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Journal articles on the topic 'Adsorptive endocytosis'

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Published: 4 June 2021
Last updated: 1 February 2022

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1

Bohn Thomsen, Louiza, Jacek Lichota, Thomas Navndrup Eskehave, et al. "Brain Delivery Systems via Mechanism Independent of Receptor-Mediated Endocytosis and Adsorptive-Mediated Endocytosis." Current Pharmaceutical Biotechnology 13, no. 12 (2012): 2349–54. http://dx.doi.org/10.2174/138920112803341842.

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2

Banks, W. A., V. Akerstrom, and A. J. Kastin. "Adsorptive endocytosis mediates the passage of HIV-1 across the blood-brain barrier: evidence for a post-internalization coreceptor." Journal of Cell Science 111, no. 4 (1998): 533–40. http://dx.doi.org/10.1242/jcs.111.4.533.

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HIV-1 induces the AIDS dementia complex and infects brain endothelial and glial cells. Because the endothelial cells comprising the blood-brain barrier (BBB) do not possess CD4 receptors or galactosylceramide binding sites, it is unclear how HIV-1 negotiates the BBB. Previous work has suggested that gp120, the glycoprotein viral coat of HIV-1, is capable of inducing adsorptive endocytosis. Glycoprotein lectins like wheatgerm agglutinin induce adsorptive endocytosis and greatly potentiate the uptake by and passage across mouse endothelial cells in vivo and in vitro. We show here that the wheatgerm agglutinin-induced binding of gp120 is dose-dependent and involves components of the cytoskeleton. The uptake is partially dependent on temperature and energy and is modestly enhanced by potassium depletion. Glycosylation of gp120 is critical for its uptake by adsorptive endocytosis since the non-glycosylated form of gp120 is unaffected by wheatgerm agglutinin. Evidence is presented for the existence of a coreceptor sensitive to protamine sulfate that is primarily involved in membrane fusion after 125I-gp120 has bound to the cell membrane and is probably activated after internalization. This coreceptor probably contains a negatively charged heparin sulfate group and could be a member of the chemokine receptor family.
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3

Raphael, Bernd, and Barbara J. McLaughlin. "Adsorptive and fluid phase endocytosis by cultured rabbit corneal endothelium." Current Eye Research 9, no. 3 (1990): 249–58. http://dx.doi.org/10.3109/02713689009044520.

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4

Wall, D. A., and T. Maack. "Endocytic uptake, transport, and catabolism of proteins by epithelial cells." American Journal of Physiology-Cell Physiology 248, no. 1 (1985): C12—C20. http://dx.doi.org/10.1152/ajpcell.1985.248.1.c12.

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Adsorptive and/or receptor-mediated endocytosis of proteins is a universal cell property, which is highly expressed in epithelial cells. Some absorbed proteins are transported intact across cells and in this manner subserve specialized functions such as the transference of immunity from mother to child. Mainly, however, absorbed proteins are transported to lysosomes, where they undergo complete hydrolysis to amino acids. This process is essential for the homeostasis of circulating proteins. This brief review considers the intracellular pathways taken by endocytosed proteins and the quantitative aspects and determinants of protein uptake and catabolism by epithelial cells. The topics to be briefly discussed are initial internalization sites, transport organelles (endosomes), and lysosomal and nonlysosomal pathways of transport; intracellular sorting of internalized proteins, membranes, and receptors; kinetics and selectivity of renal cell uptake of low-molecular-weight proteins and proteohormones; receptor-mediated endocytosis of larger proteins (e.g., glycoproteins) by hepatocytes; and lysosomal catabolism of absorbed proteins and its dependence on protein load and endosomal-lysosomal pH and function. The perspectives of the field and some of the outstanding unsolved problems are briefly discussed.
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5

Raub, T. J., and K. L. Audus. "Adsorptive endocytosis and membrane recycling by cultured primary bovine brain microvessel endothelial cell monolayers." Journal of Cell Science 97, no. 1 (1990): 127–38. http://dx.doi.org/10.1242/jcs.97.1.127.

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The dynamics of membrane recycling were examined in primary cultures of brain microvessel endothelial cells (BMECs). Because the BMEC surface was dominated by galactosylated glycoconjugates, ricin agglutinin (RCAI) was used as a tracer to follow the endocytosis and recycling of RCAI binding sites. These binding sites accounted for 75% of the iodinatable or most externally disposed plasma membrane proteins. Because greater than 90% of the RCAI that had bound to BMECs was removed by a brief, nontoxic treatment with galactose, the amounts and kinetics for internalization and efflux of [125I]RCAI were measured. Both endocytosis and efflux were energy dependent. By using pseudo-first-order kinetics, the t1/2 values for RCAI binding, internalization and efflux were 5, 18 and 13–14 min, respectively. By comparing efflux with and without galactose present, we found that 60% of the RCAI binding sites that had been internalized were returned to the cell surface and reinternalized. Quantifying the distribution of gold-RCAI following internalization showed kinetics consistent with that obtained using radiolabeled RCAI. Both horseradish peroxidase (HRP) and gold-conjugated RCAI that had bound BMEC at 4 degrees C became localized within more caveolae within 2.5 min of warming to 37 degrees C to permit endocytosis. With time, RCAI appeared within endosomes and tubules and vesicles of which some were located in the trans-Golgi network (TGN). The distribution of HRP-RCAI contrasted with that of free HRP, which was not routed to the TGN. The absence of RCAI conjugates in association with the basolateral membrane domain suggested the presence of functional tight junctions and maintenance of polarity throughout the duration of these experiments. These results showed that membrane recycling was more extensive and much slower than fluid-phase endocytosis in cultured BMECs. Moreover, we found that endocytosis of membrane by BMECs in culture was similar to that reported for brain endothelium in vivo in that a fraction of the cell surface membrane was routed to the TGN.
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6

Sai, Yoshimichi, Masahiro Kajita, Ikumi Tamai, Jun Wakama, Tateaki Wakamiya, and Akira Tsuji. "Adsorptive-mediated endocytosis of a basic peptide in enterocyte-like Caco-2 cells." American Journal of Physiology-Gastrointestinal and Liver Physiology 275, no. 3 (1998): G514—G520. http://dx.doi.org/10.1152/ajpgi.1998.275.3.g514.

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The internalization of a basic peptide, 001-C8 [H-MeTyr-Arg-MeArg-d-Leu-NH(CH2)8NH2], into enterocyte-like Caco-2 cells was evaluated. Internalization of125I-labeled 001-C8 (125I-001-C8) increased time dependently and reached steady state at 60 min. The steady-state internalization of 125I-001-C8 (7.24 ± 0.41 μl/mg protein) was temperature and concentration dependent and was significantly decreased by dansylcadaverine (500 μM), protamine (1 mM), poly-l-lysine (1 mM), E-2078 (1 mM), and ebiratide (1 mM), whereas poly-l-glutamic acid (1 mM), tyrosine (1 mM), and glycylglycine (25 mM) were not inhibitory. Predigestion of acid mucopolysaccharides by heparinase I, heparitinase, and chondroitinase ABC also decreased the internalization. The maximal internalization, the half-saturation constant, and the nonsaturable internalization of125I-001-C8 were 1.13 ± 0.23 pmol/mg protein, 0.47 ± 0.43 μM, and 3.13 ± 0.19 μl/mg protein, respectively. Confocal microscopy also indicated the internalization of fluorescence-derived 001-C8 [001-C8–4-nitrobenz-2-oxa-1,3-diazole (001-C8-NBD)]. Granular staining seen within the cell, excluding nuclei, indicated the sequestration of 001-C8-NBD within endocytotic vesicles. Dansylcadaverine and protamine strongly decreased the granular distribution of 001-C8-NBD within the cell. These results demonstrate that 001-C8 is taken up by Caco-2 cells via adsorptive-mediated endocytosis.
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7

Telfer, William H., and Muh-Liang Pan. "Adsorptive endocytosis of vitellogenin, lipophorin, and microvitellogenin during yolk formation inHyalophora." Archives of Insect Biochemistry and Physiology 9, no. 4 (1988): 339–55. http://dx.doi.org/10.1002/arch.940090408.

