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Van N, Degefu YN, Leus PA, Larkins-Ford J, Klickstein J, Maurer FP, Stone D, Poonawala H, Thorpe CM, Smith TC, Aldridge BB. Novel Synergies and Isolate Specificities in the Drug Interaction Landscape of Mycobacterium abscessus. Antimicrob Agents Chemother 2023; 67:e0009023. [PMID: 37278639 PMCID: PMC10353461 DOI: 10.1128/aac.00090-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Accepted: 05/12/2023] [Indexed: 06/07/2023] Open
Abstract
Mycobacterium abscessus infections are difficult to treat and are often considered untreatable without tissue resection. Due to the intrinsic drug-resistant nature of the bacteria, combination therapy of three or more antibiotics is recommended. A major challenge in treating M. abscessus infections is the absence of a universal combination therapy with satisfying clinical success rates, leaving clinicians to treat infections using antibiotics lacking efficacy data. We systematically measured drug combinations in M. abscessus to establish a resource of drug interaction data and identify patterns of synergy to help design optimized combination therapies. We measured 191 pairwise drug combination effects among 22 antibacterials and identified 71 synergistic pairs, 54 antagonistic pairs, and 66 potentiator-antibiotic pairs. We found that commonly used drug combinations in the clinic, such as azithromycin and amikacin, are antagonistic in the lab reference strain ATCC 19977, whereas novel combinations, such as azithromycin and rifampicin, are synergistic. Another challenge in developing universally effective multidrug therapies for M. abscessus is the significant variation in drug response between isolates. We measured drug interactions in a focused set of 36 drug pairs across a small panel of clinical isolates with rough and smooth morphotypes. We observed strain-dependent drug interactions that cannot be predicted from single-drug susceptibility profiles or known drug mechanisms of action. Our study demonstrates the immense potential to identify synergistic drug combinations in the vast drug combination space and emphasizes the importance of strain-specific combination measurements for designing improved therapeutic interventions.
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Affiliation(s)
- Nhi Van
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts, USA
- Stuart B. Levy Center for Integrated Management of Antimicrobial Resistance, Boston, Massachusetts, USA
| | - Yonatan N. Degefu
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts, USA
- Stuart B. Levy Center for Integrated Management of Antimicrobial Resistance, Boston, Massachusetts, USA
| | - Pathricia A. Leus
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts, USA
- Graduate School of Biomedical Sciences, Tufts University School of Medicine, Boston, Massachusetts, USA
| | - Jonah Larkins-Ford
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts, USA
- Stuart B. Levy Center for Integrated Management of Antimicrobial Resistance, Boston, Massachusetts, USA
- Graduate School of Biomedical Sciences, Tufts University School of Medicine, Boston, Massachusetts, USA
| | - Jacob Klickstein
- Graduate School of Biomedical Sciences, Tufts University School of Medicine, Boston, Massachusetts, USA
| | - Florian P. Maurer
- Institute of Medical Microbiology, Virology and Hygiene, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
- National and WHO Supranational Reference Center for Mycobacteria, Research Center Borstel, Borstel, Germany
| | - David Stone
- Division of Geographic Medicine and Infectious Diseases, Department of Medicine, Tufts Medical Center and Tufts University School of Medicine, Boston, Massachusetts, USA
| | - Husain Poonawala
- Stuart B. Levy Center for Integrated Management of Antimicrobial Resistance, Boston, Massachusetts, USA
- Division of Geographic Medicine and Infectious Diseases, Department of Medicine, Tufts Medical Center and Tufts University School of Medicine, Boston, Massachusetts, USA
| | - Cheleste M. Thorpe
- Stuart B. Levy Center for Integrated Management of Antimicrobial Resistance, Boston, Massachusetts, USA
- Division of Geographic Medicine and Infectious Diseases, Department of Medicine, Tufts Medical Center and Tufts University School of Medicine, Boston, Massachusetts, USA
| | - Trever C. Smith
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts, USA
- Stuart B. Levy Center for Integrated Management of Antimicrobial Resistance, Boston, Massachusetts, USA
| | - Bree B. Aldridge
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts, USA
- Stuart B. Levy Center for Integrated Management of Antimicrobial Resistance, Boston, Massachusetts, USA
- Graduate School of Biomedical Sciences, Tufts University School of Medicine, Boston, Massachusetts, USA
- Department of Biomedical Engineering, Tufts University School of Engineering, Medford, Massachusetts, USA
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Larkins-Ford J, Aldridge BB. Advances in the design of combination therapies for the treatment of tuberculosis. Expert Opin Drug Discov 2023; 18:83-97. [PMID: 36538813 PMCID: PMC9892364 DOI: 10.1080/17460441.2023.2157811] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Accepted: 12/08/2022] [Indexed: 12/24/2022]
Abstract
INTRODUCTION Tuberculosis requires lengthy multi-drug therapy. Mycobacterium tuberculosis occupies different tissue compartments during infection, making drug access and susceptibility patterns variable. Antibiotic combinations are needed to ensure each compartment of infection is reached with effective drug treatment. Despite drug combinations' role in treating tuberculosis, the design of such combinations has been tackled relatively late in the drug development process, limiting the number of drug combinations tested. In recent years, there has been significant progress using in vitro, in vivo, and computational methodologies to interrogate combination drug effects. AREAS COVERED This review discusses the advances in these methodologies and how they may be used in conjunction with new successful clinical trials of novel drug combinations to design optimized combination therapies for tuberculosis. Literature searches for approaches and experimental models used to evaluate drug combination effects were undertaken. EXPERT OPINION We are entering an era richer in combination drug effect and pharmacokinetic/pharmacodynamic data, genetic tools, and outcome measurement types. Application of computational modeling approaches that integrate these data and produce predictive models of clinical outcomes may enable the field to generate novel, effective multidrug therapies using existing and new drug combination backbones.
