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Shutinoski B, Alturki NA, Rijal D, Bertin J, Gough PJ, Schlossmacher MG, Sad S. K45A mutation of RIPK1 results in poor necroptosis and cytokine signaling in macrophages, which impacts inflammatory responses in vivo. Cell Death Differ 2016; 23:1628-37. [PMID: 27258786 DOI: 10.1038/cdd.2016.51] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2015] [Revised: 04/28/2016] [Accepted: 05/05/2016] [Indexed: 02/06/2023] Open
Abstract
Receptor interacting protein kinase 1 (RIPK1) participates in several cell signaling complexes that promote cell activation and cell death. Stimulation of RIPK1 in the absence of caspase signaling induces regulated necrosis (necroptosis), which promotes an inflammatory response. Understanding of the mechanisms through which RIPK1 promotes inflammation has been unclear. Herein we have evaluated the impact of a K45A mutation of RIPK1 on necroptosis of macrophages and the activation of inflammatory response. We show that K45A mutation of RIPK1 results in attenuated necroptosis of macrophages in response to stimulation with LPS, TNFα and IFNβ in the absence of caspase signaling. Impairment in necroptosis correlated with poor phosphorylation of RIPK1, RIPK3 and reduced trimerization of MLKL. Furthermore, K45A mutation of RIPK1 resulted in poor STAT1 phosphorylation (at S727) and expression of RANTES and MIP-1α following TNF-R engagement in the absence of caspase activation. Our results further indicate that in the absence of stimulation by pathogen-associated molecular patterns (PAMPs), cellular inhibitors of apoptotic proteins (cIAPs) prevent the K45-dependent auto-phosphorylation of RIPK1, leading to resistance against necroptosis. Finally, RIPK1(K45A) mice displayed attenuated inflammatory response in vivo as they were significantly resistant against endotoxin shock, but highly susceptible against a challenge with Salmonella typhimurium. This correlated with reduced expression of IL-1β and ROS, and poor processing of caspase 8 by RIPK1(K45A) macrophages. Overall, these results indicate that K45 mediated kinase activity of RIPK1 is not only important for necroptosis but it also has a key role in promoting cytokine signaling and host response to inflammatory stimuli.
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Affiliation(s)
- B Shutinoski
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada.,Program in Neuroscience and Division of Neurology, The Ottawa Hospital, Ottawa, ON, Canada
| | - N A Alturki
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada
| | - D Rijal
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada
| | - J Bertin
- Pattern Recognition Receptor Discovery Performance Unit, Immuno-Inflammation Therapeutic Area, GlaxoSmithKline, Collegeville, PA 19426, USA
| | - P J Gough
- Pattern Recognition Receptor Discovery Performance Unit, Immuno-Inflammation Therapeutic Area, GlaxoSmithKline, Collegeville, PA 19426, USA
| | - M G Schlossmacher
- Program in Neuroscience and Division of Neurology, The Ottawa Hospital, Ottawa, ON, Canada
| | - S Sad
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada
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2
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Affiliation(s)
- S B Berger
- Pattern Recognition Receptor Discovery Performance Unit, Immuno-Inflammation Therapeutic Area, GlaxoSmithKline, Collegeville, PA 19426, USA
| | - J Bertin
- Pattern Recognition Receptor Discovery Performance Unit, Immuno-Inflammation Therapeutic Area, GlaxoSmithKline, Collegeville, PA 19426, USA
| | - P J Gough
- Pattern Recognition Receptor Discovery Performance Unit, Immuno-Inflammation Therapeutic Area, GlaxoSmithKline, Collegeville, PA 19426, USA
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3
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Geserick P, Wang J, Schilling R, Horn S, Harris PA, Bertin J, Gough PJ, Feoktistova M, Leverkus M. Absence of RIPK3 predicts necroptosis resistance in malignant melanoma. Cell Death Dis 2015; 6:e1884. [PMID: 26355347 PMCID: PMC4650439 DOI: 10.1038/cddis.2015.240] [Citation(s) in RCA: 110] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2015] [Revised: 07/07/2015] [Accepted: 07/13/2015] [Indexed: 12/14/2022]
Abstract
Acquired or intrinsic resistance to apoptotic and necroptotic stimuli is considered a major hindrance of therapeutic success in malignant melanoma. Inhibitor of apoptosis proteins (IAPs) are important regulators of apoptotic and necroptotic cell death mediated by numerous cell death signalling platforms. In this report we investigated the impact of IAPs for cell death regulation in malignant melanoma. Suppression of IAPs strongly sensitized a panel of melanoma cells to death ligand-induced cell death, which, surprisingly, was largely mediated by apoptosis, as it was completely rescued by addition of caspase inhibitors. Interestingly, the absence of necroptosis signalling correlated with a lack of receptor-interacting protein kinase-3 (RIPK3) mRNA and protein expression in all cell lines, whereas primary melanocytes and cultured nevus cells strongly expressed RIPK3. Reconstitution of RIPK3, but not a RIPK3-kinase dead mutant in a set of melanoma cell lines overcame CD95L/IAP antagonist-induced necroptosis resistance independent of autocrine tumour necrosis factor secretion. Using specific inhibitors, functional studies revealed that RIPK3-mediated mixed-lineage kinase domain-like protein (MLKL) phosphorylation and necroptosis induction critically required receptor-interacting protein kinase-1 signalling. Furthermore, the inhibitor of mutant BRAF Dabrafenib, but not Vemurafenib, inhibited necroptosis in melanoma cells whenever RIPK3 is present. Our data suggest that loss of RIPK3 in melanoma and selective inhibition of the RIPK3/MLKL axis by BRAF inhibitor Dabrafenib, but not Vemurafenib, is critical to protect from necroptosis. Strategies that allow RIPK3 expression may allow unmasking the necroptotic signalling machinery in melanoma and points to reactivation of this pathway as a treatment option for metastatic melanoma.