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8

Lalli, M. F., V. Lacroix, L. Hermo, Y. Clermont, and C. E. Smith. "Localization of various phosphatase activities within the golgi apparatus and lysosomes of rat leydig cells." Proceedings, annual meeting, Electron Microscopy Society of America 44 (August 1986): 294–95. http://dx.doi.org/10.1017/s0424820100143092.

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The testosterone-secreting Leydig cells contain an abundance of smooth endoplasmic reticulum, peroxisomes, mitochondria as well as a large, spheroidal, juxtanuclear Golgi apparatus composed of interconnected stacks of saccules (Figs. 1,2). Each Golgi stack appears to be composed of between 5 to 7 saccules or sacculo-tubular elements (Figs.1,2). These cells also possess pale and dense multivesicular bodies and dense membrane-bound bodies identified assecondary lysosomes, all of which have been shown to be involved in fluid phase and adsorptive endocytosis as well as in receptor mediated endocytosis. The purpose of the present study was to characterize the reactivity of Golgi saccules, multivesicular bodies and lysosomes of Leydig cells for different phosphatases.
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9

Banks, William A., Abba J. Kastin, and Victoria Akerstrom. "HIV-1 protein gp120 crosses the blood-brain barrier: Role of adsorptive endocytosis." Life Sciences 61, no. 9 (1997): PL119—PL125. http://dx.doi.org/10.1016/s0024-3205(97)00597-3.

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10

Drin, Guillaume, Christophe Rousselle, Jean-Michel Scherrmann, Anthony R. Rees, and Jamal Temsamani. "Peptide delivery to the brain via adsorptive-mediated endocytosis: Advances with SynB vectors." AAPS PharmSci 4, no. 4 (2002): 61–67. http://dx.doi.org/10.1208/ps040426.

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11

Banks, William A., Abba J. Kastin, J. Matthew Brennan, and Kelly L. Vallance. "Adsorptive Endocytosis of HIV-1gp120 by Blood–Brain Barrier Is Enhanced by Lipopolysaccharide." Experimental Neurology 156, no. 1 (1999): 165–71. http://dx.doi.org/10.1006/exnr.1998.7011.

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12

Segretain, Dominique, Monique Egloff, Nadine G�rard, Charles Pineau, and Bernard J�gou. "Receptor-mediated and adsorptive endocytosis by male germ cells of different mammalian species." Cell & Tissue Research 268, no. 3 (1992): 471–78. http://dx.doi.org/10.1007/bf00319154.

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13

Hermo, L., Y. Clermont, and C. Morales. "Fluid-phase and adsorptive endocytosis in ciliated epithelial cells of the rat ductuli efferentes." Anatomical Record 211, no. 3 (1985): 285–94. http://dx.doi.org/10.1002/ar.1092110309.

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14

Bradbury, N. A., T. Jilling, K. L. Kirk, and R. J. Bridges. "Regulated endocytosis in a chloride secretory epithelial cell line." American Journal of Physiology-Cell Physiology 262, no. 3 (1992): C752—C759. http://dx.doi.org/10.1152/ajpcell.1992.262.3.c752.

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The colonic epithelial cell line T84 has been shown to be a good model to investigate the regulation of Cl- secretion by the adenosine 3',5'-cyclic monophosphate (cAMP)-mediated second messenger cascade. Regulated exocytic insertion and endocytic retrieval of transport proteins, or proteins that regulate transport proteins, is one mechanism proposed to regulate plasma membrane solute permeabilities. The aims of our studies were to characterize endocytic processes in T84 cells and to investigate their regulation by known activators of Cl- secretion that are mediated by the cAMP second messenger cascade. Forskolin, an activator of adenylate cyclase, caused a marked inhibition of endocytic uptake of the fluid-phase marker horseradish peroxidase (HRP) and the adsorptive marker wheat germ agglutinin conjugated to HRP. Similar inhibition was obtained with vasoactive intestinal peptide, a secretagogue whose receptor is coupled to adenylate cyclase, and 8-(4-chlorophenylthio)adenosine 3',5'-cyclic monophosphate, a membrane-permeable cAMP analogue. 1,9-Dideoxy-forskolin, a forskolin analogue that fails to activate adenylate cyclase, was without effect on endocytosis. Our data show that the net rate of endocytosis, as measured by fluid-phase uptake, is decreased by a cAMP-mediated mechanism. Because the number of Cl- channels or associated regulatory proteins in the plasma membrane reflects a balance between their exocytic insertion and endocytic retrieval, we propose that the cAMP-mediated decrease in endocytosis could contribute to the concomitant increase in plasma membrane Cl- permeability.
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15

Banks, William A., Eric O. Freed, Kathleen M. Wolf, Sandra M. Robinson, Mark Franko, and Vijaya B. Kumar. "Transport of Human Immunodeficiency Virus Type 1 Pseudoviruses across the Blood-Brain Barrier: Role of Envelope Proteins and Adsorptive Endocytosis." Journal of Virology 75, no. 10 (2001): 4681–91. http://dx.doi.org/10.1128/jvi.75.10.4681-4691.2001.

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ABSTRACT Blood-borne human immunodeficiency virus type 1 (HIV-1) crosses the blood-brain barrier (BBB) to induce brain dysfunction. How HIV-1 crosses the BBB is unclear. Most work has focused on the ability of infected immune cells to cross the BBB, with less attention devoted to the study of free virus. Since the HIV-1 coat glycoprotein gp120 can cross the BBB, we postulated that gp120 might be key in determining whether free virus can cross the BBB. We used radioactive virions which do (Env+) or do not (Env−) bear the envelope proteins to characterize the ability of HIV-1 to be taken up by the murine BBB. In vivo and in vitro studies showed that the envelope proteins are key to the uptake of free virus and that uptake was enhanced by wheat germ agglutinin, strongly suggesting that the envelope proteins induce viral adsorptive endocytosis and transcytosis in brain endothelia. Capillary depletion showed that Env+virus completely crossed the vascular BBB to enter the parenchyma of the brain. Virus also entered the cerebrospinal fluid, suggesting passage across the choroid plexus as well. About 0.22% of the intravenously injected dose was taken up per g of brain. In vitro studies showed that postinternalization membrane cohesion (membrane binding not reversed with acid wash or cell lysis) was a regulated event. Intact virus was recovered from the brain endothelial cytosol and was effluxed from the endothelial cells. These results show that free HIV-1 can cross the BBB by an event related to adsorptive endocytosis and mediated by the envelope proteins.
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16

Johannessen, Lene E., Bjørn Spilsberg, Christer R. Wiik-Nielsen, Anja B. Kristoffersen, Arne Holst-Jensen, and Knut G. Berdal. "DNA-Fragments Are Transcytosed across CaCo-2 Cells by Adsorptive Endocytosis and Vesicular Mediated Transport." PLoS ONE 8, no. 2 (2013): e56671. http://dx.doi.org/10.1371/journal.pone.0056671.

