhibit the SKN-1-mediated immune response to Salmonella typhimurium, exacerbate the infection and greatly decrease survival. The effect of glucose shows specificity to SKN-1 pathway, as UPRmit and UPRER that are known to be induced by infection, are not affected. Hyper-activation of SKN-1 by wdr-23 RNAi restores partly the immune response and increases the survival rate in response to S. typhimurium. In all, our study reveals a molecular pathway responsible for glucose’s negative effect on innate immunity, which could help to better understand diseases associated with hyperglycemia.
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Horsman JW, Heinis FI, Miller DL. A Novel Mechanism To Prevent H 2S Toxicity in Caenorhabditis elegans. Genetics 2019; 213:481-490. [PMID: 31371406 PMCID: PMC6781907 DOI: 10.1534/genetics.119.302326] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Accepted: 07/24/2019] [Indexed: 11/18/2022] Open
Abstract
Hydrogen sulfide (H2S) is an endogenously produced signaling molecule that can be cytoprotective, especially in conditions of ischemia/reperfusion injury. However, H2S is also toxic, and unregulated accumulation or exposure to environmental H2S can be lethal. In Caenorhabditis elegans, the hypoxia inducible factor (hif-1) coordinates the initial transcriptional response to H2S, and is essential to survive exposure to low concentrations of H2S. We performed a forward genetic screen to identify mutations that suppress the lethality of hif-1 mutant animals in H2S. The mutations we recovered are specific for H2S, as they do not suppress embryonic lethality or reproductive arrest of hif-1 mutant animals in hypoxia, nor can they prevent the death of hif-1 mutant animals exposed to hydrogen cyanide. The majority of hif-1 suppressor mutations we recovered activate the skn-1/Nrf2 transcription factor. Activation of SKN-1 by hif-1 suppressor mutations increased the expression of a subset of H2S-responsive genes, consistent with previous findings that skn-1 plays a role in the transcriptional response to H2S. Using transgenic rescue, we show that overexpression of a single gene, rhy-1, is sufficient to protect hif-1 mutant animals in H2S. The rhy-1 gene encodes a predicated O-acyltransferase enzyme that has previously been shown to negatively regulate HIF-1 activity. Our data indicate that RHY-1 has novel, hif-1 independent, function that promotes survival in H2S.
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Affiliation(s)
- Joseph W Horsman
- Department of Biochemistry, University of Washington School of Medicine, Seattle, Washington 98195
| | - Frazer I Heinis
- Department of Biochemistry, University of Washington School of Medicine, Seattle, Washington 98195
| | - Dana L Miller
- Department of Biochemistry, University of Washington School of Medicine, Seattle, Washington 98195
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The longevity-promoting factor, TCER-1, widely represses stress resistance and innate immunity. Nat Commun 2019; 10:3042. [PMID: 31316054 PMCID: PMC6637209 DOI: 10.1038/s41467-019-10759-z] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Accepted: 05/29/2019] [Indexed: 01/01/2023] Open
Abstract
Stress resistance and longevity are positively correlated but emerging evidence indicates that they are physiologically distinct. Identifying factors with distinctive roles in these processes is challenging because pro-longevity genes often enhance stress resistance. We demonstrate that TCER-1, the Caenorhabditis elegans homolog of human transcription elongation and splicing factor, TCERG1, has opposite effects on lifespan and stress resistance. We previously showed that tcer-1 promotes longevity in germline-less C. elegans and reproductive fitness in wild-type animals. Surprisingly, tcer-1 mutants exhibit exceptional resistance against multiple stressors, including infection by human opportunistic pathogens, whereas, TCER-1 overexpression confers immuno-susceptibility. TCER-1 inhibits immunity only during fertile stages of life. Elevating its levels ameliorates the fertility loss caused by infection, suggesting that TCER-1 represses immunity to augment fecundity. TCER-1 acts through repression of PMK-1 as well as PMK-1-independent factors critical for innate immunity. Our data establish key roles for TCER-1 in coordinating immunity, longevity and fertility, and reveal mechanisms that distinguish length of life from functional aspects of aging. Resistance to stress is often associated with increased longevity. Using the model organism C. elegans the authors here show that TCER-1 enhances lifespan while at the same time increasing sensitivity to a number of biotic and abiotic stressors.
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Maxeiner S, Grolleman J, Schmid T, Kammenga J, Hajnal A. The hypoxia-response pathway modulates RAS/MAPK-mediated cell fate decisions in Caenorhabditis elegans. Life Sci Alliance 2019; 2:e201800255. [PMID: 31126994 PMCID: PMC6536719 DOI: 10.26508/lsa.201800255] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2018] [Revised: 05/16/2019] [Accepted: 05/17/2019] [Indexed: 01/01/2023] Open
Abstract
Animals need to adjust many cellular functions to oxygen availability to adapt to changing environmental conditions. We have used the nematode Caenorhabditis elegans as a model to investigate how variations in oxygen concentrations affect cell fate specification during development. Here, we show that several processes controlled by the conserved RTK/RAS/MAPK pathway are sensitive to changes in the atmospheric oxygen concentration. In the vulval precursor cells (VPCs), the hypoxia-inducible factor HIF-1 activates the expression of the nuclear hormone receptor NHR-57 to counteract RAS/MAPK-induced differentiation. Furthermore, cross-talk between the NOTCH and hypoxia-response pathways modulates the capability of the VPCs to respond to RAS/MAPK signaling. Lateral NOTCH signaling positively regulates the prolyl hydroxylase EGL-9, which promotes HIF-1 degradation in uncommitted VPCs and permits RAS/MAPK-induced differentiation. By inducing DELTA family NOTCH ligands, RAS/MAPK signaling creates a positive feedback loop that represses HIF-1 and NHR-57 expression in the proximal VPCs and keeps them capable of differentiating. This regulatory network formed by the NOTCH, hypoxia, and RAS/MAPK pathways may allow the animals to adapt developmental processes to variations in oxygen concentration.
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Affiliation(s)
- Sabrina Maxeiner
- Institute of Molecular Life Sciences, University of Zurich, Zurich, Switzerland
- PhD Program in Molecular Life Sciences, University and ETH Zurich, Zurich, Switzerland
| | - Judith Grolleman
- Laboratory of Nematology, Wageningen University, Wageningen, The Netherlands
| | - Tobias Schmid
- Institute of Molecular Life Sciences, University of Zurich, Zurich, Switzerland
| | - Jan Kammenga
- Laboratory of Nematology, Wageningen University, Wageningen, The Netherlands
| | - Alex Hajnal
- Institute of Molecular Life Sciences, University of Zurich, Zurich, Switzerland
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Espinosa Ruiz C, Manuguerra S, Cuesta A, Esteban MA, Santulli A, Messina CM. Sub-lethal doses of polybrominated diphenyl ethers affect some biomarkers involved in energy balance and cell cycle, via oxidative stress in the marine fish cell line SAF-1. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2019; 210:1-10. [PMID: 30797971 DOI: 10.1016/j.aquatox.2019.02.014] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2018] [Revised: 02/18/2019] [Accepted: 02/18/2019] [Indexed: 06/09/2023]
Abstract
Polybrominated diphenyl ethers (PBDEs) are a class of persistent contaminants which are found all over the world in the marine environment. Sparus aurata fibroblast cell line (SAF-1) was exposed to increasing concentrations of PBDEs 47 and 99, until 72 h to evaluate the cytotoxicity, reactive oxygen species (ROS) production and the expression of some selected molecular markers related to cell cycle, cell signaling, energetic balance and oxidative stress (p53, erk-1, hif-1α and nrf-2), by real-time PCR. Furthermore, SAF-1 cells were exposed for 7 and 15 days to sub-lethal concentrations, in order to evaluate the response of some biomarkers by immunoblotting (p53, ERK-1, AMPK, HIF-1α and NRF-2). After 48 and 72 h, the cells showed a significant decrease of cell vitality as well as an increase of intracellular ROS production. Gene expression analysis showed that sub-lethal concentrations of BDE-99 and 47, after 72 h, up-regulated cell cycle and oxidative stress biomarkers, although exposure to 100 μmol L-1 down-regulated the selected markers related to cell cycle, cell signaling, energetic balance. After 7 and 15 days of sub-lethal doses exposure, all the analyzed markers resulted affected by the contaminants. Our results suggest that PBDEs influence the cells homeostasis first of all via oxidative stress, reducing the cell response and defense capacity and affecting its energetic levels. This situation of stress and energy imbalance could represents a condition that, modifying some of the analyzed biochemical pathways, would predispose to cellular transformation.
