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Koziel, Henryk

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Koziel

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Henryk

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Koziel, Henryk
Author's Publications: search.filters.isAuthorOfPublication.0eb4dabe-6ef3-4758-86cd-d7735962ac8f

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    Cell Elasticity Determines Macrophage Function
    (Public Library of Science, 2012) Patel, Naimish R.; Bole, Medhavi; Chen, Cheng; Hardin, Charles; Kho, Alvin; Mih, Justin; Deng, Linhong; Butler, James; Tschumperlin, Daniel J.; Fredberg, Jeffrey; Krishnan, Ramaswamy; Koziel, Henryk
    Macrophages serve to maintain organ homeostasis in response to challenges from injury, inflammation, malignancy, particulate exposure, or infection. Until now, receptor ligation has been understood as being the central mechanism that regulates macrophage function. Using macrophages of different origins and species, we report that macrophage elasticity is a major determinant of innate macrophage function. Macrophage elasticity is modulated not only by classical biologic activators such as LPS and IFN-γ, but to an equal extent by substrate rigidity and substrate stretch. Macrophage elasticity is dependent upon actin polymerization and small rhoGTPase activation, but functional effects of elasticity are not predicted by examination of gene expression profiles alone. Taken together, these data demonstrate an unanticipated role for cell elasticity as a common pathway by which mechanical and biologic factors determine macrophage function.
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    \(Leu128^{3.43}\) (L128) and \(Val247^{6.40}\) (V247) of CXCR1 Are Critical Amino Acid Residues for G Protein Coupling and Receptor Activation
    (Public Library of Science, 2012) Han, Xinbing; Tachado, Souvenir; Koziel, Henryk; Boisvert, William A.
    CXCR1, a classic GPCR that binds IL-8, plays a key role in neutrophil activation and migration by activating phospholipase C (PLC)β through \(G\alpha_{15}\) and \(G\alpha_i\) which generates diacylglycerol and inositol phosphates (IPs). In this study, two conserved amino acid residues of CXCR1 on the transmembrane domain (TM) 3 and TM6, \(Leu128^{3.43}\) (L128) and \(Val247^{6.40}\) (V247), respectively, were selectively substituted with other amino acids to investigate the role of these conserved residues in CXCR1 activation. Although two selective mutants on Leu128, Leu128Ala (L128A) and Leu128Arg (L128R), demonstrated high binding affinity to IL-8, they were not capable of coupling to G proteins and consequently lost the functional response of the receptors. By contrast, among the four mutants at residue Val247 (TM6.40), replacing Val247 with Ala (V247A) and Asn (V247N) led to constitutive activation of mutant receptors when cotransfected with \(G\alpha_{15}\). The V247N mutant also constitutively activated the \(G\alpha_i\) protein. These results indicate that L128 on TM3.43 is involved in G protein coupling and receptor activation but is unimportant for ligand binding. On the other hand, V247 on TM6.40 plays a critical role in maintaining the receptor in the inactive state, and the substitution of V247 impaired the receptor constraint and stabilized an active conformation. Functionally, there was an increase in chemotaxis in response to IL-8 in cells expressing V247A and V247N. Our findings indicate that \(Leu128^{3.43}\) and \(Val247^{6.40}\) are critical for G protein coupling and activation of signaling effectors, providing a valuable insight into the mechanism of CXCR1 activation.
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    Genome-Wide RNAi Screen in \(IFN-\gamma-Treated\) Human Macrophages Identifies Genes Mediating Resistance to the Intracellular Pathogen Francisella tularensis
    (Public Library of Science, 2012) Zhou, Hongwei; Browning, Erica; Tan, Fengxiao; Imrich, Amy; Kramnik, Igor; Gregory, David; Koziel, Henryk; Lu, Quan; Kobzik, Lester; Deloid, Glen; Bedugnis, Alice
    Interferon-gamma \((IFN-\gamma)\) inhibits intracellular replication of Francisella tularensis in human monocyte-derived macrophages (HMDM) and in mice, but the mechanisms of this protective effect are poorly characterized. We used genome-wide RNA interference (RNAi) screening in the human macrophage cell line THP-1 to identify genes that mediate the beneficial effects of \(IFN-\gamma\) on F. tularensis infection. A primary screen identified ~200 replicated candidate genes. These were prioritized according to mRNA expression in \(IFN-\gamma-primed\) and F. tularensis-challenged macrophages. A panel of 20 top hits was further assessed by re-testing using individual shRNAs or siRNAs in THP-1 cells, HMDMs and primary human lung macrophages. Six of eight validated genes tested were also found to confer resistance to Listeria monocytogenes infection, suggesting a broadly shared host gene program for intracellular pathogens. The F. tularensis-validated hits included ‘druggable’ targets such as TNFRSF9, which encodes CD137. Treating HMDM with a blocking antibody to CD137 confirmed a beneficial role of CD137 in macrophage clearance of F. tularensis. These studies reveal a number of important mediators of \(IFN-\gamma\) activated host defense against intracellular pathogens, and implicate CD137 as a potential therapeutic target and regulator of macrophage interactions with Francisella tularensis.