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Affiliation(s)
- P Geserick
- Section of Molecular Dermatology, Department of Dermatology, Venerology and Allergology, Medical Faculty Mannheim, University Heidelberg, Mannheim, Germany
| | - J Wang
- Section of Molecular Dermatology, Department of Dermatology, Venerology and Allergology, Medical Faculty Mannheim, University Heidelberg, Mannheim, Germany.,Department for Dermatology and Allergology, University Hospital Aachen, RWTH Aachen, Aachen, Germany
| | - R Schilling
- Section of Molecular Dermatology, Department of Dermatology, Venerology and Allergology, Medical Faculty Mannheim, University Heidelberg, Mannheim, Germany
| | - S Horn
- Section of Molecular Dermatology, Department of Dermatology, Venerology and Allergology, Medical Faculty Mannheim, University Heidelberg, Mannheim, Germany
| | - P A Harris
- Pattern Recognition Receptor Discovery Performance Unit, Immuno-Inflammation Therapeutic Area, GlaxoSmithKline, Collegeville, PA 19426, USA
| | - J Bertin
- Pattern Recognition Receptor Discovery Performance Unit, Immuno-Inflammation Therapeutic Area, GlaxoSmithKline, Collegeville, PA 19426, USA
| | - P J Gough
- Pattern Recognition Receptor Discovery Performance Unit, Immuno-Inflammation Therapeutic Area, GlaxoSmithKline, Collegeville, PA 19426, USA
| | - M Feoktistova
- Section of Molecular Dermatology, Department of Dermatology, Venerology and Allergology, Medical Faculty Mannheim, University Heidelberg, Mannheim, Germany.,Department for Dermatology and Allergology, University Hospital Aachen, RWTH Aachen, Aachen, Germany
| | - M Leverkus
- Section of Molecular Dermatology, Department of Dermatology, Venerology and Allergology, Medical Faculty Mannheim, University Heidelberg, Mannheim, Germany.,Department for Dermatology and Allergology, University Hospital Aachen, RWTH Aachen, Aachen, Germany
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4
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Berger SB, Harris P, Nagilla R, Kasparcova V, Hoffman S, Swift B, Dare L, Schaeffer M, Capriotti C, Ouellette M, King BW, Wisnoski D, Cox J, Reilly M, Marquis RW, Bertin J, Gough PJ. Characterization of GSK'963: a structurally distinct, potent and selective inhibitor of RIP1 kinase. Cell Death Discov 2015; 1:15009. [PMID: 27551444 PMCID: PMC4979471 DOI: 10.1038/cddiscovery.2015.9] [Citation(s) in RCA: 103] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2015] [Accepted: 06/10/2015] [Indexed: 01/28/2023] Open
Abstract
Necroptosis and signaling regulated by RIP1 kinase activity is emerging as a key driver of inflammation in a variety of disease settings. A significant amount has been learned about how RIP1 regulates necrotic cell death through the use of the RIP1 kinase inhibitor Necrostatin-1 (Nec-1). Nec-1 has been a transformational tool for exploring the function of RIP1 kinase activity; however, its utility is somewhat limited by moderate potency, off-target activity against indoleamine-2,3-dioxygenase (IDO), and poor pharmacokinetic properties. These limitations of Nec-1 have driven an effort to identify next-generation tools to study RIP1 function, and have led to the identification of 7-Cl-O-Nec-1 (Nec-1s), which has improved pharmacokinetic properties and lacks IDO inhibitory activity. Here we describe the characterization of GSK′963, a chiral small-molecule inhibitor of RIP1 kinase that is chemically distinct from both Nec-1 and Nec-1s. GSK′963 is significantly more potent than Nec-1 in both biochemical and cellular assays, inhibiting RIP1-dependent cell death with an IC50 of between 1 and 4 nM in human and murine cells. GSK′963 is >10 000-fold selective for RIP1 over 339 other kinases, lacks measurable activity against IDO and has an inactive enantiomer, GSK′962, which can be used to confirm on-target effects. The increased in vitro potency of GSK′963 also translates in vivo, where GSK′963 provides much greater protection from hypothermia at matched doses to Nec-1, in a model of TNF-induced sterile shock. Together, we believe GSK′963 represents a next-generation tool for examining the function of RIP1 in vitro and in vivo, and should help to clarify our current understanding of the role of RIP1 in contributing to disease pathogenesis.
