Página 1 dos resultados de 7336 itens digitais encontrados em 0.011 segundos

Caveolae as an additional route for influenza virus endocytosis in MDCK cells

Nunes-Correia, Isabel; Eulálio, Ana; Nir, Shlomo; Lima, Maria C. Pedroso de
Fonte: Polish Society for Cell Biology Publicador: Polish Society for Cell Biology
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
36.69%
Clathrin-mediated endocytosis has been described as the primary internalization pathway for many viruses, including the influenza virus. However, caveolae, an alternative clathrin-independent endocytotic pathway, has also been described as mediating the entry of some molecules, including viruses. To address the question of pathway selection by the influenza virus, we have investigated whether the virus is internalized via clathrin-coated pits and/or caveolae in Madin Darby canine kidney (MDCK) cells. By applying pharmacological manipulations to selectively disrupt the cell internalization pathways, we found that, in MDCK cells, the influenza virus may be internalized via caveolae in addition to entry by clathrin-mediated endocytosis. However, a small contribution by another mode of entry, as recently proposed, cannot be excluded

GD1b-Derived Gangliosides Modulate Fc epsilon RI Endocytosis in Mast Cells

MAZUCATO, Vivian Marino; SOUZA, Adriana Maria Mariano Silveira e; NICOLETTI, Liliana Martos; JAMUR, Maria Celia; OLIVER, Constance
Fonte: SAGE PUBLICATIONS LTD Publicador: SAGE PUBLICATIONS LTD
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
36.69%
The role of the mast cell-specific gangliosides in the modulation of the endocytic pathway of Fc epsilon RI was investigated in RBL-2H3 cells and in the ganglioside-deficient cell lines, E5 and D1. MAb BC4, which binds to the alpha subunit of Fc epsilon RI, was used in the analysis of receptor internalization. After incubation with BC4-FITC for 30 min, endocytic vesicles in RBL-2H3 and E5 cells were dispersed in the cytoplasm. After 1 hr, the endocytic vesicles of the RBL-2H3 cells had fused and formed clusters, whereas in the E5 cells, the fusion was slower. In contrast, in D1 cells, the endocytic vesicles were smaller and remained close to the plasma membrane even after 3 hr of incubation. When incubated with BC4-FITC and subsequently imunolabeled for markers of various endocytic compartments, a defect in the endocytic pathway in the E5 and D1 cells became evident. In the D1 cells, this defect was observed at the initial steps of endocytosis. Therefore, the ganglioside derivatives from GD1b are important in the endocytosis of Fc epsilon RI in mast cells. Because gangliosides may play a role in mast cell-related disease processes, they provide an attractive target for drug therapy and diagnosis. (J Histochem Cytochem 59:428-440, 2011); CAPES (Coordenacao de Aperfeicoamento de Pessoa de Nivel Superior); FAEPA (Fundacao de Apoio ao Ensino...

Endocytosis of prion protein is required for ERK1/2 signaling induced by stress-inducible protein 1

CAETANO, Fabiana A.; LOPES, Marilene H.; HAJJ, Glaucia N. M.; MACHADO, Cleiton F.; ARANTES, Camila Pinto; MAGALHAES, Ana C.; VIEIRA, Monica De Paoli B.; AMERICO, Tatiana A.; MASSENSINI, Andre R.; PRIOLA, Suzette A.; VORBERG, Ina; GOMEZ, Marcus V.; LINDEN,
Fonte: SOC NEUROSCIENCE Publicador: SOC NEUROSCIENCE
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
36.77%
The secreted cochaperone STI1 triggers activation of protein kinase A (PKA) and ERK1/2 signaling by interacting with the cellular prion (PrPC) at the cell surface, resulting in neuroprotection and increased neuritogenesis. Here, we investigated whether STI1 triggers PrPC trafficking and tested whether this process controls PrPC-dependent signaling. We found that STI1, but not a STI1 mutant unable to bind PrPC, induced PrPC endocytosis. STI1-induced signaling did not occur in cells devoid of endogenous PrPC; however, heterologous expression of PrPC reconstituted both PKA and ERK1/2 activation. In contrast, a PrPC mutant lacking endocytic activity was unable to promote ERK1/2 activation induced by STI1, whereas it reconstituted PKA activity in the same condition, suggesting a key role of endocytosis in the former process. The activation of ERK1/2 by STI1 was transient and appeared to depend on the interaction of the two proteins at the cell surface or shortly after internalization. Moreover, inhibition of dynamin activity by expression of a dominant-negative mutant caused the accumulation and colocalization of these proteins at the plasma membrane, suggesting that both proteins use a dynamin-dependent internalization pathway. These results show that PrPC endocytosis is a necessary step to modulate STI1-dependent ERK1/2 signaling involved in neuritogenesis.

