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Impact of RNase L overexpression on viral and cellular growth and death
A Zhou1, J M Paranjape, B A Hassel
1Department of Cancer Biology, The Lerner Research Institute, Cleveland Clinic Foundation, OH 44195, USA.
Abstract:
The biologic actions of interferons (IFNs) are complex and involve multiple biochemical mechanisms, including the 2-5A system, a regulated RNA decay pathway. The 2-5A system is implicated in the antipicornavirus activity of IFN and in the control of apoptosis. To further investigate involvement of the 2-5A system in the control of viral and cellular growth and death, human RNase L cDNA was stably expressed in murine 3T3 cells from a constitutive cytomegalovirus (CMV) promoter. A clonal cell line, 3T3/pLZ, was isolated that overexpressed RNase L by >100-fold compared with levels of the endogenous murine RNase L. Interestingly, human RNase L levels in 3T3/pLZ cells decreased 3-fold as cells entered a confluent, growth arrest state, suggesting autoregulation. Overexpression of human RNase L greatly enhanced both the cell growth inhibitory activity of IFN and the proapoptotic activity of staurosporine. Furthermore, high levels of RNase L suppressed the replication of diverse viruses: encephalomyocarditis virus, vesicular stomatitis virus, human parainfluenza virus-3, and vaccinia virus. Additional reductions in viral growth were obtained by treating 3T3/pLZ cells with IFN (a + beta) before infections. These results directly demonstrate the anticellular and antiviral potential of the 2-5A system.
Insights
The 2-5A system, involving RNase L, inhibits viral replication and controls cell growth and death. Overexpressing RNase L enhances interferon
Area of Science:
- Biochemistry
- Molecular Biology
- Virology
Background:
- Interferons (IFNs) exert complex biologic actions through mechanisms like the 2-5A system, a regulated RNA decay pathway.
- The 2-5A system is crucial for IFN's antipicornavirus activity and apoptosis regulation.
- Investigating the 2-5A system's role in viral and cellular growth and death is essential.
Purpose of the Study:
- To investigate the 2-5A system's role in controlling viral and cellular growth and death.
- To determine the effects of RNase L overexpression on cellular processes and viral replication.
Main Methods:
- Stable expression of human RNase L cDNA in murine 3T3 cells using a CMV promoter.
- Isolation of a clonal cell line (3T3/pLZ) with >100-fold overexpression of RNase L.
- Treatment of cells with IFN (alpha + beta) prior to viral infections.
Main Results:
- Human RNase L levels decreased in confluent, growth-arrested cells, suggesting autoregulation.
- RNase L overexpression significantly enhanced IFN's cell growth inhibitory activity and staurosporine's proapoptotic activity.
- High RNase L levels suppressed the replication of encephalomyocarditis virus, vesicular stomatitis virus, human parainfluenza virus-3, and vaccinia virus.
Conclusions:
- The 2-5A system, particularly RNase L, possesses significant anticellular and antiviral potential.
- Overexpression of RNase L enhances the efficacy of interferon therapy.
- The 2-5A system is a key regulator of both viral replication and host cell fate.