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Affiliation(s)
- S B Berger
- Pattern Recognition Receptor Discovery Performance Unit, Immuno-inflammation Therapeutic Area, GlaxoSmithKline , Collegeville, PA, USA
| | - P Harris
- Pattern Recognition Receptor Discovery Performance Unit, Immuno-inflammation Therapeutic Area, GlaxoSmithKline , Collegeville, PA, USA
| | - R Nagilla
- Pattern Recognition Receptor Discovery Performance Unit, Immuno-inflammation Therapeutic Area, GlaxoSmithKline , Collegeville, PA, USA
| | - V Kasparcova
- Pattern Recognition Receptor Discovery Performance Unit, Immuno-inflammation Therapeutic Area, GlaxoSmithKline , Collegeville, PA, USA
| | - S Hoffman
- Pattern Recognition Receptor Discovery Performance Unit, Immuno-inflammation Therapeutic Area, GlaxoSmithKline , Collegeville, PA, USA
| | - B Swift
- Pattern Recognition Receptor Discovery Performance Unit, Immuno-inflammation Therapeutic Area, GlaxoSmithKline , Collegeville, PA, USA
| | - L Dare
- Pattern Recognition Receptor Discovery Performance Unit, Immuno-inflammation Therapeutic Area, GlaxoSmithKline , Collegeville, PA, USA
| | - M Schaeffer
- Pattern Recognition Receptor Discovery Performance Unit, Immuno-inflammation Therapeutic Area, GlaxoSmithKline , Collegeville, PA, USA
| | - C Capriotti
- Pattern Recognition Receptor Discovery Performance Unit, Immuno-inflammation Therapeutic Area, GlaxoSmithKline , Collegeville, PA, USA
| | - M Ouellette
- Platform Technology and Science, GlaxoSmithKline , Collegeville, PA, USA
| | - B W King
- Platform Technology and Science, GlaxoSmithKline , Collegeville, PA, USA
| | - D Wisnoski
- Platform Technology and Science, GlaxoSmithKline , Collegeville, PA, USA
| | - J Cox
- Platform Technology and Science, GlaxoSmithKline , Collegeville, PA, USA
| | - M Reilly
- Pattern Recognition Receptor Discovery Performance Unit, Immuno-inflammation Therapeutic Area, GlaxoSmithKline , Collegeville, PA, USA
| | - R W Marquis
- Pattern Recognition Receptor Discovery Performance Unit, Immuno-inflammation Therapeutic Area, GlaxoSmithKline , Collegeville, PA, USA
| | - J Bertin
- Pattern Recognition Receptor Discovery Performance Unit, Immuno-inflammation Therapeutic Area, GlaxoSmithKline , Collegeville, PA, USA
| | - P J Gough
- Pattern Recognition Receptor Discovery Performance Unit, Immuno-inflammation Therapeutic Area, GlaxoSmithKline , Collegeville, PA, USA
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5
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Moriwaki K, Bertin J, Gough PJ, Orlowski GM, Chan FKM. Differential roles of RIPK1 and RIPK3 in TNF-induced necroptosis and chemotherapeutic agent-induced cell death. Cell Death Dis 2015; 6:e1636. [PMID: 25675296 PMCID: PMC4669795 DOI: 10.1038/cddis.2015.16] [Citation(s) in RCA: 179] [Impact Index Per Article: 19.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2014] [Revised: 12/30/2014] [Accepted: 01/07/2015] [Indexed: 12/12/2022]
Abstract
Apoptosis is a key mechanism for metazoans to eliminate unwanted cells. Resistance to apoptosis is a hallmark of many cancer cells and a major roadblock to traditional chemotherapy. Recent evidence indicates that inhibition of caspase-dependent apoptosis sensitizes many cancer cells to a form of non-apoptotic cell death termed necroptosis. This has led to widespread interest in exploring necroptosis as an alternative strategy for anti-cancer therapy. Here we show that in human colon cancer tissues, the expression of the essential necroptosis adaptors receptor interacting protein kinase (RIPK)1 and RIPK3 is significantly decreased compared with adjacent normal colon tissues. The expression of RIPK1 and RIPK3 was suppressed by hypoxia, but not by epigenetic DNA modification. To explore the role of necroptosis in chemotherapy-induced cell death, we used inhibitors of RIPK1 or RIPK3 kinase activity, and modulated their expression in colon cancer cell lines using short hairpin RNAs. We found that RIPK1 and RIPK3 were largely dispensable for classical chemotherapy-induced cell death. Caspase inhibitor and/or second mitochondria-derived activator of caspase mimetic, which sensitize cells to RIPK1- and RIPK3-dependent necroptosis downstream of tumor necrosis factor receptor-like death receptors, also did not alter the response of cancer cells to chemotherapeutic agents. In contrast to the RIPKs, we found that cathepsins are partially responsible for doxorubicin or etoposide-induced cell death. Taken together, these results indicate that traditional chemotherapeutic agents are not efficient inducers of necroptosis and that more potent pathway-specific drugs are required to fully harness the power of necroptosis in anti-cancer therapy.