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Affiliation(s)
- Cristobal Espinosa Ruiz
- University of Palermo, Dept of Earth and Marine Science DISTEM, Laboratory of Marine Biochemistry and Ecotoxicology, Via Barlotta 4, 91100, Trapani, Italy
| | - Simona Manuguerra
- University of Palermo, Dept of Earth and Marine Science DISTEM, Laboratory of Marine Biochemistry and Ecotoxicology, Via Barlotta 4, 91100, Trapani, Italy
| | - Alberto Cuesta
- Fish Innate Immune System Group, Department of Cell Biology and Histology, Faculty of Biology, Campus Regional de Excelencia Internacional "Campus Mare Nostrum", University of Murcia, 30100, Murcia, Spain
| | - Maria Angeles Esteban
- Fish Innate Immune System Group, Department of Cell Biology and Histology, Faculty of Biology, Campus Regional de Excelencia Internacional "Campus Mare Nostrum", University of Murcia, 30100, Murcia, Spain
| | - Andrea Santulli
- University of Palermo, Dept of Earth and Marine Science DISTEM, Laboratory of Marine Biochemistry and Ecotoxicology, Via Barlotta 4, 91100, Trapani, Italy; Consorzio Universitario della Provincia di Trapani, Marine Biology Institute, Via Barlotta 4, 91100, Trapani, Italy
| | - Concetta M Messina
- University of Palermo, Dept of Earth and Marine Science DISTEM, Laboratory of Marine Biochemistry and Ecotoxicology, Via Barlotta 4, 91100, Trapani, Italy.
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Eiserich JP, Ott SP, Kadir T, Morrissey BM, Hayakawa KA, La Merrill MA, Cross CE. Quantitative assessment of cyanide in cystic fibrosis sputum and its oxidative catabolism by hypochlorous acid. Free Radic Biol Med 2018; 129:146-154. [PMID: 30213640 DOI: 10.1016/j.freeradbiomed.2018.09.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/15/2018] [Accepted: 09/07/2018] [Indexed: 02/06/2023]
Abstract
RATIONALE Cystic fibrosis (CF) patients are known to produce cyanide (CN-) although challenges exist in determinations of total levels, the precise bioactive levels, and specificity of its production by CF microflora, especially P. aeruginosa. Our objective was to measure total CN- levels in CF sputa by a simple and novel technique in P. aeruginosa positive and negative adult patients, to review respiratory tract (RT) mechanisms for the production and degradation of CN-, and to interrogate sputa for post-translational protein modification by CN- metabolites. METHODS Sputa CN- concentrations were determined by using a commercially available CN- electrode, measuring levels before and after addition of cobinamide, a compound with extremely high affinity for CN-. Detection of protein carbamoylation was measured by Western blot. MEASUREMENTS AND MAIN RESULTS The commercial CN- electrode was found to overestimate CN- levels in CF sputum in a highly variable manner; cobinamide addition rectified this analytical issue. Although P. aeruginosa positive patients tended to have higher total CN- values, no significant differences in CN- levels were found between positive and negative sputa. The inflammatory oxidant hypochlorous acid (HOCl) was shown to rapidly decompose CN-, forming cyanogen chloride (CNCl) and the carbamoylating species cyanate (NCO-). Carbamoylated proteins were found in CF sputa, analogous to reported findings in asthma. CONCLUSIONS Our studies indicate that CN- is a transient species in the inflamed CF airway due to multiple biosynthetic and metabolic processes. Stable metabolites of CN-, such as cyanate, or carbamoylated proteins, may be suitable biomarkers of overall CN- production in CF airways.
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Affiliation(s)
- Jason P Eiserich
- Department of Internal Medicine, Division of Pulmonary/Critical Care and Sleep Medicine, University of California, Davis, CA 95616, United States; Department of Physiology and Membrane Biology, University of California, Davis, CA 95616, United States
| | - Sean P Ott
- Department of Internal Medicine, Division of Pulmonary/Critical Care and Sleep Medicine, University of California, Davis, CA 95616, United States
| | - Tamara Kadir
- Department of Internal Medicine, Division of Pulmonary/Critical Care and Sleep Medicine, University of California, Davis, CA 95616, United States
| | - Brian M Morrissey
- Department of Internal Medicine, Division of Pulmonary/Critical Care and Sleep Medicine, University of California, Davis, CA 95616, United States
| | - Keri A Hayakawa
- Department of Internal Medicine, Division of Pulmonary/Critical Care and Sleep Medicine, University of California, Davis, CA 95616, United States
| | - Michele A La Merrill
- Department of Environmental Toxicology, University of California, Davis, CA 95616, United States
| | - Carroll E Cross
- Department of Internal Medicine, Division of Pulmonary/Critical Care and Sleep Medicine, University of California, Davis, CA 95616, United States; Department of Physiology and Membrane Biology, University of California, Davis, CA 95616, United States.
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20
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Pender CL, Horvitz HR. Hypoxia-inducible factor cell non-autonomously regulates C. elegans stress responses and behavior via a nuclear receptor. eLife 2018; 7:e36828. [PMID: 30010540 PMCID: PMC6078495 DOI: 10.7554/elife.36828] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2018] [Accepted: 07/15/2018] [Indexed: 12/16/2022] Open
Abstract
The HIF (hypoxia-inducible factor) transcription factor is the master regulator of the metazoan response to chronic hypoxia. In addition to promoting adaptations to low oxygen, HIF drives cytoprotective mechanisms in response to stresses and modulates neural circuit function. How most HIF targets act in the control of the diverse aspects of HIF-regulated biology remains unknown. We discovered that a HIF target, the C. elegans gene cyp-36A1, is required for numerous HIF-dependent processes, including modulation of gene expression, stress resistance, and behavior. cyp-36A1 encodes a cytochrome P450 enzyme that we show controls expression of more than a third of HIF-induced genes. CYP-36A1 acts cell non-autonomously by regulating the activity of the nuclear hormone receptor NHR-46, suggesting that CYP-36A1 functions as a biosynthetic enzyme for a hormone ligand of this receptor. We propose that regulation of HIF effectors through activation of cytochrome P450 enzyme/nuclear receptor signaling pathways could similarly occur in humans.
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Affiliation(s)
- Corinne L Pender
- Department of Biology, Howard Hughes Medical InstituteMassachusetts Institute of TechnologyCambridgeUnited States
- McGovern Institute for Brain ResearchMassachusetts Institute of TechnologyCambridgeUnited States
- Koch Institute for Integrative Cancer ResearchMassachusetts Institute of TechnologyCambridgeUnited States
| | - H Robert Horvitz
- Department of Biology, Howard Hughes Medical InstituteMassachusetts Institute of TechnologyCambridgeUnited States
- McGovern Institute for Brain ResearchMassachusetts Institute of TechnologyCambridgeUnited States
- Koch Institute for Integrative Cancer ResearchMassachusetts Institute of TechnologyCambridgeUnited States
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21
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Angeles-Albores D, Puckett Robinson C, Williams BA, Wold BJ, Sternberg PW. Reconstructing a metazoan genetic pathway with transcriptome-wide epistasis measurements. Proc Natl Acad Sci U S A 2018; 115:E2930-E2939. [PMID: 29531064 PMCID: PMC5879656 DOI: 10.1073/pnas.1712387115] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
RNA-sequencing (RNA-seq) is commonly used to identify genetic modules that respond to perturbations. In single cells, transcriptomes have been used as phenotypes, but this concept has not been applied to whole-organism RNA-seq. Also, quantifying and interpreting epistatic effects using expression profiles remains a challenge. We developed a single coefficient to quantify transcriptome-wide epistasis that reflects the underlying interactions and which can be interpreted intuitively. To demonstrate our approach, we sequenced four single and two double mutants of Caenorhabditis elegans From these mutants, we reconstructed the known hypoxia pathway. In addition, we uncovered a class of 56 genes with HIF-1-dependent expression that have opposite changes in expression in mutants of two genes that cooperate to negatively regulate HIF-1 abundance; however, the double mutant of these genes exhibits suppression epistasis. This class violates the classical model of HIF-1 regulation but can be explained by postulating a role of hydroxylated HIF-1 in transcriptional control.
