Kaposi’s sarcoma-associated herpesvirus ubiquitin ligases downregulate cell surface expression of l-selectin

2021 ◽  
Vol 102 (11) ◽  
Author(s):  
Mizuho Kajikawa ◽  
Nanae Imaizumi ◽  
Shiho Machii ◽  
Tomoka Nakamura ◽  
Nana Harigane ◽  
...  
Keyword(s):  
Cell Surface ◽  
Nk Cells ◽  
Immune Evasion ◽  
Kaposi's Sarcoma ◽  
Kaposi’S Sarcoma ◽  
Ubiquitin Ligases ◽  
Surface Expression ◽  
Cell Surface Expression ◽  
Kaposi's Sarcoma Associated Herpesvirus ◽  
Kaposi’S Sarcoma Associated Herpesvirus

Kaposi’s sarcoma-associated herpesvirus (KSHV) is an oncogenic etiological factor for Kaposi’s sarcoma and primary effusion lymphoma in immunocompromised patients. KSHV utilizes two immune evasion E3 ubiquitin ligases, namely K3 and K5, to downregulate the expression of antigen-presenting molecules and ligands of natural killer (NK) cells in the host cells through an ubiquitin-dependent endocytic mechanism. This allows the infected cells to evade surveillance and elimination by cytotoxic lymphocytes and NK cells. The number of host cell molecular substrates reported for these ubiquitin ligases is limited. The identification of novel substrates for these ligases will aid in elucidating the mechanism underlying immune evasion of KSHV. This study demonstrated that K5 downregulated the cell surface expression of l-selectin, a C-type lectin-like adhesion receptor expressed in the lymphocytes. Tryptophan residue located at the centre of the E2-binding site in the K5 RINGv domain was essential to downregulate l-selectin expression. Additionally, the lysine residues located at the cytoplasmic tail of l-selectin were required for the K5-mediated downregulation of l-selectin. K5 promoted the degradation of l-selectin through polyubiquitination. These results suggest that K5 downregulates l-selectin expression on the cell surface by promoting polyubiquitination and ubiquitin-dependent endocytosis, which indicated that l-selectin is a novel substrate for K5. Additionally, K3 downregulated l-selectin expression. The findings of this study will aid in the elucidation of a novel immune evasion mechanism in KSHV.

Natural killer cell evasion by an E3 ubiquitin ligase from Kaposi's sarcoma-associated herpesvirus

2008 ◽  
Vol 36 (3) ◽  
pp. 459-463 ◽  
Author(s):  
Mair Thomas ◽  
Mark Wills ◽  
Paul J. Lehner
Keyword(s):  
Cell Surface ◽  
Natural Killer ◽  
Kaposi's Sarcoma ◽  
Nk Cell ◽  
Cytoplasmic Tail ◽  
Kaposi’S Sarcoma ◽  
Surface Expression ◽  
Cell Surface Expression ◽  
Lysine Residues ◽  
Kaposi’S Sarcoma Associated Herpesvirus

Viruses exploit the ubiquitin system by targeting cell-surface receptors recognized by immune cells for internalization, thereby evading recognition. We have characterized the KSHV (Kaposi's sarcoma-associated herpesvirus)-encoded E3 ubiquitin ligases, K3 and K5. We find their activities not only prevent recognition by cytotoxic T-lymphocytes, but also promote evasion of NK (natural killer) cells. NK cells recognize and lyse virus-infected cells expressing ligands for activatory receptors such as NKG2D (NK group 2D). K5 down-regulates cell-surface expression of the NKG2D ligands MICA/B (MHC class I-related chains A and B) by ubiquitination of MIC cytoplasmic tail lysine residues. Ubiquitination results in redistribution of MICA from the plasma membrane to an intracellular compartment, but does not result in an increased rate of degradation. Furthermore, K5 down-regulates cell-surface expression of another NK cell activatory receptor ligand, AICL (activation-induced C-type lectin). This activity requires the K5 RING (really interesting new gene)-CH domain and AICL cytoplasmic tail lysine residues. MICA and AICL down-regulation by K5 reduces NK cell-mediated cytotoxicity towards target cells, thus providing KSHV with an NK cell evasion mechanism.

scholarly journals The Kaposi's Sarcoma-Associated Herpesvirus K5 E3 Ubiquitin Ligase Modulates Targets by Multiple Molecular Mechanisms

