scholarly journals Herpes Simplex Virus 1 Protein Kinase Us3 Phosphorylates Viral Envelope Glycoprotein B and Regulates Its Expression on the Cell Surface

2008 ◽  
Vol 83 (1) ◽  
pp. 250-261 ◽  
Author(s):  
Akihisa Kato ◽  
Jun Arii ◽  
Ikuo Shiratori ◽  
Hiroomi Akashi ◽  
Hisashi Arase ◽  
...  

ABSTRACT Us3 is a serine-threonine protein kinase encoded by herpes simplex virus 1 (HSV-1). As reported here, we attempted to identify the previously unreported physiological substrate of Us3 in HSV-1-infected cells. Our results were as follows. (i) Bioinformatics analysis predicted two putative Us3 phosphorylation sites in the viral envelope glycoprotein B (gB) at codons 557 to 562 (RRVSAR) and codons 884 to 889 (RRNTNY). (ii) In in vitro kinase assays, the threonine residue at position 887 (Thr-887) in the gB domain was specifically phosphorylated by Us3, while the serine residue at position 560 was not. (iii) The phosphorylation of gB Thr-887 in Vero cells infected with wild-type HSV-1 was specifically detected using an antibody that recognized phosphorylated serine or threonine residues with arginine at the −3 and −2 positions. (iv) The phosphorylation of gB Thr-887 in infected cells was dependent on the kinase activity of Us3. (v) The replacement of Thr-887 with alanine markedly upregulated the cell surface expression of gB in infected cells, whereas replacement with aspartic acid, which sometimes mimics constitutive phosphorylation, restored the wild-type phenotype. The upregulation of gB expression on the cell surface also was observed in cells infected with a recombinant HSV-1 encoding catalytically inactive Us3. These results supported the hypothesis that Us3 phosphorylates gB and downregulates the cell surface expression of gB in HSV-1-infected cells.

2017 ◽  
Vol 91 (12) ◽  
Author(s):  
Fumio Maeda ◽  
Jun Arii ◽  
Yoshitaka Hirohata ◽  
Yuhei Maruzuru ◽  
Naoto Koyanagi ◽  
...  

ABSTRACT Upon herpes simplex virus 1 (HSV-1) infection, the CD98 heavy chain (CD98hc) is redistributed around the nuclear membrane (NM), where it promotes viral de-envelopment during the nuclear egress of nucleocapsids. In this study, we attempted to identify the factor(s) involved in CD98hc accumulation and demonstrated the following: (i) the null mutation of HSV-1 UL34 caused specific dispersion throughout the cytoplasm of CD98hc and the HSV-1 de-envelopment regulators, glycoproteins B and H (gB and gH); (ii) as observed with CD98hc, gB, and gH, wild-type HSV-1 infection caused redistribution of the endoplasmic reticulum (ER) markers calnexin and ERp57 around the NM, whereas the UL34-null mutation caused cytoplasmic dispersion of these markers; (iii) the ER markers colocalized efficiently with CD98hc, gB, and gH in the presence and absence of UL34 in HSV-1-infected cells; (iv) at the ultrastructural level, wild-type HSV-1 infection caused ER compression around the NM, whereas the UL34-null mutation caused cytoplasmic dispersion of the ER; and (v) the UL34-null mutation significantly decreased the colocalization efficiency of lamin protein markers of the NM with CD98hc and gB. Collectively, these results indicate that HSV-1 infection causes redistribution of the ER around the NM, with resulting accumulation of ER-associated CD98hc, gB, and gH around the NM and that UL34 is required for ER redistribution, as well as for efficient recruitment to the NM of the ER-associated de-envelopment factors. Our study suggests that HSV-1 induces remodeling of the global ER architecture for recruitment of regulators mediating viral nuclear egress to the NM. IMPORTANCE The ER is an important cellular organelle that exists as a complex network extending throughout the cytoplasm. Although viruses often remodel the ER to facilitate viral replication, information on the effects of herpesvirus infections on ER morphological integrity is limited. Here, we showed that HSV-1 infection led to compression of the global ER architecture around the NM, resulting in accumulation of ER-associated regulators associated with nuclear egress of HSV-1 nucleocapsids. We also identified HSV-1 UL34 as a viral factor that mediated ER remodeling. Furthermore, we demonstrated that UL34 was required for efficient targeting of these regulators to the NM. To our knowledge, this is the first report showing that a herpesvirus remodels ER global architecture. Our study also provides insight into the mechanism by which the regulators for HSV-1 nuclear egress are recruited to the NM, where this viral event occurs.