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Affiliation(s)
- David Angeles-Albores
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125
- Howard Hughes Medical Institute, California Institute of Technology, Pasadena, CA 91125
| | - Carmie Puckett Robinson
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125
- Howard Hughes Medical Institute, California Institute of Technology, Pasadena, CA 91125
- Department of Neurology, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033
| | - Brian A Williams
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125
| | - Barbara J Wold
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125
| | - Paul W Sternberg
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125;
- Howard Hughes Medical Institute, California Institute of Technology, Pasadena, CA 91125
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22
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Mack HID, Zhang P, Fonslow BR, Yates JR. The protein kinase MBK-1 contributes to lifespan extension in daf-2 mutant and germline-deficient Caenorhabditis elegans. Aging (Albany NY) 2017; 9:1414-1432. [PMID: 28562327 PMCID: PMC5472741 DOI: 10.18632/aging.101244] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2017] [Accepted: 05/23/2017] [Indexed: 06/07/2023]
Abstract
In Caenorhabditis elegans, reduction of insulin/IGF-1 like signaling and loss of germline stem cells both increase lifespan by activating the conserved transcription factor DAF-16 (FOXO). While the mechanisms that regulate DAF-16 nuclear localization in response to insulin/IGF-1 like signaling are well characterized, the molecular pathways that act in parallel to regulate DAF-16 transcriptional activity, and the pathways that couple DAF-16 activity to germline status, are not fully understood at present. Here, we report that inactivation of MBK-1, the C. elegans ortholog of the human FOXO1-kinase DYRK1A substantially shortens the prolonged lifespan of daf-2 and glp-1 mutant animals while decreasing wild-type lifespan to a lesser extent. On the other hand, lifespan-reduction by mutation of the MBK-1-related kinase HPK-1 was not preferential for long-lived mutants. Interestingly, mbk-1 loss still allowed for DAF-16 nuclear accumulation but reduced expression of certain DAF-16 target genes in germline-less, but not in daf-2 mutant animals. These findings indicate that mbk-1 and daf-16 functionally interact in the germline- but not in the daf-2 pathway. Together, our data suggest mbk-1 as a novel regulator of C. elegans longevity upon both, germline ablation and DAF-2 inhibition, and provide evidence for mbk-1 regulating DAF-16 activity in germline-deficient animals.
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Affiliation(s)
- Hildegard I. D. Mack
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA 94158, USA
- Present address: Institute for Biomedical Aging Research, Leopold-Franzens-Universität Innsbruck, Innsbruck 6020, Austria
| | - Peichuan Zhang
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA 94158, USA
- Present address: Calico Life Sciences, South San Francisco, CA 94080, USA
| | - Bryan R. Fonslow
- Department of Chemical Physiology, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - John R. Yates
- Department of Chemical Physiology, The Scripps Research Institute, La Jolla, CA 92037, USA
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Saldanha JN, Pandey S, Powell-Coffman JA. The effects of short-term hypergravity on Caenorhabditis elegans. LIFE SCIENCES IN SPACE RESEARCH 2016; 10:38-46. [PMID: 27662786 DOI: 10.1016/j.lssr.2016.06.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2015] [Revised: 05/23/2016] [Accepted: 06/23/2016] [Indexed: 02/08/2023]
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Leiser SF, Rossner R, Kaeberlein M. New insights into cell non-autonomous mechanisms of the C. elegans hypoxic response. WORM 2016; 5:e1176823. [PMID: 27383456 DOI: 10.1080/21624054.2016.1176823] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2016] [Accepted: 04/05/2016] [Indexed: 10/21/2022]
Abstract
The hypoxic response is a well-studied and highly conserved biological response to low oxygen availability. First described more than 20 y ago, the traditional model for this response is that declining oxygen levels lead to stabilization of hypoxia-inducible transcription factors (HIFs), which then bind to hypoxia responsive elements (HREs) in target genes to mediate the transcriptional changes collectively known as the hypoxic response.(1,2) Recent work in C. elegans has forced a re-evaluation of this model by indicating that the worm HIF (HIF-1) can mediate effects in a cell non-autonomous fashion and, in at least one case, increase expression of an intestinal hypoxic response target gene in cells lacking HIF-1.
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Affiliation(s)
- Scott F Leiser
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI, USA; Division of Geriatric and Palliative Medicine, Department of Internal Medicine, University of Michigan, Ann Arbor, MI, USA
| | - Ryan Rossner
- Department of Pathology, University of Washington , Seattle, WA, USA
| | - Matt Kaeberlein
- Department of Pathology, University of Washington , Seattle, WA, USA
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Nakad R, Snoek LB, Yang W, Ellendt S, Schneider F, Mohr TG, Rösingh L, Masche AC, Rosenstiel PC, Dierking K, Kammenga JE, Schulenburg H. Contrasting invertebrate immune defense behaviors caused by a single gene, the Caenorhabditis elegans neuropeptide receptor gene npr-1. BMC Genomics 2016; 17:280. [PMID: 27066825 PMCID: PMC4827197 DOI: 10.1186/s12864-016-2603-8] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2015] [Accepted: 03/25/2016] [Indexed: 01/22/2023] Open
Abstract
Background The invertebrate immune system comprises physiological mechanisms, physical barriers and also behavioral responses. It is generally related to the vertebrate innate immune system and widely believed to provide nonspecific defense against pathogens, whereby the response to different pathogen types is usually mediated by distinct signalling cascades. Recent work suggests that invertebrate immune defense can be more specific at least at the phenotypic level. The underlying genetic mechanisms are as yet poorly understood. Results We demonstrate in the model invertebrate Caenorhabditis elegans that a single gene, a homolog of the mammalian neuropeptide Y receptor gene, npr-1, mediates contrasting defense phenotypes towards two distinct pathogens, the Gram-positive Bacillus thuringiensis and the Gram-negative Pseudomonas aeruginosa. Our findings are based on combining quantitative trait loci (QTLs) analysis with functional genetic analysis and RNAseq-based transcriptomics. The QTL analysis focused on behavioral immune defense against B. thuringiensis, using recombinant inbred lines (RILs) and introgression lines (ILs). It revealed several defense QTLs, including one on chromosome X comprising the npr-1 gene. The wildtype N2 allele for the latter QTL was associated with reduced defense against B. thuringiensis and thus produced an opposite phenotype to that previously reported for the N2 npr-1 allele against P. aeruginosa. Analysis of npr-1 mutants confirmed these contrasting immune phenotypes for both avoidance behavior and nematode survival. Subsequent transcriptional profiling of C. elegans wildtype and npr-1 mutant suggested that npr-1 mediates defense against both pathogens through p38 MAPK signaling, insulin-like signaling, and C-type lectins. Importantly, increased defense towards P. aeruginosa seems to be additionally influenced through the induction of oxidative stress genes and activation of GATA transcription factors, while the repression of oxidative stress genes combined with activation of Ebox transcription factors appears to enhance susceptibility to B. thuringiensis. Conclusions Our findings highlight the role of a single gene, npr-1, in fine-tuning nematode immune defense, showing the ability of the invertebrate immune system to produce highly specialized and potentially opposing immune responses via single regulatory genes. Electronic supplementary material The online version of this article (doi:10.1186/s12864-016-2603-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Rania Nakad
- Department of Evolutionary Ecology and Genetics, Zoological Institute, University of Kiel, 24098, Kiel, Germany.,Cologne Excellence Cluster for Cellular Stress Responses in Ageing-Associated Diseases (CECAD) and Systems Biology of Ageing, University of Cologne, Joseph-Stelzmann-Str. 26, 50931, Cologne, Germany
| | - L Basten Snoek
- Laboratory of Nematology, Wageningen University, Wageningen, 6708 PB, The Netherlands
| | - Wentao Yang
- Department of Evolutionary Ecology and Genetics, Zoological Institute, University of Kiel, 24098, Kiel, Germany
| | - Sunna Ellendt
- Department of Evolutionary Ecology and Genetics, Zoological Institute, University of Kiel, 24098, Kiel, Germany
| | - Franziska Schneider
- Department of Evolutionary Ecology and Genetics, Zoological Institute, University of Kiel, 24098, Kiel, Germany
| | - Timm G Mohr
- Department of Evolutionary Ecology and Genetics, Zoological Institute, University of Kiel, 24098, Kiel, Germany
| | - Lone Rösingh
- Department of Evolutionary Ecology and Genetics, Zoological Institute, University of Kiel, 24098, Kiel, Germany
| | - Anna C Masche
- Department of Evolutionary Ecology and Genetics, Zoological Institute, University of Kiel, 24098, Kiel, Germany
| | - Philip C Rosenstiel
- Institute for Clinical Molecular Biology, University of Kiel, 24098, Kiel, Germany
| | - Katja Dierking
- Department of Evolutionary Ecology and Genetics, Zoological Institute, University of Kiel, 24098, Kiel, Germany
| | - Jan E Kammenga
- Laboratory of Nematology, Wageningen University, Wageningen, 6708 PB, The Netherlands
| | - Hinrich Schulenburg
- Department of Evolutionary Ecology and Genetics, Zoological Institute, University of Kiel, 24098, Kiel, Germany.
