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Efeito dos oxisteróis na sinalização através de cavéolas e sua relevância na aterosclerose; Effect of oxysterols in cell signaling through caveolae and its relevance to atherosclerosis

Jurado, Marcia Cristiane
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 11/02/2011 PT
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Oxisteróis (por exemplo, 7hidroxicolesterol) são gerados por modificações oxidativas que ocorrem na molécula de colesterol. Podem ser encontrados em elevados níveis plasmáticos em pacientes com aterosclerose e como componentes da placa aterosclerótica. Considerando que o colesterol é o principal componente da cavéola (domínios específicos da membrana plasmática que ancoram diversas proteínas de sinalização) formulamos a hipótese que os oxisteróis podem ser incorporados a estes domínios, interferindo com as vias de sinalização aí localizadas. Células endoteliais de veia umbilical humana (HUVECs) em cultura foram expostas a 7hidroxicolesterol (10g/mL) por diferentes tempos. Analisamos a incorporação desse oxisterol à cavéola utilizando espectrometria de massa e a atividade das proteínas de sinalização presentes neste domínio: óxido nítrico sintase endotelial (eNOS), CD40/CD40L, receptor do fator de crescimento de fibroblastos (rFGF), utilizando PCR quantitativo e imunoblots. Inicialmente mostramos que o 7hidroxycholesterol, em concentrações fisiológicas, foi incorporado às cavéolas mais acentuadamente que em outros domínios de membrana. Esse fenômeno impediu o desligamento entre eNOS e caveolina...

Early Steps of Polyomavirus Entry into Cells

Gilbert, Joanna M.; Benjamin, Thomas L.
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /09/2000 EN
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The mechanism by which murine polyomavirus penetrates cells and arrives at the nucleus, the site of viral replication, is not well understood. Simian virus 40 and JC virus, two closely related members of the polyomavirus subfamily, use caveola- and clathrin-mediated uptake pathways for entry, respectively. The data presented here indicate that compounds that block endocytosis of both caveola- and clathrin-derived vesicles have no effect on polyomavirus infectivity. Polyomavirus does not appear to colocalize with either clathrin light chain or caveolin-1 by immunofluorescence microscopy. Additionally, expression of a dominant-negative form of dynamin I has no effect on polyomavirus uptake and infectivity. Therefore, polyomavirus uptake occurs through a class of uncoated vesicles in a clathrin-, caveolin-1-, and dynamin I-independent manner.

Association of the Caveola Vesicular System with Cellular Entry by Filoviruses

Empig, Cyril J.; Goldsmith, Mark A.
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /05/2002 EN
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The filoviruses Ebola Zaire virus and Marburg virus are believed to infect target cells through endocytic vesicles, but the details of this pathway are unknown. We used a pseudotyping strategy to investigate the cell biology of filovirus entry. We observed that specific inhibitors of the caveola system, including cholesterol-sequestering drugs and phorbol esters, inhibited the entry of filovirus pseudotypes into human cells. We also measured slower cell entry kinetics for both filovirus pseudotypes than for pseudotypes of vesicular stomatitis virus (VSV), which has been recognized to exploit the clathrin-mediated entry pathway. Finally, visualization by immunofluorescence and confocal microscopy revealed that the filovirus pseudotypes colocalized with the caveola protein marker caveolin-1 but that VSV pseudotypes did not. Collectively, these results provide evidence suggesting that filoviruses use caveolae to gain entry into cells.

Cell Penetration and Trafficking of Polyomavirus

Gilbert, Joanna M.; Goldberg, Ilya G.; Benjamin, Thomas L.
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /02/2003 EN
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The murine polyomavirus (Py) enters mouse fibroblasts and kidney epithelial cells via an endocytic pathway that is caveola-independent (as well as clathrin-independent). In contrast, uptake of simian virus 40 into the same cells is dependent on caveola. Following the initial uptake of Py, both microtubules and microfilaments play roles in trafficking of the virus to the nucleus. Colcemid, which disrupts microtubules, inhibits the ability of Py to reach the nucleus and replicate. Paclitaxel, which stabilizes microtubules and prevents microtubule turnover, has no effect, indicating that intact but not dynamic microtubules are required for Py infectivity. Compounds that disrupt actin filaments enhance Py uptake while stabilization of actin filaments impedes Py infection. Virus particles are seen in association with actin in cells treated with microfilament-disrupting or filament-stabilizing agents at levels comparable to those in untreated cells, suggesting that a dynamic state of the microfilament system is important for Py infectivity.

