An independent endocytic pathway stimulates different monocyte subsets by the a2 N-terminus domain of vacuolar-ATPase

Christina Kwong; Alice Gilman-Sachs; Kenneth Beaman

doi:10.4161/onci.22978

The N-terminus Domain of the a2 Isoform of Vacuolar ATPase Can Regulate Interleukin-1? Production from Mononuclear Cells in Co-culture with JEG-3 Choriocarcinoma Cells

American Journal of Reproductive Immunology ◽

10.1111/j.1600-0897.2006.00463.x ◽

2007 ◽

Vol 57 (3) ◽

pp. 201-209 ◽

Cited By ~ 21

Author(s):

Evangelos Ntrivalas ◽

Alice Gilman-Sachs ◽

Joanne Kwak-Kim ◽

Kenneth Beaman

Keyword(s):

Mononuclear Cells ◽

Interleukin 1 ◽

Vacuolar Atpase ◽

N Terminus ◽

Choriocarcinoma Cells

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Synthesis and trafficking of prion proteins in cultured cells.

Molecular Biology of the Cell ◽

10.1091/mbc.3.8.851 ◽

1992 ◽

Vol 3 (8) ◽

pp. 851-863 ◽

Cited By ~ 193

Author(s):

A Taraboulos ◽

A J Raeber ◽

D R Borchelt ◽

D Serban ◽

S B Prusiner

Keyword(s):

Endoplasmic Reticulum ◽

Cell Surface ◽

Cultured Cells ◽

Prion Proteins ◽

Brefeldin A ◽

Endocytic Pathway ◽

Chromosomal Gene ◽

Golgi Stack ◽

Mouse Neuroblastoma ◽

N Terminus

Scrapie prions are composed largely, if not entirely, of the scrapie prion protein (PrPSc) that is encoded by a chromosomal gene. Scrapie-infected mouse neuroblastoma (ScN2a) and hamster brain (ScHaB) cells synthesize PrPSc from the normal PrP isoform (PrPC) or a precursor through a posttranslational process. In pulse-chase radiolabeling experiments, we found that presence of brefeldin A (BFA) during both the pulse and the chase periods prevented the synthesis of PrPSc. Removal of BFA after the chase permitted synthesis of PrPSc to resume. BFA also blocked the export of nascent PrPC to the cell surface but did not alter the distribution of intracellular deposits of PrPSc. Under the same conditions, BFA caused the redistribution of the Golgi marker MG160 into the endoplasmic reticulum (ER). Using monensin as an inhibitor of mid-Golgi glycosylation, we determined that PrP traverses the mid-Golgi stack before acquiring protease resistance. About 1 h after the formation of PrPSc, its N-terminus was removed by a proteolytic process that was inhibited by ammonium chloride, chloroquine, and monensin, arguing that this is a lysosomal event. These results suggest that the ER is not competent for the synthesis of PrPSc and that the synthesis of PrPSc occurs during the transit of PrP between the mid-Golgi stack and lysosomes. Presumably, the endocytic pathway features in the synthesis of PrPSc.

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Constitutive recycling of the store-operated Ca2+ channel Orai1 and its internalization during meiosis

The Journal of Cell Biology ◽

10.1083/jcb.201006022 ◽

2010 ◽

Vol 191 (3) ◽

pp. 523-535 ◽

Cited By ~ 76

Author(s):

Fang Yu ◽

Lu Sun ◽

Khaled Machaca

Keyword(s):

Steady State ◽

Cell Membrane ◽

Subcellular Localization ◽

Oocyte Maturation ◽

Vesicular Trafficking ◽

Endocytic Pathway ◽

Consensus Binding Site ◽

Significant Percentage ◽

Store Depletion ◽

N Terminus

The egg’s competency to activate at fertilization and transition to embryogenesis is dependent on its ability to generate a fertilization-specific Ca2+ transient. To endow the egg with this capacity, Ca2+ signals remodel during oocyte maturation, including inactivation of the primary Ca2+ influx pathway store-operated Ca2+ entry (SOCE). SOCE inactivation is coupled to internalization of the SOCE channel, Orai1. In this study, we show that Orai1 internalizes during meiosis through a caveolin (Cav)- and dynamin-dependent endocytic pathway. Cav binds to Orai1, and we map a Cav consensus–binding site in the Orai1 N terminus, which is required for Orai1 internalization. Furthermore, at rest, Orai1 actively recycles between an endosomal compartment and the cell membrane through a Rho-dependent endocytic pathway. A significant percentage of total Orai1 is intracellular at steady state. Store depletion completely shifts endosomal Orai1 to the cell membrane. These results define vesicular trafficking mechanisms in the oocyte that control Orai1 subcellular localization at steady state, during meiosis, and after store depletion.

