A pH-Sensitive Heparin-Binding Sequence from Baculovirus gp64 Protein Is Important for Binding to Mammalian Cells but Not to Sf9 Insect Cells

Wu, Chunxiao; Wang, Shu

doi:10.1128/jvi.06357-11

Cited by 44 publications

(38 citation statements)

References 54 publications

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“…pH-Dependent heparin-binding capacity is not a feature restricted to DT and CRM197 because avidin (42), selenoprotein P (43), histidine-proline-rich glycoprotein (44), serum amyloid A (45), and gp64 protein from baculovirus (46) are also endowed with this property. Furthermore, pH-dependent conformation is a characteristic shared by several classes of bacterial toxins (47,48) as well as by viral proteins (49,50).…”

Section: Discussionmentioning

confidence: 99%

Acidosis Increases MHC Class II–Restricted Presentation of a Protein Endowed with a pH-Dependent Heparan Sulfate–Binding Ability

Knittel

Savatier

Upert

et al. 2015

The Journal of Immunology

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Heparan sulfate proteoglycans (HSPGs) are ubiquitously expressed molecules that participate in numerous biological processes. We previously showed that HSPGs expressed on the surface of APCs can serve as receptors for a hybrid protein containing an HS ligand and an Ag, which leads to more efficient stimulation of Th cells. To investigate whether such behavior is shared by proteins with inherent HS-binding ability, we looked for proteins endowed with this characteristic. We found that diphtheria toxin and its nontoxic mutant, called CRM197, can interact with HS. However, we observed that their binding ability is higher at pH 6 than at pH 7.4. Therefore, as extracellular acidosis occurs during infection by various micro-organisms, we assessed whether HS-binding capacity affects MHC class II–restricted presentation at different pHs. We first observed that pH decrease allows CRM197 binding to HSPG-expressing cells, including APCs. Then, we showed that this interaction enhances Ag uptake and presentation to Th cells. Lastly, we observed that pH decrease does not affect processing and presentation abilities of the APCs. Our findings show that acidic pH causes an HSPG-mediated uptake and an enhancement of T cell stimulation of Ags with the inherent ability to bind HSPGs pH-dependently. Furthermore, they suggest that proteins from micro-organisms with this binding characteristic might be supported more efficiently by the adaptive immune system when acidosis is triggered during infection.

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Section: Discussionmentioning

confidence: 99%

Acidosis Increases MHC Class II–Restricted Presentation of a Protein Endowed with a pH-Dependent Heparan Sulfate–Binding Ability

Knittel

Savatier

Upert

et al. 2015

The Journal of Immunology

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“…In a recent study, Wu and Wang identified the sequence in GP64 responsible for binding to heparin, and this binding is essential for baculovirus internalization into mammalian cells (78). Although there are many studies on Baculovirus binds to a not-yet-identified cellular receptor(s) present in the lipid raft.…”

Section: Discussionmentioning

confidence: 99%

“…AcMNPV was shown to become internalized by receptor-mediated endocytosis (26,49,58), and GP64 is initially involved in virus attachment on the cell surface. In a recent study, heparan sulfate was shown to be essential for gene transduction by baculovirus into mammalian cells (78). After receptor-mediated internalization of AcMNPV (26), GP64 undergoes conformational change into a fusion-competent state at low pH, and the nucleocapsid is released into the cytoplasm after cell fusion (14,43,63,73).…”

mentioning

confidence: 99%

Baculovirus GP64-Mediated Entry into Mammalian Cells

Kataoka

Kaname

Taguwa

et al. 2012

J Virol

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The baculovirus Autographa californica multiple nucleopolyhedrovirus (AcMNPV) serves as an efficient viral vector, not only for abundant gene expression in insect cells, but also for gene delivery into mammalian cells. Lentivirus vectors pseudotyped with the baculovirus envelope glycoprotein GP64 have been shown to acquire more potent gene transduction than those with vesicular stomatitis virus (VSV) envelope glycoprotein G. However, there are conflicting hypotheses about the molecular mechanisms of the entry of AcMNPV. Moreover, the mechanisms of the entry of pseudotyped viruses bearing GP64 into mammalian cells are not well characterized. Determination of the entry mechanisms of AcMNPV and the pseudotyped viruses bearing GP64 is important for future development of viral vectors that can deliver genes into mammalian cells with greater efficiency and specificity. In this study, we generated three pseudotyped VSVs, NPVpv, VSVpv, and MLVpv, bearing envelope proteins of AcMNPV, VSV, and murine leukemia virus, respectively. Depletion of membrane cholesterol by treatment with methyl-␤-cyclodextrin, which removes cholesterol from cellular membranes, inhibited GP64-mediated internalization in a dose-dependent manner but did not inhibit attachment to the cell surface. Treatment of cells with inhibitors or the expression of dominant-negative mutants for dynamin-and clathrin-mediated endocytosis abrogated the internalization of AcMNPV and NPVpv into mammalian cells, whereas inhibition of caveolin-mediated endocytosis did not. Furthermore, inhibition of macropinocytosis reduced GP64-mediated internalization. These results suggest that cholesterol in the plasma membrane, dynamin-and clathrin-dependent endocytosis, and macropinocytosis play crucial roles in the entry of viruses bearing baculovirus GP64 into mammalian cells.