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Affiliation(s)
- Jonah Larkins-Ford
- Department of Molecular Biology and Microbiology and Tufts University School of Graduate Biomedical Sciences, Tufts University School of Medicine, Boston, MA, USA
- Stuart B. Levy Center for Integrated Management of Antimicrobial Resistance (CIMAR), Tufts University, Boston, MA, USA
- Current address: MarvelBiome Inc, Woburn, MA, USA
| | - Bree B. Aldridge
- Department of Molecular Biology and Microbiology and Tufts University School of Graduate Biomedical Sciences, Tufts University School of Medicine, Boston, MA, USA
- Stuart B. Levy Center for Integrated Management of Antimicrobial Resistance (CIMAR), Tufts University, Boston, MA, USA
- Department of Biomedical Engineering, Tufts University School of Engineering, Medford, MA, USA
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3
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Larkins-Ford J, Degefu YN, Van N, Sokolov A, Aldridge BB. Design principles to assemble drug combinations for effective tuberculosis therapy using interpretable pairwise drug response measurements. Cell Rep Med 2022; 3:100737. [PMID: 36084643 PMCID: PMC9512659 DOI: 10.1016/j.xcrm.2022.100737] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Revised: 05/16/2022] [Accepted: 08/16/2022] [Indexed: 11/02/2022]
Abstract
A challenge in tuberculosis treatment regimen design is the necessity to combine three or more antibiotics. We narrow the prohibitively large search space by breaking down high-order drug combinations into drug pair units. Using pairwise in vitro measurements, we train machine learning models to predict higher-order combination treatment outcomes in the relapsing BALB/c mouse model. Classifiers perform well and predict many of the >500 possible combinations among 12 antibiotics to be improved over bedaquiline + pretomanid + linezolid, a treatment-shortening regimen compared with the standard of care in mice. We reformulate classifiers as simple rulesets to reveal guiding principles of constructing combination therapies for both preclinical and clinical outcomes. One example ruleset combines a drug pair that is synergistic in a dormancy model with a pair that is potent in a cholesterol-rich growth environment. These rulesets are predictive, intuitive, and practical, thus enabling rational construction of drug combinations. Evaluate the large drug combination space for potential tuberculosis treatments In vitro 2-drug combination measurements predict 3–4 drug treatment outcomes in vivo Strongly synergistic, antagonistic, or potent drug pairs drive treatment outcome Simple rules articulate drug combination design principles for tuberculosis
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Larkins-Ford J, Greenstein T, Van N, Degefu YN, Olson MC, Sokolov A, Aldridge BB. Systematic measurement of combination-drug landscapes to predict in vivo treatment outcomes for tuberculosis. Cell Syst 2021; 12:1046-1063.e7. [PMID: 34469743 PMCID: PMC8617591 DOI: 10.1016/j.cels.2021.08.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Revised: 06/16/2021] [Accepted: 08/04/2021] [Indexed: 12/30/2022]
Abstract
Lengthy multidrug chemotherapy is required to achieve a durable cure in tuberculosis. However, we lack well-validated, high-throughput in vitro models that predict animal outcomes. Here, we provide an extensible approach to rationally prioritize combination therapies for testing in in vivo mouse models of tuberculosis. We systematically measured Mycobacterium tuberculosis response to all two- and three-drug combinations among ten antibiotics in eight conditions that reproduce lesion microenvironments, resulting in >500,000 measurements. Using these in vitro data, we developed classifiers predictive of multidrug treatment outcome in a mouse model of disease relapse and identified ensembles of in vitro models that best describe in vivo treatment outcomes. We identified signatures of potencies and drug interactions in specific in vitro models that distinguish whether drug combinations are better than the standard of care in two important preclinical mouse models. Our framework is generalizable to other difficult-to-treat diseases requiring combination therapies. A record of this paper's transparent peer review process is included in the supplemental information.
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Affiliation(s)
- Jonah Larkins-Ford
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA 02111, USA; Stuart B. Levy Center for Integrated Management of Antimicrobial Resistance, Boston, MA 02111, USA; Graduate School of Biomedical Sciences, Tufts University School of Medicine, Boston, MA 02111, USA; Laboratory of Systems Pharmacology, Harvard Program in Therapeutic Science, Harvard Medical School, Boston, MA 02115, USA
| | - Talia Greenstein
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA 02111, USA; Stuart B. Levy Center for Integrated Management of Antimicrobial Resistance, Boston, MA 02111, USA; Graduate School of Biomedical Sciences, Tufts University School of Medicine, Boston, MA 02111, USA
| | - Nhi Van
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA 02111, USA
| | - Yonatan N Degefu
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA 02111, USA; Laboratory of Systems Pharmacology, Harvard Program in Therapeutic Science, Harvard Medical School, Boston, MA 02115, USA
| | - Michaela C Olson
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA 02111, USA
| | - Artem Sokolov
- Laboratory of Systems Pharmacology, Harvard Program in Therapeutic Science, Harvard Medical School, Boston, MA 02115, USA
| | - Bree B Aldridge
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA 02111, USA; Stuart B. Levy Center for Integrated Management of Antimicrobial Resistance, Boston, MA 02111, USA; Graduate School of Biomedical Sciences, Tufts University School of Medicine, Boston, MA 02111, USA; Laboratory of Systems Pharmacology, Harvard Program in Therapeutic Science, Harvard Medical School, Boston, MA 02115, USA; Department of Biomedical Engineering, Tufts University School of Engineering, Medford, MA 02155, USA.