Caveola-Dependent Endocytic Entry of Amphotropic Murine Leukemia Virus

Beer, Christiane; Andersen, Ditte S.; Rojek, Aleksandra; Pedersen, Lene
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /08/2005 EN
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Early results suggested that the amphotropic murine leukemia virus (A-MLV) does not enter cells via endocytosis through clathrin-coated pits and this gammaretrovirus has therefore been anticipated to fuse directly with the plasma membrane. However, here we present data implicating a caveola-mediated endocytic entry route for A-MLV via its receptor Pit2. Caveolae belong to the cholesterol-rich microdomains characterized by resistance to nonionic detergents such as Triton X-100. Extraction of murine fibroblastic NIH 3T3 cells in cold Triton X-100 showed the presence of the A-MLV receptor Pit2 in detergent-insoluble microdomains. Using coimmunoprecipitation of cell extracts, we were able to demonstrate direct association of Pit2 with caveolin-1, the structural protein of caveolae. Other investigations revealed that A-MLV infection in contrast to vesicular stomatitis virus infection is a slow process (t ≈5 h), which is dependent on plasma membrane cholesterol but independent of NH4Cl treatment of cells; NH4Cl impairs entry via clathrin-coated pits. Furthermore, expression of dominant-negative caveolin-1 decreased the susceptibility to infection via Pit2 by approximately 70%. These results show that A-MLV can enter cells via a caveola-dependent entry route. Moreover...

Involvement of the Rho/Rac family member RhoG in caveolar endocytosis

Prieto-Sánchez, RM; Berenjeno, IM; Bustelo, XR
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em 18/05/2006 EN
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We show here that the GTPase RhoG is involved in caveolar trafficking. Wild-type RhoG moves sequentially to the plasma membrane, intracellular vesicles, and the Golgi apparatus along markers of this endocytic pathway. Such translocation is associated with changes in RhoG GDP/GTP levels and is highly dependent on lipid raft integrity and on the function of the GTPase dynamin2. In addition, the constitutively active RhoGQ61L mutant is preferentially located in endocytic vesicles that can be decorated with markers of the caveola-derived endocytic pathway. RhoGQ61L, but not the analogous Rac1 mutant protein, affects caveola internalization and the subsequent delivery of endocytic vesicles to the Golgi apparatus. The expression of RhoG/Rac1 chimeric proteins and RhoGQ61L effector mutants in cells induces alterations in the internalization of caveolae and severe changes in vesicle structure, respectively. However, the knockdown of endogenous rhoG transcripts using small interfering RNAs does not affect significantly the trafficking of caveola-derived vesicles, suggesting that RhoG function is dispensable for this endocytic process or, alternatively, that its function is compensated by other molecules. Taken together, these observations assign a novel function to RhoG and suggest that caveolar trafficking...

The neck of caveolae is a distinct plasma membrane subdomain that concentrates insulin receptors in 3T3-L1 adipocytes

Foti, Michelangelo; Porcheron, Geneviève; Fournier, Margot; Maeder, Christine; Carpentier, Jean-Louis
Fonte: National Academy of Sciences Publicador: National Academy of Sciences
Tipo: Artigo de Revista Científica
EN
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Insulin receptors (IRs) segregate on plasma membrane microvilli, but in cells devoid of microvilli, such as adipocytes, the localization of IRs is a matter of controversy. In the present study, we examined the distribution of IRs in the plasma membrane of 3T3-L1 adipocytes. Quantitative electron microscopy indicates that IRs are predominantly associated with the neck, but not the bulb, of caveolae. Caveola necks represent distinct microdomains of the plasma membrane. Indeed, as shown by freeze–fracture analysis, intramembrane particles are concentrated as necklaces around the craters of caveolae. In addition, subcellular fractionation suggests that the neck and the bulb of caveolae present a different resistance to detergent solubility. Finally, cytoskeletal components, including actin, are highly enriched in the membrane area underlying the neck part of caveolae. IRs coimmunoprecipitate with cytoskeletal components, and disruption of the actin cytoskeleton alters IRs expression, localization, and signaling, thus supporting the notion that caveola necks are involved in intracellular signaling by IRs. Together, these results suggest that cytoskeletal proteins anchor IRs to microdomains in the caveola necks of 3T3-L1 adipocytes. By homology with IR localization in other cell types...

