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Interferon regulates c-myc gene expression in Daudi cells at the post-transcriptional level
Abstract:
c-myc gene mRNA is reduced by greater than 75% in the human lymphoblastoid cell line Daudi when growth is inhibited by treatment with human interferon beta (IFN-beta). In the present communication, we describe the effect of IFN-beta treatment on transcription of the c-myc gene and on the steady-state level of c-myc mRNA in the cytoplasm of Daudi cells. The results show that, although the rate of c-myc transcription is not significantly different in nuclei isolated either from untreated cells or from those treated with IFN-beta for 3 or 24 hr, the level of c-myc mRNA in the cytoplasm is reduced by 60% within 3 hr of IFN-beta treatment. These results suggest that IFN-beta regulates the c-myc mRNA at a post-transcriptional level. These results are in contrast to the regulation of two IFN-beta-induced genes that under identical conditions are regulated in these cells at the transcriptional level. We have also detected induction of the (2'-5')oligoadenylate synthetase (2-5A synthetase) gene in IFN-beta-treated Daudi cells. Since certain c-myc transcripts have the capacity to form double-stranded RNA regions, we propose that one mechanism by which c-myc could be regulated post-transcriptionally in IFN-beta-treated cells is by activating, through its own double-strandedness, the 2-5A synthetase/RNase L endonuclease system, which would cause selective degradation of the c-myc RNA.
Insights
Human interferon beta (IFN-beta) significantly reduces c-myc mRNA levels in Daudi cells post-transcriptionally. This suggests IFN-beta activates a pathway leading to selective c-myc RNA degradation.
Area of Science:
- Molecular Biology
- Cell Biology
- Immunology
Background:
- The c-myc gene is crucial for cell growth and proliferation.
- Human interferon beta (IFN-beta) is known to inhibit cell growth.
- Regulation of gene expression is vital for cellular responses.
Purpose of the Study:
- To investigate the effect of IFN-beta on c-myc gene transcription and mRNA levels in Daudi cells.
- To determine the regulatory level (transcriptional or post-transcriptional) of c-myc by IFN-beta.
- To explore potential mechanisms of c-myc regulation by IFN-beta.
Main Methods:
- Treatment of Daudi cells with human interferon beta (IFN-beta).
- Isolation of cell nuclei for assessing c-myc gene transcription rates.
- Measurement of steady-state c-myc mRNA levels in the cytoplasm.
- Detection of (2'-5')oligoadenylate synthetase (2-5A synthetase) gene induction.
Main Results:
- IFN-beta treatment reduced c-myc mRNA by over 75% in Daudi cells.
- c-myc gene transcription rates remained unchanged after IFN-beta treatment.
- Cytoplasmic c-myc mRNA levels decreased by 60% within 3 hours of IFN-beta exposure.
- (2'-5')oligoadenylate synthetase (2-5A synthetase) gene was induced by IFN-beta.
Conclusions:
- IFN-beta regulates c-myc mRNA at a post-transcriptional level, not transcriptionally.
- The 2-5A synthetase/RNase L endonuclease system may mediate the selective degradation of c-myc RNA.
- IFN-beta's effect on c-myc highlights complex regulatory mechanisms in interferon response.