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5
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Smith TC, Pullen KM, Olson MC, McNellis ME, Richardson I, Hu S, Larkins-Ford J, Wang X, Freundlich JS, Ando DM, Aldridge BB. Morphological profiling of tubercle bacilli identifies drug pathways of action. Proc Natl Acad Sci U S A 2020; 117:18744-18753. [PMID: 32680963 PMCID: PMC7414088 DOI: 10.1073/pnas.2002738117] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Morphological profiling is a method to classify target pathways of antibacterials based on how bacteria respond to treatment through changes to cellular shape and spatial organization. Here we utilized the cell-to-cell variation in morphological features of Mycobacterium tuberculosis bacilli to develop a rapid profiling platform called Morphological Evaluation and Understanding of Stress (MorphEUS). MorphEUS classified 94% of tested drugs correctly into broad categories according to modes of action previously identified in the literature. In the other 6%, MorphEUS pointed to key off-target activities. We observed cell wall damage induced by bedaquiline and moxifloxacin through secondary effects downstream from their main target pathways. We implemented MorphEUS to correctly classify three compounds in a blinded study and identified an off-target effect for one compound that was not readily apparent in previous studies. We anticipate that the ability of MorphEUS to rapidly identify pathways of drug action and the proximal cause of cellular damage in tubercle bacilli will make it applicable to other pathogens and cell types where morphological responses are subtle and heterogeneous.
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Affiliation(s)
- Trever C Smith
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA 02111
- Center for Integrated Management of Antimicrobial Resistance (CIMAR), Tufts University, Boston, MA 02111
| | - Krista M Pullen
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA 02111
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Michaela C Olson
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA 02111
| | - Morgan E McNellis
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA 02111
| | - Ian Richardson
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA 02111
- Roxbury Latin School, West Roxbury, MA 02132
| | - Sophia Hu
- Department of Bioinformatics and Computational Biology, University of Maryland, Baltimore County, Baltimore, MD 21250
| | - Jonah Larkins-Ford
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA 02111
- Tufts University School of Graduate Biomedical Sciences, Boston, MA 02111
- Laboratory of Systems Pharmacology, Harvard Medical School, Boston, MA 02115
| | - Xin Wang
- Department of Pharmacology, Physiology, and Neuroscience, Rutgers University-New Jersey Medical School, Newark, NJ 07103
| | - Joel S Freundlich
- Department of Pharmacology, Physiology, and Neuroscience, Rutgers University-New Jersey Medical School, Newark, NJ 07103
- Division of Infectious Disease, Department of Medicine, Rutgers University-New Jersey Medical School, Newark, NJ 07103
- Ruy V. Lourenco Center for the Study of Emerging and Re-emerging Pathogens, Rutgers University-New Jersey Medical School, Newark, NJ 07103
| | - D Michael Ando
- Applied Science Team, Google Research, Mountain View, CA 94043
| | - Bree B Aldridge
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA 02111;
- Center for Integrated Management of Antimicrobial Resistance (CIMAR), Tufts University, Boston, MA 02111
- Tufts University School of Graduate Biomedical Sciences, Boston, MA 02111
- Laboratory of Systems Pharmacology, Harvard Medical School, Boston, MA 02115
- Department of Biomedical Engineering, Tufts University School of Engineering, Medford, MA 02155
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6
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Cokol M, Kuru N, Bicak E, Larkins-Ford J, Aldridge BB. Efficient measurement and factorization of high-order drug interactions in Mycobacterium tuberculosis. Sci Adv 2017; 3:e1701881. [PMID: 29026882 PMCID: PMC5636204 DOI: 10.1126/sciadv.1701881] [Citation(s) in RCA: 80] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2017] [Accepted: 09/19/2017] [Indexed: 05/03/2023]
Abstract
Combinations of three or more drugs are used to treat many diseases, including tuberculosis. Thus, it is important to understand how synergistic or antagonistic drug interactions affect the efficacy of combination therapies. However, our understanding of high-order drug interactions is limited because of the lack of both efficient measurement methods and theoretical framework for analysis and interpretation. We developed an efficient experimental sampling and scoring method [diagonal measurement of n-way drug interactions (DiaMOND)] to measure drug interactions for combinations of any number of drugs. DiaMOND provides an efficient alternative to checkerboard assays, which are commonly used to measure drug interactions. We established a geometric framework to factorize high-order drug interactions into lower-order components, thereby establishing a road map of how to use lower-order measurements to predict high-order interactions. Our framework is a generalized Loewe additivity model for high-order drug interactions. Using DiaMOND, we identified and analyzed synergistic and antagonistic antibiotic combinations against Mycobacteriumtuberculosis. Efficient measurement and factorization of high-order drug interactions by DiaMOND are broadly applicable to other cell types and disease models.
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Affiliation(s)
- Murat Cokol
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA 02111, USA
- Laboratory of Systems Pharmacology, Harvard Medical School, Boston, MA 02115, USA
- Faculty of Engineering and Natural Sciences, Sabanci University, Istanbul 34956, Turkey
- Corresponding author. (M.C.); (B.B.A.)
| | - Nurdan Kuru
- Faculty of Engineering and Natural Sciences, Sabanci University, Istanbul 34956, Turkey
| | - Ece Bicak
- Master of Science Program in Biotechnology, Brandeis University, Waltham, MA 02453, USA
| | - Jonah Larkins-Ford
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA 02111, USA
- Laboratory of Systems Pharmacology, Harvard Medical School, Boston, MA 02115, USA
- Sackler School of Graduate Biomedical Sciences, Tufts University School of Medicine, Boston, MA 02111, USA
| | - Bree B. Aldridge
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA 02111, USA
- Laboratory of Systems Pharmacology, Harvard Medical School, Boston, MA 02115, USA
- Department of Biomedical Engineering, Tufts University School of Engineering, Medford, MA 02155, USA
- Corresponding author. (M.C.); (B.B.A.)