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17

Hacker, Jill K., and James L. Hardy. "Adsorptive Endocytosis of California Encephalitis Virus into Mosquito and Mammalian Cells: A Role for G1." Virology 235, no. 1 (1997): 40–47. http://dx.doi.org/10.1006/viro.1997.8675.

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18

Holmes, J. M., and E. H. Morgan. "Uptake and distribution of transferrin and iron in perfused, iron-deficient rat liver." American Journal of Physiology-Gastrointestinal and Liver Physiology 256, no. 6 (1989): G1022—G1027. http://dx.doi.org/10.1152/ajpgi.1989.256.6.g1022.

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Uptake of transferrin and iron by the rat liver was investigated by perfusion in vitro with 125I-59Fe-labeled rat transferrin and subcellular fractionation on sucrose density gradients. Most of the 125I-transferrin was located in a low-density vesicle fraction. The 59Fe was in three peaks, of lower, the same, and higher densities than the transferrin peak. Iron deficiency resulted in a large increase in transferrin and iron uptake into all subcellular fractions. When livers were perfused with increasing concentrations of transferrin the uptake into the different peaks of transferrin and iron increased in a curvilinear fashion, which indicated that uptake occurred by saturable and nonsaturable processes, both of which increased in iron deficiency. In contrast, the uptake of 131I-labeled rat serum albumin increased linearly with concentration, and there was no difference between control and iron-deficient livers. It is concluded that iron deficiency leads to an increase in the number of high-affinity transferrin receptors and receptor-mediated endocytosis of transferrin. It also increases a nonsaturable transferrin uptake process that is probably due to adsorptive, but selective, endocytosis of transferrin.
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19

Huang, Rongqin, Weilun Ke, Liang Han, et al. "Brain-Targeting Mechanisms of Lactoferrin-Modified DNA-Loaded Nanoparticles." Journal of Cerebral Blood Flow & Metabolism 29, no. 12 (2009): 1914–23. http://dx.doi.org/10.1038/jcbfm.2009.104.

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Ligand-mediated brain-targeting drug delivery is one of the focuses at present. Elucidation of exact targeting mechanisms serves to efficiently design these drug delivery systems. In our previous studies, lactoferrin (Lf) was successfully exploited as a brain-targeting ligand to modify cationic dendrimer-based nanoparticles (NPs). The mechanisms of Lf-modified NPs to the brain were systematically investigated in this study for the first time. The uptake of Lf-modified vectors and NPs by brain capillary endothelial cells (BCECs) was related to clathrin-dependent endocytosis, caveolae-mediated endocytosis, and macropinocytosis. The intracellular trafficking results showed that Lf-modified NPs could rapidly enter the acidic endolysosomal compartments within 5 mins and then partly escape within 30 mins. Both Lf-modified vectors and NPs showed higher blood–brain barrier-crossing efficiency than unmodified counterparts. All the results suggest that both receptor- and adsorptive-mediated mechanisms contribute to the cellular uptake of Lf-modified vectors and NPs. Enhanced brain-targeting delivery could be achieved through the synergistic effect of the macromolecular polymers and the ligand.
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20

Vassiliadis, S., and I. Athanassakis. "Adsorptive or by Pit Formation Endocytosis of Immunoglobulins without Loss of Function as Potential Biotherapeutical Application." Cancer Biotherapy and Radiopharmaceuticals 11, no. 4 (1996): 259–66. http://dx.doi.org/10.1089/cbr.1996.11.259.

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21

Sehested, Maxwell, Torben Skovsgaard, Bo van Deurs, and Henrik Winther-Nielsen. "Increase in Nonspecific Adsorptive Endocytosis in Anthracycline-and Vinca Alkaloid-Resistant Ehrlich Ascites Tumor Cell Lines2." JNCI: Journal of the National Cancer Institute 78, no. 1 (1987): 171–79. http://dx.doi.org/10.1093/jnci/78.1.171.

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22

Van Bambeke, Françoise, Stéphane Carryn, Cristina Seral, et al. "Cellular Pharmacokinetics and Pharmacodynamics of the Glycopeptide Antibiotic Oritavancin (LY333328) in a Model of J774 Mouse Macrophages." Antimicrobial Agents and Chemotherapy 48, no. 8 (2004): 2853–60. http://dx.doi.org/10.1128/aac.48.8.2853-2860.2004.

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ABSTRACT The intracellular pharmacokinetics and pharmacodynamics of oritavancin (LY333328) were studied in cultured cells. Oritavancin was avidly accumulated by J774 and THP-1 macrophages and rat fibroblasts and to a lesser extent by LLC-PK1 and Caco-2 cells. In J774 macrophages, the level of accumulation reached a plateau (at 370-fold the extracellular concentration) within 24 h and was partly defeated by a rise in serum protein levels. Efflux was incomplete (with a plateau at two-thirds of the original level at 6 h). In short-term kinetic studies, oritavancin uptake was linear for up to 4 h (as was the case for horseradish peroxidase and small latex beads, used as markers of the fluid phase and adsorptive endocytosis, respectively), which was in contrast to azithromycin and chloroquine uptake (which accumulate in cells by diffusion and segregation). The rates of clearance of oritavancin and latex beads were comparable (150 and 120 μl × mg of protein−1 × h−1, respectively) and were approximately 200 times higher than that of horseradish peroxidase. Oritavancin accumulation was partially reduced by monensin but was unaffected by acidic pH (these conditions abolished chloroquine accumulation). Cell-associated oritavancin was found in lysosomal fractions after homogenization of J774 macrophages and fractionation by isopycnic centrifugation. Oritavancin was bactericidal against intracellular Staphylococcus aureus (phagolysosomal infection) but was unable to control the intracellular growth of Listeria monocytogenes (cytosolic infection), even though its cellular concentration largely exceeded the MIC (0.02 mg/liter) and minimal bactericidal concentration (2 mg/liter). We conclude that oritavancin enters cells by adsorptive endocytosis (favored by its lipophilic side chain and/or the presence of three protonatable amines), which drives it to lysosomes, where it exerts antibiotic activity.
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23

Ruano-Salguero, John S., and Kelvin H. Lee. "Adsorptive-Mediated Endocytosis of Sulfo-Cy5-Labeled IgG Causes Aberrant IgG Processing by Brain Endothelial-Like Cells." Molecular Pharmaceutics 17, no. 11 (2020): 4280–85. http://dx.doi.org/10.1021/acs.molpharmaceut.0c00712.

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24

Tougard, C., D. Louvard, R. Picart, and A. Tixier-Vidal. "Antibodies against a lysosomal membrane antigen recognize a prelysosomal compartment involved in the endocytic pathway in cultured prolactin cells." Journal of Cell Biology 100, no. 3 (1985): 786–93. http://dx.doi.org/10.1083/jcb.100.3.786.