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Park EC, Rongo C. The p38 MAP kinase pathway modulates the hypoxia response and glutamate receptor trafficking in aging neurons. eLife 2016; 5. [PMID: 26731517 PMCID: PMC4775213 DOI: 10.7554/elife.12010] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2015] [Accepted: 01/04/2016] [Indexed: 01/07/2023] Open
Abstract
Neurons are sensitive to low oxygen (hypoxia) and employ a conserved pathway to combat its effects. Here, we show that p38 MAP Kinase (MAPK) modulates this hypoxia response pathway in C. elegans. Mutants lacking p38 MAPK components pmk-1 or sek-1 resemble mutants lacking the hypoxia response component and prolyl hydroxylase egl-9, with impaired subcellular localization of Mint orthologue LIN-10, internalization of glutamate receptor GLR-1, and depression of GLR-1-mediated behaviors. Loss of p38 MAPK impairs EGL-9 protein localization in neurons and activates the hypoxia-inducible transcription factor HIF-1, suggesting that p38 MAPK inhibits the hypoxia response pathway through EGL-9. As animals age, p38 MAPK levels decrease, resulting in GLR-1 internalization; this age-dependent downregulation can be prevented through either p38 MAPK overexpression or removal of CDK-5, an antagonizing kinase. Our findings demonstrate that p38 MAPK inhibits the hypoxia response pathway and determines how aging neurons respond to hypoxia through a novel mechanism. DOI:http://dx.doi.org/10.7554/eLife.12010.001 The brain accounts for 2% of our body weight, but consumes about 20% of our oxygen intake. This oxygen gluttony is due to the tremendous appetite of brain cells for energy, which neurons satisfy through oxygen-dependent (aerobic) metabolism. As a result, the loss of oxygen to the brain during a stroke, heart attack, or due to another medical condition can be very damaging to cells in the brain. Human and other animal cells use a communication system called the hypoxia response pathway to sense oxygen and trigger a protective response when oxygen is low. This pathway includes an enzyme called prolyl hydroxylase, which senses oxygen and modifies another protein in the pathway that regulates the production of enzymes involved in metabolism. This alters the balance of enzymes involved in aerobic and oxygen-independent (anaerobic) metabolism in the cell. However, it is not clear how the activity of the prolyl hydroxylase is regulated. Much of our knowledge about the hypoxia response pathway has been gained from studies using a small worm called C. elegans. This worm uses the pathway to cope with hypoxia in the harsh environment of the soil. Mutant worms that lack the prolyl hydroxylase have several abnormalities including higher levels of anaerobic metabolism even in the presence of oxygen, and defects in the connections between neurons. Park and Rongo used C. elegans to study the pathway in more detail. The experiments show that another enzyme called p38 MAPK activates the prolyl hydroxylase. Mutant worms that lack this enzyme have similar abnormalities in the hypoxia response pathway as animals that lack the prolyl hydroxylase. In normal worms, decreasing levels of p38 MAPK as the animals grow older contribute to the decline in the nervous system. The p38 MAPK enzyme appears to work by regulating the activity of the prolyl hydroxylase and its location inside neurons. These findings provide a new target for the development of drugs that may help to protect us from tissue damage caused by hypoxia. Future challenges are to find out what activates p38 MAPK, and how it influences the location of prolyl hydroxylase in neurons. DOI:http://dx.doi.org/10.7554/eLife.12010.002
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Affiliation(s)
- Eun Chan Park
- The Waksman Institute, Rutgers The State University of New Jersey, New Jersey, United States.,Department of Genetics, Rutgers The State University of New Jersey, New Jersey, United States
| | - Christopher Rongo
- The Waksman Institute, Rutgers The State University of New Jersey, New Jersey, United States.,Department of Genetics, Rutgers The State University of New Jersey, New Jersey, United States
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Wang L, Cui S, Ma L, Kong L, Geng X. Current advances in the novel functions of hypoxia-inducible factor and prolyl hydroxylase in invertebrates. INSECT MOLECULAR BIOLOGY 2015; 24:634-648. [PMID: 26387499 DOI: 10.1111/imb.12189] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Oxygen is essential for aerobic life, and hypoxia has very severe consequences. Organisms need to overcome low oxygen levels to maintain biological functions during normal development and in disease states. The mechanism underlying the hypoxic response has been widely investigated in model animals such as Drosophila melanogaster and Caenorhabditis elegans. Hypoxia-inducible factor (HIF), a key gene product in the response to oxygen deprivation, is primarily regulated by prolyl hydroxylase domain enzymes (PHDs). However, recent findings have uncovered novel HIF-independent functions of PHDs. This review provides an overview of how invertebrates are able to sustain hypoxic damages, and highlights some recent discoveries in the regulation of cellular signalling by PHDs. Given that some core genes and major pathways are evolutionarily conserved, these research findings could provide insight into oxygen-sensitive signalling in mammals, and have biomedical implications for human diseases.
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Affiliation(s)
- L Wang
- School of Agriculture and Biology, Shanghai Jiao Tong University, Key Laboratory of Urban Agriculture (South), Ministry of Agriculture, Shanghai, China
| | - S Cui
- School of Agriculture and Biology, Shanghai Jiao Tong University, Key Laboratory of Urban Agriculture (South), Ministry of Agriculture, Shanghai, China
| | - L Ma
- School of Agriculture and Biology, Shanghai Jiao Tong University, Key Laboratory of Urban Agriculture (South), Ministry of Agriculture, Shanghai, China
| | - L Kong
- School of Agriculture and Biology, Shanghai Jiao Tong University, Key Laboratory of Urban Agriculture (South), Ministry of Agriculture, Shanghai, China
| | - X Geng
- School of Agriculture and Biology, Shanghai Jiao Tong University, Key Laboratory of Urban Agriculture (South), Ministry of Agriculture, Shanghai, China
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28
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Schaffer K, Taylor CT. The impact of hypoxia on bacterial infection. FEBS J 2015; 282:2260-6. [PMID: 25786849 DOI: 10.1111/febs.13270] [Citation(s) in RCA: 96] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2015] [Revised: 02/19/2015] [Accepted: 03/16/2015] [Indexed: 12/28/2022]
Abstract
Tissue hypoxia is a common microenvironmental feature during inflammation associated with bacterial infection. Hypoxia has recently been shown to play an important role in both innate and adaptive host immunity through the regulation of transcription factors, including hypoxia-inducible factor and nuclear factor-κB, in both infiltrating immunocytes and inflamed resident cells. Recent studies have suggested that, by regulating these important immune effector pathways in host tissues, hypoxia can significantly alter the process of bacterial infection and subsequent disease progression. Although hypoxia is often beneficial in terms of reducing the development of infection, its net effect depends on a number of factors, including the nature of the pathogen and the characteristics of the infection encountered. In this minireview, we will discuss the impact of local tissue hypoxia and the resulting activation of hypoxia-sensitive pathways on bacterial infection by a range of pathogens. Furthermore, we will review how this knowledge may be used to develop new approaches to anti-infective therapeutics.
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Affiliation(s)
- Kirsten Schaffer
- Department of Microbiology, St. Vincent's University Hospital, Dublin 4, Ireland
| | - Cormac T Taylor
- School of Medicine and Medical Science & The Conway Institute, University College Dublin, Dublin 4, Ireland
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29
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Feedback regulation via AMPK and HIF-1 mediates ROS-dependent longevity in Caenorhabditis elegans. Proc Natl Acad Sci U S A 2014; 111:E4458-67. [PMID: 25288734 DOI: 10.1073/pnas.1411199111] [Citation(s) in RCA: 140] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Mild inhibition of mitochondrial respiration extends the lifespan of many species. In Caenorhabditis elegans, reactive oxygen species (ROS) promote longevity by activating hypoxia-inducible factor 1 (HIF-1) in response to reduced mitochondrial respiration. However, the physiological role and mechanism of ROS-induced longevity are poorly understood. Here, we show that a modest increase in ROS increases the immunity and lifespan of C. elegans through feedback regulation by HIF-1 and AMP-activated protein kinase (AMPK). We found that activation of AMPK as well as HIF-1 mediates the longevity response to ROS. We further showed that AMPK reduces internal levels of ROS, whereas HIF-1 amplifies the levels of internal ROS under conditions that increase ROS. Moreover, mitochondrial ROS increase resistance to various pathogenic bacteria, suggesting a possible association between immunity and long lifespan. Thus, AMPK and HIF-1 may control immunity and longevity tightly by acting as feedback regulators of ROS.
