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Metropolitan Government of Nashville-Davidson (balance), TN, United States

Guyon A.,University of Nice Sophia Antipolis | Kussrow A.,French National Center for Scientific Research | Roys Olmsted I.,University of California at Berkeley | Sandoz G.,Vanderbilt Institute of Chemical Biology | And 2 more authors.
Journal of Neuroscience | Year: 2013

CXCR4, a receptor for the chemokine CXCL12 (stromal-cell derived factor-1α), is a G-protein-coupled receptor (GPCR), expressed in the immune and CNS and integrally involved in various neurological disorders. The GABAB receptor is also a GPCR that mediates metabotropic action of the inhibitory neurotransmitter GABA and is located on neurons and immune cells as well. Using diverse approaches, we report novel interaction between GABAB receptor agents and CXCR4 and demonstrate allosteric binding of these agents to CXCR4. First, both GABAB antagonists and agonists block CXCL12-elicited chemotaxis in human breast cancer cells. Second, a GABAB antagonist blocks the potentiation by CXCL12 of high-threshold Ca 2+ channels in rat neurons. Third, electrophysiology in Xenopus oocytes and human embryonic kidney cell line 293 cells in which we coexpressed rat CXCR4 and the G-protein inward rectifier K+ (GIRK) channel showed that GABAB antagonist and agonist modified CXCL12-evoked activation of GIRK channels. To investigate whether GABAB ligands bind to CXCR4, we expressed this receptor in heterologous systems lacking GABAB receptors and performed competition binding experiments. Our fluorescent resonance energy transfer experiments suggest that GABAB ligands do not bind CXCR4 at the CXCL12 binding pocket suggesting allosteric modulation, in accordance with our electrophysiology experiments. Finally, using backscattering interferometry and lipoparticles containing only the CXCR4 receptor, we quantified the binding affinity for the GABAB ligands, confirming a direct interaction with the CXCR4 receptor. The effect of GABAergic agents on CXCR4 suggests new therapeutic potentials for neurological and immune diseases. © 2013 the authors. Source

Smathers R.L.,Aurora Pharmaceutical | Galligan J.J.,Aurora University | Galligan J.J.,Vanderbilt Institute of Chemical Biology | Shearn C.T.,Aurora Pharmaceutical | And 6 more authors.
Journal of Lipid Research | Year: 2013

Chronic ethanol consumption is a prominent cause of liver disease worldwide. Dysregulation of an important lipid uptake and trafficking gene, liver-fatty acid binding protein (L-FABP), may contribute to alterations in lipid homeostasis during early-stage alcoholic liver. We have reported the detrimental effects of ethanol on the expression of L-FABP and hypothesize this may deleteriously impact metabolic networks regulating fatty acids. Male wild-type (WT) and L-FABP -/- mice were fed a modified Lieber-DeCarli liquid diet for six weeks. To assess the response to chronic ethanol ingestion, standard biochemical indicators for alcoholic liver disease (ALD) and oxidative stress were measured. Ethanol ingestion resulted in attenuation of hepatic triglyceride accumulation and elevation of cholesterol in L-FABP -/- mice. Lipidomics analysis validated multiple alterations in hepatic lipids resulting from ethanol treatment. Increased immunohistochemical staining for the reactive aldehydes 4-hydroxynonenal and malondialdehyde were observed in WT mice ingesting ethanol; however, L-FABP -/- mice displayed prominent protein adducts in liver sections evaluated from pair-fed and ethanolfed mice. Likewise, alterations in glutathione, thiobarbituric acid reactive substances (TBARS), 8-isoprostanes, and protein carbonyl content all indicated L-FABP -/- mice exhibit high sustained oxidative stress in the liver. These data establish that L-FABP is an indirect antioxidant protein essential for sequestering FFA and that its impairment could contribute to in the pathogenesis of ALD. Copyright © 2013 by the American Society for Biochemistry and Molecular Biology, Inc. Source

