The fate of the surface protein gp70 during entry of retrovirus into mouse fibroblasts

Andersen, Klaus B.

doi:10.1016/0042-6822(85)90426-x

Cited by 27 publications

(24 citation statements)

References 11 publications

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“…Our results were in agreement with previous work showing that fusion is associated with the mature form of TM 8 and with labeling studies demonstrating persistence of this integral membrane protein p12 (TM) in target cells for Ն18 hours after retrovirus infection. 21 Taken together, all of these results supported the hypothesis that retroviral env proteins contribute to the cell membranes of target cells, turning them into virus-like particles with fusion activity. For example, polycations were necessary for maximal effect, and their effect was proportional to their relative ability to enhance retroviral infections.…”

Section: Discussionsupporting

confidence: 72%

Fusogenic effects of murine retroviruses and cationic enhancers of transduction

Solaiman

Zink

et al. 2000

Cancer Gene Ther

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The maturation of retrovirus particles involves proteolytic cleavage of the envelope glycoprotein transmembrane component, resulting in conversion of the virus particle to a fusogenic or infectious state. Susceptible murine cells exposed to virus-containing supernatants from ecotropic retroviral helper cells occasionally fused to neighboring cells, resulting in syncytia (giant cells with multiple nuclei). Polycationic molecules dramatically enhanced the effect, leading to widespread cell death. The degree of cell fusion was dependent upon the retroviral envelope subtype (ecotropic3amphotropic, gibbon ape leukemia virus was negative) as well as on the polycationic reagent used (G9 dendrimer3 Lipofectamine3polybrene). Cell fusion effects were not mediated by the retroviral vector backbone, because virus-containing supernatants from helper cells (without vector) and vector producer cells had a similar effect. Human target cells were not fused by any type of murine retrovirus; in addition, amphotropic virus from human helper cells was not fusogenic toward murine cells. Thus, fusogenic effects were important during the propagation of vectors using murine helper cells but were not a significant factor during the transduction of human cells. Cancer Gene Therapy (2000) 7, 53-58

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Section: Discussionsupporting

confidence: 72%

Fusogenic effects of murine retroviruses and cationic enhancers of transduction

Solaiman

Zink

et al. 2000

Cancer Gene Ther

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“…The effect of leupeptin on the gp70 cleavage in the ceils was tested. Leupeptin reduced the degradation of gp70 (Andersen, 1985), but caused only minor changes of the cleavage pattern (results not shown).…”

Section: Discussionmentioning

confidence: 97%

“…We have previously shown that the viral proteins are degraded in acid vesicles in the cell (endosomes or lysosomes). Basically all gp70 was shown to be totally degraded after internalization, but whereas the amino acids were expelled from the cell, the carbohydrate moieties remained inside the cells (Andersen & Nexo, 1983;Andersen, 1985). The cleavage fragments observed in this study are therefore assumed to be intermediates in the full degradation of gp70.…”

Section: Discussionmentioning

confidence: 97%

“…They also inhibit degradation of viral proteins (Andersen & Nexa, 1983;Andersen, 1985). Thus in the proposed route of endocytosis and membrane fusion in the vesicles, it is not clear whether low pH or cleavage of the viral envelope, or both, are responsible for fusion.…”

Section: Discussionmentioning

confidence: 99%

“…All virus proteins were internalized (Andersen, 1985), indicating that the whole virion was internalized. A majority of the virions was degraded in the cell by a mechanism sensitive to lysosomotropic bases (Andersen & Nexo, 1983).…”

Section: Introductionmentioning

confidence: 99%

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Cleavage Fragments of the Retrovirus Surface Protein gp70 during Virus Entry

Andersen¹

1987

Journal of General Virology

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SUMMARYThe surface protein gp70 of an ecotropic murine retrovirus was followed during entry of[3H]glucosamine-labelled virions into SC-1 mouse fibroblasts. Upon entry, gp70 was cleaved into fragments with molecular weights 35K, 30K and 17K. The 35K and 17K fragments were also observed after trypsin or thermolysin cleavage of the virion, indicating that certain locations on the gp70 molecule are easily accessible from the outside of the virion. The conformation of gp70 on the membrane was shown to have a major effect on the cleavage. This protein is known to be important for early intera~ctions with the cell (binding and membrane fusion). The results indicate that gp70 cleavage may be important for membrane fusion.

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