Intersectin-2L Regulates Caveola Endocytosis Secondary to Cdc42-mediated Actin Polymerization*

Klein, Irene K.; Predescu, Dan N.; Sharma, Tiffany; Knezevic, Ivana; Malik, Asrar B.; Predescu, Sanda
Fonte: American Society for Biochemistry and Molecular Biology Publicador: American Society for Biochemistry and Molecular Biology
Tipo: Artigo de Revista Científica
EN
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Here we addressed the role of intersectin-2L (ITSN-2L), a guanine nucleotide exchange factor for the Rho GTPase Cdc42, in the mechanism of caveola endocytosis in endothelial cells (ECs). Immunoprecipitation and co-localization studies showed that ITSN-2L associates with members of the Cdc42-WASp-Arp2/3 actin polymerization pathway. Expression of Dbl homology-pleckstrin homology (DH-PH) region of ITSN-2L (DH-PHITSN-2L) induced specific activation of Cdc42, resulting in formation of extensive filopodia, enhanced cortical actin, as well as a shift from G-actin to F-actin. The “catalytically dead” DH-PH domain reversed these effects and induced significant stress fiber formation, without a detectable shift in actin pools. A biotin assay for caveola internalization indicated a significant decrease in the uptake of biotinylated proteins in DH-PHITSN-2L-transfected cells compared with control and 1 μm jasplakinolide-treated cells. ECs depleted of ITSN-2L by small interfering RNA, however, showed decreased Cdc42 activation and actin remodeling similar to the defective DH-PH, resulting in 62% increase in caveola-mediated uptake compared with controls. Thus, ITSN-2L, a guanine nucleotide exchange factor for Cdc42, regulates different steps of caveola endocytosis in ECs by controlling the temporal and spatial actin polymerization and remodeling sub-adjacent to the plasma membrane.

WNK4 Kinase Stimulates Caveola-mediated Endocytosis of TRPV5 Amplifying the Dynamic Range of Regulation of the Channel by Protein Kinase C*

Cha, Seung-Kuy; Huang, Chou-Long
Fonte: American Society for Biochemistry and Molecular Biology Publicador: American Society for Biochemistry and Molecular Biology
Tipo: Artigo de Revista Científica
EN
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WNK4 (with-no-lysine (K) kinase-4) is present in the distal nephron of the kidney and plays an important role in the regulation of renal ion transport. The epithelial Ca2+ channel TRPV5 (transient receptor potential vanilloid 5) is the gatekeeper of transcellular Ca2+ reabsorption in the distal nephron. Previously, we reported that activation of protein kinase C (PKC) increases cell-surface abundance of TRPV5 by inhibiting caveola-mediated endocytosis of the channel. Here, we report that WNK4 decreases cell-surface abundance of TRPV5 by enhancing its endocytosis. Deletion analysis revealed that stimulation of endocytosis of TRPV5 involves amino acids outside the kinase domain of WNK4. We also investigated interplay between WNK4 and PKC regulation of TRPV5. The maximal level of TRPV5 current density stimulated by the PKC activator 1-oleoyl-acetyl-sn-glycerol (OAG) is the same with or without WNK4. The relative increase of TRPV5 current stimulated by OAG, however, is greater in the presence of WNK4 compared with that without WNK4 (∼215% increase versus 60% increase above the level without OAG). Moreover, the rate of increase of TRPV5 by OAG is faster with WNK4 than without WNK4. The enhanced increase of TRPV5 in the presence of WNK4 is also observed when PKC is activated by parathyroid hormones. Thus...