Mechanisms involved in calcium oxalate endocytosis by Madin-Darby canine kidney cells

Campos,A.H.; Schor,N.
Fonte: Associação Brasileira de Divulgação Científica Publicador: Associação Brasileira de Divulgação Científica
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2000 EN
Relevância na Pesquisa
36.69%
Calcium oxalate (CaOx) crystals adhere to and are internalized by tubular renal cells and it seems that this interaction is related (positively or negatively) to the appearance of urinary calculi. The present study analyzes a series of mechanisms possibly involved in CaOx uptake by Madin-Darby canine kidney (MDCK) cells. CaOx crystals were added to MDCK cell cultures and endocytosis was evaluated by polarized light microscopy. This process was inhibited by an increase in intracellular calcium by means of ionomycin (100 nM; N = 6; 43.9% inhibition; P<0.001) or thapsigargin (1 µM; N = 6; 33.3% inhibition; P<0.005) administration, and via blockade of cytoskeleton assembly by the addition of colchicine (10 µM; N = 8; 46.1% inhibition; P<0.001) or cytochalasin B (10 µM; N = 8; 34.2% inhibition; P<0.001). Furthermore, CaOx uptake was reduced when the activity of protein kinase C was inhibited by staurosporine (10 nM; N = 6; 44% inhibition; P<0.01), or that of cyclo-oxygenase by indomethacin (3 µM; N = 12; 17.2% inhibition; P<0.05); however, the uptake was unaffected by modulation of potassium channel activity with glibenclamide (3 µM; N = 6), tetraethylammonium (1 mM; N = 6) or cromakalim (1 µM; N = 6). Taken together...

Ligand-induced endocytosis and nuclear localization of angiotensin II receptors expressed in CHO cells

Merjan,A.J.; Kanashiro,C.A.; Krieger,J.E.; Han,S.W.; Paiva,A.C.M.
Fonte: Associação Brasileira de Divulgação Científica Publicador: Associação Brasileira de Divulgação Científica
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/09/2001 EN
Relevância na Pesquisa
36.69%
A construct (AT1R-NF) containing a "Flag" sequence added to the N-terminus of the rat AT1 receptor was stably expressed in Chinese hamster ovary cells and quantified in the cell membrane by confocal microscopy after reaction with a fluorescein-labeled anti-Flag monoclonal antibody. Angiotensin II bound to AT1R-NF and induced endocytosis with a half-time of 2 min. After 60-90 min, fluorescence accumulated around the cell nucleus, suggesting migration of the ligand-receptor complex to the nuclear membrane. Angiotensin antagonists also induced endocytosis, suggesting that a common step in the transduction signal mechanism occurring after ligand binding may be responsible for the ligand-receptor complex internalization.

Nephrotoxicity of Bence-Jones proteins: correlation with endocytosis by BHK cells and intracellular movement

Nicastri,Ana Lucia; Gomes,Elisa Maines; Prado,Maria José Brandão de Almeida; Prado,Euthymia Brandão de Almeida
Fonte: Instituto de Tecnologia do Paraná - Tecpar Publicador: Instituto de Tecnologia do Paraná - Tecpar
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2001 EN
Relevância na Pesquisa
36.57%
The aim of this investigation was to evaluate the endocytosis of two Bence-Jones proteins by renal cells in order to elucidate the interference of their physical and chemical characteristics on nephrotoxicity. Bence-Jones proteins (AK and GL) were purified and isolated from the urine of two patients with multiple myeloma. The isotype of both proteins was characterised as being human monoclonal lambda light chain. The AK protein presented mainly an Ip>7.0, a high content of galactose and a low amount of sialic acid molecules. On the other hand, the GL protein presented a single band with an Ip of 4.3, a higher level of sialic acid and a reduced amount of galactose, in comparison with the AK protein. Baby Hamster Kidney (BHK) cells were maintained in culture in bottles at 37ºC, using DMEM culture media supplemented with 10% of calf serum with a pH of 7.4. Once the monolayer was observed to be confluent, the BHK cells were incubated with the two proteins, dissolved in a serum-free medium for 1, 5, 15, 30, 60 minutes and 24 hours. Control cells were established omitting the incubation with Bence-Jones proteins, but maintaining all of the other conditions. After, this the cells were washed, trypsinised, centrifuged and fixed in a solution of 4% paraformaldehyde and 0.5% glutaraldehyde on a 0.1 M...

