Arenavirus entry occurs through a cholesterol-dependent, non-caveolar, clathrin-mediated endocytic mechanism

Vela, Eric M.; Zhang, Lihong; Colpitts, Tonya M.; Davey, Robert A.; Aronson, Judith F.

doi:10.1016/j.virol.2007.07.014

Cited by 57 publications

(51 citation statements)

References 64 publications

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“…3c). Furthermore, as severe cholesterol depletion has been shown to also inhibit CME (Vela et al, 2007), we confirmed that MbCD treatment did not inhibit uptake of Alexa-568 transferrin (data not shown). These data suggest that MNV-1 infection is cholesterol-sensitive and likely to be mediated by a lipid-raft-dependent pathway.…”

Section: Depletion Of Cellular Cholesterol Inhibits Mnv-1 Endocytosissupporting

confidence: 79%

Murine norovirus-1 cell entry is mediated through a non-clathrin-, non-caveolae-, dynamin- and cholesterol-dependent pathway

Gerondopoulos

Jackson

Monaghan

et al. 2010

Journal of General Virology

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For many viruses, endocytosis and exposure to the low pH within acidic endosomes is essential for infection. It has previously been reported that feline calicivirus uses clathrin-mediated endocytosis for entry into mammalian cells. Here, we report that infection of RAW264.7 macrophages by the closely related murine norovirus-1 (MNV-1) does not require the clathrin pathway, as infection was not inhibited by expression of dominant-negative Eps15 or by knockdown of the adaptin-2 complex. Further, infection was not inhibited by reagents that raise endosomal pH. RAW264.7 macrophages were shown not to express caveolin, and flotillin depletion did not inhibit infection, suggesting that caveolae and the flotillin pathway are not required for cell entry. However, MNV-1 infection was inhibited by methyl-b-cyclodextrin and the dynamin inhibitor, dynasore. Addition of these drugs to the cells after a period of virus internalization did not inhibit infection, suggesting the involvement of cholesterol-sensitive lipid rafts and dynamin in the entry mechanism. Macropinocytosis (MPC) was shown to be active in RAW264.7 macrophages (as indicated by uptake of dextran) and could be blocked by 5-(N-ethyl-N-isopropyl) amiloride (EIPA), which is reported to inhibit this pathway. However, infection was enhanced in the presence of EIPA. Similarly, actin disruption, which also inhibits MPC, resulted in enhanced infection. These results suggest that MPC could contribute to virus degradation or that inhibition of MPC could lead to the upregulation of other endocytic pathways of virus uptake. INTRODUCTIONThe family Caliciviridae is divided into four genera: Vesivirus, Lagovirus, Sapovirus and Norovirus. The human noroviruses are the most common cause of acute viral gastroenteritis, especially in industrialized countries (Lopman et al., 2003); there is currently no treatment or vaccine for these viruses. In addition, there is still no routine tissue culture system for the propagation of human noroviruses, but the recent discovery of murine norovirus-1 (MNV-1) has provided an efficient model system for the study of norovirus replication, as this virus replicates efficiently in murine macrophages and dendritic cells (DCs) (Karst et al., 2003;Wobus et al., 2004). MNV-1 is highly prevalent in laboratory mice and has been shown to be lethal to mice with impaired innate immunity (Hsu et al., 2006;Karst et al., 2003;Muller et al., 2007).Noroviruses are non-enveloped and contain a singlestranded RNA genome of about 7.3 kb, which is linked to the viral VPg protein at the 59 end and is polyadenylated at the 39 end (Karst et al., 2003;Wobus et al., 2004). The genome is organized into four open reading frames (ORF-1-4). ORF-1 encodes the non-structural proteins, whereas ORF-2 and ORF-3 encode structural proteins (Sosnovtsev et al., 2006). ORF-4 was recently identified within the MNV-1 genome and encodes a single protein of unknown function (Thackray et al., 2007).For many viruses, infection requires virus uptake by endocytosis. A number of different endo...

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Section: Depletion Of Cellular Cholesterol Inhibits Mnv-1 Endocytosissupporting

confidence: 79%

Murine norovirus-1 cell entry is mediated through a non-clathrin-, non-caveolae-, dynamin- and cholesterol-dependent pathway

Gerondopoulos

Jackson

Monaghan

et al. 2010

Journal of General Virology

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“…The involvement of lipids in clathrin-mediated pathways has been previously reported, especially for the uptake of toxins and viruses toward the cytoplasm (45,46). Also, internalization of the apolipoprotein E receptor 2 internalizes through a clathrin-mediated pathway after association with caveolar and noncaveolar lipid rafts (55).…”

Section: Discussionmentioning

confidence: 88%

“…Such a mechanism has been previously described for the entry of viruses and bacterial toxins in the cell (45,46).…”

Section: Micb Endocytosis and Clathrin-independent Pathwaysmentioning

confidence: 81%

Brief Residence at the Plasma Membrane of the MHC Class I-Related Chain B Is Due to Clathrin-Mediated Cholesterol-Dependent Endocytosis and Shedding