2007 ◽  
Vol 81 (12) ◽  
pp. 6573-6583 ◽  
Author(s):  
Robert E. Means ◽  
Sabine M. Lang ◽  
Jae U. Jung
Keyword(s):  
Cell Surface ◽  
Ubiquitin Ligase ◽  
Kaposi's Sarcoma ◽  
E3 Ubiquitin Ligase ◽  
Kaposi’S Sarcoma ◽  
Down Regulation ◽  
Class I Mhc ◽  
Mhc I ◽  
Kaposi's Sarcoma Associated Herpesvirus ◽  
Kaposi’S Sarcoma Associated Herpesvirus

ABSTRACT Kaposi's sarcoma-associated herpesvirus encodes two highly related membrane-associated, RING-CH-containing (MARCH) family E3 ubiquitin ligases, K3 and K5, that can down regulate a variety of cell surface proteins through enhancement of their endocytosis and degradation. In this report we present data that while K5 modulation of major histocompatibility complex class I (MHC-I) closely mirrors the mechanisms used by K3, alternative molecular pathways are utilized by this E3 ligase in the down regulation of intercellular adhesion molecule 1 (ICAM-1) and B7.2. Internalization assays demonstrate that down regulation of each target can occur through increased endocytosis from the cell surface. However, mutation of a conserved tyrosine-based endocytosis motif in K5 resulted in a protein lacking the ability to direct an increased rate of MHC-I or ICAM-1 internalization but still able to down regulate B7.2 in a ubiquitin-dependent but endocytosis-independent manner. Further, mutation of two acidic clusters abolished K5-mediated MHC-I degradation while only slightly decreasing ICAM-1 or B7.2 protein destruction. This same mutant abolished detectable ubiquitylation of all targets. These data indicate that while K5 can act as an E3 ubiquitin ligase to directly mediate cell surface molecule destruction, regulation of its targets occurs through multiple pathways, including ubiquitin-independent mechanisms.

scholarly journals Downregulation of Gamma Interferon Receptor 1 by Kaposi's Sarcoma-Associated Herpesvirus K3 and K5

2006 ◽  
Vol 81 (5) ◽  
pp. 2117-2127 ◽  
Author(s):  
Qinglin Li ◽  
Robert Means ◽  
Sabine Lang ◽  
Jae U. Jung
Keyword(s):  
Kaposi's Sarcoma ◽  
Kaposi’S Sarcoma ◽  
Surface Expression ◽  
Life Cycles ◽  
Gamma Interferon ◽  
Cell Mediated Immunity ◽  
Amino Terminal ◽  
Interferon Receptor ◽  
Kaposi's Sarcoma Associated Herpesvirus ◽  
Kaposi’S Sarcoma Associated Herpesvirus

ABSTRACT Upon viral infection, the major defense mounted by the host immune system is activation of the interferon (IFN)-mediated antiviral pathway. In order to complete their life cycles, viruses must modulate the host IFN-mediated immune response. The K3 and K5 proteins of a human tumor-inducing herpesvirus, Kaposi's sarcoma-associated herpesvirus (KSHV), have been shown to downregulate the surface expression of host immune modulatory receptors by increasing their endocytosis rates, which leads to suppression of cell-mediated immunity. In this report, we demonstrate that K3 and K5 both specifically target gamma interferon receptor 1 (IFN-γR1) and induce its ubiquitination, endocytosis, and degradation, resulting in downregulation of IFN-γR1 surface expression and, thereby, inhibition of IFN-γ action. Mutational analysis indicated that K5 appeared to downregulate IFN-γR1 more strongly than K3 and that the amino-terminal ring finger motif and the carboxyl-terminal region of K5 were necessary for IFN-γR1 downregulation. These results suggest that KSHV K3 and K5 suppress both cytokine-mediated and cell-mediated immunity, which ensures efficient viral avoidance of host immune controls.

scholarly journals Kaposi's Sarcoma-Associated Herpesvirus Inhibitor of cGAS (KicGAS), Encoded by ORF52, Is an Abundant Tegument Protein and Is Required for Production of Infectious Progeny Viruses

2016 ◽  
Vol 90 (11) ◽  
pp. 5329-5342 ◽  
Author(s):  
Wenwei Li ◽  
Denis Avey ◽  
Bishi Fu ◽  
Jian-jun Wu ◽  
Siming Ma ◽  
...  
Keyword(s):  
Life Cycle ◽  
Immune Evasion ◽  
Kaposi's Sarcoma ◽  
Kaposi’S Sarcoma ◽  
Lytic Replication ◽  
Tegument Protein ◽  
Tegument Proteins ◽  
Viral Particles ◽  
Kaposi's Sarcoma Associated Herpesvirus ◽  
Kaposi’S Sarcoma Associated Herpesvirus