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Khaperskyy DA, Schmaling S, Larkins-Ford J, McCormick C, Gaglia MM. Selective Degradation of Host RNA Polymerase II Transcripts by Influenza A Virus PA-X Host Shutoff Protein. PLoS Pathog 2016; 12:e1005427. [PMID: 26849127 PMCID: PMC4744033 DOI: 10.1371/journal.ppat.1005427] [Citation(s) in RCA: 92] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2015] [Accepted: 01/10/2016] [Indexed: 11/30/2022] Open
Abstract
Influenza A viruses (IAVs) inhibit host gene expression by a process known as host shutoff. Host shutoff limits host innate immune responses and may also redirect the translation apparatus to the production of viral proteins. Multiple IAV proteins regulate host shutoff, including PA-X, a ribonuclease that remains incompletely characterized. We report that PA-X selectively targets host RNA polymerase II (Pol II) transcribed mRNAs, while sparing products of Pol I and Pol III. Interestingly, we show that PA-X can also target Pol II-transcribed RNAs in the nucleus, including non-coding RNAs that are not destined to be translated, and reporter transcripts with RNA hairpin structures that block ribosome loading. Transcript degradation likely occurs in the nucleus, as PA-X is enriched in the nucleus and its nuclear localization correlates with reduction in target RNA levels. Complete degradation of host mRNAs following PA-X-mediated endonucleolytic cleavage is dependent on the host 5’->3’-exonuclease Xrn1. IAV mRNAs are structurally similar to host mRNAs, but are synthesized and modified at the 3’ end by the action of the viral RNA-dependent RNA polymerase complex. Infection of cells with wild-type IAV or a recombinant PA-X-deficient virus revealed that IAV mRNAs resist PA-X-mediated degradation during infection. At the same time, loss of PA-X resulted in changes in the synthesis of select viral mRNAs and a decrease in viral protein accumulation. Collectively, these results significantly advance our understanding of IAV host shutoff, and suggest that the PA-X causes selective degradation of host mRNAs by discriminating some aspect of Pol II-dependent RNA biogenesis in the nucleus. All viruses depend on host components to convert viral mRNAs into proteins. Several viruses, including influenza A virus, encode factors that trigger RNA destruction. The influenza A virus factor that serves in this capacity is known as PA-X. PA-X limits accumulation of host mRNAs and proteins in infected cells and suppresses host responses to infection, but to date its precise mechanism of action remains obscure. Here we report that PA-X selectively targets cellular mRNAs, while sparing viral mRNAs, thereby compromising host gene expression and ensuring priority access of viral mRNAs to the protein synthesis machinery. We demonstrate that complete degradation of mRNAs cut by PA-X is dependent on the host factor Xrn1 and that PA-X likely works in the cell’s nuclei. Interestingly, PA-X targeting appears to be selective for products of host RNA polymerase II, and canonical mRNA processing is required for cleavage. Even though viral mRNAs are spared from PA-X-mediated degradation, PA-X-deficient viruses displayed defects in the synthesis of certain viral mRNAs and decreased viral protein accumulation. Thus, PA-X-mediated host shutoff influences the efficiency of viral gene expression. These studies significantly advance our understanding of this important viral host shutoff protein and may provide future opportunities to limit the pathogenesis of influenza A virus infection.
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Affiliation(s)
- Denys A. Khaperskyy
- Department of Microbiology and Immunology, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Summer Schmaling
- Department of Molecular Biology and Microbiology and Graduate Program in Molecular Microbiology, Tufts University School of Medicine, Boston, Massachusetts, United States of America
| | - Jonah Larkins-Ford
- Department of Molecular Biology and Microbiology and Graduate Program in Molecular Microbiology, Tufts University School of Medicine, Boston, Massachusetts, United States of America
| | - Craig McCormick
- Department of Microbiology and Immunology, Dalhousie University, Halifax, Nova Scotia, Canada
- * E-mail: (CM); (MMG)
| | - Marta M. Gaglia
- Department of Molecular Biology and Microbiology and Graduate Program in Molecular Microbiology, Tufts University School of Medicine, Boston, Massachusetts, United States of America
- * E-mail: (CM); (MMG)
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8
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Govindan JA, Jayamani E, Zhang X, Breen P, Larkins-Ford J, Mylonakis E, Ruvkun G. Lipid signalling couples translational surveillance to systemic detoxification in Caenorhabditis elegans. Nat Cell Biol 2015; 17:1294-303. [PMID: 26322678 PMCID: PMC4589496 DOI: 10.1038/ncb3229] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [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: 11/18/2014] [Accepted: 07/24/2015] [Indexed: 12/17/2022]
Abstract
Translation in eukaryotes is surveilled to detect toxins and virulence factors and coupled to the induction of defense pathways. C. elegans germline-specific mutations in translation components are detected by this system to induce detoxification and immune responses in distinct somatic cells. An RNAi screen revealed gene inactivations that act at multiple steps in lipid biosynthetic and kinase pathways that act upstream of MAP kinase to mediate the systemic communication of translation-defects to induce detoxification genes. Mammalian bile acids can rescue the defect in detoxification gene induction caused by C. elegans lipid biosynthetic gene inactivations. Extracts prepared from C. elegans with translation deficits but not from wild type can also rescue detoxification gene induction in lipid biosynthetic defective strains. These eukaryotic antibacterial countermeasures are not ignored by bacteria: particular bacterial species suppress normal C. elegans detoxification responses to mutations in translation factors.
