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Interferon induces a unique protein in mouse cells bearing a gene for resistance to influenza virus
Abstract:
Mouse cells carrying the dominant resistance gene Mx develop a more efficient antiviral state toward influenza viruses in response to interferon than do Mx-negative cells. We have identified an Mx gene-associated product by labeling cultured peritoneal macrophages and embryonic cells with [35S]methionine in the presence or absence of interferon. The radioactive proteins from unfractionated cytoplasmic extracts were separated electrophoretically in two dimensions and were revealed by fluorography. A protein with a Mr of 72,500 and an isoelectric point of 6.3 was induced by mouse interferon type I (a mixture of alpha and beta interferons) in cells carrying the gene Mx but not in cells lacking Mx. The induction of this protein could be blocked by actinomycin D. The maximal rate of synthesis was reached in embryonic cells 4-5 hr after treatment with 10(3) reference units of interferon per ml. When the allele Mx (present in the inbred mouse strain A2G) was repeatedly backcrossed on different genetic backgrounds (BALB/c, C57BL/6, A/J), a clear correlation between the inducibility by interferon of this protein and the presence of the allele Mx was observed. The results suggest that this protein induced by the interaction of interferon with Mx plays a role in the selective antiviral state against influenza viruses that is observed in interferon-treated Mx-bearing cells.
Insights
Mouse cells with the Mx gene show a stronger antiviral defense against influenza after interferon treatment. Researchers identified a specific protein induced by interferon in Mx-positive cells, crucial for this enhanced resistance.
Area of Science:
- Immunology
- Virology
- Molecular Biology
Background:
- Mouse cells with the Mx gene exhibit enhanced antiviral states against influenza upon interferon stimulation.
- The precise molecular mechanisms underlying this interferon-induced resistance are not fully understood.
Purpose of the Study:
- To identify and characterize a protein product associated with the Mx gene that is induced by interferon.
- To investigate the role of this protein in the antiviral state against influenza viruses.
Main Methods:
- Cultured mouse peritoneal macrophages and embryonic cells were labeled with [35S]methionine in the presence or absence of interferon.
- Radioactive proteins were separated using two-dimensional gel electrophoresis and visualized by fluorography.
- The effect of actinomycin D on protein induction was assessed.
Main Results:
- A protein (Mr 72,500, pI 6.3) was specifically induced by mouse interferon type I in Mx-bearing cells, but not in Mx-negative cells.
- Protein induction was blocked by actinomycin D, indicating de novo synthesis.
- Maximal synthesis occurred 4-5 hours post-interferon treatment in embryonic cells.
- A strong correlation was observed between the presence of the Mx allele and interferon-inducibility of this protein across different genetic backgrounds.
Conclusions:
- The identified protein, induced by the interaction of interferon with the Mx gene, plays a significant role in the selective antiviral state against influenza in Mx-bearing cells.
- This finding elucidates a key molecular component of interferon-mediated antiviral immunity in mice.