Cells Respond to Mechanical Stress by Rapid Disassembly of Caveolae

Sinha, Bidisha; Köster, Darius; Ruez, Richard; Gonnord, Pauline; Bastiani, Michele; Abankwa, Daniel; Stan, Radu. V.; Butler-Browne, Gillian; Vedie, Benoit; Johannes, Ludger; Morone, Nobuhiro; Parton, Robert G.; Raposo, Graça; Sens, Pierre; Lamaze, Chris
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em 04/02/2011 EN
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The precise role of caveolae, the characteristic plasma membrane invaginations present in many cells, still remains debated. The high density of caveolae in cells experiencing mechanical stress led us to investigate their role in membrane-mediated mechanical response. Acute mechanical stress induced by cell osmotic swelling or by uniaxial stretching results in the immediate disappearance of caveolae, which is associated with a reduced caveolin/Cavin1 interaction, and an increase of free caveolins at the plasma membrane. Tether pulling force measurements in live cells and in plasma membrane spheres demonstrate that caveola flattening and disassembly is the primary actin and ATP-independent cell response which buffers membrane tension surges during mechanical stress. Conversely, stress release leads to complete caveola reassembly in an actin and ATP-dependent process. The absence of a functional caveola reservoir in myotubes from muscular dystrophic patients enhanced membrane fragility under mechanical stress. Our findings support a new role for caveolae as a physiological membrane reservoir that allows cells to quickly accommodate sudden and acute mechanical stresses.

Entry of Tiger Frog Virus (an Iridovirus) into HepG2 Cells via a pH-Dependent, Atypical, Caveola-Mediated Endocytosis Pathway▿

Guo, Chang-Jun; Liu, Dong; Wu, Yan-Yan; Yang, Xiao-Bo; Yang, Li-Shi; Mi, Shu; Huang, Yu-Xin; Luo, Yong-Wen; Jia, Kun-Tong; Liu, Zhao-Yu; Chen, Wei-Jian; Weng, Shao-Ping; Yu, Xiao-Qiang; He, Jian-Guo
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /07/2011 EN
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Tiger frog virus (TFV), in the genus Ranavirus of the family Iridoviridae, causes high mortality of cultured tiger frog tadpoles in China. To explore the cellular entry mechanism of TFV, HepG2 cells were treated with drugs that inhibit the main endocytic pathways. We observed that TFV entry was inhibited by NH4Cl, chloroquine, and bafilomycin, which can all elevate the pH of acidic organelles. In contrast, TFV entry was not influenced by chlorpromazine or overexpression of a dominant-negative form of Esp15, which inhibit the assembly of clathrin-coated pits. These results suggested that TFV entry was not associated with clathrin-mediated endocytosis, but was related to the pH of acidic organelles. Subsequently, we found that endocytosis of TFV was dependent on membrane cholesterol and was inhibited by the caveolin-1 scaffolding domain peptide. Dynamin and actin were also required for TFV entry. In addition, TFV virions colocalized with the cholera toxin subunit B, indicating that TFV enters as caveola-internalized cargo into the Golgi complex. Taken together, our results demonstrated that TFV entry occurs by caveola-mediated endocytosis with a pH-dependent step. This atypical caveola-mediated endocytosis is different from the clathrin-mediated endocytosis of frog virus 3 (FV3) by BHK cells...

Infectious Spleen and Kidney Necrosis Virus (a Fish Iridovirus) Enters Mandarin Fish Fry Cells via Caveola-Dependent Endocytosis

