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A possible role for c-Myc oncoproteins in post-transcriptional regulation of ribosomal RNA
A W Gibson1, R Ye, R N Johnston
1Department of Medical Biochemistry, University of Calgary, Alberta, Canada.
Abstract:
Overexpression of members of the myc family of oncogenes contributes to the development of many vertebrate malignancies. Although several functions for myc gene products have been proposed, the targets for Myc activity during oncogenesis or normal development remain to be identified. Oocytes of Xenopus laevis, which are non-dividing cells that accumulate abundant c-Myc protein, provide an unusual opportunity to examine c-Myc function. We have investigated whether the accumulation of massive amounts of ribosomal RNA (rRNA) by Xenopus laevis oocytes may be related to their elevated expression of myc proto-oncogenes. Our data show that anti-Myc antibodies and some (but not all) c-Myc peptides from conserved regions of the c-Myc protein enhance the turnover of rRNA synthesized in homogenates of oocyte nuclei. These results suggest that one or more members of the Myc protein family may be involved in post-transcriptional regulation of rRNA metabolism. The regulation by c-Myc of rRNA could account, in part, for the generalized stimulation of cells during tumorigenesis.
Insights
Myc proteins may regulate ribosomal RNA (rRNA) turnover in Xenopus oocytes. This finding suggests a role for Myc in post-transcriptional rRNA metabolism, potentially linking to cancer development.
Area of Science:
- Molecular Biology
- Oncology
- Developmental Biology
Background:
- Myc oncogenes are implicated in various cancers.
- The precise functions and targets of Myc proteins are not fully understood.
- Xenopus laevis oocytes accumulate high levels of c-Myc protein without dividing.
Purpose of the Study:
- To investigate the link between elevated myc proto-oncogene expression and massive ribosomal RNA (rRNA) accumulation in Xenopus oocytes.
- To explore the potential role of c-Myc in regulating rRNA metabolism.
Main Methods:
- Utilized Xenopus laevis oocytes as a model system.
- Employed anti-Myc antibodies and specific c-Myc peptides.
- Assessed rRNA turnover in homogenates of oocyte nuclei.
Main Results:
- Anti-Myc antibodies and certain c-Myc peptides enhanced rRNA turnover.
- This effect was observed in synthesized rRNA within oocyte nuclear homogenates.
- Not all tested c-Myc peptides showed this effect, indicating specificity.
Conclusions:
- Myc protein family members may play a role in the post-transcriptional regulation of rRNA metabolism.
- This regulation of rRNA by c-Myc could contribute to cellular stimulation observed in tumorigenesis.
- Xenopus oocytes offer a unique system for studying c-Myc function in rRNA regulation.