scholarly journals Role of Envelope Protein gE Endocytosis in the Pseudorabies Virus Life Cycle

1998 ◽  
Vol 72 (6) ◽  
pp. 4571-4579 ◽  
Author(s):  
R. S. Tirabassi ◽  
L. W. Enquist
Keyword(s):  
Plasma Membrane ◽  
Life Cycle ◽  
Pseudorabies Virus ◽  
Host Protein ◽  
Membrane Glycoproteins ◽  
Varicella Zoster ◽  
Culture Cells ◽  
Virus Life Cycle ◽  
Gi Protein

ABSTRACT Several groups have reported that certain herpesvirus envelope proteins do not remain on the surface of cells that express them but rather are internalized by endocytosis in a recycling process. The biological function of membrane protein endocytosis in the virus life cycle remains a matter of speculation and debate. In this report, we demonstrate that some, but not all, membrane proteins encoded by the alphaherpesvirus pseudorabies virus (PRV) are internalized after reaching the plasma membrane. Glycoproteins gE and gB are internalized from the plasma membrane of cells, while gI and gC are not internalized efficiently. We show for gE that the cytoplasmic domain of the protein is required for endocytosis. While the gI protein is incapable of endocytosis on its own, it can be internalized when complexed with gE. We demonstrate that endocytosis of the gE-gI complex and gB occurs early after infection of tissue culture cells but that this process stops completely after 6 h of infection, a time that correlates with significant shutoff of host protein synthesis. We also show that gE protein internalized at 4 h postinfection is not present in virions formed at a later time. We discuss the differences in PRV gE and gI endocytosis compared to that of the varicella-zoster virus homologs and the possible roles of glycoprotein endocytosis in the virus life cycle.

scholarly journals Host BAG3 Is Degraded by Pseudorabies Virus pUL56 C-Terminal 181L-185L and Plays a Negative Regulation Role during Viral Lytic Infection

2020 ◽  
Vol 21 (9) ◽  
pp. 3148
Author(s):  
Chuang Lyu ◽  
Wei-Dong Li ◽  
Shu-Wen Wang ◽  
Jin-Mei Peng ◽  
Yong-Bo Yang ◽  
...  
Keyword(s):  
Life Cycle ◽  
Pseudorabies Virus ◽  
Negative Regulation ◽  
Lytic Infection ◽  
Host Protein ◽  
Dependent Manner ◽  
Golgi Retention ◽  
Infected Cells ◽  
Species Specific

Bcl2-associated athanogene (BAG) 3, which is a chaperone-mediated selective autophagy protein, plays a pivotal role in modulating the life cycle of a wide variety of viruses. Both positive and negative modulations of viruses by BAG3 were reported. However, the effects of BAG3 on pseudorabies virus (PRV) remain unknown. To investigate whether BAG3 could modulate the PRV life cycle during a lytic infection, we first identified PRV protein UL56 (pUL56) as a novel BAG3 interactor by co-immunoprecipitation and co-localization analyses. The overexpression of pUL56 induced a significant degradation of BAG3 at protein level via the lysosome pathway. The C-terminal mutations of 181L/A, 185L/A, or 181L/A-185L/A in pUL56 resulted in a deficiency in pUL56-induced BAG3 degradation. In addition, the pUL56 C-terminal mutants that lost Golgi retention abrogated pUL56-induced BAG3 degradation, which indicates a Golgi retention-dependent manner. Strikingly, BAG3 was not observed to be degraded in either wild-type or UL56-deleted PRV infected cells as compared to mock infected ones, whereas the additional two adjacent BAG3 cleaved products were found in the infected cells in a species-specific manner. Overexpression of BAG3 significantly suppressed PRV proliferation, while knockdown of BAG3 resulted in increased viral yields in HEK293T cells. Thus, these data indicated a negative regulation role of BAG3 during PRV lytic infection. Collectively, our findings revealed a novel molecular mechanism on host protein degradation induced by PRV pUL56. Moreover, we identified BAG3 as a host restricted protein during PRV lytic infection in cells.

scholarly journals Role of Virally-Encoded Deubiquitinating Enzymes in Regulation of the Virus Life Cycle

2021 ◽  
Vol 22 (9) ◽  
pp. 4438
Author(s):  
Jessica Proulx ◽  
Kathleen Borgmann ◽  
In-Woo Park
Keyword(s):  
Immune Response ◽  
Life Cycle ◽  
Deubiquitinating Enzyme ◽  
Deubiquitinating Enzymes ◽  
Antiviral Immune Response ◽  
Cellular Processes ◽  
Virus Life Cycle ◽  
Infected Cells ◽  
Dependent Processes