Guo, Chang-Jun; Wu, Yan-Yan; Yang, Li-Shi; Yang, Xiao-Bo; He, Jian; Mi, Shu; Jia, Kun-Tong; Weng, Shao-Ping; Yu, Xiao-Qiang; He, Jian-Guo
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /03/2012 EN
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Infectious spleen and kidney necrosis virus (ISKNV) is the type species of the genus Megalocytivirus from the family Iridoviridae. Megalocytiviruses have been implicated in more than 50 fish species infections and currently threaten the aquaculture industry, causing great economic losses in China, Japan, and Southeast Asia. However, the cellular entry mechanisms of megalocytiviruses remain largely uncharacterized. In this study, the main internalization mechanism of ISKNV was investigated by using mandarin fish fry (MFF-1) cells. The progression of ISKNV infection is slow, and infection is not inhibited when the cells are treated with ammonium chloride (NH4Cl), chloroquine, sucrose, and chlorpromazine, which are inhibitors of clathrin-dependent endocytosis. The depletion of cellular cholesterol by methyl-β-cyclodextrin results in the significant inhibition of ISKNV infection; however, the infection is resumed with cholesterol replenishment. Inhibitors of caveolin-1-involved signaling events, including phorbol 12-myristate 13-acetate (PMA), genistein, and wortmannin, impair ISKNV entry into MFF-1 cells. Moreover, ISKNV entry is dependent on dynamin and the microtubule cytoskeleton. Cofraction analysis of ISKNV and caveolin-1 showed that ISKNV colocates with caveolin-1 during virus infection. These results indicate that ISKNV entry into MFF-1 cells proceeds via classical caveola-mediated endocytosis and is dependent on the microtubules that serve as tracks along which motile cavicles may move via a caveola-caveosome-endoplasmic reticulum (ER) pathway. As a fish iridovirus...

Co-Regulation of Cell Polarization and Migration by Caveolar Proteins PTRF/Cavin-1 and Caveolin-1

Hill, Michelle M.; Daud, Noor Huda; Aung, Cho Sanda; Loo, Dorothy; Martin, Sally; Murphy, Samantha; Black, Debra M.; Barry, Rachael; Simpson, Fiona; Liu, Libin; Pilch, Paul F.; Hancock, John F.; Parat, Marie-Odile; Parton, Robert G.
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 13/08/2012 EN
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Caveolin-1 and caveolae are differentially polarized in migrating cells in various models, and caveolin-1 expression has been shown to quantitatively modulate cell migration. PTRF/cavin-1 is a cytoplasmic protein now established to be also necessary for caveola formation. Here we tested the effect of PTRF expression on cell migration. Using fluorescence imaging, quantitative proteomics, and cell migration assays we show that PTRF/cavin-1 modulates cellular polarization, and the subcellular localization of Rac1 and caveolin-1 in migrating cells as well as PKCα caveola recruitment. PTRF/cavin-1 quantitatively reduced cell migration, and induced mesenchymal epithelial reversion. Similar to caveolin-1, the polarization of PTRF/cavin-1 was dependent on the migration mode. By selectively manipulating PTRF/cavin-1 and caveolin-1 expression (and therefore caveola formation) in multiple cell systems, we unveil caveola-independent functions for both proteins in cell migration.

Phosphocaveolin-1 is a mechanotransducer that induces caveola biogenesis via Egr1 transcriptional regulation

Joshi, Bharat; Bastiani, Michele; Strugnell, Scott S.; Boscher, Cecile; Parton, Robert G.; Nabi, Ivan R.
Fonte: The Rockefeller University Press Publicador: The Rockefeller University Press
Tipo: Artigo de Revista Científica
Publicado em 29/10/2012 EN
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Phosphocaveolin-1 regulates a positive feedback loop that responds to mechanical stress to induce caveola biogenesis by relieving Egr1 transcriptional inhibition of caveolin-1 and cavin-1.

Rift Valley Fever Virus Strain MP-12 Enters Mammalian Host Cells via Caveola-Mediated Endocytosis