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“…Heparin and heparinase I and II treatment of cells have also been shown to prevent the virus binding (2,3). The role of HS in baculovirus entry was further studied in our article (1).…”

mentioning

confidence: 93%

Reply to “Heparan Sulfate in Baculovirus Binding and Entry of Mammalian Cells”

Makkonen¹,

Turkki²,

Laakkonen³

et al. 2014

J Virol

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In our article "6-O-and N-Sulfated Syndecan-1 Promotes Baculovirus Binding and Entry into Mammalian Cells" by Makkonen et al. in Journal of Virology (1), we investigated the interaction of baculovirus and mammalian cell surface heparan sulfate proteoglycans (HSPG). The data show that baculovirus requires HSPG sulfation, particularly N-and 6-O-sulfation, to bind and transduce mammalian cells. We also show that baculovirus associates specifically with syndecan-1 (SDC-1) but not with other syndecans or glypicans.As discussed in the article, HS has previously been shown to be involved in glycoprotein 64 (gp64)-mediated baculovirus binding onto mammalian cells. Heparin and heparinase I and II treatment of cells have also been shown to prevent the virus binding (2, 3). The role of HS in baculovirus entry was further studied in our article (1). Binding and baculovirus-mediated gene delivery were seen to decrease after NaClO 3 treatment, an inhibitor of sulfation. Sulfation studies also indicated that N-sulfation and 6-O-sulfation of HSPGs are important for the virus binding. Thus, it can be concluded that several studies including ours indeed support the role of HS in baculovirus interaction with mammalian cells. Since there are several HS-bearing proteins at the cell surface, we wanted to investigate further whether the virus prefers HS chains that are linked to a specific core protein. Core protein defines the type, size, amount, and orientation of the HS chains. Additionally, the core protein locates the HS chains to a specific location on the cell membrane, thus enabling, for example, the interaction with possible coreceptors. Thus, the optimal HS chain composition for virus binding can be found from specific core protein(s). The role of the core protein is equally important during virus internalization, since receptor signaling defines the entry route taken.Decreased virus entry seen by Dr. M. Nasimuzzaman in hamster pgsD-677 cells with low or severely impaired HS expression (4) supports our data well. However, even high HSPG expression/ sulfation does not guarantee efficient entry of baculovirus into cells if the virus entry and intracellular trafficking are impaired in nonpermissive cells. As stated in our article, although some cells (e.g., EA.hy926) have high HSPG/SDC-1 expression on their cell surface, the transduction rate/entry of baculovirus can be very low. This dilemma has been studied further in another one of our articles (5), in which baculovirus entry is shown to be arrested at the cell surface where the virus forms aggregates with SDC-1. Thus, the amount of HS is not necessarily directly proportional to efficient virus entry and other cellular factors such as protein kinase C phosphorylation and vimentin organization contribute to the cell susceptibility to baculovirus transduction (5).Antibody inhibition studies were performed in our article with a polyclonal rabbit SDC-1 antibody (sc-5632; Santa Cruz Biotechnology, CA). Although the antibody is against SDC-1 ectodomain and not HS, it was able to d...

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A pH-Sensitive Heparin-Binding Sequence from Baculovirus gp64 Protein Is Important for Binding to Mammalian Cells but Not to Sf9 Insect Cells

Cited by 44 publications

References 54 publications

Acidosis Increases MHC Class II–Restricted Presentation of a Protein Endowed with a pH-Dependent Heparan Sulfate–Binding Ability

Acidosis Increases MHC Class II–Restricted Presentation of a Protein Endowed with a pH-Dependent Heparan Sulfate–Binding Ability

Baculovirus GP64-Mediated Entry into Mammalian Cells

Reply to “Heparan Sulfate in Baculovirus Binding and Entry of Mammalian Cells”

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