Endocytosis of hyaluronic acid by rat liver endothelial cells. Evidence for receptor recycling.

McGary, C T; Raja, R H; Weigel, P H
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em 01/02/1989 EN
Relevância na Pesquisa
27%
Hyaluronic acid (HA) is cleared from the blood by liver endothelial cells through receptor-mediated endocytosis [Eriksson, Fraser, Laurent, Pertoft & Smedsrod (1983) Exp. Cell Res. 144, 223-238]. We have measured the capacity of cultured rat liver endothelial cells to endocytose and degrade 125I-HA (Mr approximately 44,000) at 37 degrees C. Endocytosis was linear for 3 h and then reached a plateau. The rate of endocytosis was concentration-dependent and reached a maximum of 250 molecules/s per cell. Endocytosis of 125I-HA was inhibited more than 92% by a 150-fold excess of non-radiolabelled HA. HA, chondroitin sulphate and heparin effectively competed for endocytosis of 125I-HA, whereas glucuronic acid, N-acetylglucosamine, DNA, RNA, polygalacturonic acid and dextran did not compete. In the absence of cycloheximide, endothelial cells processed 13 times more 125I-HA in 6 h than their total (cell-surface and intracellular) specific HA-binding capacity. This result was not due to degradation and rapid replacement of receptors, because, even in the presence of cycloheximide, these cells processed 6 times more HA than their total receptor content in 6 h. Also, in the presence of cycloheximide, no decrease in 125I-HA-binding capacity was seen in cells processing or not processing HA for 6 h...

Activity-dependent acceleration of endocytosis at a central synapse

Wu, Wei; Xu, Jianhua; Wu, Xin-Sheng; Wu, Ling-Gang
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em 14/12/2005 EN
Relevância na Pesquisa
27.01%
Accumulated evidence indicates the existence of rapid and slow endocytosis at many synapses. It has been proposed that rapid endocytosis is activated by intense stimulation when vesicle recycling needs to be speeded up to supply vesicles at hippocampal synapses. However, the evidence, as obtained with imaging techniques, which are somewhat indirect in indicating rapid endocytosis, is controversial. Furthermore, a slower time course of endocytosis is often found after more intense nerve activity, casting the doubt on the role of rapid endocytosis at synapses. Here we addressed this issue at a mammalian central synapse, the calyx of Held, using a capacitance measurement technique that provides a higher time resolution than imaging techniques. We found that rapid endocytosis with a time constant of ~1 - 2 s was activated during intense nerve activity. Reducing the presynaptic calcium current or buffering the intracellular calcium with EGTA significantly inhibited rapid endocytosis, suggesting that calcium triggers rapid endocytosis. During intense stimulation, rapid endocytosis retrieved up to ~8 vesicles per second per active zone, about 8 folds larger than reported in hippocampus, and thus played a dominant role during and within 3 s after intense stimulation. Slow endocytosis became dominant 3 s after intense stimulation likely because of the fall of the intracellular calcium level that deactivated rapid endocytosis. These results underscore the importance of calcium-triggered rapid endocytosis...

The kinetics of exocytosis and endocytosis in the synaptic terminal of goldfish retinal bipolar cells

Neves, Guilherme; Lagnado, Leon
Fonte: Blackwell Science Inc Publicador: Blackwell Science Inc
Tipo: Artigo de Revista Científica
Publicado em 15/02/1999 EN
Relevância na Pesquisa
27%
The kinetics of exocytosis and endocytosis were studied in the giant synaptic terminal of depolarizing bipolar cells from the goldfish retina. Two techniques were applied: capacitance measurements of changes in membrane surface area, and fluorescence measurements of exocytosis using the membrane dye FM1-43.Three phases of exocytosis occurred during maintained depolarization to 0 mV. The first component was complete within about 10 ms and involved a pool of 1200–1800 vesicles (with a total membrane area equivalent to about 1.6% of the surface of the terminal). The second component of exocytosis involved the release of about 4400 vesicles over 1 s. The third component of exocytosis was stimulated continuously at a rate of about 1000 vesicles s−1.After short depolarizations (< 200 ms), neither the FM1-43 signal nor the capacitance signal continued to rise, indicating that exocytosis stopped rapidly after closure of Ca2+ channels. The fall in capacitance could therefore be used to monitor endocytosis independently of exocytosis. The capacitance measured after brief stimuli began to fall immediately, recovering to the pre-stimulus baseline with a rate constant of 0.8 s−1.The amount of exocytosis measured using the capacitance and FM1-43 techniques was similar during the first 200 ms of depolarization...