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Antibodies against a lysosomal membrane antigen (A-Ly-M) have recently been obtained and characterized (Reggio, H., D. Bainton, E. Harms, E. Coudrier, and D. Louvard, 1984, J. Cell Biol., 99:1511-1526). They recognize a 100,000-mol-wt antigen immunologically related to a purified [H+,K+]ATPase from pig gastric mucosa. In the present study, we have localized this antigen during adsorptive endocytosis in rat prolactin cells in culture using cationized ferritin (CF) as a tracer. CF was rapidly internalized (after 5 min) in coated pits and vesicles that were labeled by antibodies against clathrin. The tracer was then delivered (after 15 min) to vacuoles and multivesicular bodies. These structures were labeled with A-Ly-M. These organelles were devoid of acid phosphatase activity. At later stages (after 30 min) CF was observed within larger structures that were strongly stained by A-Ly-M and displayed a strong acid phosphatase activity. These findings clearly indicate that A-Ly-M react with prelysosomal and lysosomal compartments involved in the endocytic pathway in cultured prolactin cells. The membrane of these structures therefore contains antigenic determinant(s) related to the 100,000-mol-wt polypeptide. Our results suggest that the prelysosomal structure stained by A-Ly-M may represent in GH3 cells the acidic prelysosomal compartment recently described in the early steps of endocytosis in other cell types (Tycko, B., and F. R. Maxfield, 1982, Cell, 28:643-651).
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25

Volkman, Loy E., and Phyllis A. Goldsmith. "Mechanism of neutralization of budded Autographs californica nuclear polyhedrosis virus by a monoclonal antibody: Inhibition of entry by adsorptive endocytosis." Virology 143, no. 1 (1985): 185–95. http://dx.doi.org/10.1016/0042-6822(85)90107-2.

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26

B�guena-Cervellera, R., J. Renau-Piqueras, J. E. O'Connor, and S. Grisolia. "Effects of prolonged exposure to ammonia on fluid-phase, receptor-mediated, and adsorptive (non specific) endocytosis in cultured neuroblastoma cells." Histochemistry 87, no. 5 (1987): 445–55. http://dx.doi.org/10.1007/bf00496816.

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27

Croix, D. A., J. M. Ahearn, A. M. Rosengard, et al. "Antibody response to a T-dependent antigen requires B cell expression of complement receptors." Journal of Experimental Medicine 183, no. 4 (1996): 1857–64. http://dx.doi.org/10.1084/jem.183.4.1857.

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Several lines of evidence indicate that antibody responses to T-dependent antigens require complement receptors expressed on either B lymphocytes or follicular dendritic cells. We have used RAG-2 deficient blastocyst complementation to create mice specifically lacking B cell complement receptors. Despite normal expression of complement receptor 1 (CR1[CD35]) and CR2 (CD21) on follicular dendritic cells, these mice have a profound defect in their capacity to mount a T-dependent antibody response. This is the first direct demonstration in vivo that B cell expression of complement receptors is required for a humoral immune response. This is the first direct demonstration in vivo that B cell expression of complement receptors is required for a humoral immune response. This suggests that CD21 and/or CD35 on B lymphocytes may be required for cellular activation, adsorptive endocytosis of antigen, recruitment to germinal centers, and/or protection from apoptosis during the humoral response to T-dependent antigens.
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28

González-Noriega, Alfonso, Rocio Coutiño, Victor M. Saavedra, and Raul Barrera. "Adsorptive endocytosis of lysosomal enzymes by human fibroblasts: Presence of two different functional systems that deliver an acid hydrolase to lysosomes." Archives of Biochemistry and Biophysics 268, no. 2 (1989): 649–58. http://dx.doi.org/10.1016/0003-9861(89)90333-0.

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29

Hall, Christina, and Jan-Olof Karlsson. "Identification of the principal receptor responsible for adsorptive endocytosis of a fucose-specific lectin from Aleuria aurantia in the rabbit retina." Neuroscience Letters 58, no. 1 (1985): 79–82. http://dx.doi.org/10.1016/0304-3940(85)90332-5.

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30

Shazali, Nur, Noorzaileen Zaidi, Hidayah Ariffin, et al. "Characterization and Cellular Internalization of Spherical Cellulose Nanocrystals (CNC) into Normal and Cancerous Fibroblasts." Materials 12, no. 19 (2019): 3251. http://dx.doi.org/10.3390/ma12193251.

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The aim was to isolate cellulose nanocrystals (CNC) from commercialized oil palm empty fruit bunch cellulose nanofibre (CNF) through sulphuric acid hydrolysis and explore its safeness as a potential nanocarrier. Successful extraction of CNC was confirmed through a field emission scanning electron microscope (FESEM) and attenuated total reflection Fourier transmission infrared (ATR-FTIR) spectrometry analysis. For subsequent cellular uptake study, the spherical CNC was covalently tagged with fluorescein isothiocyanate (FITC), resulting in negative charged FITC-CNC nanospheres with a dispersity (Ð) of 0.371. MTT assay revealed low degree cytotoxicity for both CNC and FITC-CNC against C6 rat glioma and NIH3T3 normal fibroblasts up to 50 µg/mL. FITC conjugation had no contribution to the particle’s toxicity. Through confocal laser scanning microscope (CLSM), synthesized FITC-CNC manifested negligible cellular accumulation, indicating a poor non-selective adsorptive endocytosis into studied cells. Overall, an untargeted CNC-based nanosphere with less cytotoxicity that posed poor selectivity against normal and cancerous cells was successfully synthesized. It can be considered safe and suitable to be developed into targeted nanocarrier.
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31

Gottlieb, T. A., I. E. Ivanov, M. Adesnik, and D. D. Sabatini. "Actin microfilaments play a critical role in endocytosis at the apical but not the basolateral surface of polarized epithelial cells." Journal of Cell Biology 120, no. 3 (1993): 695–710. http://dx.doi.org/10.1083/jcb.120.3.695.

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Treatment with cytochalasin D, a drug that acts by inducing the depolymerization of the actin cytoskeleton, selectively blocked endocytosis of membrane bound and fluid phase markers from the apical surface of polarized MDCK cells without affecting the uptake from the basolateral surface. Thus, in MDCK cell transformants that express the VSV G protein, cytochalasin blocked the internalization of an anti-G mAb bound to apical G molecules, but did not reduce the uptake of antibody bound to the basolateral surface. The selective effect of cytochalasin D on apical endocytosis was also demonstrated by the failure of the drug to reduce the uptake of 125I-labeled transferrin, which occurs by receptor-mediated endocytosis, via clathrin-coated pits, almost exclusively from the basolateral surface. The actin cytoskeleton appears to play a critical role in adsorptive as well as fluid phase apical endocytic events, since treatment with cytochalasin D prevented the apical uptake of cationized ferritin, that occurs after the marker binds to the cell surface, as well as uptake of Lucifer yellow, a fluorescent soluble dye. Moreover, the drug efficiently blocked infection of the cells with influenza virus, when the viral inoculum was applied to the apical surface. On the other hand, it did not inhibit the basolateral uptake of Lucifer yellow, nor did it prevent infection with VSV from the basolateral surface, or with influenza when this virus was applied to monolayers in which the formation of tight junctions had been prevented by depletion of calcium ions. EM demonstrated that cytochalasin D leads to an increase in the number of coated pits in the apical surface where it suppresses the pinching off of coated vesicles. In addition, in drug-treated cells cationized ferritin molecules that were bound to microvilli were not cleared from the microvillar surface, as is observed in untreated cells. These findings indicate that there is a fundamental difference in the process by which endocytic vesicles are formed at the two surfaces of polarized epithelial cells and that the integrity and/or the polymerization of actin filaments are required at the apical surface. Actin filaments in microvilli may be part of a mechanochemical motor that moves membrane components along the microvillar surface towards intermicrovillar spaces, or provides the force required for converting a membrane invagination or pit into an endocytic vesicle within the cytoplasm.
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32

Predescu, Sanda A., Dan N. Predescu, and Asrar B. Malik. "Molecular determinants of endothelial transcytosis and their role in endothelial permeability." American Journal of Physiology-Lung Cellular and Molecular Physiology 293, no. 4 (2007): L823—L842. http://dx.doi.org/10.1152/ajplung.00436.2006.