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Affiliation(s)
- K Moriwaki
- Department of Pathology, Immunology and Microbiology Program, University of Massachusetts Medical School (UMMS), Worcester, MA 01655, USA
| | - J Bertin
- Pattern Recognition Receptor Discovery Performance Unit, Immuno-Inflammation Therapeutic Area, GlaxoSmithKline, Collegeville, PA 19422, USA
| | - P J Gough
- Pattern Recognition Receptor Discovery Performance Unit, Immuno-Inflammation Therapeutic Area, GlaxoSmithKline, Collegeville, PA 19422, USA
| | - G M Orlowski
- Department of Pathology, Immunology and Microbiology Program, University of Massachusetts Medical School (UMMS), Worcester, MA 01655, USA
| | - F K M Chan
- Department of Pathology, Immunology and Microbiology Program, University of Massachusetts Medical School (UMMS), Worcester, MA 01655, USA
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6
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Stringwell R, Lock A, Stutchbury CJ, Baggett E, Taylor J, Gough PJ, Garcia de Leaniz C. Maladaptation and phenotypic mismatch in hatchery-reared Atlantic salmon Salmo salar released in the wild. J Fish Biol 2014; 85:1927-45. [PMID: 25469952 DOI: 10.1111/jfb.12543] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2014] [Accepted: 09/12/2014] [Indexed: 05/18/2023]
Abstract
Changes in body shape, fluctuating asymmetry (FA) and crypsis were compared among Atlantic salmon Salmo salar fry kept as controls in captivity and those released and subsequently recaptured in the wild according to a before-after-control-impact (BACI) design. Hatchery fish that survived in the wild became more cryptic and displayed a much lower incidence of fin erosion and of asymmetric individuals than control fish kept in captivity. Significant differences in body shape were also apparent, and survivors had longer heads, thicker caudal peduncles and a more streamlined body shape than hatchery controls as early as 20 days following stocking, most likely as a result of phenotypic plasticity and non-random, selective mortality of maladapted phenotypes. Hatchery-reared fish typically perform poorly in the wild and the results of this study indicate that this may be due to phenotypic mismatch, i.e. because hatcheries generate fish that are phenotypically mismatched to the natural environment.
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Affiliation(s)
- R Stringwell
- Swansea University, Centre for Sustainable Aquatic Research, Department of BioSciences, Swansea SA2 8PP, U.K
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7
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Roberts LJ, Taylor J, Gough PJ, Forman DW, Garcia de Leaniz C. Silver spoons in the rough: can environmental enrichment improve survival of hatchery Atlantic salmon Salmo salar in the wild? J Fish Biol 2014; 85:1972-91. [PMID: 25469954 DOI: 10.1111/jfb.12544] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2014] [Accepted: 09/12/2014] [Indexed: 05/18/2023]
Abstract
This study tested the 'silver spoon' hypothesis which posits that individuals that develop under favourable conditions should enjoy a fitness advantage later in life because they are more likely to recognize and settle in high-quality habitats. Atlantic salmon Salmo salar of two age classes (0+ and 1+ years) were reared in environmentally enriched or standard hatchery tanks for a short period (c. 10 weeks), were then released into a natural river and sampled on repeated occasions to test for silver-spoon effects. Compared with controls, enriched fish had a 6.4% higher recapture rate and settled in higher velocity habitats when they were stocked as 0+ year fry, but not when they were stocked as 1+ year parr. The opportunity for selection was generally higher for environmentally enriched fish than for controls, and also higher for 0+ than for 1+ year fish. Selection favoured individuals with high condition factor, extensive fat reserves and longer than average pectoral fins in both age classes but favoured a small body size in 1+ year and a large body size in 0+ year releases. Stomach analysis showed that enriched fish ate more, and adapted quicker to natural prey than controls. These results provide support for silver-spoon effects in fish and indicate that enrichment can improve post-release performance in conservation programmes, but seemingly only if fish are not kept in captivity for too long.