Endocytosis in identified rat corticotrophs

Lee, Andy K; Tse, Amy
Fonte: Blackwell Science Inc Publicador: Blackwell Science Inc
Tipo: Artigo de Revista Científica
Publicado em 01/06/2001 EN
Relevância na Pesquisa
27.06%
We used the patch-clamp technique, in conjunction with membrane capacitance measurement, fluorescence measurement of intracellular calcium concentration ([Ca2+]i), and flash photolysis of caged Ca2+ to study exo- and endocytosis in identified rat corticotrophs.Exocytosis stimulated by depolarization pulses was typically followed by a ‘slow’ endocytosis that retrieved the membrane with a time constant of ∼6 s. The efficiency (the endocytosis/exocytosis amplitude ratio) of ‘slow’ endocytosis was ∼1.2 at [Ca2+]i < 3 μm and increased to ∼1.6 at [Ca2+]i > 3 μm.Whole-cell dialysis through a patch pipette did not affect the kinetics and the efficiency of ‘slow’ endocytosis, but the amplitude of exocytosis was reduced.‘Slow’ endocytosis did not require sustained [Ca2+]i elevation and its kinetics was only weakly [Ca2+]i dependent. Our results suggest that ‘slow’ endocytosis involves a Ca2+ sensor with a high Ca2+ affinity (∼500 nm).At high [Ca2+]i (> 10 μm), the ‘slow’ endocytosis was frequently preceded by a ‘fast’ endocytosis that comprised multiple steps of rapid decrease in membrane capacitance.Neither calmodulin nor calcineurin appeared to be the Ca2+ sensor for endocytosis because the two forms of endocytosis were not affected by the calmodulin inhibitor calmidazolium (500 μm) or the calcineurin inhibitors cyclosporin A (1 μm) and calcineurin autoinhibitory peptide (1 mg ml−1). Ba2+...

Mechanisms of homomeric alpha1 glycine receptor endocytosis

Huang, Renqi; He, Shaoqing; Chen, Zhenglan; Dillon, Glenn H.; Leidenheimer, Nancy J.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
27.01%
Little is known regarding the mechanism(s) by which glycine receptors are endocytosed. Here we examined the endocytosis of homomeric α1 glycine receptors expressed in HEK 293 cells using immunofluorescence/confocal microscopy and whole-cell patch-clamp recordings. Our studies demonstrate that constitutive endocytosis of glycine receptors is blocked by the dominant negative dynamin construct K44A and that intracellular dialysis with peptide P4, a dynamin/amphiphysin disrupting peptide, increased whole-cell glycine-gated chloride currents. To examine whether receptor endocytosis could be regulated by PKC, experiments with the PKC activator PMA (phorbol 12-myristate-13-acetate) were performed. PMA, but not its inactive analogue PMM (phorbol 12-monomyristate), stimulated receptor endocytosis and inhibited glycine-gated chloride currents. Similar to constitutive endocytosis, PKC-stimulated endocytosis was blocked by dynamin K44A. Mutation of a putative AP2 adaptin dileucine motif (L314A, L315A) present in the receptor cytoplasmic loop blocked PMA-stimulated receptor endocytosis and also prevented PMA inhibition of glycine receptor currents. In patch-clamp experiments, intracellular dialysis of a 12-amino acid peptide corresponding to the region of the receptor containing the dileucine motif prevented PKC modulation of wildtype glycine receptors. Unlike PKC modulation of the receptor...

The mother of all endocytosis

Clapham, David E
Fonte: eLife Sciences Publications, Ltd Publicador: eLife Sciences Publications, Ltd
Tipo: Artigo de Revista Científica
EN_US
Relevância na Pesquisa
36.57%
Massive endocytosis is initiated by a series of steps that involve a sudden influx of calcium ions, changes in mitochondria, and modification of surface proteins by lipids. A better understanding of this process could lead to new approaches to reducing the tissue damage that is caused by heart attacks.