Harmon, Brooke; Schudel, Benjamin R.; Maar, Dianna; Kozina, Carol; Ikegami, Tetsuro; Tseng, Chien-Te Kent; Negrete, Oscar A.
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /12/2012 EN
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Rift Valley fever virus (RVFV) is a zoonotic pathogen capable of causing serious morbidity and mortality in both humans and livestock. The lack of efficient countermeasure strategies, the potential for dispersion into new regions, and the pathogenesis in humans and livestock make RVFV a serious public health concern. The receptors, cellular factors, and entry pathways used by RVFV and other members of the family Bunyaviridae remain largely uncharacterized. Here we provide evidence that RVFV strain MP-12 uses dynamin-dependent caveola-mediated endocytosis for cell entry. Caveolae are lipid raft domains composed of caveolin (the main structural component), cholesterol, and sphingolipids. Caveola-mediated endocytosis is responsible for the uptake of a wide variety of host ligands, as well as bacteria, bacterial toxins, and a number of viruses. To determine the cellular entry mechanism of RVFV, we used small-molecule inhibitors, RNA interference (RNAi), and dominant negative (DN) protein expression to inhibit the major mammalian cell endocytic pathways. Inhibitors and RNAi specific for macropinocytosis and clathrin-mediated endocytosis had no effect on RVFV infection. In contrast, inhibitors of caveola-mediated endocytosis, and RNAi targeted to caveolin-1 and dynamin...

Japanese Encephalitis Virus Enters Rat Neuroblastoma Cells via a pH-Dependent, Dynamin and Caveola-Mediated Endocytosis Pathway

Zhu, Yong-Zhe; Xu, Qing-Qiang; Wu, Da-Ge; Ren, Hao; Zhao, Ping; Lao, Wen-Guang; Wang, Yan; Tao, Qing-Yuan; Qian, Xi-Jing; Wei, You-Heng; Cao, Ming-Mei; Qi, Zhong-Tian
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /12/2012 EN
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Japanese encephalitis virus (JEV) is a mosquito-borne flavivirus and one of the most common agents of viral encephalitis. The infectious entry process of JEV into host cells remains largely unknown. Here, we present a systemic study concerning the cellular entry mechanism of JEV to B104 rat neuroblastoma cells. It was observed that JEV internalization was inhibited by chloroquine and ammonium chloride, both of which can elevate the pH of acidic organelles. However, JEV entry was not affected by chlorpromazine, overexpression of a dominant-negative form of EPS 15 protein, or silencing of the clathrin heavy chain by small interfering RNA (siRNA). These results suggested that JEV entry depended on the acidic intracellular pH but was independent of clathrin. We found that endocytosis of JEV was dependent on membrane cholesterol and was inhibited by inactivation of caveolin-1 with siRNA or dominant-negative mutants. It was also shown, by using the inhibitor dynasore, the K44A mutant, and specific siRNA, that dynamin was required for JEV entry. Phagocytosis or macropinocytosis did not play a role in JEV internalization. In addition, we showed that JEV entry into the neuroblastoma cells is not virus strain specific by assessing the effect of the pharmacological inhibitors on the internalization of JEV belonging to different genotypes. Taken together...

Exosomes Derived from Epstein-Barr Virus-Infected Cells Are Internalized via Caveola-Dependent Endocytosis and Promote Phenotypic Modulation in Target Cells

Nanbo, Asuka; Kawanishi, Eri; Yoshida, Ryuji; Yoshiyama, Hironori
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /09/2013 EN
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Epstein-Barr virus (EBV), a human gammaherpesvirus, establishes a lifelong latent infection in B lymphocytes and epithelial cells following primary infection. Several lines of evidence suggest that exosomes derived from EBV-infected cells are internalized and transfer viral factors, including EBV-encoded latent membrane protein and microRNAs, to the recipient cells. However, the detailed mechanism by which exosomes are internalized and their physiological impact on the recipient cells are still poorly understood. In this study, we visualized the internalization of fluorescently labeled exosomes derived from EBV-uninfected and EBV-infected B cells of type I and type III latency into EBV-negative epithelial cells. In this way, we demonstrated that exosomes derived from all three cell types were internalized into the target cells in a similar fashion. Internalization of exosomes was significantly suppressed by treatment with an inhibitor of dynamin and also by the knockdown of caveolin-1. Labeled exosomes were colocalized with caveolae and subsequently trafficked through endocytic pathways. Moreover, we observed that exosomes derived from type III latency cells upregulated proliferation and expression of intercellular adhesion molecule 1 (ICAM-1) in the recipient cells more significantly than did those derived from EBV-negative and type I latency cells. We also identified the EBV latent membrane protein 1 (LMP1) gene as responsible for induction of ICAM-1 expression. Taken together...

