The chemokine CXCL8 (also known as interleukin-8) plays a key role in innate immunity and inflammation by recruiting neutrophils from the bloodstream to tissue damaged by such insults as bacterial infection. Our long-term goal is to understand the molecular mechanisms of CXCL8 function, and so lay the foundation for new anti-inflammatory treatments. CXCL8 exerts its function by binding to G protein-coupled receptors (GPCRs) on neutrophils, and to glycosaminoglycans (GAGs) on the extracellular matrix and endothelium. A fundamental property of chemokines is the ability to exist reversibly as both monomers and dinners. Therefore, knowledge of CXCL8 monomer and dimer binding to GPCRs and GAGs is critical for understanding in vivo neutrophil recruitment. Our hypothesis is that a dynamic equilibrium among four CXCL8 forms, monomers and dinners in solution and monomers and dinners bound to GAG, regulates in vivo neutrophil recruitment. In this project, we will test our hypothesis by characterizing mutants of trapped monomers and dimers and of native CXCL8 that show reduced binding to either GPCRs or GAGs, and mutants of native CXCL8 that show reduced dimerization potency. We will determine how monomer-dimer equilibrium, and the binding interactions of monomers and dimers for GAGs and GPCRs, regulate in vivo CXCL8 function in animal models (Aim 1). We will determine whether monomers and dinners elicit similar signaling events (but with different potencies), or elicit unique signaling events (Aim 2). Finally, by determining how monomers and dimers bind GAGs, we will better define the distribution of monomers and dimers in solution and bound to GAGs (Aim 3). Innovations in our research design include using a combination of biophysical, in vitro cell-based, and in vivo animal-based studies; novel reagents (trapped monomers and dimers); and a novel microfluid device technology to measure chemotaxis. Lay Abstract: Inflammation plays a central role in the pathology of many vascular and allergic diseases, and of bacterial and viral infections. These diseases cause significant infirmity and mortality, and exact a high economic cost. Current medications either treat the symptoms and not the disease, or are nonspecifically targeted to inhibit the immune and inflammatory responses. New drugs that are highly specific designed on the basis of chemokine function should thus provide better treatments for these diseases. ? ? ?

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
5R01AI069152-02
Application #
7221286
Study Section
Immunity and Host Defense Study Section (IHD)
Program Officer
Ferguson, Stacy E
Project Start
2006-05-01
Project End
2011-04-30
Budget Start
2007-05-01
Budget End
2008-04-30
Support Year
2
Fiscal Year
2007
Total Cost
$329,897
Indirect Cost
Name
University of Texas Medical Br Galveston
Department
Biochemistry
Type
Schools of Medicine
DUNS #
800771149
City
Galveston
State
TX
Country
United States
Zip Code
77555
Sawant, Kirti V; Xu, Renling; Cox, Robert et al. (2015) Chemokine CXCL1-Mediated Neutrophil Trafficking in the Lung: Role of CXCR2 Activation. J Innate Immun 7:647-58
Rajarathnam, Krishna; Rösgen, Jörg (2014) Isothermal titration calorimetry of membrane proteins - progress and challenges. Biochim Biophys Acta 1838:69-77
Joseph, Prem Raj B; Sawant, Kirti V; Isley, Angela et al. (2013) Dynamic conformational switching in the chemokine ligand is essential for G-protein-coupled receptor activation. Biochem J 456:241-51
Chaudhuri, Arunima; Basu, Pritam; Haldar, Sourav et al. (2013) Organization and dynamics of the N-terminal domain of chemokine receptor CXCR1 in reverse micelles: effect of graded hydration. J Phys Chem B 117:1225-33
Joseph, Prem Raj B; Poluri, Krishna Mohan; Gangavarapu, Pavani et al. (2013) Proline substitution of dimer interface ?-strand residues as a strategy for the design of functional monomeric proteins. Biophys J 105:1491-501
Ravindran, Aishwarya; Sawant, Kirti V; Sarmiento, Jose et al. (2013) Chemokine CXCL1 dimer is a potent agonist for the CXCR2 receptor. J Biol Chem 288:12244-52
Gangavarapu, Pavani; Rajagopalan, Lavanya; Kolli, Deepthi et al. (2012) The monomer-dimer equilibrium and glycosaminoglycan interactions of chemokine CXCL8 regulate tissue-specific neutrophil recruitment. J Leukoc Biol 91:259-65
Sarmiento, Jose; Shumate, Christie; Suetomi, Katsutoshi et al. (2011) Diverging mechanisms of activation of chemokine receptors revealed by novel chemokine agonists. PLoS One 6:e27967
Das, Sandhya Thulasi; Rajagopalan, Lavanya; Guerrero-Plata, Antonieta et al. (2010) Monomeric and dimeric CXCL8 are both essential for in vivo neutrophil recruitment. PLoS One 5:e11754
Joseph, Prem Raj B; Sarmiento, Jose M; Mishra, Anurag K et al. (2010) Probing the role of CXC motif in chemokine CXCL8 for high affinity binding and activation of CXCR1 and CXCR2 receptors. J Biol Chem 285:29262-9

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