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Affiliation(s)
- L J Roberts
- Swansea University, Centre for Sustainable Aquatic Research, Department of Biosciences, Swansea SA2 8PP, U.K
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Garton KJ, Gough PJ, Blobel CP, Murphy G, Greaves DR, Dempsey PJ, Raines EW. Tumor necrosis factor-alpha-converting enzyme (ADAM17) mediates the cleavage and shedding of fractalkine (CX3CL1). J Biol Chem 2001; 276:37993-8001. [PMID: 11495925 DOI: 10.1074/jbc.m106434200] [Citation(s) in RCA: 472] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Fractalkine (CX3CL1) is an unusual member of the chemokine family that is synthesized with its chemokine domain at the end of a mucin-rich, transmembrane stalk. This membrane-bound localization allows fractalkine to function as an adhesion molecule for cells bearing its receptor, CX3CR1. In addition, fractalkine can be proteolytically released from the cell surface, generating a soluble molecule that functions as a chemoattractant similar to the other members of the chemokine family. In this study, we have examined the mechanisms that regulate the conversion between these two functionally distinct forms of fractalkine. We demonstrate that under normal conditions fractalkine is synthesized as an intracellular precursor that is rapidly transported to the cell surface where it becomes a target for metalloproteinase-dependent cleavage that causes the release of a fragment containing the majority of the fractalkine extracellular domain. We show that the cleavage of fractalkine can be markedly enhanced by stimulating cells with phorbol 12-myristate 13-acetate (PMA), and we identify tumor necrosis factor-alpha converting enzyme (TACE; ADAM17) as the protease responsible for this PMA-induced fractalkine release. In addition, we provide data showing that TACE-mediated fractalkine cleavage occurs at a site distinct from the dibasic juxtamembrane motif that had been suggested previously based on protein sequence homologies. The identification of TACE as a major protease responsible for the conversion of fractalkine from a membrane-bound adhesion molecule to a soluble chemoattractant will provide new information for understanding the physiological function of this chemokine.
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Affiliation(s)
- K J Garton
- Department of Pathology, University of Washington, Harborview Medical Center, Seattle, Washington 98104, USA
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Gough PJ, Gordon S, Greaves DR. The use of human CD68 transcriptional regulatory sequences to direct high-level expression of class A scavenger receptor in macrophages in vitro and in vivo. Immunology 2001; 103:351-61. [PMID: 11454064 PMCID: PMC1783239 DOI: 10.1046/j.1365-2567.2001.01256.x] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Macrophages (Mphi) play a key role in innate and acquired immunity. The study of Mphi biology has been hampered by the absence of suitable gene regulatory sequences for the overexpression of heterologous genes in Mphi. The human CD68 gene encodes a glycoprotein that is expressed in monocytes and Mphi, and therefore represents an attractive candidate gene for the generation of a Mphi-specific gene-targeting vector. A transgene expression cassette that combines 2.9 kb of CD68 5' flanking sequence with the 83-bp first intron (IVS-1) of the CD68 gene, directed high-level, long-lasting expression of class A human scavenger receptor (hSR-A) isoforms in the murine Mphi cell line, RAW-264. By using this CD68 expression cassette to generate Mphi cell lines that overexpress a soluble secreted form of the extracellular portion of type I human SR-A, we were able to purify significant quantities of this protein and show its ability to inhibit SR-A-mediated endocytosis. Analysis of two independent lines of transgenic mice that expressed type III human SR-A under the control of the CD68 gene sequences revealed transgene mRNA expression in elicited Mphi populations and in mouse tissues in a pattern that was consistent with Mphi-specific gene targeting. These data show that CD68 transcriptional regulatory sequences can be used to direct high-level transgene expression in Mphi in vitro and in vivo.