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Caveolae transcytosis with its diverse mechanisms–fluid phase, adsorptive, and receptor-mediated–plays an important role in the continuous exchange of molecules across the endothelium. We will discuss key features of endothelial transcytosis and caveolae that have been studied recently and have increased our understanding of caveolae function in transcytosis at the molecular level. During transcytosis, caveolae “pinch off” from the plasma membrane to form discrete vesicular carriers that shuttle to the opposite front of endothelial cells, fuse with the plasma membrane, and discharge their cargo into the perivascular space. Endothelial transcytosis exhibits distinct properties, the most important being rapid and efficient coupling of endocytosis to exocytosis on opposite plasma membrane. We address herein the membrane fusion-fission reactions that underlie transcytosis. Caveolae move across the endothelial cells with their cargo predominantly in the fluid phase through an active process that bypasses the lysosomes. Endothelial transcytosis is a constitutive process of vesicular transport. Recent studies show that transcytosis can be upregulated in response to pathological stimuli. Transcytosis via caveolae is an important route for the regulation of endothelial barrier function and may participate in different vascular diseases.
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33

Kang, Byoung K., and Eugene Spaziani. "Uptake of high-density lipoprotein by Y-organs of the crabCancer antennarius: III. Evidence for adsorptive endocytosis and the absence of lysosomal processing." Journal of Experimental Zoology 273, no. 5 (1995): 425–33. http://dx.doi.org/10.1002/jez.1402730506.

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34

Rybak, ME, MA Jr Gimbrone, PF Davies, and RI Handin. "Interaction of platelet factor four with cultured vascular endothelial cells." Blood 73, no. 6 (1989): 1534–39. http://dx.doi.org/10.1182/blood.v73.6.1534.1534.

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Abstract Platelets secrete a low-molecular-weight protein, platelet factor four (PF-4), which binds to and neutralizes heparin and related sulfated glycosaminoglycans (GAGs). To examine the interactions of PF-4 with the GAGs present on endothelial cell surfaces, we incubated 125I-PF-4 with cell suspensions derived from confluent monolayers of cultured bovine aortic endothelium. Binding of 125I-PF-4 was inhibited by a 100-fold excess of nonradioactive PF-4 and varied with duration and temperature of incubation. At 4 degrees C, binding reached equilibrium at 20 minutes with kd = 2.87 mumol/L and Bmax of 63.83 pmol/10(5) cells. Binding capacity was reduced 83.4% by brief incubation of endothelial cells with trypsin and 46.67% by incubation with Flavobacterium heparinase, but was unchanged by chondroitin-ABCase treatment. At 37 degrees C, PF-4 was internalized by confluent monolayer of bovine aortic endothelial cells primarily through low-affinity adsorptive endocytosis. The internalized PF-4 was degraded to amino acids and small peptides with 50% conversion after 18-hour incubation. These studies demonstrate that a secreted platelet protein can bind to and enter endothelial cells. Binding may explain the rapid clearance of released PF-4 from plasma and could have important local effects on endothelial structure and function.
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35

Rybak, ME, MA Jr Gimbrone, PF Davies, and RI Handin. "Interaction of platelet factor four with cultured vascular endothelial cells." Blood 73, no. 6 (1989): 1534–39. http://dx.doi.org/10.1182/blood.v73.6.1534.bloodjournal7361534.

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Platelets secrete a low-molecular-weight protein, platelet factor four (PF-4), which binds to and neutralizes heparin and related sulfated glycosaminoglycans (GAGs). To examine the interactions of PF-4 with the GAGs present on endothelial cell surfaces, we incubated 125I-PF-4 with cell suspensions derived from confluent monolayers of cultured bovine aortic endothelium. Binding of 125I-PF-4 was inhibited by a 100-fold excess of nonradioactive PF-4 and varied with duration and temperature of incubation. At 4 degrees C, binding reached equilibrium at 20 minutes with kd = 2.87 mumol/L and Bmax of 63.83 pmol/10(5) cells. Binding capacity was reduced 83.4% by brief incubation of endothelial cells with trypsin and 46.67% by incubation with Flavobacterium heparinase, but was unchanged by chondroitin-ABCase treatment. At 37 degrees C, PF-4 was internalized by confluent monolayer of bovine aortic endothelial cells primarily through low-affinity adsorptive endocytosis. The internalized PF-4 was degraded to amino acids and small peptides with 50% conversion after 18-hour incubation. These studies demonstrate that a secreted platelet protein can bind to and enter endothelial cells. Binding may explain the rapid clearance of released PF-4 from plasma and could have important local effects on endothelial structure and function.
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36

Robinson, J. M., J. A. Badwey, M. L. Karnovsky, and M. J. Karnovsky. "Cell surface dynamics of neutrophils stimulated with phorbol esters or retinoids." Journal of Cell Biology 105, no. 1 (1987): 417–26. http://dx.doi.org/10.1083/jcb.105.1.417.

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Neutrophils undergo rapid morphological changes as well as metabolic perturbations when stimulated with certain phorbol esters. Stimulated cells initially exhibit pronounced projections emanating from the cell bodies, followed by rounding of the cells, reduction in granule number, and the appearance of intracellular vesicles. We show these vesicles to be derived, at least in part, from the plasmalemma. The experimental approach involved labeling stimulated and unstimulated cells with native ferritin and cationized ferritin, along with the cytochemical localization of ecto-5'-nucleotidase. The labeling patterns of the vesicles indicate that these structures are involved in both phorbol ester-stimulated adsorptive and fluid-phase endocytosis. Neutrophils stimulated with 12-O-tetradecanoyl-phorbol-13-acetate (TPA) exhibit two distinct rates of superoxide release in which the second, prolonged level is approximately 50% of the initial rate. All-trans-retinal, which we have recently shown to stimulate O2- release but not granule exocytosis or cell vesiculation, induces a single prolonged rate of maximal O2- release. Neutrophils treated with both all-trans-retinal and TPA exhibit only a single sustained rate of maximal O2- release similar to that observed with all-trans-retinal alone. Moreover, treatment of cells with all-trans-retinal blocks the vesiculation of neutrophils induced by TPA in a dose-dependent manner. This observation provides a possible explanation for the differences in the kinetics of superoxide release.
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37

Pan, Weihong, Yongmei Yu, Courtney M. Cain, Fred Nyberg, Pierre O. Couraud, and Abba J. Kastin. "Permeation of Growth Hormone across the Blood-Brain Barrier." Endocrinology 146, no. 11 (2005): 4898–904. http://dx.doi.org/10.1210/en.2005-0587.