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Affiliation(s)
- J Amaranath Govindan
- Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts 02114, USA.,Department of Genetics, Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Elamparithi Jayamani
- Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts 02114, USA.,Division of Infectious Diseases, Rhode Island Hospital, Alpert Medical School of Brown University, Providence, Rhode Island 02903, USA
| | - Xinrui Zhang
- Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts 02114, USA
| | - Peter Breen
- Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts 02114, USA
| | - Jonah Larkins-Ford
- Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts 02114, USA
| | - Eleftherios Mylonakis
- Division of Infectious Diseases, Rhode Island Hospital, Alpert Medical School of Brown University, Providence, Rhode Island 02903, USA
| | - Gary Ruvkun
- Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts 02114, USA.,Department of Genetics, Harvard Medical School, Boston, Massachusetts 02115, USA
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9
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Abstract
In recent history, the nematode Caenorhabditis elegans has provided a compelling platform for the discovery of novel antimicrobial drugs. In this protocol, we present an automated, high-throughput C. elegans pathogenesis assay, which can be used to screen for anti-infective compounds that prevent nematodes from dying due to Pseudomonas aeruginosa. New antibiotics identified from such screens would be promising candidates for treatment of human infections, and also can be used as probe compounds to identify novel targets in microbial pathogenesis or host immunity.
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Affiliation(s)
- Annie L Conery
- Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts.,Department of Genetics, Harvard Medical School, Boston, Massachusetts
| | - Jonah Larkins-Ford
- Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts
| | - Frederick M Ausubel
- Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts.,Department of Genetics, Harvard Medical School, Boston, Massachusetts
| | - Natalia V Kirienko
- Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts.,Department of Genetics, Harvard Medical School, Boston, Massachusetts
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10
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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: 140] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [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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11
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Rajamuthiah R, Fuchs BB, Jayamani E, Kim Y, Larkins-Ford J, Conery A, Ausubel FM, Mylonakis E. Whole animal automated platform for drug discovery against multi-drug resistant Staphylococcus aureus. PLoS One 2014; 9:e89189. [PMID: 24586584 PMCID: PMC3929655 DOI: 10.1371/journal.pone.0089189] [Citation(s) in RCA: 74] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2013] [Accepted: 01/15/2014] [Indexed: 11/19/2022] Open
Abstract
Staphylococcus aureus, the leading cause of hospital-acquired infections in the United States, is also pathogenic to the model nematode Caenorhabditis elegans. The C. elegans-S. aureus infection model was previously carried out on solid agar plates where the bacteriovorous C. elegans feeds on a lawn of S. aureus. However, agar-based assays are not amenable to large scale screens for antibacterial compounds. We have developed a high throughput liquid screening assay that uses robotic instrumentation to dispense a precise amount of methicillin resistant S. aureus (MRSA) and worms in 384-well assay plates, followed by automated microscopy and image analysis. In validation of the liquid assay, an MRSA cell wall defective mutant, MW2ΔtarO, which is attenuated for killing in the agar-based assay, was found to be less virulent in the liquid assay. This robust assay with a Z'-factor consistently greater than 0.5 was utilized to screen the Biomol 4 compound library consisting of 640 small molecules with well characterized bioactivities. As proof of principle, 27 of the 30 clinically used antibiotics present in the library conferred increased C. elegans survival and were identified as hits in the screen. Surprisingly, the antihelminthic drug closantel was also identified as a hit in the screen. In further studies, we confirmed the anti-staphylococcal activity of closantel against vancomycin-resistant S. aureus isolates and other Gram-positive bacteria. The liquid C. elegans-S. aureus assay described here allows screening for anti-staphylococcal compounds that are not toxic to the host.
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Affiliation(s)
- Rajmohan Rajamuthiah
- Division of Infectious Diseases, Rhode Island Hospital, Alpert Medical School of Brown University, Providence, Rhode Island, United States of America
- Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Beth Burgwyn Fuchs
- Division of Infectious Diseases, Rhode Island Hospital, Alpert Medical School of Brown University, Providence, Rhode Island, United States of America
- Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Elamparithi Jayamani
- Division of Infectious Diseases, Rhode Island Hospital, Alpert Medical School of Brown University, Providence, Rhode Island, United States of America
- Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Younghoon Kim
- Department of Animal Science, Chonbuk National University, Jeonju, Republic of Korea
| | - Jonah Larkins-Ford
- Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Annie Conery
- Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Frederick M. Ausubel
- Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Eleftherios Mylonakis
- Division of Infectious Diseases, Rhode Island Hospital, Alpert Medical School of Brown University, Providence, Rhode Island, United States of America
- Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
- * E-mail:
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Dolla NK, Chen C, Larkins-Ford J, Rajamuthiah R, Jagadeesan S, Conery AL, Ausubel FM, Mylonakis E, Bremner JB, Lewis K, Kelso MJ. On the Mechanism of Berberine-INF55 (5-Nitro-2-phenylindole) Hybrid Antibacterials. Aust J Chem 2014; 67:1471-1480. [PMID: 26806960 DOI: 10.1071/ch14426] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Berberine-INF55 hybrids are a promising class of antibacterials that combine berberine and the NorA multidrug resistance pump inhibitor INF55 (5-nitro-2-phenylindole) together in one molecule via a chemically stable linkage. Previous studies demonstrated the potential of these compounds for countering efflux-mediated antibacterial drug resistance but they didn't establish whether the compounds function as originally intended, i.e. with the berberine moiety providing antibacterial activity and the attached INF55 component independently blocking multidrug resistance pumps, thereby enhancing the activity of berberine by reducing its efflux. We hypothesised that if the proposed mechanism is correct, then hybrids carrying more potent INF55 pump inhibitor structures should show enhanced antibacterial effects relative to those bearing weaker inhibitors. Two INF55 analogues showing graded reductions in NorA inhibitory activity compared with INF55 were identified and their corresponding berberine-INF55 hybrids carrying equivalent INF55 inhibitor structures synthesised. Multiple assays comparing the antibacterial effects of the hybrids and their corresponding berberine-INF55 analogue combinations showed that the three hybrids all show very similar activities, leading us to conclude that the antibacterial mechanism(s) of berberine-INF55 hybrids is different from berberine-INF55 combinations.