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Affiliation(s)
- P J Gough
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK
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Hiltunen TP, Gough PJ, Greaves DR, Gordon S, Ylä-Herttuala S. Rabbit atherosclerotic lesions express scavenger receptor AIII mRNA, a naturally occurring splice variant that encodes a non-functional, dominant negative form of the macrophage scavenger receptor. Atherosclerosis 2001; 154:415-9. [PMID: 11166774 DOI: 10.1016/s0021-9150(00)00519-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Macrophage class A scavenger receptor types I and II (SR-AI and II) mediate the uptake of oxidized LDL in atherosclerotic lesions. The recently described type III receptor (SR-AIII), which lacks amino acids encoded by exon 10 of the SR-A gene, is unable to mediate the uptake of ligands and acts as a dominant negative regulator in the trimeric SR-A molecule. To find out whether SR-AIII might play a role in the regulation of SR-A activity in the arterial wall, we studied its expression in normal and atherosclerotic aortic intima-medias of Watanabe heritable hyperlipidemic (WHHL) and cholesterol-fed New Zealand white (NZW) rabbits. SR-A mRNA was amplified by reverse transcription-polymerase chain reaction (RT-PCR) with a SR-AIII-specific primer pair and with a primer pair suitable for both SR-AI and III. Very low SR-AI expression and no SR-AIII expression was found in the lesion-free aortic intima-medias of WHHL rabbits and control NZW rabbits. WHHL rabbit fatty streaks contained abundant SR-AI expression and low-level SR-AIII expression. In contrast, the numerous fatty streaks and fatty plaques appearing in the aortas of cholesterol-fed (14 weeks) NZW rabbits, and the fatty plaques of WHHL rabbits contained clearly detectable SR-AIII expression in addition to the abundant SR-AI expression. In addition, SR-AIII mRNA was detected in NZW and WHHL rabbit livers. The results suggest that in advanced atherosclerotic lesions, cells may protect themselves from the excessive uptake of oxidized lipoproteins by generating SR-A molecules which cannot bind modified LDL.
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Affiliation(s)
- T P Hiltunen
- Department of Medicine, Helsinki University Central Hospital, Helsinki, Finland
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Peiser L, Gough PJ, Kodama T, Gordon S. Macrophage class A scavenger receptor-mediated phagocytosis of Escherichia coli: role of cell heterogeneity, microbial strain, and culture conditions in vitro. Infect Immun 2000; 68:1953-63. [PMID: 10722588 PMCID: PMC97372 DOI: 10.1128/iai.68.4.1953-1963.2000] [Citation(s) in RCA: 167] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Macrophage class A scavenger receptors (SR-AI and SR-AII) contribute to host defense by binding polyanionic ligands such as lipopolysaccharide and lipoteichoic acid. SR-A knockout (SR-A(-/-)) mice are more susceptible to endotoxic shock and Listeria monocytogenes infection in vivo, possibly due to decreased clearance of lipopolysaccharide and microorganisms, respectively. We have used flow cytometry to analyze the role of SR-A and other scavenger-like receptors in phagocytosis of bacteria in vitro. Chinese hamster ovary cells stably transfected with human SR-A bound Escherichia coli and Staphylococcus aureus but ingested few organisms. Primary human monocyte-derived macrophages (Mphi) bound and ingested E. coli more efficiently, and this was partially but selectively blocked by the general SR inhibitor, poly(I). A specific and selective role for SR-A was shown, since bone marrow culture-derived Mphi from SR-A(-/-) mice ingested fewer E. coli organisms than did wild-type cells, while uptake of antibody-opsonized E. coli was unaffected. SR-A-dependent uptake of E. coli varied with the bacterial strain; ingestion of DH5alpha and K1 by SR-A(-/-) Mphi was reduced by 30 to 60% and 70 to 75%, respectively. Phagocytosis and endocytosis via SR-A were markedly down-modulated when Mphi were plated on serum-coated tissue culture plastic compared to bacteriologic plastic, where cell adhesion is mediated by SR-A and CR3, respectively. This paper demonstrates that SR-A can bind and ingest bacteria directly, consistent with a role in host defense in vivo, and highlights the importance of the source of the Mphi, bacterial strain, and culture conditions on receptor function in vitro.
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Affiliation(s)
- L Peiser
- Sir William Dunn School of Pathology, University of Oxford, Oxford OX1 3RE, United Kingdom.
