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An antisense interferon-beta RNA abolishes repression of c-fos gene expression
C Lallemand1, A Kahan, L Telvi
1Unité 153 INSERM, Paris, France.
Abstract:
To determine the cellular functions which are modified when interferon-beta (IFN-beta) gene expression is inhibited, a plasmid allowing the constitutive expression of RNA complementary to IFN-beta mRNA was constructed and stably introduced into L929 cells. Some of the selected clones expressing this antisense IFN-beta mRNA, named L-ASI, were unable to produce IFN-beta and lost the ability to arrest in the G0 phase of the cell cycle. Indeed, the usual transrepression of the c-fos gene observed in quiescent cells was blocked in IFN-beta antisense L-ASI clones and the c-fos gene was permanently stimulated. This overexpression of c-fos was not modified in response to protein kinase C agonists such as phorbol esters, but increased in response to the adenylate cyclase activator forskolin. In addition, the ability to induce major histocompatibility class I genes following recombinant IFN-beta treatment was impaired in antisense IFN-beta L-ASI clones, suggesting an important alteration of this cell with regard to the interferon system. Unexpectedly, the tumorigenicity of the clones was significantly diminished. We postulate that IFN-beta antisense RNA blocks the repression of the c-fos gene and thus prevents the arrest of cells in the G0 phase of the cycle.
Insights
Inhibiting interferon-beta (IFN-beta) gene expression in L929 cells blocked c-fos gene repression, preventing cell cycle arrest. Unexpectedly, this also significantly reduced tumor formation in the modified cells.
Area of Science:
- Cell Biology
- Molecular Biology
- Immunology
Background:
- Interferon-beta (IFN-beta) is a crucial cytokine involved in immune responses and cell cycle regulation.
- Understanding the specific cellular functions modulated by IFN-beta gene expression is essential for its therapeutic applications.
Purpose of the Study:
- To investigate the cellular consequences of inhibiting interferon-beta (IFN-beta) gene expression.
- To elucidate the role of IFN-beta in cell cycle regulation, specifically G0 phase arrest and c-fos gene expression.
Main Methods:
- Construction and stable introduction of a plasmid for constitutive antisense IFN-beta mRNA expression into L929 cells (L-ASI clones).
- Analysis of IFN-beta production, cell cycle progression (G0 arrest), c-fos gene expression, and major histocompatibility class I gene induction.
- Assessment of tumorigenicity in modified L929 cell clones.
Main Results:
- L-ASI clones, unable to produce IFN-beta, lost the ability to arrest in the G0 phase of the cell cycle.
- Transrepression of the c-fos gene in quiescent cells was blocked, leading to permanent c-fos stimulation.
- Induction of major histocompatibility class I genes by recombinant IFN-beta was impaired, and tumorigenicity was significantly diminished.
Conclusions:
- IFN-beta antisense RNA prevents G0 phase arrest by blocking the repression of the c-fos gene.
- Inhibition of IFN-beta impacts multiple cellular functions, including cell cycle control and immune gene regulation.
- The study reveals an unexpected link between IFN-beta, c-fos regulation, cell cycle arrest, and tumor suppression.