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Affiliation(s)
- Naveen K Dolla
- School of Chemistry, University of Wollongong, Wollongong, NSW 2522, Australia
| | - Chao Chen
- Department of Biology and Antimicrobial Discovery Center, Northeastern University, Boston, MA 02115, USA
| | - Jonah Larkins-Ford
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Rajmohan Rajamuthiah
- Department of Medicine, Infectious Diseases Division, Rhode Island Hospital, Warren Alpert Medical School of Brown University, Providence, RI 02903, USA
| | - Sakthimala Jagadeesan
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114, USA; Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
| | - Annie L Conery
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114, USA; Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
| | - Frederick M Ausubel
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114, USA; Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
| | - Eleftherios Mylonakis
- Department of Medicine, Infectious Diseases Division, Rhode Island Hospital, Warren Alpert Medical School of Brown University, Providence, RI 02903, USA
| | - John B Bremner
- School of Chemistry, University of Wollongong, Wollongong, NSW 2522, Australia
| | - Kim Lewis
- Department of Biology and Antimicrobial Discovery Center, Northeastern University, Boston, MA 02115, USA
| | - Michael J Kelso
- School of Chemistry, University of Wollongong, Wollongong, NSW 2522, Australia
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13
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Okoli I, Coleman JJ, Tempakakis E, An WF, Holson E, Wagner F, Conery AL, Larkins-Ford J, Wu G, Stern A, Ausubel FM, Mylonakis E. Identification of antifungal compounds active against Candida albicans using an improved high-throughput Caenorhabditis elegans assay. PLoS One 2009; 4:e7025. [PMID: 19750012 PMCID: PMC2737148 DOI: 10.1371/journal.pone.0007025] [Citation(s) in RCA: 78] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2009] [Accepted: 08/16/2009] [Indexed: 11/18/2022] Open
Abstract
Candida albicans, the most common human pathogenic fungus, can establish a persistent lethal infection in the intestine of the microscopic nematode Caenorhabditis elegans. The C. elegans–C. albicans infection model was previously adapted to screen for antifungal compounds. Modifications to this screen have been made to facilitate a high-throughput assay including co-inoculation of nematodes with C. albicans and instrumentation allowing precise dispensing of worms into assay wells, eliminating two labor-intensive steps. This high-throughput method was utilized to screen a library of 3,228 compounds represented by 1,948 bioactive compounds and 1,280 small molecules derived via diversity-oriented synthesis. Nineteen compounds were identified that conferred an increase in C. elegans survival, including most known antifungal compounds within the chemical library. In addition to seven clinically used antifungal compounds, twelve compounds were identified which are not primarily used as antifungal agents, including three immunosuppressive drugs. This assay also allowed the assessment of the relative minimal inhibitory concentration, the effective concentration in vivo, and the toxicity of the compound in a single assay.
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Affiliation(s)
- Ikechukwu Okoli
- Division of Infectious Diseases, Massachusetts General Hospital, Boston, Massachusetts, United States of America
| | - Jeffrey J. Coleman
- Division of Infectious Diseases, Massachusetts General Hospital, Boston, Massachusetts, United States of America
| | - Emmanouil Tempakakis
- Division of Infectious Diseases, Massachusetts General Hospital, Boston, Massachusetts, United States of America
| | - W. Frank An
- Broad Institute of Massachusetts Institute of Technology and Harvard, Cambridge, Massachusetts, United States of America
| | - Edward Holson
- Broad Institute of Massachusetts Institute of Technology and Harvard, Cambridge, Massachusetts, United States of America
| | - Florence Wagner
- Broad Institute of Massachusetts Institute of Technology and Harvard, Cambridge, Massachusetts, United States of America
| | - Annie L. Conery
- Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts, United States of America
| | - Jonah Larkins-Ford
- Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts, United States of America
| | - Gang Wu
- Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts, United States of America
| | - Andy Stern
- Broad Institute of Massachusetts Institute of Technology and Harvard, Cambridge, Massachusetts, United States of America
| | - Frederick M. Ausubel
- Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts, United States of America
| | - Eleftherios Mylonakis
- Division of Infectious Diseases, Massachusetts General Hospital, Boston, Massachusetts, United States of America
- * E-mail:
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14
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Moy TI, Conery AL, Larkins-Ford J, Wu G, Mazitschek R, Casadei G, Lewis K, Carpenter AE, Ausubel FM. High-throughput screen for novel antimicrobials using a whole animal infection model. ACS Chem Biol 2009; 4:527-33. [PMID: 19572548 DOI: 10.1021/cb900084v] [Citation(s) in RCA: 142] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The nematode Caenorhabditis elegans is a unique whole animal model system for identifying small molecules with in vivo anti-infective properties. C. elegans can be infected with a broad range of human pathogens, including Enterococcus faecalis, an important human nosocomial pathogen. Here, we describe an automated, high-throughput screen of 37,200 compounds and natural product extracts for those that enhance survival of C. elegans infected with E. faecalis. Using a robot to dispense live, infected animals into 384-well plates and automated microscopy and image analysis, we identified 28 compounds and extracts not previously reported to have antimicrobial properties, including six structural classes that cure infected C. elegans animals but do not affect the growth of the pathogen in vitro, thus acting by a mechanism of action distinct from antibiotics currently in clinical use.
