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We hypothesized that ADP-ribosylation factor 1 (Arf1) plays an important role in the biogenesis and maintenance of infectious hepatitis C virus (HCV). Huh7.5 cells, in which HCV replicates and produces infectious viral particles, were... more
We hypothesized that ADP-ribosylation factor 1 (Arf1) plays an important role in the biogenesis and maintenance of infectious hepatitis C virus (HCV). Huh7.5 cells, in which HCV replicates and produces infectious viral particles, were exposed to brefeldin A or golgicide A, pharmacological inhibitors of Arf1 activation. Treatment with these agents caused a reduction in viral RNA levels, the accumulation of infectious particles within the cells, and a reduction in the levels of these particles in the extracellular medium. Fluorescence analyses showed that the viral nonstructural (NS) proteins NS5A and NS3, but not the viral structural protein core, shifted their localization from speckle-like structures in untreated cells to the rims of lipid droplets (LDs) in treated cells. Using pulldown assays, we showed that ectopic overexpression of NS5A in Huh7 cells reduces the levels of GTP-Arf1. Downregulation of Arf1 expression by small interfering RNA (siRNA) decreased both the levels of HC...
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Antisense prevention of neuronal damages following head injury in mice
Research Interests: Molecular Medicine, Flow Cytometry, Biology, Immunohistochemistry, Medicine, and 15 moreGene expression, In Situ Hybridization, Cell Division, Hematopoietic Stem Cells, Cortisol, Cell Differentiation, Humans, Mice, Animals, Acetylcholinesterase, Peptides, Blood cells, Biochemistry and cell biology, hydrocortisone, and Peripheral blood
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Research Interests: Engineering, Physics, Chemistry, Biology, Cell Adhesion, and 14 moreConfocal Microscopy, Medicine, Multidisciplinary, Dogs, Endocytosis, Animals, Surface plasmon resonance, PLoS one, Epithelial cells, Host Pathogen Interactions, Infrared Rays, Refractometry, Escherichia Coli Infections, and Cell Size
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Research Interests: Fluorescence Microscopy, Gene expression, Multidisciplinary, Cell Culture, Hippocampus, and 13 moreSmooth muscle, Lizards, Animals, Calcium Signaling, Neurons, Rats, Transmitter release, Fluorescent probes, Xenopus laevis, Confocal Laser Scanning Microscopy, Nervous System, Neuromuscular Junction, and Intracellular Calcium
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Phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2] and phosphatidylinositol 3,4,5-trisphosphate [PI(3,4,5)P3] are phosphoinositides (PIs) present in small amounts in the inner leaflet of the plasma membrane (PM) lipid bilayer of host... more
Phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2] and phosphatidylinositol 3,4,5-trisphosphate [PI(3,4,5)P3] are phosphoinositides (PIs) present in small amounts in the inner leaflet of the plasma membrane (PM) lipid bilayer of host target cells. They are thought to modulate the activity of proteins involved in enteropathogenic Escherichia coli (EPEC) infection. However, the role of PI(4,5)P2 and PI(3,4,5)P3 in EPEC pathogenesis remains obscure. Here we show that EPEC induces a transient PI(4,5)P2 accumulation at bacterial infection sites. Simultaneous actin accumulation, likely involved in the construction of the actin-rich pedestal, is also observed at these sites. Acute PI(4,5)P2 depletion partially diminishes EPEC adherence to the cell surface and actin pedestal formation. These findings are consistent with a bimodal role, whereby PI(4,5)P2 contributes to EPEC association with the cell surface and to the maximal induction of actin pedestals. Finally, we show that EPEC induces PI...
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Research Interests: Calcium, Signal Transduction, Serotonin, Stroke, Cerebral Cortex, and 15 moreNitric oxide, Animals, Male, Acetylcholinesterase, Muscarinic Receptors, Clinical Sciences, Rats, FLUOXETINE, Mecamylamine, Atropine, Vasodilatation, Serotonin Uptake Inhibitors, Biochemistry and cell biology, Arterioles, and Reperfusion
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Various human disorders are associated with misdistribution of iron within or across cells. Friedreich ataxia (FRDA), a deficiency in the mitochondrial iron-chaperone frataxin, results in defective use of iron and its misdistribution... more
Various human disorders are associated with misdistribution of iron within or across cells. Friedreich ataxia (FRDA), a deficiency in the mitochondrial iron-chaperone frataxin, results in defective use of iron and its misdistribution between mitochondria and cytosol. We assessed the possibility of functionally correcting the cellular properties affected by frataxin deficiency with a siderophore capable of relocating iron and facilitating its metabolic use. Adding the chelator deferiprone at clinical concentrations to inducibly frataxin-deficient HEK-293 cells resulted in chelation of mitochondrial labile iron involved in oxidative stress and in reactivation of iron-depleted aconitase. These led to (1) restoration of impaired mitochondrial membrane and redox potentials, (2) increased adenosine triphosphate production and oxygen consumption, and (3) attenuation of mitochondrial DNA damage and reversal of hypersensitivity to staurosporine-induced apoptosis. Permeant chelators of higher...
Research Interests: Mitochondria, DNA damage, Cell line, Mitochondrial DNA, Humans, and 11 moreBlood, Functional impairment, Iron, Clinical Sciences, Oxygen Consumption, Friedreich Ataxia, Adenosine Triphosphate, Iron binding proteins, Cardiovascular medicine and haematology, Paediatrics and reproductive medicine, and anemia of chronic disease
We report on the application of surface plasmon resonance (SPR), based on Fourier transform infrared spectroscopy in the mid-infrared wavelength range, for real-time and label-free sensing of transferrin-induced endocytic processes in... more
We report on the application of surface plasmon resonance (SPR), based on Fourier transform infrared spectroscopy in the mid-infrared wavelength range, for real-time and label-free sensing of transferrin-induced endocytic processes in human melanoma cells. The evanescent field of the mid-infrared surface plasmon penetrates deep into the cell, allowing highly sensitive SPR measurements of dynamic processes occurring at significant cellular depths. We monitored in real-time, infrared reflectivity spectra in the SPR regime from living cells exposed to human transferrin (Tfn). We show that although fluorescence microscopy measures primarily Tfn accumulation in recycling endosomes located deep in the cell's cytoplasm, the SPR technique measures mainly Tfn-mediated formation of early endocytic organelles located in close proximity to the plasma membrane. Our SPR and fluorescence data are very well described by a kinetic model of Tfn endocytosis, suggested previously in similar cell systems. Hence, our SPR data provide further support to the rather controversial ability of Tfn to stimulate its own endocytosis. Our analysis also yields what we believe is novel information on the role of membrane cholesterol in modulating the kinetics of endocytic vesicle biogenesis and consumption.