Analyzing Anthrax Toxins in Drosophilia

Summary

Principal Investigator: Ethan Bier
Abstract: DESCRIPTION (provided by applicant): In the past granting period we made a paradigm shifting discovery in which we showed that the two key virulence factors from Bacillus anthracis, edema factor (EF) and lethal factor (LF) act cooperatively to inhibit protein trafficking to cell-cll junctions. EF (a highly active adenylate cyclase) reduces the levels and activity of a small GTPase (Rab11) required in the final step of endocytic recycling to the cell surface, while LF (a metalloprotease that cleaves and inactivates MEKs) inhibits the Rab11 binding partner, Sec15, a component of the exocyst complex located at the plasma membrane. By inhibiting endocytic recycling, anthrax toxins also reduce levels of cell adhesion molecules (e.g., cadherins) and signaling proteins (e.g., Notch components) at cell-cell junctions, resulting in barrier disruption We discovered this novel effect of anthrax toxins using the model genetic system Drosophila melanogaster (fruit fly) and then validated these effects in human vascular endothelial cells as well as in vivo in mice. Another key finding, with important practical implications, was that over-expression of Rab11, can reverse the junction disrupting effects of EF in both flies and human cells. In the current grant, we propose two integrated aims to determine the mechanisms by which anthrax toxins inhibit endocytic recycling (Aim 1), and to investigate the role of endocytic recycling the pathogenesis of anthrax infection (Aim 2). In Aim 1.1, we will focus on how high levels of cAMP produced by EF interfere with effector pathways promoting exocyst function and lead to reduced Rab11 protein levels. In Aim 1.2, we will determine whether inhibiting MEKs can account for the ability of LF to block exocyst-mediated trafficking, and whether exocyst function is regulated by down-stream MAP-Kinases. In Aim 2.1, we will first survey the effects of anthrax toxins on expression of Rab11 and Sec15 in known target organs and cell types. We will also examine how various cell biological processes and barrier-regulating pathways contribute to the permeabilizing effects of anthrax toxins in vascular endothelial cells since vascular collapse is a frequent cause of death in anthrax. Finally, in Aim 2.2, we will determine whether increasing Rab11 levels or treating with known barrier protective agents can reverse the vascular leakage caused by EF. The proposed studies are highly relevant to treating anthrax since toxins typically reach critical lethal levels in the blood just as patients begin to seek medical intervention, when antibiotics are no longer effective. Thus, treatments based on restoring endocytic recycling could be used in conjunction with existing anti-toxin therapies (e.g., anti-toxin antibodies, enzymatic inhibitors) to neutralize toxins already present in the circulation. An advantage of barrier-protective agents is that they would intervene at the very last step when vascular integrity collapses and other organ systems fail. Such barrier enhancing compounds could also have broad applications to a variety of barrier disruptive diseases including other infectious diseases, cardiac ischemia, asthma, dermatitis, inflammatory bowel diseases, cancer, ciliary diseases, and neurodegenerative disorders.
Funding Period: 2006-07-01 - 2014-08-31
more information: NIH RePORT