Agüera-González

Boutet

Reyburn

et al. 2009

The Journal of Immunology

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Recognition of MHC class I-related chain (MIC) molecules on the surface of target cells by the activating receptor NKG2D leads to their lysis by immune effector cells. Up-regulation of NKG2D ligands is broadly related to stress, although the detailed molecular mechanisms that control the presence of these molecules at the plasma membrane are unclear. To investigate the posttranslational mechanisms that control surface expression of the human NKG2D ligand MICB, we studied the subcellular localization and trafficking of this molecule. We found that in several cellular systems, the expression of MICB molecules on the cell surface is accompanied by an intracellular accumulation of the molecule in the trans-Golgi network and late endosome-related compartments. Surprisingly, MICB has a much shorter half-life at the plasma membrane than MHC molecules and this depends on both recycling to internal compartments and shedding to the extracellular medium. Internalization of MICB depends partially on clathrin, but importantly, the lipid environment of the membrane also plays a crucial role in this process. We suggest that the brief residence of MICB at the plasma membrane modulates, at least in part, the function of this molecule in the immune system. The Journal of Immunology, 2009, 182: 4800 -4808. M ajor histocompatibility complex class I-related chain (MIC)4 A and B are two MHC-like molecules encoded within the human MHC, but distinct from classical HLA class I proteins in that they bind neither ␤ 2 -microglobulin nor antigenic peptides (1-4). MIC proteins bind the activating receptor NKG2D that is constitutively expressed on all NK cells and CD8 ϩ T cell subpopulations and is upregulated after activation on CD4 ϩ T cells (5). Engagement of NKG2D by its ligands leads to the activation of lysis and cytokine secretion by NK cells and T cells either directly or as a costimulatory factor (for review, see Ref. 6). Thus, the presence of MIC at the surface of putative target cells must be tightly regulated so that the immune response is not triggered or hidden inappropriately (which would lead to autoimmunity in the first instance and immune evasion in the latter). In fact, with the exception of gastrointestinal epithelium, the vast majority of normal cells do not express MIC molecules at the cell surface; instead, the expression of these proteins is up-regulated in a number of pathological situations, mainly cancer and autoimmunity (for review, see Refs. 7 and 8). For example, MIC expression has been found in tumors of various origins and the presence of pathogens like Mycobacterium tuberculosis has been shown to up-regulate its expression (9). Recently, a number of external stimuli such as DNA-damaging agents and proteasome inhibitors have been shown to induce expression of NKG2D ligands (10, 11). Thus, although the precise mechanisms that regulate MIC expression are still unknown, the presence of MIC at the plasma membrane can be related broadly with stress and this coincides with the presence of heat shock elements in the M...

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“…First, depletion of cellular cholesterol by methyl-␤-cyclodextrin has been reported to inhibit arenavirus replication (61,69), and because the arenavirus receptors TfR1 and ␣-dystroglycan (15, 54, 64) do not themselves associate with lipid rafts, we surmised that the requirement for cholesterol might arise in virus egress. Second, myristoylation is essential for both GPC and the Z matrix protein (52,77), and the addition of a saturated fatty acid moiety in raft proteins is often required for association (39,46).…”

Section: Discussionmentioning

confidence: 99%

Assembly of Arenavirus Envelope Glycoprotein GPC in Detergent-Soluble Membrane Microdomains

Agnihothram

Dancho²,

Grant

et al. 2009

J Virol

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The family Arenaviridae includes a number of highly pathogenic viruses that are responsible for acute hemorrhagic fevers in humans. Genetic diversity among arenavirus species in their respective rodent hosts supports the continued emergence of new pathogens. In the absence of available vaccines or therapeutic agents, the hemorrhagic fever arenaviruses remain a serious public health and biodefense concern. Arenaviruses are enveloped virions that assemble and bud from the plasma membrane. In this study, we have characterized the microdomain organization of the virus envelope glycoprotein (GPC) on the cell surface by using immunogold electron microscopy. We find that Junín virus (JUNV) GPC clusters into discrete microdomains of 120 to 160 nm in diameter and that this property of GPC is independent of its myristoylation and of coexpression with the virus matrix protein Z. In cells infected with the Candid#1 strain of JUNV, and in purified Candid#1 virions, these GPC microdomains are soluble in cold Triton X-100 detergent and are thus distinct from conventional lipid rafts, which are utilized by numerous other viruses for assembly. Virion morphogenesis ultimately requires colocalization of viral components, yet our dual-label immunogold staining studies failed to reveal a spatial association of Z with GPC microdomains. This observation may reflect either rapid Z-dependent budding of virus-like particles upon coassociation or a requirement for additional viral components in the assembly process. Together, these results provide new insight into the molecular basis for arenavirus morphogenesis.

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Arenavirus entry occurs through a cholesterol-dependent, non-caveolar, clathrin-mediated endocytic mechanism

Cited by 57 publications

References 64 publications

Murine norovirus-1 cell entry is mediated through a non-clathrin-, non-caveolae-, dynamin- and cholesterol-dependent pathway

Murine norovirus-1 cell entry is mediated through a non-clathrin-, non-caveolae-, dynamin- and cholesterol-dependent pathway

Brief Residence at the Plasma Membrane of the MHC Class I-Related Chain B Is Due to Clathrin-Mediated Cholesterol-Dependent Endocytosis and Shedding

Assembly of Arenavirus Envelope Glycoprotein GPC in Detergent-Soluble Membrane Microdomains

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