2017 ◽  
Vol 91 (12) ◽  
Author(s):  
Thibaut Deschamps ◽  
Christos Dogrammatzis ◽  
Ranajoy Mullick ◽  
Maria Kalamvoki

ABSTRACT The Cbl E3 ligase has been linked to the down-modulation of surface signaling responses by inducing internalization of surface receptors. The adaptor protein CIN85 is a partner of Cbl that augments many of these interactions. Previously, an interaction was demonstrated between ICP0 and CIN85, which results in the removal of epidermal growth factor receptor (EGFR) from the surface of the infected cells with a concomitant attenuation of EGFR signaling. Here, we examined whether Cbl mediates the removal of the herpes simplex virus 1 (HSV-1) entry receptor Nectin-1 from the surface of infected cells. We found the following: (i) that Cbl, Nectin-1, and the viral glycoprotein D (gD) form a complex in infected cells; (ii) that during infection Nectin-1 is removed from the surface of the infected cells but is retained on the surface of cells that have been depleted of Cbl; and (iii) that in cells infected with a ΔICP0 mutant virus, Nectin-1 remained on the cell surface. Thus, Cbl is necessary but not sufficient for the removal of Nectin-1 from the cell surface. In addition, we observed that in Cbl-depleted cells there was enhanced entry after infection. These cells were susceptible to secondary infections by HSV-1. Viral entry in CIN85-depleted cells was only moderately enhanced compared to that in the Cbl-depleted cells, suggesting that the Cbl–Nectin-1 interaction is likely the key to the downregulation of surface Nectin-1. The removal of the HSV-1 entry receptor Nectin-1 from the surface of the infected cells may be part of the strategy of the virus to efficiently spread to uninfected cells. IMPORTANCE The Cbl E3 ligase suppresses surface signaling responses by inducing internalization of surface components. The targets of Cbl include such components as immune system receptors, growth factor receptors, adhesion, and cell-to-cell contact molecules. The immediate early protein ICP0 of herpes simplex virus 1 (HSV-1) interacts with CIN85, an adaptor protein that augments Cbl functions. The consequence of this interaction is the removal of the epidermal growth factor receptor (EGFR) from the surface of the infected cells with concomitant suppression of the EGF ligand signaling. The viral entry receptor Nectin-1 is also internalized during HSV-1 infection in a Cbl-dependent mechanism, and that increases the opportunity of the virus to spread to uninfected cells. The diversion of the Cbl/CIN85 endocytic machinery may be a strategy utilized by the virus to alter the cell surface pattern to prevent detrimental host responses.


2015 ◽  
Vol 89 (13) ◽  
pp. 6646-6655 ◽  
Author(s):  
Ran Xiong ◽  
Ping Rao ◽  
Seil Kim ◽  
Michelle Li ◽  
Xiangshu Wen ◽  
...  

ABSTRACTHerpes simplex virus 1 (HSV-1) causes one of the most prevalent herpesviral infections in humans and is the leading etiological agent of viral encephalitis and eye infections. Our understanding of how HSV-1 interacts with the host at the cellular and organismal levels is still limited. We and others previously reported that, upon infection, HSV-1 rapidly and efficiently downregulates CD1d cell surface expression and suppresses the function of NKT cells, a group of innate T cells with critical immunoregulatory function. The viral protein kinase US3 plays a major role in this immune evasion mechanism, and its kinase activity is required for this function. In this study, we investigated the cellular substrate(s) phosphorylated by US3 and how it mediates US3 suppression of CD1d recycling. We identified the type II kinesin motor protein KIF3A as a critical kinesin factor in the cell surface expression of CD1d. Interestingly, KIF3A is phosphorylated by US3 bothin vitroand in infected cells. Mass spectrometry analysis of purified KIF3A showed that it is phosphorylated predominantly at serine 687 by US3. Ablation of this phosphorylation abolished US3-mediated downregulation of CD1d expression, suggesting that phosphorylation of KIF3A is the primary mechanism of HSV-1 suppression of CD1d expression by US3 protein. Understanding of the precise mechanism of viral modulation of CD1d expression will help to develop more efficient vaccines in the future to boost host NKT cell-mediated immune responses against herpesviruses.IMPORTANCEHerpes simplex virus 1 (HSV-1) is among the most common human pathogens. Little is known regarding the exact mechanism by which this virus evades the human immune system, particularly the innate immune system. We previously reported that HSV-1 employs its protein kinase US3 to modulate the expression of the key antigen-presenting molecule CD1d to evade the antiviral function of NKT cells. Here we identified the key cellular motor protein KIF3A as a cellular substrate phosphorylated by US3, and this phosphorylation event mediates US3-induced immune evasion.