Microtubule Motors Power Plasma Membrane Tubulation in Clathrin-Independent Endocytosis

Day, Charles A.; Baetz, Nicholas W.; Copeland, Courtney A.; Kraft, Lewis J.; Han, Bing; Tiwari, Ajit; Drake, Kimberly R.; De Luca, Heidi; Chinnapen, Daniel J.-F.; Davidson, Michael W.; Holmes, Randall K.; Jobling, Michael G.; Schroer, Trina A.; Lencer, Wa
Fonte: Harvard University Publicador: Harvard University
Tipo: Artigo de Revista Científica
EN_US
Relevância na Pesquisa
36.69%
How the plasma membrane is bent to accommodate clathrin-independent endocytosis remains uncertain. Recent studies suggest Shiga and cholera toxin induce membrane curvature required for their uptake into clathrin-independent carriers by binding and cross-linking multiple copies of their glycosphingolipid receptors on the plasma membrane. But it remains unclear if toxin-induced sphingolipid crosslinking provides sufficient mechanical force for deforming the plasma membrane, or if host cell factors also contribute to this process. To test this, we imaged the uptake of cholera toxin B-subunit into surface-derived tubular invaginations. We found that cholera toxin mutants that bind to only one glycosphingolipid receptor accumulated in tubules, and that toxin binding was entirely dispensable for membrane tubulations to form. Unexpectedly, the driving force for tubule extension was supplied by the combination of microtubules, dynein and dynactin, thus defining a novel mechanism for generating membrane curvature during clathrin-independent endocytosis.

Selective and Specific Activation of Rab5 during Endocytosis of Receptor Tyrosine Kinases

Jozic, Ivan
Fonte: FIU Digital Commons Publicador: FIU Digital Commons
Tipo: Artigo de Revista Científica Formato: application/pdf
Relevância na Pesquisa
36.57%
The Rab family of proteins are low molecular weight GTPases that have the ability to switch between GTP- (active) and GDP- (inactive) bound form, and in that sense act as molecular switches. Through distinct localization on various vesicles and organelles and by cycling through GTP/GDP bound forms, Rabs are able to recruit and activate numerous effector proteins, both spatially and temporally, and hence behave as key regulators of trafficking in both endocytic and biosynhtetic pathways. The Rab5 protein has been shown to regulate transport from plasma membrane to the early endosome as well as activate signaling pathways from the early endosome. This dissertation focused on understanding Rab5 activation via endocytosis of receptor tyrosine kinases (RTKs). First, tyrosine kinase activity of RTKs was linked to endosome fusion by demonstrating that tyrosine kinase inhibitors block endosome fusion and activation of Rab5, and a constitutively active form of Rab5 is able to rescue endosome fusion. However, depending on how much ligand is available at the cell surface, the receptor-ligand complexes can be internalized via a number of distinct pathways. Similarly, Rab5 was activated in a ligand-dependent concentration dependent manner via clathrin- and caveolin-mediated pathways...

Effect of cholesterol and its autooxidation derivatives on endocytosis and dipeptidyl peptidases of aortic endothelial cells

Fornas, E.; Mayordomo, F.; Renau-Piqueras, J.; Alborch, E.
Fonte: Murcia : F. Hernández Publicador: Murcia : F. Hernández
Tipo: Artigo de Revista Científica Formato: application/pdf
ENG
Relevância na Pesquisa
36.69%
The effects of cholesterol (CHO) and cholesterol autooxidation derivatives (CAD) on the endocytosis of cationized ferritin (CF) by endothelial cells have been investigated. The effect of both substances on the activity of lysosomal enzymes dipeptidyl peptidase 1 (DPP 1) and dipeptidyl peptidase 11 (DPP 11) was also studied. Treatment of rats with CAD induced striking alterations in the ultrastructure of endothelial cells and makes it impossible to analyze the effect of this toxin on endocytosis processes. In contrast, CHO-treated cells displayed a good ultrastructural preservation and showed an increased ability to endocyte ferritin, as compared with controls. Both DPPI and DPP 11 activities increased after 3 weeks of CAD or CHO treatment. Our results indicate that although CHO damage endothelial cells, the most important effects could be attributed to CAD which usually accompanies CHO-supplemented diets.

