Search results for "endosome"
showing 10 items of 104 documents
γ2-Adaptin, a Novel Ubiquitin-interacting Adaptor, and Nedd4 Ubiquitin Ligase Control Hepatitis B Virus Maturation
2006
Hepatitis B virus (HBV) budding from infected cells is a tightly regulated process that requires both core and envelope structures. Here we report that HBV uses cellular γ2-adaptin and Nedd4, possibly in conjunction with ubiquitin, to coordinate its assembly and release. In search of interaction partners of the viral L envelope protein, we previously discovered γ2-adaptin, a putative endosomal sorting and trafficking adaptor of the adaptor protein complex family. We now demonstrate that the viral core interacts with the same γ2-adaptor and that disruption of the HBV/γ2-adaptin interactions inhibits virus production. Mutational analyses revealed a hitherto unknown ubiquitin-binding activity …
Isoproterenol inhibits fluid-phase endocytosis from early to late endosomes
1999
We have shown recently that isoproterenol affects both the cellular location and the morphology of late endosomes in a pH-dependent manner [Marjomäki et al., Eur. J. Cell Biol. 65, 1-13 (1994)]. In this study, using fluorescence and quantitative electron microscopy, we wanted to examine further what is the fate of internalized markers during their translocation from early to late endosomes under isoproterenol treatment. Fluorescein dextran internalized for 30 min (10-min pulse followed by a 20-min chase) showed accumulation in the cellular periphery during isoproterenol treatment in contrast to the control cells, which accumulated dextran in the perinuclear region. Quantitative electron mic…
At reduced temperature, endocytic membrane traffic is blocked in multivesicular carrier endosomes in rat cardiac myocytes.
1998
Temperatures around 20 degrees C are known to block degradation of endocytosed material by preventing its transport to lysosomes, accordingly reduced temperature has been widely used to define endosomes. Newer studies have revealed that the low temperature block is proximal to perinuclear late endosomes, but it is not clear whether the block is already in early endosomes, or whether the traffic proceeds to multivesicular carrier endosomes which mediate transport from early to late compartments. We have now focused on this problem using rat cardiac myocytes. First, cell fractionation on Percoll gradients showed that at reduced temperatures (22 degrees C and 26 degrees C), with prolonged chas…
Raman Spectroscopic Signatures of Echovirus 1 Uncoating
2014
ABSTRACT In recent decades, Raman spectroscopy has entered the biological and medical fields. It enables nondestructive analysis of structural details at the molecular level and has been used to study viruses and their constituents. Here, we used Raman spectroscopy to study echovirus 1 (EV1), a small, nonenveloped human pathogen, in two different uncoating states induced by heat treatments. Raman signals of capsid proteins and RNA genome were observed from the intact virus, the uncoating intermediate, and disrupted virions. Transmission electron microscopy data revealed general structural changes between the studied particles. Compared to spectral characteristics of proteins in the intact v…
Mobilization of late-endosomal cholesterol is inhibited by Rab guanine nucleotide dissociation inhibitor
2000
AbstractCholesterol entering cells in low-density lipoproteins (LDL) via receptor-mediated endocytosis is transported to organelles of the late endocytic pathway for degradation of the lipoprotein particles. The fate of the free cholesterol released remains poorly understood, however. Recent observations suggest that late-endosomal cholesterol sequestration is regulated by the dynamics of lysobisphosphatidic acid (LBPA)-rich membranes [1]. Genetic studies have pinpointed a protein, Niemann–Pick C-1 (NPC-1), that is required for the mobilization of late-endosomal/lysosomal cholesterol by an unknown mechanism [2]. Here, we report the removal of accumulated cholesterol by overexpression of the…
Cholesterol Dependence of Collagen and Echovirus 1 Trafficking along the Novel α2β1 Integrin Internalization Pathway
2013
We have previously shown that soluble collagen and a human pathogen, echovirus 1 (EV1) cluster α2β1 integrin on the plasma membrane and cause their internalization into cytoplasmic endosomes. Here we show that cholesterol plays a major role not only in the uptake of α2β1 integrin and its ligands but also in the formation of α2 integrin-specific multivesicular bodies (α2-MVBs) and virus infection. EV1 infection and α2β1 integrin internalization were totally halted by low amounts of the cholesterol-aggregating drugs filipin or nystatin. Inhibition of cholesterol synthesis and accumulation of lanosterol after ketoconazole treatment inhibited uptake of collagen, virus and clustered integrin, an…
Differences in the signaling pathways of α(1A)- and α(1B)-adrenoceptors are related to different endosomal targeting.
2013
AIMS: To compare the constitutive and agonist-dependent endosomal trafficking of α(1A)- and α(1B)-adrenoceptors (ARs) and to establish if the internalization pattern determines the signaling pathways of each subtype. METHODS: Using CypHer5 technology and VSV-G epitope tagged α(1A)- and α(1B)-ARs stably and transiently expressed in HEK 293 cells, we analyzed by confocal microscopy the constitutive and agonist-induced internalization of each subtype, and the temporal relationship between agonist induced internalization and the increase in intracellular calcium (determined by FLUO-3 flouorescence), or the phosphorylation of ERK1/2 and p38 MAP kinases (determined by Western blot). RESULTS AND C…
The Late Endosomal Adaptor Molecule p14 (LAMTOR2) Regulates TGFβ1-Mediated Homeostasis of Langerhans Cells
2014
Langerhans cells (LCs), a sub-population of dendritic cells (DCs) in the skin, participate in the regulation of immunity and peripheral tolerance. The adaptor molecule p14 is part of the late endosomal/lysosomal adaptor and mitogen-activated protein kinase and mammalian target of rapamycin (mTOR) activator/regulator (LAMTOR) complex, which mediates the activation of lysosome-associated extracellular signaling regulated kinase (ERK) and the mTOR cascade. In previous work, we demonstrated that CD11c-specific deficiency of p14 disrupts LC homeostasis by affecting the LAMTOR-mediated ERK and mTOR signaling. In this study, we extended our analysis on p14 deficiency specifically in LCs. Langerin-…
Fine-tuning DNA/albumin polyelectrolyte interactions to produce the efficient transfection agent cBSA-147.
2010
We present the preparation and isolation of different chemically modified BSA species with varying numbers of primary amino groups at the surface. Highly cationic albumin proteins with increased numbers of amino groups were achieved and complex formation with plasmid DNA was carefully investigated. We compare the transfection results, polyelectrolyte complexes morphologies with their impact on complex stabilities, cytotoxicities and DNA accessibility. This knowledge-driven approach led to the identification of the efficient non-viral DNA delivery agent cBSA-147, which showed high transfection efficacies and stability.
Transport of the major myelin proteolipid protein is directed by VAMP3 and VAMP7.
2011
CNS myelination by oligodendrocytes requires directed transport of myelin membrane components and a timely and spatially controlled membrane expansion. In this study, we show the functional involvement of the R-solubleN-ethylmaleimide-sensitive factor attachment protein receptor (R-SNARE) proteins VAMP3/cellubrevin and VAMP7/TI-VAMP in myelin membrane trafficking. VAMP3 and VAMP7 colocalize with the major myelin proteolipid protein (PLP) in recycling endosomes and late endosomes/lysosomes, respectively. Interference with VAMP3 or VAMP7 function using small interfering RNA-mediated silencing and exogenous expression of dominant-negative proteins diminished transport of PLP to the oligodendro…