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Affiliation(s)
- Terence I. Moy
- Department of Genetics, Harvard Medical School, Boston, Massachusetts 02115
- Department of Molecular Biology
- Center for Computational and Integrative Biology
| | - Annie L. Conery
- Department of Molecular Biology
- Center for Computational and Integrative Biology
| | - Jonah Larkins-Ford
- Department of Molecular Biology
- Center for Computational and Integrative Biology
| | - Gang Wu
- Department of Molecular Biology
- Center for Computational and Integrative Biology
| | - Ralph Mazitschek
- Center for Systems Biology, Massachusetts General Hospital, Boston, Massachusetts 02114
| | - Gabriele Casadei
- Department of Biology, Northeastern University, Boston, Massachusetts 02115
| | - Kim Lewis
- Department of Biology, Northeastern University, Boston, Massachusetts 02115
| | - Anne E. Carpenter
- Imaging Platform, Broad Institute of MIT and Harvard, Cambridge, Massachusetts 02142
| | - Frederick M. Ausubel
- Department of Genetics, Harvard Medical School, Boston, Massachusetts 02115
- Department of Molecular Biology
- Center for Computational and Integrative Biology
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15
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Komatsu H, Chao MY, Larkins-Ford J, Corkins ME, Somers GA, Tucey T, Dionne HM, White JQ, Wani K, Boxem M, Hart AC. OSM-11 facilitates LIN-12 Notch signaling during Caenorhabditis elegans vulval development. PLoS Biol 2008; 6:e196. [PMID: 18700817 PMCID: PMC2504490 DOI: 10.1371/journal.pbio.0060196] [Citation(s) in RCA: 100] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2008] [Accepted: 06/26/2008] [Indexed: 01/06/2023] Open
Abstract
Notch signaling is critical for cell fate decisions during development. Caenorhabditis elegans and vertebrate Notch ligands are more diverse than classical Drosophila Notch ligands, suggesting possible functional complexities. Here, we describe a developmental role in Notch signaling for OSM-11, which has been previously implicated in defecation and osmotic resistance in C. elegans. We find that complete loss of OSM-11 causes defects in vulval precursor cell (VPC) fate specification during vulval development consistent with decreased Notch signaling. OSM-11 is a secreted, diffusible protein that, like previously described C. elegans Delta, Serrate, and LAG-2 (DSL) ligands, can interact with the lineage defective-12 (LIN-12) Notch receptor extracellular domain. Additionally, OSM-11 and similar C. elegans proteins share a common motif with Notch ligands from other species in a sequence defined here as the Delta and OSM-11 (DOS) motif. osm-11 loss-of-function defects in vulval development are exacerbated by loss of other DOS-motif genes or by loss of the Notch ligand DSL-1, suggesting that DOS-motif and DSL proteins act together to activate Notch signaling in vivo. The mammalian DOS-motif protein Deltalike1 (DLK1) can substitute for OSM-11 in C. elegans development, suggesting that DOS-motif function is conserved across species. We hypothesize that C. elegans OSM-11 and homologous proteins act as coactivators for Notch receptors, allowing precise regulation of Notch receptor signaling in developmental programs in both vertebrates and invertebrates.
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Affiliation(s)
- Hidetoshi Komatsu
- Massachusetts General Hospital, Center for Cancer Research, Charlestown, Massachusetts, United States of America
- Department of Pathology, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Michael Y Chao
- Department of Biology, California State University San Bernardino, San Bernardino, California, United States of America
| | - Jonah Larkins-Ford
- Massachusetts General Hospital, Center for Cancer Research, Charlestown, Massachusetts, United States of America
| | - Mark E Corkins
- Massachusetts General Hospital, Center for Cancer Research, Charlestown, Massachusetts, United States of America
| | - Gerard A Somers
- Massachusetts General Hospital, Center for Cancer Research, Charlestown, Massachusetts, United States of America
| | - Tim Tucey
- Massachusetts General Hospital, Center for Cancer Research, Charlestown, Massachusetts, United States of America
| | - Heather M Dionne
- Massachusetts General Hospital, Center for Cancer Research, Charlestown, Massachusetts, United States of America
| | - Jamie Q White
- Massachusetts General Hospital, Center for Cancer Research, Charlestown, Massachusetts, United States of America
- Department of Pathology, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Khursheed Wani
- Massachusetts General Hospital, Center for Cancer Research, Charlestown, Massachusetts, United States of America
| | - Mike Boxem
- Center for Cancer Systems Biology (CCSB) and Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, Massachusetts, United States of America
- Department of Genetics, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Anne C Hart
- Massachusetts General Hospital, Center for Cancer Research, Charlestown, Massachusetts, United States of America
- Department of Pathology, Harvard Medical School, Boston, Massachusetts, United States of America
- * To whom correspondence should be addressed. E-mail:
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16
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Cummings ME, Larkins-Ford J, Reilly CRL, Wong RY, Ramsey M, Hofmann HA. Sexual and social stimuli elicit rapid and contrasting genomic responses. Proc Biol Sci 2008; 275:393-402. [PMID: 18055387 PMCID: PMC2212751 DOI: 10.1098/rspb.2007.1454] [Citation(s) in RCA: 104] [Impact Index Per Article: 6.5] [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] [Indexed: 01/24/2023] Open
Abstract
Sensory physiology has been shown to influence female mate choice, yet little is known about the mechanisms within the brain that regulate this critical behaviour. Here we examine preference behaviour of 58 female swordtails, Xiphophorus nigrensis, in four different social environments (attractive and unattractive males, females only, non-attractive males only and asocial conditions) followed by neural gene expression profiling. We used a brain-specific cDNA microarray to identify patterns of genomic response and candidate genes, followed by quantitative PCR (qPCR) examination of gene expression with variation in behaviour. Our microarray results revealed patterns of genomic response differing more between classes of social stimuli than between presence versus absence of stimuli. We identified suites of genes showing diametrically opposed patterns of expression: genes that are turned ‘on’ while females interact with attractive males are turned ‘off’ when interacting with other females, and vice versa. Our qPCR results identified significant predictive relationships between five candidate genes and specific mate choice behaviours (preference and receptivity) across females exposed to males, with no significant patterns identified in female or asocial conditions or with overall locomotor activity. The identification of stimulus- and behaviour-specific responses opens an exciting window into the molecular pathways associated with social behaviour and mechanisms that underlie sexual selection.
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Affiliation(s)
- Molly E Cummings
- Section of Integrative Biology, University of Texas, Austin, TX 78712, USA.