Hypothesis review: are clathrin-mediated endocytosis and clathrin-dependent membrane and protein trafficking core pathophysiological processes in schizophrenia and bipolar disorder?

Schubert, K.O.; Föcking, M.; Prehn, J.H.M.; Cotter, D.R.
Fonte: Macmillan Publicador: Macmillan
Tipo: Artigo de Revista Científica
Publicado em //2012 EN
Relevância na Pesquisa
36.57%
Clathrin-mediated endocytosis (CME) is the best-characterized mechanism governing cellular membrane and protein trafficking. In this hypothesis review, we integrate recent evidence implicating CME and related cellular trafficking mechanisms in the pathophysiology of psychotic disorders such as schizophrenia and bipolar disorder. The evidence includes proteomic and genomic findings implicating proteins and genes of the clathrin interactome. Additionally, several important candidate genes for schizophrenia, such as dysbindin, are involved in processes closely linked to CME and membrane trafficking. We discuss that key aspects of psychosis neuropathology such as synaptic dysfunction, white matter changes and aberrant neurodevelopment are all influenced by clathrin-dependent processes, and that other cellular trafficking mechanisms previously linked to psychoses interact with the clathrin interactome in important ways. Furthermore, many antipsychotic drugs have been shown to affect clathrin-interacting proteins. We propose that the targeted pharmacological manipulation of the clathrin interactome may offer fruitful opportunities for novel treatments of schizophrenia.; KO Schubert, M Fo, cking, JHM Prehn, and DR Cotter

SAMP8 mice have altered hippocampal gene expression in long term potentiation, phosphatidylinositol signaling, and endocytosis pathways

Armbrecht, H.J.; Siddiqui, A.M.; Green, M.; Farr, S.A.; Kumar, V.B.; Banks, W.A.; Patrick, P.; Shah, G.N.; Morley, J.E.
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Publicado em //2014 EN
Relevância na Pesquisa
36.83%
The senescence-accelerated mouse (SAMP8) strain exhibits decreased learning and memory and increased amyloid beta (Aβ) peptide accumulation at 12 months. To detect differences in gene expression in SAMP8 mice, we used a control mouse that was a 50% cross between SAMP8 and CD-1 mice and which showed no memory deficits (50% SAMs). We then compared gene expression in the hippocampus of 4- and 12-month-old SAMP8 and control mice using Affymetrix gene arrays. At 12 months, but not at 4 months, pathway analysis revealed significant differences in the long term potentiation (6 genes), phosphatidylinositol signaling (6 genes), and endocytosis (10 genes) pathways. The changes in long term potentiation included mitogen-activated protein kinase (MAPK) signaling (N-ras, cAMP responsive element binding protein [CREB], protein phosphatase inhibitor 1) and Ca-dependent signaling (inositol triphosphate [ITP] receptors 1 and 2 and phospholipase C). Changes in phosphatidylinositol signaling genes suggested altered signaling through phosphatidylinositol-3-kinase, and Western blotting revealed phosphorylation changes in serine/threonine protein kinase AKT and 70S6K. Changes in the endocytosis pathway involved genes related to clathrin-mediated endocytosis (dynamin and clathrin). Endocytosis is required for receptor recycling...

Estudio de la endocitosis y señalización mitogénica y metabólica de las dos variantes de splicing del receptor de insulina; Study of the endocytosis and metabolic and mitogenic signaling of the insulin receptor splice variants

