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Cell surface expression of the env gene polyprotein of dual-tropic mink cell focus-forming murine leukemia virus
Abstract:
Differences have been observed in the kinetics of processing of the env gene polyprotein of ecotropic, xenotropic, and dual-tropic mink cell focus-forming (MCF) murine leukemia virus. In pulse-chase experiments, the env gene polyprotein of the dural-tropic MCF virus exhibits a marked increase in stability relative to that of either ecotropic or xenotropic virus. A comparison of cell surface expression of env gene products of ecotropic, xenotropic, and dual-tropic MCF murine leukemia virus has been made. Only gp70 is accessible to lactoperoxidase-catalyzed radioiodination of fibroblasts infected by ecotropic or xenotropic virus, whereas both gp70 and the env gene polyprotein are expressed on the surface of dual-tropic MCF virus-infected cells.
Insights
Dual-tropic MCF virus env gene polyprotein is more stable and expressed on cell surfaces, unlike ecotropic or xenotropic murine leukemia viruses. This difference impacts viral processing and cell surface display.
Area of Science:
- Virology
- Molecular Biology
- Cell Biology
Background:
- Murine leukemia viruses (MLVs) are retroviruses with diverse tropisms, including ecotropic, xenotropic, and dual-tropic MCF (mink cell focus-forming) variants.
- The env gene encodes viral envelope glycoproteins crucial for host cell entry and virus-host interactions.
- Understanding differences in env gene polyprotein processing and cell surface expression is key to deciphering MLV infection pathways.
Purpose of the Study:
- To investigate the processing kinetics of the env gene polyprotein in different MLV tropisms.
- To compare the cell surface expression of env gene products among ecotropic, xenotropic, and dual-tropic MCF MLVs.
- To identify potential differences in viral protein stability and accessibility.
Main Methods:
- Pulse-chase experiments were utilized to analyze the processing and stability of the env gene polyprotein.
- Lactoperoxidase-catalyzed radioiodination was employed to assess the cell surface expression of viral envelope proteins.
- Fibroblast cell lines infected with ecotropic, xenotropic, or dual-tropic MCF MLVs were used for comparative analysis.
Main Results:
- The env gene polyprotein of dual-tropic MCF MLV demonstrated significantly increased stability compared to ecotropic or xenotropic MLVs.
- In ecotropic and xenotropic MLV-infected cells, only the gp70 envelope glycoprotein was accessible to surface radioiodination.
- In dual-tropic MCF MLV-infected cells, both gp70 and the env gene polyprotein were found to be expressed on the cell surface.
Conclusions:
- Dual-tropic MCF MLV exhibits distinct env gene polyprotein processing kinetics and enhanced cell surface expression compared to other MLV tropisms.
- The increased stability and cell surface presence of the env gene polyprotein in dual-tropic MCF MLV may influence its infectivity and cell-cell fusion capabilities.
- These findings highlight tropism-specific variations in MLV envelope protein maturation and display, offering insights into viral pathogenesis.