ABSTRACTAlthough Kaposi's sarcoma-associated herpesvirus (KSHV) ORF52 (also known as KSHV inhibitor of cGAS [KicGAS]) has been detected in purified virions, the roles of this protein during KSHV replication have not been characterized. Using specific monoclonal antibodies, we revealed that ORF52 displays true late gene expression kinetics and confirmed its cytoplasmic localization in both transfected and KSHV-infected cells. We demonstrated that ORF52 comigrates with other known virion proteins following sucrose gradient centrifugation. We also determined that ORF52 resides inside the viral envelope and remains partially associated with capsid when extracellular virions are treated with various detergents and/or salts. There results indicate that ORF52 is a tegument protein abundantly present in extracellular virions. To characterize the roles of ORF52 in the KSHV life cycle, we engineered a recombinant KSHV ORF52-null mutant virus and found that loss of ORF52 results in reduced virion production and a further defect in infectivity. Upon analysis of the virion composition of ORF52-null viral particles, we observed a decrease in the incorporation of ORF45, as well as other tegument proteins, suggesting that ORF52 is important for the packaging of other virion proteins. In summary, our results indicate that, in addition to its immune evasion function, KSHV ORF52 is required for the optimal production of infectious virions, likely due to its roles in virion assembly as a tegument protein.IMPORTANCEThe tegument proteins of herpesviruses, including Kaposi's sarcoma-associated herpesvirus (KSHV), play key roles in the viral life cycle. Each of the three subfamilies of herpesviruses (alpha, beta, and gamma) encode unique tegument proteins with specialized functions. We recently found that one such gammaherpesvirus-specific protein, ORF52, has an important role in immune evasion during KSHV primary infection, through inhibition of the host cytosolic DNA sensing pathway. In this report, we further characterize ORF52 as a tegument protein with vital roles during KSHV lytic replication. We found that ORF52 is important for the production of infectious viral particles, likely through its role in virus assembly, a critical process for KSHV replication and pathogenesis. More comprehensive investigation of the functions of tegument proteins and their roles in viral replication may reveal novel targets for therapeutic interventions against KSHV-associated diseases.

scholarly journals Construction and Manipulation of a New Kaposi's Sarcoma-Associated Herpesvirus Bacterial Artificial Chromosome Clone

2012 ◽  
Vol 86 (18) ◽  
pp. 9708-9720 ◽  
Author(s):  
Kevin F. Brulois ◽  
Heesoon Chang ◽  
Amy Si-Ying Lee ◽  
Armin Ensser ◽  
Lai-Yee Wong ◽  
...  
Keyword(s):  
Bacterial Artificial Chromosome ◽  
Kaposi's Sarcoma ◽  
Kaposi’S Sarcoma ◽  
Artificial Chromosome ◽  
Surface Expression ◽  
Class I Mhc ◽  
Mhc I ◽  
E3 Ligases ◽  
Kaposi's Sarcoma Associated Herpesvirus ◽  
Kaposi’S Sarcoma Associated Herpesvirus

Efficient genetic modification of herpesviruses such as Kaposi's sarcoma-associated herpesvirus (KSHV) has come to rely on bacterial artificial chromosome (BAC) technology. In order to facilitate this approach, we generated a new KSHV BAC clone, called BAC16, derived from the rKSHV.219 virus, which stems from KSHV and Epstein-Barr virus-coinfected JSC1 primary effusion lymphoma (PEL) cells. Restriction enzyme and complete sequencing data demonstrate that the KSHV of JSC1 PEL cells showed a minimal level of sequence variation across the entire viral genome compared to the complete genomic sequence of other KSHV strains. BAC16 not only stably propagated in bothEscherichia coliand mammalian cells without apparent genetic rearrangements, but also was capable of robustly producing infectious virions (∼5 × 107/ml). We also demonstrated the utility of BAC16 by generating deletion mutants of either the K3 or K5 genes, whose products are E3 ligases of the membrane-associated RING-CH (MARCH) family. While previous studies have shown that individual expression of either K3 or K5 results in efficient downregulation of the surface expression of major histocompatibility complex class I (MHC-I) molecules, we found that K5, but not K3, was the primary factor critical for the downregulation of MHC-I surface expression during KSHV lytic reactivation or followingde novoinfection. The data presented here demonstrate the utility of BAC16 for the generation and characterization of KSHV knockout and mutant recombinants and further emphasize the importance of functional analysis of viral genes in the context of the KSHV genome besides the study of individual gene expression.

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