Giudice, Jimena
Fonte: Facultad de Ciencias Exactas y Naturales. Universidad de Buenos Aires Publicador: Facultad de Ciencias Exactas y Naturales. Universidad de Buenos Aires
Tipo: info:eu-repo/semantics/doctoralThesis; tesis doctoral; info:eu-repo/semantics/publishedVersion Formato: application/pdf
Publicado em //2011 SPA
Relevância na Pesquisa
36.69%
La señalización por insulina comprende una compleja cascada de eventos que llevan a la regulación del metabolismo de la glucosa y al crecimiento celular. Fallas en la respuesta a insulina conducen a diabetes mientras que en ciertos tipos de cáncer se encontraron aumentos en la actividad de esta vía se señalización. En mamíferos el gen del receptor de insulina (IR) adquirió un exón adicional junto con la capacidad de procesarlo alternativamente originando dos isoformas, IR-A e IR-B. En esta tesis se presenta el desarrollo de herramientas que permitieron visualizar procesos celulares in vivo por técnicas de microscopía. Esto permitió estudiar la endocitosis de las dos isoformas del IR en células individuales en respuesta a insulina y al factor de crecimiento similar a la insulina II (IGF-II). Una mayor internalización para el IR-A que para el IR-B en respuesta a ambos ligandos fue demostrada. Esto condujo a estudiar la señalización río abajo del receptor observando que la insulina desencadena una cascada mitogénica a través del IR-A y una predominantemente metabólica a través del IR-B. Cuando el estudio se extendió al IGF-II, pudo mostrarse que un mismo receptor sea mitogénico (IR-A) o metabólico (IR-B) se comporta diferente en respuesta a un ligando mitogénico (IGF-II) o metabólico (insulina). La existencia de los híbridos IR-A/IR-B en la membrana fue estudiada generando una quimera del IR capaz de ser modificada extracelularmente y que actúa como dominante negativo selectivo del efecto mitogénico. Esto permitió detectar los dímeros en membrana...

HSV-1 glycoproteins are delivered to virus assembly sites through dynamin-dependent endocytosis; HSV-1 glycoprotein endocytosis

Albecka, Anna; Laine, Romain F.; Janssen, Anne F. J.; Kaminski, Clemens F.; Crump, Colin M.
Fonte: Wiley Publicador: Wiley
Tipo: Article; accepted version
EN
Relevância na Pesquisa
36.91%
This is the author accepted manuscript. The final version is available from Wiley via http://dx.doi.org/10.1111/tra.12340; Herpes simplex virus-1 (HSV-1) is a large enveloped DNA virus that belongs to the family of Herpesviridae. It has been recently shown that the cytoplasmic membranes that wrap the newly assembled capsids are endocytic compartments derived from the plasma membrane. Here we show that dynamin-dependent endocytosis plays a major role in this process. Dominant-negative dynamin and clathrin adaptor AP180 significantly decrease virus production. Moreover inhibitors targeting dynamin and clathrin lead to a decreased transport of glycoproteins to cytoplasmic capsids confirming that glycoproteins are delivered to assembly sites via endocytosis. We also show that certain combinations of glycoproteins colocalize with each other and with the components of clathrin-dependent and clathrin-independent endocytosis pathways. Importantly, we demonstrate that the uptake of neutralizing antibodies that bind to glycoproteins when they become exposed on the cell surface during virus particle assembly leads to the production of noninfectious HSV-1. Our results demonstrate that transport of viral glycoproteins to the plasma membrane prior to endocytosis is the major route by which these proteins are localized to the cytoplasmic virus assembly compartments. This highlights the importance of endocytosis as a major protein-sorting event during HSV-1 envelopment.; Authors would like to thank Michael Hollinshead and Kevin Moreau for helpful discussions...

Mechanisms of Molecular Chaperone Surface Binding and Endocytosis: Insights into the Molecular Basis for GRP94 Immune Function

Jockheck-Clark, Angela Roberta
Fonte: Universidade Duke Publicador: Universidade Duke
Tipo: Dissertação
Publicado em //2010
Relevância na Pesquisa
36.77%

Extracellular GRP94 can elicit both innate and adaptive immune responses by interacting with endocytic and signaling receptors on professional antigen presenting cells (pAPCs). CD91 was the first receptor proposed to facilitate GRP94-mediated immune responses. Using a GRP94 affinity matrix, a CD91 fragment was isolated from the detergent-solubilized membranes of a pAPC cell line. It was then demonstrated that CD91 ligands could inhibit GRP94-mediated peptide cross-presentation, suggesting that CD91 played a critical role in this process. While these studies implied that CD91 could function as a GRP94 endocytic receptor, later works suggested that CD91 may not recognize GRP94 at the cell surface. These opposing observations have lead to a significant controversy surrounding the identity of CD91 as an endocytic receptor for GRP94. Because the ability of CD91 to directly mediate GRP94 surface binding and uptake has not been established, the studies included in this dissertation have focused on evaluating the ability of CD91 to facilitate three processes that are necessary for GRP94-mediated peptide cross-presentation: surface binding, internalization, and processing.

These studies utilized a recombinantly-expressed N-terminal domain of GRP94 (GRP94.NTD)...