The ubiquitin (Ub) proteasome system (UPS) plays a pivotal role in regulation of numerous cellular processes, including innate and adaptive immune responses that are essential for restriction of the virus life cycle in the infected cells. Deubiquitination by the deubiquitinating enzyme, deubiquitinase (DUB), is a reversible molecular process to remove Ub or Ub chains from the target proteins. Deubiquitination is an integral strategy within the UPS in regulating survival and proliferation of the infecting virus and the virus-invaded cells. Many viruses in the infected cells are reported to encode viral DUB, and these vial DUBs actively disrupt cellular Ub-dependent processes to suppress host antiviral immune response, enhancing virus replication and thus proliferation. This review surveys the types of DUBs encoded by different viruses and their molecular processes for how the infecting viruses take advantage of the DUB system to evade the host immune response and expedite their replication.

scholarly journals Biogenesis of plasma membrane glycoproteins in hepatoma tissue culture cells.

1978 ◽  
Vol 253 (3) ◽  
pp. 965-973 ◽  
Author(s):  
D. Doyle ◽  
H. Baumann ◽  
B. England ◽  
E. Friedman ◽  
E. Hou ◽  
...  
Keyword(s):  
Tissue Culture ◽  
Plasma Membrane ◽  
Membrane Glycoproteins ◽  
Culture Cells ◽  
Tissue Culture Cells ◽  
Hepatoma Tissue

Inhibition of sperm-egg fusion in the hamster and mouse by carbohydrates

Zygote ◽  
1994 ◽  
Vol 2 (3) ◽  
pp. 253-262 ◽  
Author(s):  
Ruben H. Ponce ◽  
Umbert A. Urch ◽  
Ryuzo Yanagimachi
Keyword(s):  
Extracellular Matrix ◽  
Plasma Membrane ◽  
Zona Pellucida ◽  
Binding Proteins ◽  
Toxic Effects ◽  
Carbohydrate Binding ◽  
Dextran Sulphate ◽  
Membrane Glycoproteins ◽  
Carbohydrate Binding Proteins

SummaryAfter spermatozoa bind to and penetrate the extracellular matrix of the egg, the zona pellucida, they adhere to and fuse with the plasma membrane of the egg. Since sperm–egg fusion may involve membrane glycoproteins and/or carbohydrate binding proteins, we sought to test this hypothesis by challenging sperm–egg fusion in hamster and in mouse with added carbohydrates. In this study, a number of carbohydrate and glycoconjugates were examined for their ability to inhibit sperm–eggfusion. In the hamster, D(+)-glucosamine, D(+)-galactosamine, albumin-bovine-glucosamide and-galactosamide, fucoidan and dextran sulphate inhibited the fusion of spermatozoa with zona-free eggs. The same effects were seen in the mouse, except for the toxic effects of D(+)-galactosamine. These facts suggest a role of carbohydrate binding proteins or glycoproteins in the fertilisation process at the level of binding to and fusing with the oolemma.

scholarly journals Lysosomal Fusion Is Essential for the Retention of Trypanosoma cruzi Inside Host Cells

2004 ◽  
Vol 200 (9) ◽  
pp. 1135-1143 ◽  
Author(s):  
Luciana O. Andrade ◽  
Norma W. Andrews
Keyword(s):  
Plasma Membrane ◽  
Life Cycle ◽  
Trypanosoma Cruzi ◽  
Parasitophorous Vacuole ◽  
Cell Types ◽  
Significant Fraction ◽  
Host Cells ◽  
Productive Infection ◽  
Kinase Inhibition

Trypomastigotes, the highly motile infective forms of Trypanosoma cruzi, are capable of infecting several cell types. Invasion occurs either by direct recruitment and fusion of lysosomes at the plasma membrane, or through invagination of the plasma membrane followed by intracellular fusion with lysosomes. The lysosome-like parasitophorous vacuole is subsequently disrupted, releasing the parasites for replication in the cytosol. The role of this early residence within lysosomes in the intracellular cycle of T. cruzi has remained unclear. For several other cytosolic pathogens, survival inside host cells depends on an early escape from phagosomes before lysosomal fusion. Here, we show that when lysosome-mediated T. cruzi invasion is blocked through phosophoinositide 3-kinase inhibition, a significant fraction of the internalized parasites are not subsequently retained inside host cells for a productive infection. A direct correlation was observed between the lysosomal fusion rates after invasion and the intracellular retention of trypomastigotes. Thus, formation of a parasitophorous vacuole with lysosomal properties is essential for preventing these highly motile parasites from exiting host cells and for allowing completion of the intracellular life cycle.