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30
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Bile acids repress hypoxia-inducible factor 1 signaling and modulate the airway immune response. Infect Immun 2014; 82:3531-41. [PMID: 24914220 DOI: 10.1128/iai.00674-13] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Gastroesophageal reflux (GER) frequently occurs in patients with respiratory disease and is particularly prevalent in patients with cystic fibrosis. GER is a condition in which the duodenogastric contents of the stomach leak into the esophagus, in many cases resulting in aspiration into the respiratory tract. As such, the presence of GER-derived bile acids (BAs) has been confirmed in the bronchoalveolar lavage fluid and sputum of affected patients. We have recently shown that bile causes cystic fibrosis-associated bacterial pathogens to adopt a chronic lifestyle and may constitute a major host trigger underlying respiratory infection. The current study shows that BAs elicit a specific response in humans in which they repress hypoxia-inducible factor 1α (HIF-1α) protein, an emerging master regulator in response to infection and inflammation. HIF-1α repression was shown to occur through the 26S proteasome machinery via the prolyl hydroxylase domain (PHD) pathway. Further analysis of the downstream inflammatory response showed that HIF-1α repression by BAs can significantly modulate the immune response of airway epithelial cells, correlating with a decrease in interleukin-8 (IL-8) production, while IL-6 production was strongly increased. Importantly, the effects of BAs on cytokine production can also be more dominant than the bacterium-mediated effects. However, the effect of BAs on cytokine levels cannot be fully explained by their ability to repress HIF-1α, which is not surprising, given the complexity of the immune regulatory network. The suppression of HIF-1 signaling by bile acids may have a significant influence on the progression and outcome of respiratory disease, and the molecular mechanism underpinning this response warrants further investigation.
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31
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Kirienko NV, Kirienko DR, Larkins-Ford J, Wählby C, Ruvkun G, Ausubel FM. Pseudomonas aeruginosa disrupts Caenorhabditis elegans iron homeostasis, causing a hypoxic response and death. Cell Host Microbe 2014; 13:406-16. [PMID: 23601103 DOI: 10.1016/j.chom.2013.03.003] [Citation(s) in RCA: 147] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2012] [Revised: 01/30/2013] [Accepted: 02/18/2013] [Indexed: 12/24/2022]
Abstract
The opportunistic pathogen Pseudomonas aeruginosa causes serious human infections, but effective treatments and the mechanisms mediating pathogenesis remain elusive. Caenorhabditis elegans shares innate immune pathways with humans, making it invaluable to investigate infection. To determine how P. aeruginosa disrupts host biology, we studied how P. aeruginosa kills C. elegans in a liquid-based pathogenesis model. We found that P. aeruginosa-mediated killing does not require quorum-sensing pathways or host colonization. A chemical genetic screen revealed that iron chelators alleviate P. aeruginosa-mediated killing. Consistent with a role for iron in P. aeruginosa pathogenesis, the bacterial siderophore pyoverdin was required for virulence and was sufficient to induce a hypoxic response and death in the absence of bacteria. Loss of the C. elegans hypoxia-inducing factor HIF-1, which regulates iron homeostasis, exacerbated P. aeruginosa pathogenesis, further linking hypoxia and killing. As pyoverdin is indispensable for virulence in mice, pyoverdin-mediated hypoxia is likely to be relevant in human pathogenesis.
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Affiliation(s)
- Natalia V Kirienko
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114, USA
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32
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Ghose P, Park EC, Tabakin A, Salazar-Vasquez N, Rongo C. Anoxia-reoxygenation regulates mitochondrial dynamics through the hypoxia response pathway, SKN-1/Nrf, and stomatin-like protein STL-1/SLP-2. PLoS Genet 2013; 9:e1004063. [PMID: 24385935 PMCID: PMC3873275 DOI: 10.1371/journal.pgen.1004063] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2013] [Accepted: 11/12/2013] [Indexed: 12/04/2022] Open
Abstract
Many aerobic organisms encounter oxygen-deprived environments and thus must have adaptive mechanisms to survive such stress. It is important to understand how mitochondria respond to oxygen deprivation given the critical role they play in using oxygen to generate cellular energy. Here we examine mitochondrial stress response in C. elegans, which adapt to extreme oxygen deprivation (anoxia, less than 0.1% oxygen) by entering into a reversible suspended animation state of locomotory arrest. We show that neuronal mitochondria undergo DRP-1-dependent fission in response to anoxia and undergo refusion upon reoxygenation. The hypoxia response pathway, including EGL-9 and HIF-1, is not required for anoxia-induced fission, but does regulate mitochondrial reconstitution during reoxygenation. Mutants for egl-9 exhibit a rapid refusion of mitochondria and a rapid behavioral recovery from suspended animation during reoxygenation; both phenotypes require HIF-1. Mitochondria are significantly larger in egl-9 mutants after reoxygenation, a phenotype similar to stress-induced mitochondria hyperfusion (SIMH). Anoxia results in mitochondrial oxidative stress, and the oxidative response factor SKN-1/Nrf is required for both rapid mitochondrial refusion and rapid behavioral recovery during reoxygenation. In response to anoxia, SKN-1 promotes the expression of the mitochondrial resident protein Stomatin-like 1 (STL-1), which helps facilitate mitochondrial dynamics following anoxia. Our results suggest the existence of a conserved anoxic stress response involving changes in mitochondrial fission and fusion. Oxygen deprivation plays a role in multiple human diseases ranging from heart attack, ischemic stroke, and traumatic injury. Aerobic organisms use oxygen to generate cellular energy in mitochondria; thus, oxygen deprivation results in energy depletion. Low oxygen can be catastrophic in tissues like the nervous system, which has high-energy demands and few glycolytic reserves. By contrast, other cells, including stem cells and cancerous cells within tumors, adapt and thrive in low oxygen. We are just beginning to understand how different organisms and even different cell types within the same organism respond to low oxygen conditions. The response of mitochondria to oxygen deprivation is particularly critical given their role in aerobic energy production. In addition, mitochondria actively injure cells during oxygen deprivation through the generation of reactive oxygen species, the disruption of calcium homeostasis, and the activation of cell death pathways. Here we use a genetic approach to show that mitochondria undergo fission during oxygen deprivation and refusion upon oxygen restoration. The hypoxia response pathway and the oxidative stress response pathway together modulate this response. We identify a new factor, stomatin-like protein, as a promoter of mitochondrial fusion in response to oxygen deprivation stress. Our findings uncover a new mechanism – regulated mitochondrial dynamics – by which cells adapt to oxygen deprivation stress.
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Affiliation(s)
- Piya Ghose
- The Waksman Institute, Department of Genetics, Rutgers The State University of New Jersey, Piscataway, New Jersey, United States of America
- The Graduate Program in Neuroscience, Rutgers The State University of New Jersey, Piscataway, New Jersey, United States of America
| | - Eun Chan Park
- The Waksman Institute, Department of Genetics, Rutgers The State University of New Jersey, Piscataway, New Jersey, United States of America
| | - Alexandra Tabakin
- The Waksman Institute, Department of Genetics, Rutgers The State University of New Jersey, Piscataway, New Jersey, United States of America
| | - Nathaly Salazar-Vasquez
- The Waksman Institute, Department of Genetics, Rutgers The State University of New Jersey, Piscataway, New Jersey, United States of America
- The Graduate Program in Genetics and Microbiology, Rutgers The State University of New Jersey, Piscataway, New Jersey, United States of America
| | - Christopher Rongo
- The Waksman Institute, Department of Genetics, Rutgers The State University of New Jersey, Piscataway, New Jersey, United States of America
- * E-mail:
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33
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Vozdek R, Hnízda A, Krijt J, Será L, Kožich V. Biochemical properties of nematode O-acetylserine(thiol)lyase paralogs imply their distinct roles in hydrogen sulfide homeostasis. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2013; 1834:2691-701. [PMID: 24100226 DOI: 10.1016/j.bbapap.2013.09.020] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/14/2013] [Revised: 09/23/2013] [Accepted: 09/25/2013] [Indexed: 01/08/2023]
Abstract
O-Acetylserine(thiol)lyases (OAS-TLs) play a pivotal role in a sulfur assimilation pathway incorporating sulfide into amino acids in microorganisms and plants, however, these enzymes have not been found in the animal kingdom. Interestingly, the genome of the roundworm Caenorhabditis elegans contains three expressed genes predicted to encode OAS-TL orthologs (cysl-1-cysl-3), and a related pseudogene (cysl-4); these genes play different roles in resistance to hypoxia, hydrogen sulfide and cyanide. To get an insight into the underlying molecular mechanisms we purified the three recombinant worm OAS-TL proteins, and we determined their enzymatic activities, substrate binding affinities, quaternary structures and the conformations of their active site shapes. We show that the nematode OAS-TL orthologs can bind O-acetylserine and catalyze the canonical reaction although this ligand may more likely serve as a competitive inhibitor to natural substrates instead of being a substrate for sulfur assimilation. In addition, we propose that S-sulfocysteine may be a novel endogenous substrate for these proteins. However, we observed that the three OAS-TL proteins are conformationally different and exhibit distinct substrate specificity. Based on the available evidences we propose the following model: CYSL-1 interacts with EGL-9 and activates HIF-1 that upregulates expression of genes detoxifying sulfide and cyanide, the CYSL-2 acts as a cyanoalanine synthase in the cyanide detoxification pathway and simultaneously produces hydrogen sulfide, while the role of CYSL-3 remains unclear although it exhibits sulfhydrylase activity in vitro. All these data indicate that C. elegans OAS-TL paralogs have distinct cellular functions and may play different roles in maintaining hydrogen sulfide homeostasis.