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Exogenous GH can affect central nervous system function when given peripherally to animals and as a supplemental therapy to humans. This study tested whether GH crosses the blood-brain barrier (BBB) by a specific transport system and found that both mice and rats have small but significant uptake of GH into the brain without a species difference. Determined by multiple-time regression analysis, the blood-to-brain influx transfer constants of 125I-labeled rat GH in mice (0.23 ± 0.07 μl/g·min) and rats (0.32 ± 0.04 μl/g·min) were comparable to those of some cytokines of similar size, with a half-time disappearance of 125I-GH of 3.8–7.6 min in blood. Intact 125I-GH was present in both serum and brain homogenate 20 min after iv injection. At this time, about 26.8% of GH in brain entered the parenchyma, whereas 10% was entrapped in endothelial cells. Neither excess GH nor insulin showed acute modulation of the influx, indicating lack of a saturable transport system for GH at the BBB. Binding and cellular uptake studies in cultured cerebral microvessel endothelial cells (RBE4) further ruled out the presence of high-capacity adsorptive endocytosis. The brain influx of GH by simple diffusion adds definitive value to the long-disputed question of whether and how GH crosses the BBB. The central nervous system effects of peripheral GH can be attributed to permeation of the BBB despite the absence of a specific transport system.
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38

Lui, Eric Chi-Chung, and Reina Bendayan. "Gentamicin uptake by LLCPK1 cells: effect of intracellular and extracellular pH changes." Canadian Journal of Physiology and Pharmacology 76, no. 2 (1998): 155–60. http://dx.doi.org/10.1139/y98-008.

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The mechanisms by which aminoglycosides are transported across the luminal membrane of renal proximal tubular cells remain unclear. A luminal organic cation/H+ exchange as well as an adsorptive endocytosis membrane process has been proposed to be involved in gentamicin renal accumulation. The objectives of this work were to explore further the effects of intracellular and extracellular pH changes on gentamicin uptake. [3H]Gentamicin uptake by a continuous renal epithelial cell line, LLCPK1, grown as a monolayer on an impermeable surface was measured at different temperatures and pH conditions and in the presence of various inhibitors. Uptake of gentamicin was found to be carrier mediated (Km = 1.26 ± 0.22 mM, Vmax = 289 ± 27 pmol ·mg-1 ·min-1), energy dependent (inhibited in part by sodium azide), and temperature dependent (37°C > 4°C). Fifteen-minute gentamicin (10 µM) uptake was inhibited by 1 mM of the organic cations cimetidine (61.0%), quinidine (73.5%), quinine (68.6%), and verapamil (61.5%). More importantly, while an outwardly directed proton gradient did not have a significant effect on gentamicin uptake, extracellular acidification (pH 6.5), which leads to a higher degree of gentamicin ionization, significantly enhanced gentamicin uptake by LLCPK1 monolayer cells. These results suggest that the luminal organic cation/H+ exchanger is not involved in gentamicin uptake by renal cultured epithelial cells. Rather, the cationic charge of gentamicin appears to be one of the primary determinants for renal luminal uptake.Key words: gentamicin, LLCPK1 cells, pH, nephrotoxicity.
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39

Balin, B. J., and R. D. Broadwell. "Lectin-labeled membrane is transferred to the Golgi complex in mouse pituitary cells in vivo." Journal of Histochemistry & Cytochemistry 35, no. 4 (1987): 489–98. http://dx.doi.org/10.1177/35.4.2434560.

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Labeling of the Golgi complex with the lectin conjugate wheat germ agglutinin-horseradish peroxidase (WGA-HRP), which binds to cell surface membrane and enters cells by adsorptive endocytosis, was analyzed in secretory cells of the anterior, intermediate, and posterior lobes of mouse pituitary gland in vivo. WGA-HRP was administered intravenously or by ventriculo-cisternal perfusion to control and salt-stressed mice; post-injection survival times were 30 min-24 hr. Peroxidase reaction product was identified within the extracellular clefts of anterior and posterior pituitary lobes through 24 hr but was absent in intermediate lobe. Endocytic vesicles, spherical endosomes, tubules, dense and multivesicular bodies, the trans-most saccule of the Golgi complex, and dense-core secretory granules attached or unattached to the trans Golgi saccule were peroxidase-positive in the different types of anterior pituitary cells and in perikarya of supraoptico-neurohypophyseal neurons; endoplasmic reticulum and the cis and intermediate Golgi saccules in the same cell types were consistently devoid of peroxidase reaction product. Dense-core secretory granules derived from cis and intermediate Golgi saccules in salt-stressed supraoptic perikarya likewise failed to exhibit peroxidase reaction product. The results suggest that in secretory cells of anterior and posterior pituitary lobes, WGA-HRP, initially internalized with cell surface membrane, is eventually conveyed to the trans-most Golgi saccule, in which the lectin conjugate and associated membrane are packaged in dense-core secretory granules for export and potential exocytosis of the tracer. Endoplasmic reticulum and the cis and intermediate Golgi saccules appear not to be involved in the endocytic/exocytic pathways of pituitary cells exposed to WGA-HRP.
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40

Hansen, G. H., B. Delmas, L. Besnardeau, et al. "The Coronavirus Transmissible Gastroenteritis Virus Causes Infection after Receptor-Mediated Endocytosis and Acid-Dependent Fusion with an Intracellular Compartment." Journal of Virology 72, no. 1 (1998): 527–34. http://dx.doi.org/10.1128/jvi.72.1.527-534.1998.

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ABSTRACT Aminopeptidase N is a species-specific receptor for transmissible gastroenteritis virus (TGEV), which infects piglets, and for the 229E virus, which infects humans. It is not known whether these coronaviruses are endocytosed before fusion with a membrane of the target cell, causing a productive infection, or whether they fuse directly with the plasma membrane. We have studied the interaction between TGEV and a cell line (MDCK) stably expressing recombinant pig aminopeptidase N (pAPN). By electron microscopy and flow cytometry, TGEV was found to be associated with the plasma membrane after adsorption to the pAPN-MDCK cells. TGEV was also observed in endocytic pits and apical vesicles after 3 to 10 min of incubation at 38°C. The number of pits and apical vesicles was increased by the TGEV incubation, indicating an increase in endocytosis. After 10 min of incubation, a distinct TGEV-pAPN-containing population of large intracellular vesicles, morphologically compatible with endosomes, was found. A higher density of pAPN receptors was observed in the pits beneath the virus particles than in the surrounding plasma membrane, indicating that TGEV recruits pAPN receptors before endocytosis. Ammonium chloride and bafilomycin A1 markedly inhibited the TGEV infection as judged from virus production and protein biosynthesis analyses but did so only when added early in the course of the infection, i.e., about 1 h after the start of endocytosis. Together our results point to an acid intracellular compartment as the site of fusion for TGEV.
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41

Johnson, Tory A., and Suzanne R. Pfeffer. "Ezetimibe-sensitive cholesterol uptake by NPC1L1 protein does not require endocytosis." Molecular Biology of the Cell 27, no. 11 (2016): 1845–52. http://dx.doi.org/10.1091/mbc.e16-03-0154.

