CoBRE Phase II Projects

Project Leader: Veronique A. Lacombe, Ph.D.

Associate Professor
Department of Physiological Sciences
Center for Veterinary Health Sciences
Oklahoma State University- Stillwater

Contact Information:
E-mail: veronique.lacombe@okstate.edu
Phone: (405) 744-8089
Office: Rm 283, McElroy Hall
Stillwater, Ok 74078

Project Summary: 
While diabetes, defined by a persistent hyperglycemic state, has reached epidemic levels, respiratory infections (e.g., influenza) have long held a high spot in the list of worldwide causes of death. Importantly, the incidence of hyperglycemia is a major and independent risk factor for the development and worsening severity of pulmonary infection. Although the lung is a major organ to utilize glucose, the role and the regulation of glucose homeostasis in the lung have received little attention. Glucose uptake from the bloodstream, the rate-limiting in glucose utilization, is tightly regulated by a family of specialized proteins, called the glucose transporters (GLUTs). Because every cell expresses these GLUTs, they are recognized as major regulators of whole-body glucose metabolism and thus are key pharmacological targets. However, little is known about the regulation of glucose transport in the respiratory system, particularly during a hyperglycemic state. Therefore, we hypothesize that GLUT activity in the diabetic lung modulates airway surface liquid glucose concentration and viral proliferation. The specific aims of this project are to test the hypotheses that: 1) diabetes will alter GLUT activity in the lung through an Akt/AS160 dependent pathway; 2) rescuing GLUT activity will improve airway surface liquid glucose concentration and thus decrease viral proliferation in the lung and the severity of influenza infection of diabetic animals. We will use a comprehensive, integrated approach at multiple system levels using state-of-the-art techniques. Insights gained from this study could lead to the identification of novel metabolic therapeutic targets for patients affected by diabetes and concurrent respiratory infections, a crucial outcome of this award.

Project Leader: Shitao Li, Ph.D.

Assistant Professor
Department of Physiological Sciences
Center for Veterinary and Health Sciences
Oklahoma State University-Stillwater

Contact Information:
E-mail: shitao.li@okstate.edu
Phone: (405) 744-2158
Office: Rm 157B, McElroy Hall
Stillwater, OK 74078

Project Summary: 
Influenza A virus (IAV) is a highly transmissible respiratory pathogen and presents a continued threat to global health, with considerable economic and social impact. IAV comprises a plethora of strains with different virulence determinants that contribute to influenza pathogenesis. Several determinants in non-structural protein 1 (NS1) of high pathogenic IAV strains have been found to subvert host defense and increase virulence. However, the NS1 of 2009 pandemic IAV lacks all these virulence determinants. To discover the new virulence determinant, we recently systematically analyzed NS1 protein complexes and found that the host factor, zinc finger C3H1-type containing protein (ZFC3H1) specifically interacted with NS1 of 2009 pandemic IAV. Our pilot experiments revealed that ZFC3H1 facilitates RNA exosome to degrade viral RNA, thereby limiting influenza replication. Based on our preliminary data, we hypothesize that the pandemic flu NS1 possesses a new virulence determinant that inhibits ZFC3H1-mediated RNA degradation and improves viral RNA stability. Aim 1 will identify the new NS1 virulence determinant of pandemic flu and determine its role in IAV pathogenesis. Aim 2 will define how ZFC3H1 restricts IAV replication via destabilizing viral RNA. Aim 3 will determine the mechanisms by which the new NS1 determinant antagonizes ZFC3H1. Overall, this proposal will uncover a new NS1 virulence determinant of 2009 pandemic flu and reveal how the determinant perturbs host RNA decay machinery by engagement with ZFC3H1. The outcomes of our study will not only help develop effective therapeutics, but is also crucial for prediction of future potential epidemics and pandemics. 

Project Leader: William Michael McShan, Ph.D.