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Affiliation(s)
- Roman Vozdek
- Institute of Inherited Metabolic Disorders, First Faculty of Medicine, Charles University in Prague and General University Hospital in Prague, Ke Karlovu 2, Prague 2, 128 08, Czech Republic
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Gharbi H, Fabretti F, Bharill P, Rinschen MM, Brinkkötter S, Frommolt P, Burst V, Schermer B, Benzing T, Müller R. Loss of the Birt-Hogg-Dubé gene product folliculin induces longevity in a hypoxia-inducible factor-dependent manner. Aging Cell 2013; 12:593-603. [PMID: 23566034 DOI: 10.1111/acel.12081] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/28/2013] [Indexed: 01/09/2023] Open
Abstract
Signaling through the hypoxia-inducible factor hif-1 controls longevity, metabolism, and stress resistance in Caenorhabditis elegans. Hypoxia-inducible factor (HIF) protein levels are regulated through an evolutionarily conserved ubiquitin ligase complex. Mutations in the VHL gene, encoding a core component of this complex, cause a multitumor syndrome and renal cell carcinoma in humans. In the nematode, deficiency in vhl-1 promotes longevity mediated through HIF-1 stabilization. However, this longevity assurance pathway is not yet understood. Here, we identify folliculin (FLCN) as a novel interactor of the hif-1/vhl-1 longevity pathway. FLCN mutations cause Birt-Hogg-Dubé syndrome in humans, another tumor syndrome with renal tumorigenesis reminiscent of the VHL disease. Loss of the C. elegans ortholog of FLCN F22D3.2 significantly increased lifespan and enhanced stress resistance in a hif-1-dependent manner. F22D3.2, vhl-1, and hif-1 control longevity by a mechanism distinct from insulin-like signaling. Daf-16 deficiency did not abrogate the increase in lifespan mediated by flcn-1. These findings define FLCN as a player in HIF-dependent longevity signaling and connect organismal aging, stress resistance, and regulation of longevity with the formation of renal cell carcinoma.
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Affiliation(s)
- Hakam Gharbi
- Department 2 of Internal Medicine and Center for Molecular Medicine Cologne University of Cologne Cologne Germany
- Cologne Excellence Cluster on Cellular Stress Responses in Aging‐Associated Diseases University of Cologne Cologne Germany
| | - Francesca Fabretti
- Department 2 of Internal Medicine and Center for Molecular Medicine Cologne University of Cologne Cologne Germany
| | - Puneet Bharill
- Department 2 of Internal Medicine and Center for Molecular Medicine Cologne University of Cologne Cologne Germany
| | - Markus M. Rinschen
- Department 2 of Internal Medicine and Center for Molecular Medicine Cologne University of Cologne Cologne Germany
| | - Sibylle Brinkkötter
- Department 2 of Internal Medicine and Center for Molecular Medicine Cologne University of Cologne Cologne Germany
| | - Peter Frommolt
- Cologne Excellence Cluster on Cellular Stress Responses in Aging‐Associated Diseases University of Cologne Cologne Germany
- Cologne Center for Genomics University of Cologne Cologne Germany
| | - Volker Burst
- Department 2 of Internal Medicine and Center for Molecular Medicine Cologne University of Cologne Cologne Germany
| | - Bernhard Schermer
- Department 2 of Internal Medicine and Center for Molecular Medicine Cologne University of Cologne Cologne Germany
- Cologne Excellence Cluster on Cellular Stress Responses in Aging‐Associated Diseases University of Cologne Cologne Germany
- Systems Biology of Ageing Cologne University of Cologne Cologne Germany
| | - Thomas Benzing
- Department 2 of Internal Medicine and Center for Molecular Medicine Cologne University of Cologne Cologne Germany
- Cologne Excellence Cluster on Cellular Stress Responses in Aging‐Associated Diseases University of Cologne Cologne Germany
- Systems Biology of Ageing Cologne University of Cologne Cologne Germany
| | - Roman‐Ulrich Müller
- Department 2 of Internal Medicine and Center for Molecular Medicine Cologne University of Cologne Cologne Germany
- Cologne Excellence Cluster on Cellular Stress Responses in Aging‐Associated Diseases University of Cologne Cologne Germany
- Systems Biology of Ageing Cologne University of Cologne Cologne Germany
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Saldanha JN, Parashar A, Pandey S, Powell-Coffman JA. Multiparameter behavioral analyses provide insights to mechanisms of cyanide resistance in Caenorhabditis elegans. Toxicol Sci 2013; 135:156-68. [PMID: 23805000 DOI: 10.1093/toxsci/kft138] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Environmental toxicants influence development, behavior, and ultimately survival. The nematode Caenorhabditis elegans has proven to be an exceptionally powerful model for toxicological studies. Here, we develop novel technologies to describe the effects of cyanide toxicity with high spatiotemporal resolution. Importantly, we use these methods to examine the genetic underpinnings of cyanide resistance. Caenorhabditis elegans that lack the EGL-9 oxygen sensing enzyme have been shown to be resistant to hydrogen cyanide (HCN) gas produced by the pathogen Pseudomonas aeruginosa PAO1. We demonstrate that the cyanide resistance exhibited by egl-9 mutants is completely dependent on the HIF-1 hypoxia-inducible factor and is mediated by the cysl-2 cysteine synthase, which likely functions in metabolic pathways that inactivate cyanide. Further, the expression of cysl-2 correlates with the degree of cyanide resistance exhibited in each genetic background. We find that each mutant exhibits similar relative resistance to HCN gas on plates or to aqueous potassium cyanide in microfluidic chambers. The design of the microfluidic devices, in combination with real-time imaging, addresses a series of challenges presented by mutant phenotypes and by the chemical nature of the toxicant. The microfluidic assay produces a set of behavioral parameters with increased resolution that describe cyanide toxicity and resistance in C. elegans, and this is particularly useful in analyzing subtle phenotypes. These multiparameter analyses of C. elegans behavior hold great potential as a means to monitor the effects of toxicants or chemical interventions in real time and to study the biological networks that underpin toxicant resistance.
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Affiliation(s)
- Jenifer N Saldanha
- Department of Genetics, Development and Cell Biology, Iowa State University, Ames, Iowa 50011, USA
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Pseudomonas aeruginosa Alkyl quinolones repress hypoxia-inducible factor 1 (HIF-1) signaling through HIF-1α degradation. Infect Immun 2012; 80:3985-92. [PMID: 22949552 DOI: 10.1128/iai.00554-12] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
The transcription factor hypoxia-inducible factor 1 (HIF-1) has recently emerged to be a crucial regulator of the immune response following pathogen perception, including the response to the important human pathogen Pseudomonas aeruginosa. However, as mechanisms involved in HIF-1 activation by bacterial pathogens are not fully characterized, understanding how bacteria and bacterial compounds impact on HIF-1α stabilization remains a major challenge. In this context, we have focused on the effect of secreted factors of P. aeruginosa on HIF-1 regulation. Surprisingly, we found that P. aeruginosa cell-free supernatant significantly repressed HIF-1α protein levels. Further characterization revealed that HIF-1α downregulation was dependent on a subset of key secreted factors involved in P. aeruginosa pathogenesis, the 2-alkyl-4-quinolone (AQ) quorum sensing (QS) signaling molecules, and in particular the pseudomonas quinolone signal (PQS). Under hypoxic conditions, the AQ-dependent downregulation of HIF-1α was linked to the suppressed induction of the important HIF-1 target gene hexokinase II. Furthermore, we demonstrated that AQ molecules directly target HIF-1α protein degradation through the 26S-proteasome proteolytic pathway but independently of the prolyl hydroxylase domain (PHD). In conclusion, this is the first report showing that bacterial molecules can repress HIF-1α protein levels. Manipulation of HIF-1 signaling by P. aeruginosa AQs could have major consequences for the host response to infection and may facilitate the infective properties of this pathogen.