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17
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Duftner N, Larkins-Ford J, Legendre M, Hofmann HA. Efficacy of RNA amplification is dependent on sequence characteristics: implications for gene expression profiling using a cDNA microarray. Genomics 2007; 91:108-17. [PMID: 18006269 DOI: 10.1016/j.ygeno.2007.09.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2007] [Revised: 09/05/2007] [Accepted: 09/07/2007] [Indexed: 12/15/2022]
Abstract
Minute tissue samples or single cells increasingly provide the starting material for gene expression profiling, which often requires RNA amplification. Although much effort has been put into optimizing amplification protocols, the relative abundance of RNA templates in the amplified product is frequently biased. We applied a T7 polymerase-based technique to amplify RNA from two tissues of a cichlid fish and compared expression levels of unamplified and amplified RNA on a cDNA microarray. Amplification bias was generally minor and comprised features that were lost (1.3%) or gained (2.5%) through amplification and features that were scored as regulated before but unregulated after amplification (4.2%) or vice versa (19.5%). We examined 10 sequence-specific properties and found that GC content, folding energy, hairpin length and number, and lengths of poly(A) and poly(T) stretches significantly affected RNA amplification. We conclude that, if RNA amplification is used in gene expression studies, preceding experiments controlling for amplification bias should be performed.
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Affiliation(s)
- Nina Duftner
- Section for Integrative Biology, University of Texas at Austin, Austin, TX 78712, USA
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18
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Abstract
BACKGROUND Notch signaling pathways are conserved across species and traditionally have been implicated in cell fate determination during embryonic development. Notch signaling components are also expressed postdevelopmentally in the brains of adult mice and Drosophila. Recent studies suggest that Notch signaling may play a role in the physiological, rather than developmental, regulation of neurons. Here, we investigate a new non-developmental role for Caenorhabditis elegans lin-12 Notch signaling in neurons regulating the spontaneous reversal rate during locomotion. RESULTS The spontaneous reversal rate of C. elegans during normal locomotion is constant. Both lin-12 gain and loss of function mutant animals had significantly increased reversal rates compared to wild type controls. These defects were caused by lin-12 activity, because the loss of function defect could be rescued by a wild type lin-12 transgene. Furthermore, overexpression of lin-12 recapitulated the gain-of-function defect. Increasing or decreasing lin-12 activity in the postdevelopmental adult animal was sufficient to rapidly and reversibly increase reversals, thereby excluding a developmental role for lin-12. Although lin-12 is expressed in the vulval and somatic gonad lineages, we find that these tissues play no role in regulating reversal rates. In contrast, altering lin-12 activity specifically in the nervous system was sufficient to increase reversals. These behavioral changes require components of the canonical lin-12 signaling cascade, including the ligand lag-2 and the transcriptional effector lag-1. Finally, the C. elegans AMPA/kainate glutamate receptor homolog glr-1 shows strong genetic interactions with lin-12, suggesting that glr-1 and/or other glutamate gated channels may be targets of lin-12 regulation. CONCLUSION Our results demonstrate a neuronal role for lin-12 Notch in C. elegans and suggest that lin-12 acutely regulates neuronal physiology to modulate animal behavior, without altering neuronal cell fate specification or neurite outgrowth. This is consistent with a role for Notch signaling in neurological disease with late onset symptoms.
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Affiliation(s)
- Michael Y Chao
- Center for Cancer Research, Massachusetts General Hospital, Charlestown MA, USA
- Department of Pathology, Harvard Medical School, Boston MA, USA
| | - Jonah Larkins-Ford
- Center for Cancer Research, Massachusetts General Hospital, Charlestown MA, USA
| | - Tim M Tucey
- Center for Cancer Research, Massachusetts General Hospital, Charlestown MA, USA
| | - Anne C Hart
- Center for Cancer Research, Massachusetts General Hospital, Charlestown MA, USA
- Department of Pathology, Harvard Medical School, Boston MA, USA
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Dunlap KD, Larkins-Ford J. Production of aggressive electrocommunication signals to progressively realistic social stimuli in maleApteronotus leptorhynchus. Ethology 2003. [DOI: 10.1046/j.1439-0310.2003.00865.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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20
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Dunlap KD, Larkins-Ford J. Diversity in the structure of electrocommunication signals within a genus of electric fish, Apteronotus. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2003; 189:153-61. [PMID: 12607044 DOI: 10.1007/s00359-003-0393-3] [Citation(s) in RCA: 33] [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] [Received: 08/08/2002] [Revised: 11/21/2002] [Accepted: 01/01/2003] [Indexed: 10/25/2022]
Abstract
Some gymnotiform electric fish modulate their electric organ discharge for intraspecific communication. In Apteronotus leptorhynchus, chirps are usually rapid (10-30 ms) modulations that are activated through non- N-methyl- d-aspartate (non-NMDA) glutamate receptors in the hindbrain pacemaker nucleus. Males produce longer chirp types than females and chirp at higher rates. In Apteronotus albifrons, chirp rate is sexually monomorphic, but chirp structure (change in frequency and amplitude during a chirp) was unknown. To better understand the neural regulation and evolution of chirping behavior, we compared chirp structure in these two species under identical stimulus regimes. A. albifrons, like A. leptorhynchus, produced distinct types of chirps that varied, in part, by frequency excursion. However, unlike in A. leptorhynchus, chirp types in A. albifrons varied little in duration, and chirps were all longer (70-200 ms) than those of A. leptorhynchus. Chirp type production was not sexually dimorphic in A. albifrons, but within two chirp types males produced longer chirps than females. We suggest that species differences in chirp duration might be attributable to differences in the relative proportions of fast-acting (non-NMDA) and slow-acting (NMDA) glutamate receptors in the pacemaker. Additionally, we map species difference onto a phylogeny and hypothesize an evolutionary sequence for the diversification of chirp structure.
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Affiliation(s)
- K D Dunlap
- Department of Biology, Trinity College, Hartford, CT 06106, USA.
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