Detail Information

Research Grants30

  1. The Shelf Live Evaluation of Investigational Dosage Forms
    Jonathan White; Fiscal Year: 2013
    ..This contract is essential for continued assurance of the quality of drugs undergoing clinical investigation for different types of cancer by Cancer Therapeutics Evaluation Program. ..
  2. Anthrax Lethal Toxin-Induced Heart Failure: Role of PP2A and MAP Kinases
    David E Dostal; Fiscal Year: 2013
    ..This information could lead to rationale drug therapies that preserve cardiac function in active duty military/Veterans exposed to this biological agent, as well as individuals with other causes of heart failure. ..
  3. Glycan Modulation of Inflammatory Responses
    Ajit P Varki; Fiscal Year: 2013
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  4. Optimization of HIV vaccines for the induction of cross-reactive antibodies
    Shan Lu; Fiscal Year: 2013
    ..RELEVANCE: To optimize the next generation polyvalent Env HIV vaccine formulations using the multi-gene, polyvalent DNA prime - protein boost technology platform. ..
  5. Molecular mechanisms of hypoxia tolerance and susceptibility
    Gabriel G Haddad; Fiscal Year: 2013
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  6. Genomics for Transplantation: Discovery and Biomarkers
    Daniel R Salomon; Fiscal Year: 2013
    ..Ultimately, we hope to create the genomic tools that will allow physicians to optimize and personalize the safety and efficacy of immunosuppression. ..
  7. The Virtual Physiological Rat Project
    Daniel A Beard; Fiscal Year: 2013
    ..This proposal targets the grand challenge of understanding complex multi-faceted disease phenotypes through experiments and simulations that capture the complex genotype-environment-phenotype relationship. ..
  8. Innate/Adaptive Immune Interactions in Gut Inflammation
    Sergio A Lira; Fiscal Year: 2013
    ..Overall the focus and interactive nature of the program (20 joint publications in 4 years, 3 additional NIH grants on related areas) provide a solid basis for a productive outcome. ..
  9. Four-Dimensional Heterogeneity of Fluid Phase Biopsies in Cancer (4DB-Center)
    Peter Kuhn; Fiscal Year: 2013
    ..The 4DB Center will also serve to disseminate information, education, and training to a new generation of cancer physicists;a generation that will implement the power of physics to conquer the problems of cancer. ..
  10. Secreted RNA during CRC progression biogenesis function and clinical markers
    Robert J Coffey; Fiscal Year: 2013
    ..We are confident that these specific RNA trafficking mechanisms will be acting in other tissues in the body and are of general relevance to multiple fields. ..
  11. Novel Strategies to Prevent Malaria and Improve Maternal-Child Health in Africa
    Diane V Havlir; Fiscal Year: 2013
    ..Administrative, laboratory, and data cores provide infrastructure support to the projects, including the capacity to process and evaluate placental malaria using histopathology. ..
  12. Caloric Restricted Rodent Colony
    RICK MORIN; Fiscal Year: 2013
    ..The purpose of this project is to develop, maintain and distribute a standing colony ofaged, calorically restricted rodents ofdefined strains for use by investigators in studies of aging. ..
  13. Distinct and Overlapping Pathways of Fibrosis and Emphysema in Cigarette Smokers
    Augustine M Choi; Fiscal Year: 2013
    ..4) Clinical Outcomes and Molecular Phenotypes in Smokers with Parenchymal Lung Disease Cores: 1) Administrative Core 2) Respiratory Computational Discovery Core 3) Clinical Biorepository Core 4) Murine Models and Molecular Analysis Core ..
  14. AMPK Endothelial Cell Dysfunction and the Metabolic Syndrome (PROGRAM PROJECT)
    Neil B Ruderman; Fiscal Year: 2013
    ..The proposed studies should both yield novel insights into the biological bases for the premature atherosclerosis and impaired angiogenesis associated with this entity and suggest new therapeutic targets for their prevention...
  15. Alternative approaches for NALT-based immunity to respiratory pathogens
    Prosper N Boyaka; Fiscal Year: 2013
    ..We will also validate a new route for mucosal vaccine delivery, as well as new PA-based mucosal adjuvant(s) for the induction of immunity against respiratory pathogens. ..
  16. Molecular Mechanisms linking Aging, Abeta Proteotoxicity and Neurodegeneration
    Jeffery W Kelly; Fiscal Year: 2013
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  17. CryoEM analysis of Anthrax Toxin Pore Complexes
    Mark T Fisher; Fiscal Year: 2013
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  18. Expanding Excellence in Developmental Biology in Oklahoma
    Linda F Thompson; Fiscal Year: 2013
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  19. Pacific NorthWest Regional Center of Excellence (PNWRCE)
    Jay A Nelson; Fiscal Year: 2013
    ..pseudomallei host pathogen response during both the septicemic as well as the intracellular phases of the disease. ..
  20. Southeast Regional Centers of Excellence for Biodefense &Emerging Infectious Di
    Philip Frederick Sparling; Fiscal Year: 2013
    ..SERCEB brings new investigators to the biodefense effort through a combination of educational programs, support of innovative new projects, and the synergistic interactions among its world-class investigators. ..
  21. New England Regional Center of Excellence in Biodefense and Emerging Infectious D
    Dennis L Kasper; Fiscal Year: 2013
    ..NERCE will also continue its Developmental Projects program and Career Development in Biodefense program in an effort to initiate new research efforts and to attract new investigators to this field. ..
  22. Northeast Biodefense Center
    W Ian Lipkin; Fiscal Year: 2013
    ..As a Center based in a School of Public Health and a State Department of Health, the NBC has a firm commitment to and practical understanding of Emergency Preparedness. ..
  23. Pacific Southwest RCE for Biodefense &Emerging Infectious Diseases Research
    Alan G Barbour; Fiscal Year: 2013
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  24. Rocky Mountain Regional Center of Excellence or Biodefense and Emerging Infectiou
    John T Belisle; Fiscal Year: 2013
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  25. Interactive Signaling Modules in Vascular Inflammation
    Linda H Shapiro; Fiscal Year: 2013
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  26. IND Enabling Studies for Small Molecule Anthrax Lethal Factor Inhibitors
    ALAN THOMAS JOHNSON; Fiscal Year: 2013
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