Search results for "ENDOCYTOSIS"
showing 10 items of 185 documents
Echovirus 1 Endocytosis into Caveosomes Requires Lipid Rafts, Dynamin II, and Signaling EventsV⃞
2004
Binding of echovirus 1 (EV1, a nonenveloped RNA virus) to the α2β1 integrin on the cell surface is followed by endocytic internalization of the virus together with the receptor. Here, video-enhanced live microscopy revealed the rapid uptake of fluorescently labeled EV1 into mobile, intracellular structures, positive for green fluorescent protein-tagged caveolin-1. Partial colocalization of EV1 with SV40 (SV40) and cholera toxin, known to traffic via caveosomes, demonstrated that the vesicles were caveosomes. The initiation of EV1 infection was dependent on dynamin II, cholesterol, and protein phosphorylation events. Brefeldin A, a drug that prevents SV40 transport, blocked the EV1 infection…
Protein Kinase C-dependent Ubiquitination and Clathrin-mediated Endocytosis of the Cationic Amino Acid Transporter CAT-1*
2011
Cationic amino acid transporter 1 (CAT-1) is responsible for the bulk of the uptake of cationic amino acids in most mammalian cells. Activation of protein kinase C (PKC) leads to down-regulation of the cell surface CAT-1. To examine the mechanisms of PKC-induced down-regulation of CAT-1, a functional mutant of CAT-1 (CAT-1-HA-GFP) was generated in which a hemagglutinin antigen (HA) epitope tag was introduced into the second extracellular loop and GFP was attached to the carboxyl terminus. CAT-1-HA-GFP was stably expressed in porcine aorthic endothelial and human epithelial kidney (HEK) 293 cells. Using the HA antibody internalization assay we have demonstrated that PKC-dependent endocytosis…
Bradykinin-induced Internalization of the Human B2Receptor Requires Phosphorylation of Three Serine and Two Threonine Residues at Its Carboxyl Tail
1999
The binding of bradykinin (BK) to B2 receptor triggers the internalization of the agonist-receptor complex. To investigate the mechanisms and the receptor structures involved in this fundamental process of receptor regulation, the human B2 receptor was mutated within its cytoplasmic tail by complementary strategies of truncation, deletion, and amino acid substitution. Ligand binding, signal transduction, internalization as well as phosphorylation were studied for the mutated receptors expressed in COS, CHO, and HEK 293 cells. Truncation of 44 out of 55 amino acid residues of the receptor's cytoplasmic tail corresponding to positions 321-364 did not alter the kinetics of BK binding and the r…
Detoxifying antitumoral drugs via nanoconjugation: the case of gold nanoparticles and cisplatin
2021
Nanoparticles (NPs) have emerged as a potential tool to improve cancer treatment. Among the proposed uses in imaging and therapy, their use as a drug delivery scaffold has been extensively highlighted. However, there are still some controversial points which need a deeper understanding before clinical application can occur. Here the use of gold nanoparticles (AuNPs) to detoxify the antitumoral agent cisplatin, linked to a nanoparticle via a pH-sensitive coordination bond for endosomal release, is presented. The NP conjugate design has important effects on pharmacokinetics, conjugate evolution and biodistribution and results in an absence of observed toxicity. Besides, AuNPs present unique o…
Interactions of silica nanoparticles with lung epithelial cells and the association to flotillins
2012
Amorphous silica nanoparticles (aSNPs) gain increasing popularity for industrial and therapeutic claims. The lung with its surface area of 100-140 m(2) displays an ideal target for therapeutic approaches, but it represents also a serious area of attack for harmful nanomaterials. The exact nature of the cytotoxic effects of NPs is still unknown. Furthermore, cellular pathways and the destiny of internalized NPs are still poorly understood. Therefore, we examined the cytotoxicity (MTS, LDH) and inflammatory responses (IL-8) for different-sized aSNPs (30, 70, 300 nm) on our lung epithelial cells line NCI H441 and endothelial cell line ISO-HAS-1. Additionally, colocalization studies have been c…
From attachment to damage: defined genes of Candida albicans mediate adhesion, invasion and damage during interaction with oral epithelial cells.
2010
Candida albicans frequently causes superficial infections by invading and damaging epithelial cells, but may also cause systemic infections by penetrating through epithelial barriers. C. albicans is an unusual pathogen because it can invade epithelial cells via two distinct mechanisms: induced endocytosis, analogous to facultative intracellular enteropathogenic bacteria, and active penetration, similar to plant pathogenic fungi. Here we investigated the molecular basis of C. albicans epithelial interactions. By systematically assessing the contributions of defined fungal pathways and factors to different stages of epithelial interactions, we provide an expansive portrait of the processes an…
Hydrodynamic liver gene transfer mechanism involves transient sinusoidal blood stasis and massive hepatocyte endocytic vesicles
2005
The present study contributes to clarify the mechanism underlying the high efficacy of hepatocyte gene transfer mediated by hydrodynamic injection. Gene transfer experiments were performed employing the hAAT gene, and the efficacy and differential identification in mouse plasma of human transgene versus mouse gene was assessed by ELISA and proteomic procedures, respectively. By applying different experimental strategies such as cumulative dose-response efficacy, hemodynamic changes reflected by venous pressures, intravital microscopy, and morphological changes established by transmission electron microscopy, we found that: (a) cumulative multiple doses of transgene by hydrodynamic injection…
Inhibition by cellular vacuolar ATPase impairs human papillomavirus uncoating and infection.
2014
ABSTRACT Several viruses, including human papillomaviruses, depend on endosomal acidification for successful infection. Hence, the multisubunit enzyme vacuolar ATPase (V-ATPase), which is mainly responsible for endosome acidification in the cell, represents an attractive target for antiviral strategies. In the present study, we show that V-ATPase is required for human papillomavirus (HPV) infection and that uncoating/disassembly but not endocytosis is affected by V-ATPase inhibition. The infection inhibitory potencies of saliphenylhalamide, a proven V-ATPase inhibitor, and its derivatives, as well as those of other V-ATPase inhibitors, were analyzed on different HPV types in relevant cell l…
Cryptogein treatment stimulates clathrin-endocytosis correlated with ROS production in tobacco cells
2007
International audience; During plant pathogen interactions, specific molecules elicit defense response of plant cells. Cryptogein, an elicitin produced by the pathogenic fungus Phytophtora cryptogea, induces a hypersensitive response (HR) in tobacco plants. The mode of action for cryptogein starts with recognition of this elicitor by an unidentified plasma membrane (PM) receptor. This ligand-receptor binding trigger a cascade of events at the PM level including rapid calcium influx, ions effluxes, extracellular medium alcalinization and plasma membrane depolarization both in tobacco plants and suspension cells. These events lead to the activation of plasma membrane-bound NADPH oxidase, Ntrb…
Candida albicans-epithelial interactions: dissecting the roles of active penetration, induced endocytosis and host factors on the infection process
2012
International audience; Candida albicans frequently causes superficial infections by invading and damaging epithelial cells, but may also cause systemic infections by penetrating through epithelial barriers. C. albicans is a remarkable pathogen because it can invade epithelial cells via two distinct mechanisms: induced endocytosis, analogous to facultative intracellular enteropathogenic bacteria, and active penetration, similar to plant pathogenic fungi. Here we investigated the contributions of the two invasion routes of C. albicans to epithelial invasion. Using selective cellular inhibition approaches and differential fluorescence microscopy, we demonstrate that induced endocytosis contri…