Heparan Sulfate-Binding Foot-and-Mouth Disease Virus Enters Cells via Caveola-Mediated Endocytosis▿

O'Donnell, Vivian; LaRocco, Michael; Baxt, Barry
Fonte: American Society for Microbiology (ASM) Publicador: American Society for Microbiology (ASM)
Tipo: Artigo de Revista Científica
EN
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Foot-and-mouth disease virus (FMDV) utilizes different cell surface macromolecules to facilitate infection of cultured cells. Virus, which is virulent for susceptible animals, infects cells via four members of the αV subclass of cellular integrins. In contrast, tissue culture adaptation of some FMDV serotypes results in the loss of viral virulence in the animal, accompanied by the loss of virus' ability to use integrins as receptors. These avirulent viral variants acquire positively charged amino acids on surface-exposed structural proteins, resulting in the utilization of cell surface heparan sulfate (HS) molecules as receptors. We have recently shown that FMDV serotypes utilizing integrin receptors enter cells via a clathrin-mediated mechanism into early endosomes. Acidification within the endosome results in a breakdown of the viral capsid, releasing the RNA, which enters the cytoplasm by a still undefined mechanism. Since there is evidence that HS internalizes bound ligands via a caveola-mediated mechanism, it was of interest to analyze the entry of FMDV by cell-surface HS. Using a genetically engineered variant of type O1Campos (O1C3056R) which can utilize both integrins and HS as receptors and a second variant (O1C3056R-KGE) which can utilize only HS as a receptor...

Caveola--vesicle complexes in the plasmalemma of erythrocytes infected by Plasmodium vivax and P cynomolgi. Unique structures related to Schüffner's dots.

Aikawa, M.; Miller, L. H.; Rabbege, J.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /05/1975 EN
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Erythrocytes infected with Plasmodium vivax and P cynomolgi, characterized by Schüffner's dots on Giemsa-stained thin films, were studied by electron microscopy and immunocytochemistry. A caveola-vesicle complex, which consisted of a caveola surrounded by vesicles, in an alveolar fashion, formed along the erythrocyte plasmalemma. Horseradish-peroxidase-labeled immunoglobulin from a monkey infected with P vivax bound to the vesicle membrane. Cationized ferritin appeared within the vesicles after incubation with viable parasitized erythrocytes, suggesting that these vesicles were pinocytotic in origin. This caveola-vesicle complex probably corresponds to Schüffner's dots because the alteration is unique to vivax- and ovale-type malarias, and its size and distribution are consistent with Schüffner's dots. Clefts observed within the cytoplasm of infected erythrocytes are present in all malarias and are unlikely candidates for Schüffner's data.

Involvement of the Rho/Rac family member RhoG in caveolar endocytosis

Prieto-Sánchez, Rosario M.; Berenjeno, Inmaculada M.; Bustelo, Xosé R.
Fonte: Nature Publishing Group Publicador: Nature Publishing Group
Tipo: Artículo Formato: 1871635 bytes; application/pdf
ENG
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13 páginas, 8 figuras.-- El pdf del artículo es el manuscrito de autor.; We show here that the GTPase RhoG is involved in caveolar trafficking. Wild-type RhoG moves sequentially to the plasma membrane, intracellular vesicles, and the Golgi apparatus along markers of this endocytic pathway. Such translocation is associated with changes in RhoG GDP/GTP levels and is highly dependent on lipid raft integrity and on the function of the GTPase dynamin2. In addition, the constitutively active RhoGQ61L mutant is preferentially located in endocytic vesicles that can be decorated with markers of the caveola-derived endocytic pathway. RhoGQ61L, but not the analogous Rac1 mutant protein, affects caveola internalization and the subsequent delivery of endocytic vesicles to the Golgi apparatus. The expression of RhoG/Rac1 chimeric proteins and RhoGQ61L effector mutants in cells induces alterations in the internalization of caveolae and severe changes in vesicle structure, respectively. However, the knockdown of endogenous rhoG transcripts using small interfering RNAs does not affect significantly the trafficking of caveola-derived vesicles, suggesting that RhoG function is dispensable for this endocytic process or, alternatively, that its function is compensated by other molecules. Taken together...