Toki S.,Pulmonary and Critical Care Medicine | Omary R.A.,Vanderbilt University | Wilson K.,Vanderbilt University | Gore J.C.,Vanderbilt University | And 3 more authors.
Nanomedicine: Nanotechnology, Biology, and Medicine | Year: 2013

Polylysine (PL) has been used to facilitate dendritic cell (DC) uptake of super paramagnetic iron oxide (SPIO) nanoparticles for use in magnetic resonance imaging (MRI). In this work, we examined the effect of PL on cell toxicity and induction of cell maturation as manifested by the up-regulation of surface molecules. We found that PL became toxic to bone marrow-derived DCs (BMDCs) at the 10. μg/ml threshold. Incubation of BMDCs with 20. μg/ml of PL for 1. h resulted in approximately 90% cell death. However, addition of SPIO nanoparticles rescued DCs from PL-induced death as the combination of SPIO with PL did not cause cytotoxicity until the PL concentration was 1000. μg/ml. Prolonged exposure to PL induced BMDC maturation as noted by the expression of surface molecules such as MHC class II, CD40, CCR7 and CD86. However, the combination of SPIO and PL did not induce BMDC maturation at 1. h. However prolonged exposure to SPIO nanoparticles induced CD40 expression and protein expression of TNFα and KC. The data suggest that the use of PL to enhance the labeling of DCs with SPIO nanoparticles is a dedicated work. Appropriate calibration of the incubation time and concentrations of PL and SPIO nanoparticles is crucial to the development of MRI technology for noninvasive imaging of DCs in vivo. From the Clinical Editor: The authors of this study present detailed data on toxicity and efficiency of polylysine-facilitated uptake of USPIO-s by dendritic cells for cell-specific MR imaging. © 2013. Source

Bruntz R.C.,Vanderbilt University | Taylor H.E.,Depts. of Medicine | Lindsley C.W.,Vanderbilt University | Lindsley C.W.,Vanderbilt Institute of Chemical Biology | Brown H.A.,Vanderbilt University
Journal of Biological Chemistry | Year: 2014

Background: Phospholipase D (PLD) and phosphatidic acid regulate fundamental cellular processes that contribute to cancer cell proliferation and survival. Results: Inhibition of PLD2 decreases activation of the pro-survival kinase Akt leading to cell death through inhibition of autophagic flux. Conclusion: PLD2 promotes autophagy through regulation of Akt in glioblastoma cells. © 2014 by the American Society for Biochemistry and Molecular Biology, Inc. . Source

Cipriano R.,Case Western Reserve University | Bryson B.L.,Case Western Reserve University | Miskimen K.L.S.,Case Western Reserve University | Bartel C.A.,Case Western Reserve University | And 6 more authors.
Oncogene | Year: 2014

Despite the progress made in targeted anticancer therapies in recent years, challenges remain. The identification of new potential targets will ensure that the arsenal of cancer therapies continues to expand. FAM83B was recently discovered in a forward genetic screen for novel oncogenes that drive human mammary epithelial cell (HMEC) transformation. We report here that elevated FAM83B expression increases Phospholipase D (PLD) activity, and that suppression of PLD1 activity prevents FAM83B-mediated transformation. The increased PLD activity is engaged by hyperactivation of epidermal growth factor receptor (EGFR), which is regulated by an interaction involving FAM83B and EGFR. Preventing the FAM83B/EGFR interaction by site-directed mutation of lysine 230 of FAM83B suppressed PLD activity and MAPK signaling. Furthermore, ablation of FAM83B expression from breast cancer cells inhibited EGFR phosphorylation and suppressed cell proliferation. We propose that understanding the mechanism of FAM83B-mediated transformation will provide a foundation for future therapies aimed at targeting its function as an intermediary in EGFR, MAPK and mTOR activation. © 2014 Macmillan Publishers Limited. Source

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