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12
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Laukkanen J, Lehtolainen P, Gough PJ, Greaves DR, Gordon S, Ylä-Herttuala S. Adenovirus-mediated gene transfer of a secreted form of human macrophage scavenger receptor inhibits modified low-density lipoprotein degradation and foam-cell formation in macrophages. Circulation 2000; 101:1091-6. [PMID: 10715253 DOI: 10.1161/01.cir.101.10.1091] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Macrophage scavenger receptors (MSRs) play an important role in the pathogenesis of atherosclerosis. Therefore, local modulation of MSR activity could have a beneficial effect on atherogenesis. METHODS AND RESULTS We cloned a secreted "decoy" MSR (sMSR) that contains an extracellular portion of the human MSR type AI and constructed an adenoviral vector that directs high-level expression of sMSR in macrophages under the control of the human CD68 promoter. Expression of the sMSR protein inhibited the degradation of (125)I-labeled acetylated LDL and oxidized LDL by murine macrophages up to 90%. sMSRs also reduced acetylated LDL degradation in MSR knockout mouse peritoneal macrophages by 60% to 80%, which suggests that the decoy construct can compete for the uptake mediated via other related scavenger receptors. In addition, sMSRs inhibited foam-cell formation in murine macrophages in the presence of cytochalasin D. The mechanism of inhibition is through ligand binding to the sMSRs, which prevents the ligand binding to MSRs on cell membranes. CONCLUSIONS The demonstration that recombinant adenovirus-mediated gene transfer of decoy sMSRs can block foam-cell formation suggests a possible new strategy for gene therapy of atherosclerosis and for the treatment of lipid accumulation after arterial manipulations.
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Affiliation(s)
- J Laukkanen
- A.I. Virtanen Institute, Department of Medicine, University of Kuopio, Kuopio, Finland
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13
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Abstract
Akey aspect of the innate immune system is the ability to discriminate between self and infectious nonself. This is achieved through pattern recognition receptors which directly recognise molecular epitopes expressed by microbes. Scavenger receptors (SRs) have been studied primarily due to their ability to bind and internalise modified lipoproteins, suggesting an important role in foam cell formation and the pathogenesis of atherosclerosis. However, the ability of some SRs to function as pattern recognition receptors through their binding of a wide variety of pathogens indicates a potential role in host defence. This review will detail our current understanding of the function of SRs in innate immunity, and in the initiation of aquired immune responses.
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Affiliation(s)
- P J Gough
- Department of Pathology, University of Washington, Box 357470, Seattle, Washington 98195-7470, USA
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14
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Gough PJ, Greaves DR, Suzuki H, Hakkinen T, Hiltunen MO, Turunen M, Herttuala SY, Kodama T, Gordon S. Analysis of macrophage scavenger receptor (SR-A) expression in human aortic atherosclerotic lesions. Arterioscler Thromb Vasc Biol 1999; 19:461-71. [PMID: 10073945 DOI: 10.1161/01.atv.19.3.461] [Citation(s) in RCA: 96] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The class A scavenger receptors (SR-As) are trimeric, integral membrane glycoproteins that exhibit unusually broad ligand-binding properties. A number of studies have suggested that these receptors may play an important role in host defense and in many macrophage-associated pathological processes, including atherosclerosis and Alzheimer's disease. The study of the expression and function of these receptors in human disease has been hampered by the lack of suitable antibodies recognizing human SR-A. This has generated questions regarding the nature of receptors responsible for scavenger receptor activity detected in a variety of cell types, including monocytes, macrophages, smooth muscle cells, and endothelial cells. To address these questions, we have produced high-titer antisera recognizing human SR-A by using mice deficient for SR-A (SR-A -/-). We show that SR-A -/- mice produce a significantly higher-titer immune response than do wild-type (SR-A +/+) littermates, with antisera of the former having a broad species reactivity and recognizing SR-A from humans, mice, and rabbits. The antisera recognize both type I and II SR-A in a wide range of immunological techniques. Using these antisera we show that the expression of SR-A protein is induced during monocyte to macrophage differentiation and that SR-A mediates 80% of the uptake of acetylated low density lipoprotein by human monocyte-derived macrophages. We also establish that human SR-A is expressed by tissue macrophages in liver and lung and by macrophage-derived foam cells within aortic atherosclerotic lesions, with little detectable expression by smooth muscle cells or aortic endothelium.
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MESH Headings
- Actins/analysis
- Actins/immunology
- Animals
- Antibodies
- Aorta/chemistry
- Aorta/injuries
- Aorta/pathology
- Aortic Diseases/genetics
- Aortic Diseases/pathology
- Arteriosclerosis/genetics
- Arteriosclerosis/pathology
- CHO Cells
- Catheterization
- Cell Adhesion Molecules/analysis
- Cell Adhesion Molecules/genetics
- Cell Adhesion Molecules/immunology
- Cells, Cultured
- Cricetinae
- Endothelium, Vascular/chemistry
- Endothelium, Vascular/cytology
- Endothelium, Vascular/physiology
- Flow Cytometry
- Gene Expression/physiology
- Humans
- Macrophages/chemistry
- Macrophages/physiology
- Mice
- Mice, Knockout
- Muscle, Smooth, Vascular/chemistry
- Muscle, Smooth, Vascular/cytology
- Muscle, Smooth, Vascular/physiology
- Platelet Endothelial Cell Adhesion Molecule-1/analysis
- Platelet Endothelial Cell Adhesion Molecule-1/immunology
- Rabbits
- Receptors, Immunologic/analysis
- Receptors, Immunologic/genetics
- Receptors, Immunologic/immunology
- Receptors, Scavenger
- Scavenger Receptors, Class A
- Transfection
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Affiliation(s)
- P J Gough
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK.