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Induction of cytoprotective pathways is central to the extension of lifespan conferred by multiple longevity pathways. PLoS Genet 2012; 8:e1002792. [PMID: 22829775 PMCID: PMC3400582 DOI: 10.1371/journal.pgen.1002792] [Citation(s) in RCA: 88] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2012] [Accepted: 05/11/2012] [Indexed: 11/19/2022] Open
Abstract
Many genetic and physiological treatments that extend lifespan also confer resistance to a variety of stressors, suggesting that cytoprotective mechanisms underpin the regulation of longevity. It has not been established, however, whether the induction of cytoprotective pathways is essential for lifespan extension or merely correlated. Using a panel of GFP-fused stress response genes, we identified the suites of cytoprotective pathways upregulated by 160 gene inactivations known to increase Caenorhabditis elegans longevity, including the mitochondrial UPR (hsp-6, hsp-60), the ER UPR (hsp-4), ROS response (sod-3, gst-4), and xenobiotic detoxification (gst-4). We then screened for other gene inactivations that disrupt the induction of these responses by xenobiotic or genetic triggers, identifying 29 gene inactivations required for cytoprotective gene expression. If cytoprotective responses contribute directly to lifespan extension, inactivation of these genes would be expected to compromise the extension of lifespan conferred by decreased insulin/IGF-1 signaling, caloric restriction, or the inhibition of mitochondrial function. We find that inactivation of 25 of 29 cytoprotection-regulatory genes shortens the extension of longevity normally induced by decreased insulin/IGF-1 signaling, disruption of mitochondrial function, or caloric restriction, without disrupting normal longevity nearly as dramatically. These data demonstrate that induction of cytoprotective pathways is central to longevity extension and identify a large set of new genetic components of the pathways that detect cellular damage and couple that detection to downstream cytoprotective effectors. Many mutations that increase animal lifespan also confer stress tolerance, suggesting that cytoprotective mechanisms underpin the regulation of longevity. It has not been established, however, whether the induction of individual cytoprotective pathways is essential for lifespan extension, or merely correlated. To establish whether the regulatory pathways for the induction of cytoprotective responses are key in the extension of lifespan, we performed an RNAi screen for gene inactivations that decouple the activation of cytoprotective pathways from xenobiotic stimuli that normally induce them. The screen identified 29 genes that constitute the regulatory cascades of the unfolded protein response, oxidative stress response, and detoxification. These upstream regulatory genes are critical to stress tolerance and the extension of lifespan conferred by decreased insulin/IGF-1 signaling, disruption of mitochondrial function, or caloric restriction, but have little effect on normal longevity.
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Luhachack LG, Visvikis O, Wollenberg AC, Lacy-Hulbert A, Stuart LM, Irazoqui JE. EGL-9 controls C. elegans host defense specificity through prolyl hydroxylation-dependent and -independent HIF-1 pathways. PLoS Pathog 2012; 8:e1002798. [PMID: 22792069 PMCID: PMC3390412 DOI: 10.1371/journal.ppat.1002798] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2012] [Accepted: 05/29/2012] [Indexed: 12/28/2022] Open
Abstract
Understanding host defense against microbes is key to developing new and more effective therapies for infection and inflammatory disease. However, how animals integrate multiple environmental signals and discriminate between different pathogens to mount specific and tailored responses remains poorly understood. Using the genetically tractable model host Caenorhabditis elegans and pathogenic bacterium Staphylococcus aureus, we describe an important role for hypoxia-inducible factor (HIF) in defining the specificity of the host response in the intestine. We demonstrate that loss of egl-9, a negative regulator of HIF, confers HIF-dependent enhanced susceptibility to S. aureus while increasing resistance to Pseudomonas aeruginosa. In our attempt to understand how HIF could have these apparently dichotomous roles in host defense, we find that distinct pathways separately regulate two opposing functions of HIF: the canonical pathway is important for blocking expression of a set of HIF-induced defense genes, whereas a less well understood noncanonical pathway appears to be important for allowing the expression of another distinct set of HIF-repressed defense genes. Thus, HIF can function either as a gene-specific inducer or repressor of host defense, providing a molecular mechanism by which HIF can have apparently opposing roles in defense and inflammation. Together, our observations show that HIF can set the balance between alternative pathogen-specific host responses, potentially acting as an evolutionarily conserved specificity switch in the host innate immune response. Understanding how animals detect infection and mount appropriate responses is key to treating infection and inflammatory disease. We use the tractable model Caenorhabditis elegans to study mechanisms of host defense against pathogenic bacteria. Here we show that hypoxia-inducible factor (HIF) is important for ensuring that the intestinal host response to infection has the appropriate specificity. HIF acts as an inducer and a repressor of host genes in the intestine, and regulation of these opposing activities is genetically separable. One well-understood regulatory pathway requires EGL-9 and VHL-1, negative regulators of HIF, to prevent constitutive expression of host defense genes. Noncanonical pathways are less understood; a recently identified noncanonical pathway requires EGL-9 and SWAN-1. This pathway appears to be more important for lifting the repression of defense genes by HIF-1. Mutants defective in EGL-9 are more susceptible to S. aureus but more resistant to the distinct pathogen P. aeruginosa, indicating that the defense role of HIF-1 is pathogen-specific. These studies are relevant to mammalian defense because mutations in hif-1, egl-9, and vhl-1 homologs in mice have similar effects on intestinal inflammation as in worms, and provide a framework to further explore the role of noncanonical HIF signaling in human infection and inflammatory disease.
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Affiliation(s)
- Lyly G. Luhachack
- Program of Developmental Immunology, Department of Pediatrics, Massachusetts General Hospital, and Department of Pediatrics, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Orane Visvikis
- Program of Developmental Immunology, Department of Pediatrics, Massachusetts General Hospital, and Department of Pediatrics, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Amanda C. Wollenberg
- Program of Developmental Immunology, Department of Pediatrics, Massachusetts General Hospital, and Department of Pediatrics, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Adam Lacy-Hulbert
- Program of Developmental Immunology, Department of Pediatrics, Massachusetts General Hospital, and Department of Pediatrics, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Lynda M. Stuart
- Program of Developmental Immunology, Department of Pediatrics, Massachusetts General Hospital, and Department of Pediatrics, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Javier E. Irazoqui
- Program of Developmental Immunology, Department of Pediatrics, Massachusetts General Hospital, and Department of Pediatrics, Harvard Medical School, Boston, Massachusetts, United States of America
- * E-mail:
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Quantification of Pseudomonas aeruginosa hydrogen cyanide production by a polarographic approach. J Microbiol Methods 2012; 90:20-4. [DOI: 10.1016/j.mimet.2012.04.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2011] [Revised: 04/02/2012] [Accepted: 04/10/2012] [Indexed: 01/25/2023]
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Ma DK, Vozdek R, Bhatla N, Horvitz HR. CYSL-1 interacts with the O2-sensing hydroxylase EGL-9 to promote H2S-modulated hypoxia-induced behavioral plasticity in C. elegans. Neuron 2012; 73:925-40. [PMID: 22405203 PMCID: PMC3305813 DOI: 10.1016/j.neuron.2011.12.037] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/22/2011] [Indexed: 12/17/2022]
Abstract
The C. elegans HIF-1 proline hydroxylase EGL-9 functions as an O(2) sensor in an evolutionarily conserved pathway for adaptation to hypoxia. H(2)S accumulates during hypoxia and promotes HIF-1 activity, but how H(2)S signals are perceived and transmitted to modulate HIF-1 and animal behavior is unknown. We report that the experience of hypoxia modifies a C. elegans locomotive behavioral response to O(2) through the EGL-9 pathway. From genetic screens to identify novel regulators of EGL-9-mediated behavioral plasticity, we isolated mutations of the gene cysl-1, which encodes a C. elegans homolog of sulfhydrylases/cysteine synthases. Hypoxia-dependent behavioral modulation and H(2)S-induced HIF-1 activation require the direct physical interaction of CYSL-1 with the EGL-9 C terminus. Sequestration of EGL-9 by CYSL-1 and inhibition of EGL-9-mediated hydroxylation by hypoxia together promote neuronal HIF-1 activation to modulate behavior. These findings demonstrate that CYSL-1 acts to transduce signals from H(2)S to EGL-9 to regulate O(2)-dependent behavioral plasticity in C. elegans.