Associate Professor
Department of Pharmaceutical Sciences
University of Oklahoma Health Sciences Center
Oklahoma City, Ok

Contact Information:
Email: William-McShan@ouhsc.edu
Phone: (405) 271-6593
Office: 1110 North Stonewall Ave.
CPB307
Oklahoma City, OK. 73117

Project Summary: 
Streptococcus pneumoniae is a major cause of human respiratory disease worldwide. 30% of severe cases are caused by strains that are fully resistant to one or more clinically relevant antibiotics. Previously, the PI has shown that phage-like chromosomal islands (CI) in group A streptococci cause the cell to 1) adopt a mutator phenotype through disruption of DNA mismatch repair, which promotes antibiotic resistance, and 2) alter global transcription, up-regulating virulence genes that can enhance pathogenecity, including biofilm formation and antibiotic resistance. We have constructed strains of S. pneumoniae TIGR4 that differ by the presence or absence of a novel Cl in S. pneumoniae (SpnCI) has been identified that has the potential to inactivate a required gene for nucleotide excision repair. Preliminary studies show that such element alter global transcription patterns, including genes that contribute to survival and/or biofilm formation. The hypothesis of this application is that SpnCI also confers a mutator phenotype and alters global transcriptional patterns that may increase virulence or promote survival. To test this hypothesis, the following specific aims will be performed: 1) analyze impact SpnCI has in the acute immune response in an infection model, and 2) determine the SpnCI-associated impact upon biofilm formation and virulence. The PI is highly qualified to perform these studies, having pioneered the discovery and characterization of these streptococcal Cl. The proposed studies will have a positive impact, fundamental advancing our understanding of the biology of this pathogen and may lead to new antimicrobial strategies and improved patient care.

Project Leader: Marianna Patrauchan, Ph.D.

Associate Professor
Department of Microbiology and Molecular Genetics
College of Arts and Sciences
Oklahoma State University- Stillwater

Contact Information:
E-mail: m.patrauchan@okstate.edu
Phone: (405) 744 8148
Office: Rm 304A Life Sciences East
Stillwater, OK 74074

Project Summary:
Pseudomonas aeruginosa is an opportunistic human pathogen that causes severe, life threatening infections in patients with cystic fibrosis (CF), endocarditis, wounds, artificial implants, and in healthcare-associated infections. The versatility of P. aeruginosa pathogenicity is associated with an outstanding physiological adaptability of the organism and its ability to modulate host responses, due in part to a tightly coordinated regulation of gene expression. Therefore, to gain control over currently untreatable Pseudomonas infections, it is critically important to generate new knowledge of the regulatory circuits coordinating the pathogen virulence in response to host factors. Calcium ion (Ca2+) is an essential intracellular messenger in eukaryotic cells, regulating vital cellular processes. It accumulates in pulmonary fluids of CF patients and in mitral annulus of endocarditis patients. Alterations in the host Ca2+ homeostasis may serve as a trigger for enhanced virulence of invading pathogens. In support, we showed that Ca2+ positively regulates biofilm formation, swarming, and production of several virulence factors in P. aeruginosa. However, the molecular mechanisms of such regulation are not known. It is also not known whether intracellular Ca2+ plays role as a second messenger in prokaryotes as it does in eukaryotes. Understanding the mechanisms of Ca2+ regulation, signaling and homeostasis will provide novel means for controlling P. aeruginosa viability, virulence, and interactions with the host. Earlier, we identified two putative Ca2+-binding proteins EfhP and CarP, mutations in which cause multiple Ca2+-dependent defects in virulence and infectivity.  EfhP contains two EF-hand motives, known to bind Ca2+ and relay Ca2+ signal through conformational changes. CarP is predicted to form a beta-propeller and has a putative phytase domain. Based on the bioinformatics and preliminary studies, we hypothesize that EfhP and CarP provide different routes of Ca2+ signal transduction regulating virulence and host-pathogen interactions in response to Ca2+ in a host. To test this, we propose to determine the cellular localization and identify binding partners and signal-transducing pathways regulated by the two proteins. We will also characterize the role of EfhP and CarP in P. aeruginosa interactions with a host, and define their involvement in the development of acute and chronic infections. By utilizing the expertise of three OCRID core facilities, we will unravel the mechanisms of Ca2+ signaling and its role in regulating the ability of P. aeruginosa to cause infections at the molecular, cellular, and organismal level.  This research is highly innovative as for the first time it will experimentally demonstrate Ca2+ signaling in bacteria, identify the components of Ca2+ signal transduction pathways, and define the role of Ca2+ signaling in P. aeruginosa pathogenicity in vivo.