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15
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Abstract
Scavenger receptors bind and internalize modified lipoproteins. There are several different classes of scavenger receptors in mammalian cells and their relative contribution to lipid transport in normal physiology and pathological conditions such as atherosclerosis has been the subject of intense investigation. Mice with a disruption in the macrophage scavenger receptor SR-A gene exhibit a reduced size of atherosclerotic lesions and also exhibit an enhanced susceptibility to pathogens and endotoxic shock. In addition to their role in lipid transport, scavenger receptors play important roles in host defence and in the regulation of acquired immunity. Recent progress in delineating the mechanisms by which oxidized LDL effects changes in gene expression will be reviewed.
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Affiliation(s)
- D R Greaves
- Sir William Dunn School of Pathology, University of Oxford, UK.
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16
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Honda M, Akiyama H, Yamada Y, Kondo H, Kawabe Y, Takeya M, Takahashi K, Suzuki H, Doi T, Sakamoto A, Ookawara S, Mato M, Gough PJ, Greaves DR, Gordon S, Kodama T, Matsushita M. Immunohistochemical evidence for a macrophage scavenger receptor in Mato cells and reactive microglia of ischemia and Alzheimer's disease. Biochem Biophys Res Commun 1998; 245:734-40. [PMID: 9588184 DOI: 10.1006/bbrc.1998.8120] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Macrophage scavenger receptors (MSR) are implicated in the development of atherosclerosis and amyloid b-protein deposition in Alzheimer's disease. However, histopathological studies of MSR expression in human tissues have been hampered by a lack of specific antibodies. Using MSR-deficient mice, we successfully raised a novel monoclonal antibody against human MSR together with high-titer antisera. These antibodies specifically recognized human tissue macrophages and human MSR protein purified from differentiated THP1 cells. In normal brain, MSR staining was mainly distributed to the perivascular cells, which correspond to Mato's fluorescent granular perithelial cells (Mato cells). In the lesions of ischemia and Alzheimer's disease, a subset of microglia stained positive for MSR. These novel antibodies are useful tools for analysis of MSR expression in human tissues.
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Affiliation(s)
- M Honda
- Department of Neuropsychiatry, University of Tokyo, Japan
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17
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Gough PJ, Greaves DR, Gordon S. A naturally occurring isoform of the human macrophage scavenger receptor (SR-A) gene generated by alternative splicing blocks modified LDL uptake. J Lipid Res 1998; 39:531-43. [PMID: 9548586] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The class A macrophage scavenger receptors (SR-A) are macrophage-specific trimeric integral membrane glycoproteins that have been implicated in many macrophage-associated physiological and pathological processes including atherosclerosis, Alzheimer's disease, and host defense. There are two forms of the receptor that have been previously cloned, and both are generated by alternative splicing of a single gene. Here we report the cloning of a third, alternatively spliced isoform of the human SR-A gene (type III hSR-A). The novel isoform is expressed in the human monocytic leukemia cell line THP-1 and also in primary human monocyte derived macrophages. When expressed in CHO-K1 cells, type III hSR-A does not internalize AcLDL despite having the domain shown to mediate this function in type I and II hSR-A. We show that type III protein has altered intracellular processing and is trapped within the endoplasmic reticulum, making it unable to perform endocytosis. Type III protein acts as a dominant negative isoform by reducing modified LDL uptake in CHO cells stably expressing either type I or type II SR-A. The demonstration that a naturally occurring splice variant of SR-A mRNA can act as a dominant negative isoform suggests a novel mechanism for regulation of scavenger receptor activity in macrophages.
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MESH Headings
- Alternative Splicing
- Amino Acid Sequence
- Animals
- Base Sequence
- CHO Cells
- Carbocyanines
- Cell Line
- Cloning, Molecular
- Cricetinae
- Fluorescent Dyes
- Gene Expression
- Humans
- Leukemia, Monocytic, Acute
- Lipoproteins, LDL/metabolism
- Macrophages/metabolism
- Molecular Sequence Data
- Polymerase Chain Reaction
- Receptors, Immunologic/chemistry
- Receptors, Immunologic/genetics
- Receptors, Immunologic/physiology
- Receptors, Scavenger
- Scavenger Receptors, Class A
- Transfection
- Tumor Cells, Cultured
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Affiliation(s)
- P J Gough
- Sir William Dunn School of Pathology, University of Oxford, United Kingdom
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