2009 ◽  
Vol 83 (22) ◽  
pp. 11624-11634 ◽  
Author(s):  
Tomomi Morimoto ◽  
Jun Arii ◽  
Michiko Tanaka ◽  
Tetsutaro Sata ◽  
Hiroomi Akashi ◽  
...  

ABSTRACT Us3 protein kinases encoded by herpes simplex virus 1 (HSV-1) and 2 (HSV-2) are serine/threonine protein kinases and play critical roles in viral replication and pathogenicity in vivo. In the present study, we investigated differences in the biological properties of HSV-1 and HSV-2 Us3 protein kinases and demonstrated that HSV-2 Us3 did not have some of the HSV-1 Us3 kinase functions, including control of nuclear egress of nucleocapsids, localization of UL31 and UL34, and cell surface expression of viral envelope glycoprotein B. In agreement with the observations that HSV-2 Us3 was less important for these functions, the effect of HSV-2 Us3 kinase activity on virulence in mice following intracerebral inoculation was much lower than that of HSV-1 Us3. Furthermore, we showed that alanine substitution in HSV-2 Us3 at a site (aspartic acid at position 147) corresponding to one that can be autophosphorylated in HSV-1 Us3 abolished HSV-2 Us3 kinase activity. Thus, the regulatory and functional effects of Us3 kinase activity are different between HSV-1 and HSV-2.


2006 ◽  
Vol 80 (7) ◽  
pp. 3341-3348 ◽  
Author(s):  
Luca Benetti ◽  
Bernard Roizman

ABSTRACT The product of the herpes simplex virus 1 (HSV-1) US3 gene is a multifunctional serine-threonine protein kinase that can block apoptosis induced by proapoptotic cellular proteins, exogenous agents, or replication-defective viruses. Earlier studies showed that the US3 kinase activates and functionally overlaps cellular protein kinase A (PKA). In this study we examined the status of phosphatidylinositol 3-kinase [PI(3)K] and of its effector, protein kinase B/Akt (PKB/Akt), a component of a major pathway of mammalian antiapoptotic signaling systems. We report the following. (i) Infection of target cells with HSV-1 induces transient phosphorylation of serine 473 of PKB/Akt early in infection, with a mechanism that is dependent on PI(3)K. Inhibition of PI(3)K induced apoptosis in mock-infected or ΔUS3 mutant-virus-infected but not in wild-type-virus-infected cells and reduced the accumulation of specific viral gene products, including the US3 protein kinase, but had a marginal effect on virus yields. (ii) At later times after infection, the total amounts of PKB/Akt decreased and phosphorylated PKB/Akt forms disappeared in a US3-dependent and protein phosphatase 2A-independent manner. (iii) Activation of PKA by forskolin did not mediate significant dephosphorylation of PKB/Akt. Our results are consistent with the model that PKB/Akt is activated early in infection and acts to block apoptosis in infected cells prior to the accumulation of US3 protein kinase and that it persists and continues to function as an antiapoptotic protein in the absence of US3 but becomes redundant or even inimical once US3 protein kinase accumulates in effective amounts.


2016 ◽  
Vol 90 (22) ◽  
pp. 10414-10422 ◽  
Author(s):  
Songfang Wu ◽  
Shuang Pan ◽  
Liming Zhang ◽  
Joel Baines ◽  
Richard Roller ◽  
...  

ABSTRACTHerpes simplex virus 1 (HSV-1) remodels nuclear membranes during virus egress. Although the UL31 and UL34 proteins control nucleocapsid transit in infected cells, the molecular interactions required for their function are unclear. Here we report that the γ134.5 gene product of HSV-1 facilitates nucleocapsid release to the cytoplasm through bridging the UL31/UL34 complex, cellular p32, and protein kinase C. Unlike wild-type virus, an HSV mutant devoid of γ134.5 or its amino terminus is crippled for viral growth and release. This is attributable to a defect in virus nuclear egress. In infected cells, wild-type virus recruits protein kinase C to the nuclear membrane and triggers its activation, whereas the γ134.5 mutants fail to exert such an effect. Accordingly, the γ134.5 mutants are unable to induce phosphorylation and reorganization of lamin A/C. When expressed in host cells γ134.5 targets p32 and protein kinase C. Meanwhile, it communicates with the UL31/UL34 complex through UL31. Deletion of the amino terminus from γ134.5 disrupts its activity. These results suggest that disintegration of the nuclear lamina mediated by γ134.5 promotes HSV replication.IMPORTANCEHSV nuclear egress is a key step that determines the outcome of viral infection. While the nuclear egress complex mediates capsid transit across the nuclear membrane, the regulatory components are not clearly defined in virus-infected cells. We report that the γ134.5 gene product, a virulence factor of HSV-1, facilitates nuclear egress cooperatively with cellular p32, protein kinase C, and the nuclear egress complex. This work highlights a viral mechanism that may contribute to the pathogenesis of HSV infection.