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Extracellular Conformational Changes in the Capsid of Human Papillomaviruses Contribute to Asynchronous Uptake into Host Cells

Journal of Virology ◽

10.1128/jvi.02106-17 ◽

2018 ◽

Vol 92 (11) ◽

pp. e02106-17 ◽

Cited By ~ 13

Author(s):

Miriam Becker ◽

Lilo Greune ◽

M. Alexander Schmidt ◽

Mario Schelhaas

Keyword(s):

Capsid Protein ◽

Conformational Changes ◽

Structural Changes ◽

Human Papillomaviruses ◽

Endocytic Pathway ◽

Host Cells ◽

Initial Infection ◽

Structural Modifications ◽

N Terminus ◽

Rate Limiting

ABSTRACT Human papillomavirus 16 (HPV16) is the leading cause of cervical cancer. For initial infection, HPV16 utilizes a novel endocytic pathway for host cell entry. Unique among viruses, uptake occurs asynchronously over a protracted period of time, with half-times between 9 and 12 h. To trigger endocytic uptake, the virus particles need to undergo a series of structural modifications after initial binding to heparan sulfate proteoglycans (HSPGs). These changes involve proteolytic cleavage of the major capsid protein L1 by kallikrein-8 (KLK8), exposure of the N terminus of the minor capsid protein L2 by cyclophilins, and cleavage of this N terminus by furin. Overall, the structural changes are thought to facilitate the engagement of an elusive secondary receptor for internalization. Here, we addressed whether structural changes are the rate-limiting steps during infectious internalization of HPV16 by using structurally primed HPV16 particles. Our findings indicate that the structural modifications mediated by cyclophilins and furin, which lead to exposure and cleavage, respectively, of the L2 N terminus contribute to the slow and asynchronous internalization kinetics, whereas conformational changes elicited by HSPG binding and KLK8 cleavage did not. However, these structural modifications accounted for only 30 to 50% of the delay in internalization. Therefore, we propose that limited internalization receptor availability for engagement of HPV16 causes slow and asynchronous internalization in addition to rate-limiting structural changes in the viral capsid. IMPORTANCE HPVs are the main cause of anogenital cancers. Their unique biology is linked to the differentiation program of skin or mucosa. Here, we analyzed another unique aspect of HPV infections using the prototype HPV16. After initial cell binding, HPVs display an unusually protracted residence time on the plasma membrane prior to asynchronous uptake. As viruses typically do not expose themselves to host immune sensing, we analyzed the underlying reasons for this unusual behavior. This study provides evidence that both extracellular structural modifications and possibly a limited availability of the internalization receptor contribute to the slow internalization process of the virus. These findings indicate that perhaps a unique niche for initial infection that could allow for rapid infection exists. In addition, our results may help to develop novel, preventive antiviral measures.

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Novel role for the N-terminus domain of the a2 isoform of vacuolar ATPase in interleukin-1β production

Human Immunology ◽

10.1016/j.humimm.2007.02.010 ◽

2007 ◽

Vol 68 (6) ◽

pp. 469-477 ◽

Cited By ~ 14

Author(s):

Evangelos Ntrivalas ◽

Richard Derks ◽

Alice Gilman-Sachs ◽

Joanne Kwak-Kim ◽

Rita Levine ◽

...

Keyword(s):

Vacuolar Atpase ◽

Interleukin 1Β ◽

N Terminus

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Characteristics of the Interaction between Thrombin Exosite1 and the Sequence 269-297 of Platelet Glycoprotein Ibα

Thrombosis and Haemostasis ◽

10.1055/s-0037-1615193 ◽

1998 ◽

Vol 80 (08) ◽

pp. 310-315 ◽

Cited By ~ 8

Author(s):

Marie-Christine Bouton ◽

Christophe Thurieau ◽

Marie-Claude Guillin ◽

Martine Jandrot-Perrus

Keyword(s):

Platelet Activation ◽

Electrostatic Interactions ◽

Platelet Glycoprotein ◽

Thrombin Receptor ◽

Central Position ◽

Amidolytic Activity ◽

N Terminus ◽

Hydrolysis Of ◽

Chemical Cross Linking ◽

Positively Charged

SummaryThe interaction between GPIb and thrombin promotes platelet activation elicited via the hydrolysis of the thrombin receptor and involves structures located on the segment 238-290 within the N-terminal domain of GPIbα and the positively charged exosite 1 on thrombin. We have investigated the ability of peptides derived from the 269-287 sequence of GPIbα to interact with thrombin. Three peptides were synthesized, including Ibα 269-287 and two scrambled peptides R1 and R2 which are comparable to Ibα 269-287 with regards to their content and distribution of anionic residues. However, R2 differs from both Ibα 269-287 and R1 by the shifting of one proline from a central position to the N-terminus. By chemical cross-linking, we observed the formation of a complex between 125I-Ibα 269-287 and α-thrombin that was inhibited by hirudin, the C-terminal peptide of hirudin, sodium pyrophosphate but not by heparin. The complex did not form when γ-thrombin was substituted for α-thrombin. Ibα 269-287 produced only slight changes in thrombin amidolytic activity and inhibited thrombin binding to fibrin. R1 and R2 also formed complexes with α-thrombin, modified slightly its catalytic activity and inhibited its binding to fibrin. Peptides Ibα 269-287 and R1 inhibited platelet aggregation and secretion induced by low thrombin concentrations whereas R2 was without effect. Our results indicate that Ibα 269-287 interacts with thrombin exosite 1 via mainly electrostatic interactions, which explains why the scrambled peptides also interact with exosite 1. Nevertheless, the lack of effect of R2 on thrombin-induced platelet activation suggests that proline 280 is important for thrombin interaction with GPIb.

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