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Human NPC1L1 protein mediates cholesterol absorption in the intestine and liver and is the target of the drug ezetimibe, which is used to treat hypercholesterolemia. Previous studies concluded that NPC1L1-GFP protein trafficking is regulated by cholesterol binding and that ezetimibe blocks NPC1L1-GFP function by inhibiting its endocytosis. We used cell surface biotinylation to monitor NPC1L1-GFP endocytosis and show that ezetimibe does not alter the rate of NPC1L1-GFP endocytosis in cultured rat hepatocytes grown under normal growth conditions. As expected, NPC1L1-GFP endocytosis depends in part on C-terminal, cytoplasmically oriented sequences, but endocytosis does not require cholesterol binding to NPC1L1’s N-terminal domain. In addition, two small- molecule inhibitors of general (and NPC1L1-GFP) endocytosis failed to inhibit the ezetimibe-sensitive uptake of [3H]cholesterol from taurocholate micelles. These experiments demonstrate that cholesterol uptake by NPC1L1 does not require endocytosis; moreover, ezetimibe interferes with NPC1L1’s cholesterol adsorption activity without blocking NPC1L1 internalization in RH7777 cells.
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42

Schmid, S. L., and L. L. Carter. "ATP is required for receptor-mediated endocytosis in intact cells." Journal of Cell Biology 111, no. 6 (1990): 2307–18. http://dx.doi.org/10.1083/jcb.111.6.2307.

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We have demonstrated a requirement for cellular ATP in the receptor-mediated endocytosis of transferrin. This has been accomplished using a novel assay for endocytosis based on acquisition of resistance to the membrane impermeable reducing agent, glutathione (GSH). Diferric-transferrin was conjugated to biotin via a cleavable disulfide bond and iodinated. Internalization of 125I-biotin-S-S-transferrin (125I-BSST) was quantitated by adsorption to avidin-Sepharose after treatment of cells with GSH. Receptor-mediated endocytosis of 125I-BSST was severely inhibited in ATP-depleted cells. Similar results were obtained when ATP was depleted by incubation of cells either under a N2-atmosphere or in the presence of NaN3 and NaF. The latter treatment, alone, also resulted in a loss of surface transferrin receptors which could not be correlated to reductions in cellular ATP. In contrast to the acquisition of GSH resistance, the apparent internalization of 125I-BSST as assessed by inaccessibility to antitransferrin antibodies reached control levels in ATP-depleted cells. Our biochemical and morphological data suggested that, although ATP is required for receptor-mediated endocytosis, in ATP-depleted cells ligands can become efficiently sequestered into deeply invaginated pits that are inaccessible to large probes such as antibodies, but remain accessible to small molecules such as GSH.
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43

Han, Xing, Sidi Li, Xueping Li, et al. "The effect of zwitterionic surface content on blood circulation time of nanocapsule." Journal of Biomaterials Applications 35, no. 3 (2020): 371–84. http://dx.doi.org/10.1177/0885328220935381.

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Zwitterionic modification can prolong the blood circulation time of nanocarrier in vivo, but zwitterionic content will affect the functions of nanocarrier such as enzyme-responsive and intracellular or extracellular delivery. Therefore, it is necessary to explore the relationship between the zwitterionic content and circulation time of nanocarrier so as to figure out what content of zwitterion can enable the nanocarrier to obtain both the long blood circulation ability and other functions mentioned above. Herein, using nanocapsule as a research model, we investigated the nanocapsule modified with zwitterion of phosphorylcholine (PC) or carboxybetaine (CB) respectively, and through 1H-NMR quantification we determined the zwitterionic surface content, so as to study the effect of PC or CB surface content on blood circulation performance of nanocapsule. In vivo study showed that the nanocapsule possessed an optimal surface filling ratios range for blood circulation of 43–68% for PC and of 20–68% for CB, with the longest t1/2=37.35 h for PC-nanocapsule and t1/2=45.27 h for CB-nanocapsule. Furthermore, the protein adsorption and macrophage endocytosis experiments indicated that when the surface filling ratio reached 43% for PC-nanocapsule and 20% for CB-nanocapsule, it could effectively reduce the protein adsorption and weaken macrophage endocytosis, thus explaining the phenomenon of long circulation time of nanocapsules from the point of protein adsorption and interaction with immune cells. This study proposes a new direction for designing long-circulating nanocarrier, and provides basis for constructing enzyme-responsive and intracellular or extracellular delivery platform.
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44

Cantín, Celia, Javier Holguera, Laura Ferreira, Enrique Villar, and Isabel Muñoz-Barroso. "Newcastle disease virus may enter cells by caveolae-mediated endocytosis." Journal of General Virology 88, no. 2 (2007): 559–69. http://dx.doi.org/10.1099/vir.0.82150-0.

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The entry into cells of Newcastle disease virus (NDV), a prototype member of the paramyxoviruses, is believed to occur by direct fusion at the plasma membrane through a pH-independent mechanism. In addition, NDV may enter host cells by an endocytic pathway. Treatment of cells with drugs that block caveolae-dependent endocytosis reduced NDV fusion and infectivity, the degree of inhibition being dependent on virus concentration. The inhibitory effect was reduced greatly when drugs were added after virus adsorption. Cells treated with methyl β-cyclodextrin, a drug that sequesters cholesterol from membranes, reduced the extent of fusion, infectivity and virus–cell binding; this indicates that cholesterol plays a role in NDV entry. Double-labelling immunofluorescence assays performed with anti-NDV monoclonal antibodies and antibodies against the early endosome marker EEA1 revealed the localization of the virus in these intracellular structures. Using fluorescence microscopy, it was found that cell–cell fusion was enhanced at low pH. It is concluded that NDV may infect cells through a caveolae-dependent endocytic pathway, suggesting that this pathway could be an alternative route for virus entry into cells.
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45

Maginnis, Melissa S., Bernardo A. Mainou, Aaron Derdowski, Elizabeth M. Johnson, Roy Zent та Terence S. Dermody. "NPXY Motifs in the β1 Integrin Cytoplasmic Tail Are Required for Functional Reovirus Entry". Journal of Virology 82, № 7 (2008): 3181–91. http://dx.doi.org/10.1128/jvi.01612-07.

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ABSTRACT Reovirus cell entry is mediated by attachment to cell surface carbohydrate and junctional adhesion molecule A (JAM-A) and internalization by β1 integrin. The β1 integrin cytoplasmic tail contains two NPXY motifs, which function in recruitment of adaptor proteins and clathrin for endocytosis and serve as sorting signals for internalized cargo. As reovirus infection requires disassembly in the endocytic compartment, we investigated the role of the β1 integrin NPXY motifs in reovirus internalization. In comparison to wild-type cells (β1+/+ cells), reovirus infectivity was significantly reduced in cells expressing mutant β1 integrin in which the NPXY motifs were altered to NPXF (β1+/+Y783F/Y795F cells). However, reovirus displayed equivalent binding and internalization levels following adsorption to β1+/+ cells and β1+/+Y783F/Y795F cells, suggesting that the NPXY motifs are essential for transport of reovirus within the endocytic pathway. Reovirus entry into β1+/+ cells was blocked by chlorpromazine, an inhibitor of clathrin-mediated endocytosis, while entry into β1+/+Y783F/Y795F cells was unaffected. Furthermore, virus was distributed to morphologically distinct endocytic organelles in β1+/+ and β1+/+Y783F/Y795F cells, providing further evidence that the β1 integrin NPXY motifs mediate sorting of reovirus in the endocytic pathway. Thus, NPXY motifs in the β1 integrin cytoplasmic tail are required for functional reovirus entry, which indicates a key role for these sequences in endocytosis of a pathogenic virus.
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46

Ukkonen, P., V. Lewis, M. Marsh, A. Helenius, and I. Mellman. "Transport of macrophage Fc receptors and Fc receptor-bound ligands to lysosomes." Journal of Experimental Medicine 163, no. 4 (1986): 952–71. http://dx.doi.org/10.1084/jem.163.4.952.