scholarly journals Role of the Pseudorabies Virus gI Cytoplasmic Domain in Neuroinvasion, Virulence, and Posttranslational N-Linked Glycosylation

2000 ◽  
Vol 74 (8) ◽  
pp. 3505-3516 ◽  
Author(s):  
R. S. Tirabassi ◽  
L. W. Enquist
Keyword(s):  
Pseudorabies Virus ◽  
Cytoplasmic Domain ◽  
Cytoplasmic Domains ◽  
Nonsense Mutations ◽  
Cytoplasmic Tails ◽  
Gi Protein ◽  
The Individual ◽  
Cell Spread ◽  
Better Than

ABSTRACT The glycoproteins I and E of pseudorabies virus are important mediators of cell-to-cell spread and virulence in all animal models tested. Although these two proteins form a complex with one another, ascribing any function to the individual proteins has been difficult. We have shown previously, using nonsense mutations, that the N-terminal ectodomain of the gE protein is sufficient for gE-mediated transsynaptic spread whereas the cytoplasmic domain of the protein is required for full expression of virulence. These same studies demonstrated that the cytoplasmic domain of gE is also required for endocytosis of the protein. In this report, we describe the construction of viruses with nonsense mutations in gI that allowed us to determine the contributions of the gI cytoplasmic domain to protein expression as well as virus neuroinvasion and virulence after infection of the rat eye. We also constructed double mutants with nonsense mutations in both gE and gI so that the contributions of both the gE and gI cytoplasmic domains could be determined. We observed that the gI cytoplasmic domain is required for efficient posttranslational modification of the gI protein. The gE cytoplasmic domain has no effect on gE posttranslational glycosylation. In addition, we found that infection of all gE-gI-dependent anterograde circuits projecting from the rat retina requires both ectodomains and at least one of the cytoplasmic domains of the proteins. The gI cytoplasmic domain promotes transsynaptic spread of virus better than the gE cytoplasmic domain. Interestingly, both gE and gI cytoplasmic tails are required for virulence; lack of either one or both results in an attenuated infection. These data suggest that gE and gI play differential roles in mediating directional neuroinvasion of the rat; however, the gE and gI cytoplasmic domains most likely function together to promote virulence.

scholarly journals HSC70, HSPA1A, and HSP90AB1 Facilitate Ebola Virus trVLPs to Induce Autophagy

2020 ◽  
Author(s):  
Dong-Shan Yu ◽  
Shu-Hao Yao ◽  
Wen-Na Xi ◽  
Lin-Fang Cheng ◽  
Fu-Min Liu ◽  
...  
Keyword(s):  
Life Cycle ◽  
Ebola Virus ◽  
Immunoblot Analysis ◽  
Host Protein ◽  
Virus Protein ◽  
List Type ◽  
Virus Life Cycle ◽  
Transmission Electron ◽  
Chaperone Mediated Autophagy ◽  
Insight Into

ABSTRACTEbola virus (EBOV) can induce autophagy to benefit the virus life cycle, but detailed mechanisms remain to be elucidated. We previously found that EBOV GP and VP40 proteins interact with HSC70 (HSPA8), HSPA1A, and HSP90AB1. Thus, we presumed that EBOV likely induced autophagy by virus protein-host HSC70 or co-chaperon interactions via chaperone-mediated autophagy (CMA). We developed EBOV-trVLPs to model the EBOV life cycle, infected 293T cells with trVLPs, evaluated CMA by GFP-LC3 and RFP-LAMP1 co-localization, transmission electron microscopy (TEM) observation, and immunoblot analysis. The results demonstrated that EBOV-trVLPs induce autophagy which could not be inhibited by 3-MA significantly; autophagosomes and autolysosomes are obviously in the cytoplasm confirming CMA in cells infected with trVLPs. Meanwhile, a knockdown of HSC70 and relevant co-chaperones could inhibit trVLPs-associated autophagy, but no effort to Akt/mTOR/PHLPP1 pathway. These data indicate that EBOV-trVLPs could induce autophagy by CMA but was not limited by the CMA pathway. HSC70, HSPA1A, and HSP90AB1 participate and regulate CMA induced by EBOV-trVLPs. This was the first study about EBOV-trVLPs-induction of CMA and provides insight into the viral protein-host protein interaction, which is probably associated with CMA.HighlightsEBOV-trVLPs induce chaperone-mediated autophagy (CMA) but are not limit by CMA.HSC70, HSPA1A, and HSP90AB1 facilitate EBOV-trVLPs to induce autophagyKnockdown of HSC70, HSPA1A, and HSP90AB1 inhibit EBOV-trVLPs-induced CMA.

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