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Affiliation(s)
- Dengke K. Ma
- Howard Hughes Medical Institute, Department of Biology, and McGovern Institute for Brain Research, MIT, Cambridge, MA 02139, USA
| | - Roman Vozdek
- Institute of Inherited Metabolic Disorders, First Faculty of Medicine, Charles University in Prague and General University Hospital in Prague, Ke Karlovu 2, Prague 2, 128 08 Czech Republic
| | - Nikhil Bhatla
- Howard Hughes Medical Institute, Department of Biology, and McGovern Institute for Brain Research, MIT, Cambridge, MA 02139, USA
| | - H. Robert Horvitz
- Howard Hughes Medical Institute, Department of Biology, and McGovern Institute for Brain Research, MIT, Cambridge, MA 02139, USA
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Ackerman D, Gems D. Insulin/IGF-1 and hypoxia signaling act in concert to regulate iron homeostasis in Caenorhabditis elegans. PLoS Genet 2012; 8:e1002498. [PMID: 22396654 PMCID: PMC3291539 DOI: 10.1371/journal.pgen.1002498] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2011] [Accepted: 12/09/2011] [Indexed: 01/08/2023] Open
Abstract
Iron plays an essential role in many biological processes, but also catalyzes the formation of reactive oxygen species (ROS), which can cause molecular damage. Iron homeostasis is therefore a critical determinant of fitness. In Caenorhabditis elegans, insulin/IGF-1 signaling (IIS) promotes growth and reproduction but limits stress resistance and lifespan through inactivation of the DAF-16/FoxO transcription factor (TF). We report that long-lived daf-2 insulin/IGF-1 receptor mutants show a daf-16–dependent increase in expression of ftn-1, which encodes the iron storage protein H-ferritin. To better understand the regulation of iron homeostasis, we performed a TF–limited genetic screen for factors influencing ftn-1 gene expression. The screen identified the heat-shock TF hsf-1, the MAD bHLH TF mdl-1, and the putative histone acetyl transferase ada-2 as activators of ftn-1 expression. It also revealed that the HIFα homolog hif-1 and its binding partner aha-1 (HIFβ) are potent repressors of ftn-1 expression. ftn-1 expression is induced by exposure to iron, and we found that hif-1 was required for this induction. In addition, we found that the prolyl hydroxylase EGL-9, which represses HIF-1 via the von Hippel-Lindau tumor suppressor VHL-1, can also act antagonistically to VHL-1 in regulating ftn-1. This suggests a novel mechanism for HIF target gene regulation by these evolutionarily conserved and clinically important hydroxylases. Our findings imply that the IIS and HIF pathways act together to regulate iron homeostasis in C. elegans. We suggest that IIS/DAF-16 regulation of ftn-1 modulates a trade-off between growth and stress resistance, as elevated iron availability supports growth but also increases ROS production. Iron plays a role in many biological processes, including energy generation and DNA replication. But to maintain health, levels of cellular iron must be just right: too much or too little iron can cause illnesses, such as anemia and hemochromatosis, respectively. Animals therefore carefully control their iron levels by regulating of iron uptake, transport, and storage within protein capsules called ferritins. But how do they coordinate this? Using the model organism C. elegans, we have discovered a network of genes and pathways that control iron homeostasis. We find that ferritin is regulated by insulin/IGF-1 signaling, which also controls growth and resistance to oxidative stress in response to harsh environmental conditions. Ferritin is also regulated by the hypoxia signaling pathway, which responds to oxygen and iron levels as well as to metabolic cues. We find that the hypoxia pathway acts as an iron sensor, a role it may also play in humans. Our work defines a network of signaling pathways that can adjust iron availability in response to a range of environmental cues. Understanding this network in C. elegans can help us to understand the causes of iron dyshomeostasis in humans, which can profoundly affect health.
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Affiliation(s)
- Daniel Ackerman
- Institute of Healthy Aging and Department of Genetics Evolution and Environment, University College London, London, United Kingdom
| | - David Gems
- Institute of Healthy Aging and Department of Genetics Evolution and Environment, University College London, London, United Kingdom
- * E-mail:
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Hypoxia regulates glutamate receptor trafficking through an HIF-independent mechanism. EMBO J 2012; 31:1379-93. [PMID: 22252129 DOI: 10.1038/emboj.2011.499] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2011] [Accepted: 12/23/2011] [Indexed: 12/14/2022] Open
Abstract
Oxygen influences behaviour in many organisms, with low levels (hypoxia) having devastating consequences for neuron survival. How neurons respond physiologically to counter the effects of hypoxia is not fully understood. Here, we show that hypoxia regulates the trafficking of the glutamate receptor GLR-1 in C. elegans neurons. Either hypoxia or mutations in egl-9, a prolyl hydroxylase cellular oxygen sensor, result in the internalization of GLR-1, the reduction of glutamate-activated currents, and the depression of GLR-1-mediated behaviours. Surprisingly, hypoxia-inducible factor (HIF)-1, the canonical substrate of EGL-9, is not required for this effect. Instead, EGL-9 interacts with the Mint orthologue LIN-10, a mediator of GLR-1 membrane recycling, to promote LIN-10 subcellular localization in an oxygen-dependent manner. The observed effects of hypoxia and egl-9 mutations require the activity of the proline-directed CDK-5 kinase and the CDK-5 phosphorylation sites on LIN-10, suggesting that EGL-9 and CDK-5 compete in an oxygen-dependent manner to regulate LIN-10 activity and thus GLR-1 trafficking. Our findings demonstrate a novel mechanism by which neurons sense and respond to hypoxia.
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Abstract
Hydrogen sulfide (H2S), an endogenously produced small molecule, protects animals from various stresses. Recent studies demonstrate that animals exposed to H2S are long lived, resistant to hypoxia, and resistant to ischemia–reperfusion injury. We performed a forward genetic screen to gain insights into the molecular mechanisms Caenorhabditis elegans uses to appropriately respond to H2S. At least two distinct pathways appear to be important for this response, including the H2S-oxidation pathway and the hydrogen cyanide (HCN)-assimilation pathway. The H2S-oxidation pathway requires two distinct enzymes important for the oxidation of H2S: the sulfide:quinone reductase sqrd-1 and the dioxygenase ethe-1. The HCN-assimilation pathway requires the cysteine synthase homologs cysl-1 and cysl-2. A low dose of either H2S or HCN can activate hypoxia-inducible factor 1 (HIF-1), which is required for C. elegans to respond to either gas. sqrd-1 and cysl-2 represent the entry points in the H2S-oxidation and HCN-assimilation pathways, respectively, and expression of both of these enzymes is highly induced by HIF-1 in response to both H2S and HCN. In addition to their role in appropriately responding to H2S and HCN, we found that cysl-1 and cysl-2 are both essential mediators of innate immunity against fast paralytic killing by Pseudomonas. Furthermore, in agreement with these data, we showed that growing worms in the presence of H2S is sufficient to confer resistance to Pseudomonas fast paralytic killing. Our results suggest the hypoxia-independent hif-1 response in C. elegans evolved to respond to the naturally occurring small molecules H2S and HCN.
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Legendre C, Mooij MJ, Adams C, O'Gara F. Impaired expression of hypoxia-inducible factor-1α in cystic fibrosis airway epithelial cells - a role for HIF-1 in the pathophysiology of CF? J Cyst Fibros 2011; 10:286-90. [PMID: 21420913 DOI: 10.1016/j.jcf.2011.02.005] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2010] [Revised: 02/18/2011] [Accepted: 02/21/2011] [Indexed: 11/17/2022]
Abstract
The continuous infection-inflammation cycle plays a crucial role in the progression of cystic fibrosis (CF) disease. This noxious loop can be aggravated by a reduced partial pressure of oxygen in the blood, hypoxemia, present in CF patients. These interconnected factors, hypoxia, inflammation and infection, by stabilizing the hypoxia-inducible factor-1α (HIF-1α) protein subunit, are able to activate the transcription factor HIF-1. To date, data investigating the potential role of HIF-1 in CF are scarce. Our results demonstrated that HIF-1α protein expression was altered in CF-affected compared to CFTR-corrected airway epithelial cells in unsimulated and simulated hypoxic conditions. In contrast, when CF-affected cells were infected with Pseudomonas aeruginosa, HIF-1α was more stabilized compared to CFTR-corrected cells. As HIF-1 is linked with an efficient immune response and pulmonary complications in cystic fibrosis, this difference in HIF-1α protein levels could have an impact in the CF pathology and the persistence of P. aeruginosa infection.
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Affiliation(s)
- Claire Legendre
- BIOMERIT Research Centre, Department of Microbiology, University College Cork, Cork, Ireland
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