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Mouse macrophage Fc receptors specific for IgG1/IgG2b mediate the binding and pinocytic uptake of soluble IgG-containing antibody-antigen complexes. Internalization of these multivalent IgG complexes is accompanied not only by the intracellular degradation of the ligand, but also by a net decrease in the number of plasma membrane Fc receptors and an accelerated rate of receptor turnover. In contrast, internalized receptors bound to a monovalent ligand, the high affinity Fab fragment of the antireceptor mAb 2.4G2, escape degradation by rapidly recycling to the cell surface. In this paper, we have characterized the intracellular pathway involved in the endocytosis and transport of Fc receptors in the J774 macrophage cell line. The results show that the uptake of multivalent ligands follows the normal pathway of receptor-mediated endocytosis: internalization in clathrin-coated pits and coated vesicles, delivery to endosomes, and finally to acid hydrolase-rich lysosomes. Immunoprecipitation of radiolabeled receptor from Percoll density gradients showed that endocytosis of the IgG complexes also results in the concomitant transport of the receptor to lysosomes. Although uptake of the monovalent Fab fragment had no detectable effect on intracellular receptor distribution, preparations of 2.4G2 Fab rendered multivalent by adsorption to colloidal gold were as effective as the IgG complexes at causing lysosomal accumulation of internalized receptors. Thus, it is likely that the down-regulation and degradation of Fc receptors which occurs during the endocytosis of antibody-antigen complexes is due to the transport of internalized receptors to lysosomes. Moreover, the ability of certain Fc receptor-bound ligands to interfere with receptor recycling and trigger lysosomal transport seems to depend on ligand valency rather than on the presence or absence of Fc domains on intact IgG molecules.
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47

Wang, Yifan, Liang He, Bing Yu, Yang Chen, Youqing Shen, and Hailin Cong. "ZnO Quantum Dots Modified by pH-Activated Charge-Reversal Polymer for Tumor Targeted Drug Delivery." Polymers 10, no. 11 (2018): 1272. http://dx.doi.org/10.3390/polym10111272.

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In this paper, we reported a pH responsive nano drug delivery system (NDDS) based on ZnO quantum dots (QDs) for controlled release of drugs. Zwitterionic poly(carboxybetaine methacrylate) (PCBMA) and poly(2-(dimethylamino) ethyl methacrylate) (PDMAEMA) were introduced to modify ZnO QDs, which can help enhance water stability, increase blood circulation time, and promote endocytosis. After tuning of PCBMA/PDMAEMA ratios, the ZnO@P(CBMA-co-DMAEMA) nanoplatform shows a sensitive switch from strong protein adsorption resistance (with negatively charged surface) at physiological pH to strong adhesion to tumor cell membranes (with positively charged surface) at the slightly acidic extracellular pH of tumors. Anti-cancer drug, Doxorubicin (DOX), molecules were demonstrated to be successfully loaded to ZnO@P(CBMA-co-DMAEMA) with a relatively large drug loading content (24.6%). In addition, ZnO@P(CBMA-co-DMAEMA) loaded with DOX can achieve lysosomal acid degradation and release of DOX after endocytosis by tumor cells, resulting in synergistic treatment of cancer, which is attributed to a combination of the anticancer effect of Zn2+ and DOX.
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48

Tanner, Jerome, Janis Weis, Douglas Fearon, Young Whang, and Elliott Kieff. "Epstein-barr virus gp350/220 binding to the B lymphocyte C3d receptor mediates adsorption, capping, and endocytosis." Cell 50, no. 2 (1987): 203–13. http://dx.doi.org/10.1016/0092-8674(87)90216-9.

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49

Ryckman, Brent J., Michael A. Jarvis, Derek D. Drummond, Jay A. Nelson, and David C. Johnson. "Human Cytomegalovirus Entry into Epithelial and Endothelial Cells Depends on Genes UL128 to UL150 and Occurs by Endocytosis and Low-pH Fusion." Journal of Virology 80, no. 2 (2006): 710–22. http://dx.doi.org/10.1128/jvi.80.2.710-722.2006.

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ABSTRACT Human cytomegalovirus (HCMV) replication in epithelial and endothelial cells appears to be important in virus spread, disease, and persistence. It has been difficult to study infection of these cell types because HCMV laboratory strains (e.g., AD169 and Towne) have lost their ability to infect cultured epithelial and endothelial cells during extensive propagation in fibroblasts. Clinical strains of HCMV (e.g., TR and FIX) possess a cluster of genes (UL128 to UL150) that are largely mutated in laboratory strains, and recent studies have indicated that these genes facilitate replication in epithelial and endothelial cells. The mechanisms by which these genes promote infection of these two cell types are unclear. We derived an HCMV UL128-to-UL150 deletion mutant from strain TR, TRΔ4, and studied early events in HCMV infection of epithelial and endothelial cells, and the role of genes UL128 to UL150. Analysis of wild-type TR indicated that HCMV enters epithelial and endothelial cells by endocytosis followed by low-pH-dependent fusion, which is different from the pH-independent fusion with the plasma membrane observed with human fibroblasts. TRΔ4 displayed a number of defects in early infection processes. Adsorption and entry of TRΔ4 on epithelial cells were poor compared with those of TR, but these defects could be overcome with higher doses of virus and the use of polyethylene glycol (PEG) to promote fusion between virion and cellular membranes. High multiplicity and PEG treatment did not promote infection of endothelial cells by TRΔ4, yet virus particles were internalized. Together, these data indicate that genes UL128 to UL150 are required for HCMV adsorption and penetration of epithelial cells and to promote some early stage of virus replication, subsequent to virus entry, in endothelial cells.
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50

Russo, Laura, Valerio Berardi, Franco Tardani, Camillo La Mesa, and Gianfranco Risuleo. "Delivery of RNA and Its Intracellular Translation into Protein Mediated by SDS-CTAB Vesicles: Potential Use in Nanobiotechnology." BioMed Research International 2013 (2013): 1–6. http://dx.doi.org/10.1155/2013/734596.

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Catanionic vesicles are supramolecular aggregates spontaneously forming in water by electrostatic attraction between two surfactants mixed in nonstoichiometric ratios. The outer surface charges allow adsorption to the biomembrane by electrostatic interactions. The lipoplex thus obtained penetrates the cell by endocytosis or membrane fusion. We examined the possible cytotoxic effects and evaluated the transfection efficiency of one vesicle type as compared to known commercial carriers. We show that the individual components of two different vesicles types, CTAB (cetyltrimethylammonium bromide) and DDAB (didodecyldimethylammonium bromide) are detrimental for cell survival. We also assayed the cytotoxicity of SDS-DDAB vesicles and showed dose and time dependency, with the DDAB component beingper seextremely cytotoxic. The transfection efficiency of exogenous RNA mediated by SDS-CTAB increases if vesicles assemble in the presence of the reporter RNA; finally, freezing abrogates the transfection ability. The results of our experimental strategy suggest that catanionic vesicles may be adopted in gene therapy and control of antiproliferative diseases.
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