2004 ◽  
Vol 78 (15) ◽  
pp. 8015-8025 ◽  
Author(s):  
Elisa Avitabile ◽  
Giulia Lombardi ◽  
Tatiana Gianni ◽  
Miriam Capri ◽  
Gabriella Campadelli-Fiume

ABSTRACT Syncytium formation in cells that express herpes simplex virus glycoprotein B (gB), gD, gH, and gL is blocked by gK (E. Avitabile, G. Lombardi, and G. Campadelli-Fiume, J. Virol. 77:6836-6844, 2003). Here, we report the results of two series of experiments. First, UL20 protein (UL20p) expression weakly inhibited cell-cell fusion. Coexpression of UL20p and gK drastically reduced fusion in a cell-line-dependent manner, with the highest inhibition in BHK cells. Singly expressed UL20p and gK localized at the endoplasmic reticulum and nuclear membranes. When they were coexpressed, both proteins relocalized to the Golgi apparatus. Remarkably, in cells that coexpressed UL20p and gK, the antifusion activity correlated with a downmodulation of gD, gB, gH, and gL cell surface expression. Second, gBΔ867 has a partial deletion in the cytoplasmic tail that removed endocytosis motifs. Whereas wild-type (wt) gB was internalized in vesicles lined with the endosomal marker Rab5, gBΔ867 was not internalized, exhibited enhanced cell surface expression, and was more efficient in mediating cell-cell fusion than wt gB. The antifusion activity of UL20p and gK was also exerted when gBΔ867 replaced wt gB in the cell fusion assay. These studies show that the gB C tail carries a functional endocytosis motif(s) and that the removal of the motif correlated with increased gB surface expression and increased fusion activity. We conclude that cell-cell fusion in wt-virus-infected cells is negatively controlled by at least two mechanisms. The novel mechanism described here involves the concerted action of UL20p and gK and correlates with a moderate but consistent reduction in the cell surface expression of the fusion glycoproteins. This mechanism is independent of the one exerted through endocytosis-mediated downmodulation of gB from the plasma membrane.


2002 ◽  
Vol 76 (18) ◽  
pp. 9355-9367 ◽  
Author(s):  
Pascal Lopez ◽  
Robert J. Jacob ◽  
Bernard Roizman

ABSTRACT A key early event in the replication of herpes simplex virus 1 (HSV-1) is the localization of infected-cell protein no. 0 (ICP0) in nuclear structures knows as ND10 or promyelocytic leukemia oncogenic domains (PODs). This is followed by dispersal of ND10 constituents such as the promyelocytic leukemia protein (PML), CREB-binding protein (CBP), and Daxx. Numerous experiments have shown that this dispersal is mediated by ICP0. PML is thought to be the organizing structural component of ND10. To determine whether the virus targets PML because it is inimical to viral replication, telomerase-immortalized human foreskin fibroblasts and HEp-2 cells were transduced with wild-type baculovirus or a baculovirus expressing the M r 69,000 form of PML. The transduced cultures were examined for expression and localization of PML in mock-infected and HSV-1-infected cells. The results obtained from studies of cells overexpressing PML were as follows. (i) Transduced cells accumulate large amounts of unmodified and SUMO-I-modified PML. (ii) Mock-infected cells exhibited enlarged ND10 structures containing CBP and Daxx in addition to PML. (iii) In infected cells, ICP0 colocalized with PML in ND10 early in infection, but the two proteins did not overlap or were juxtaposed in orderly structures. (iv) The enlarged ND10 structures remained intact at least until 12 h after infection and retained CBP and Daxx in addition to PML. (v) Overexpression of PML had no effect on the accumulation of viral proteins representative of α, β, or γ groups and had no effect on the accumulation of infectious virus in cells infected with wild-type virus or a mutant (R7910) from which the α0 genes had been deleted. These results indicate the following: (i) PML overexpressed in transduced cells cannot be differentiated from endogenous PML with respect to sumoylation and localization in ND10 structures. (ii) PML does not affect viral replication or the changes in the localization of ICP0 through infection. (iii) Disaggregation of ND10 structures is not an obligatory event essential for viral replication.


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