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Mitogen-responsive expression of RhoB is regulated by RNA stability
Tom Malcolm1, Elham Ettehadieh, Ivan Sadowski
1Department of Biochemistry and Molecular Biology, University of British Columbia, 2146 Health Sciences Mall, Vancouver, B.C., Canada V6 T 1Z3.
Oncogene
|September 19, 2003
Summary
Growth factor stimulation stabilizes RhoB mRNA, not increases transcription. The 3' untranslated region (UTR) of RhoB mRNA controls its abundance in response to growth factors and DNA damage signals.
Area of Science:
- Molecular Biology
- Cell Biology
- Gene Regulation
Background:
- The RhoB gene, encoding a small GTPase, is rapidly induced by serum in fibroblasts.
- Understanding RhoB's growth factor responsiveness is crucial for comprehending cellular signaling pathways.
Purpose of the Study:
- To elucidate the mechanism behind growth factor-induced RhoB expression in Rat-2 fibroblasts.
- To investigate whether RhoB induction is regulated at the transcriptional or post-transcriptional level.
Main Methods:
- Northern blotting and ribonuclease protection assays to quantify RhoB mRNA levels.
- Analysis of RhoB promoter fusions and stable integrants in transient and stable transfections.
- Examination of RhoB mRNA decay rates and the role of the 3' untranslated region (UTR).
Main Results:
- RhoB mRNA levels are low in quiescent cells but transiently increase after serum stimulation.
- RhoB promoter activity is constitutive and not enhanced by serum, indicating non-transcriptional regulation.
- Serum stimulation significantly stabilizes RhoB mRNA, and the 3' UTR mediates this stabilization and response to growth factors and DNA damage.
Conclusions:
- Growth factor-inducible RhoB expression is primarily regulated by mRNA stabilization, not transcriptional activation.
- The 3' UTR of RhoB mRNA contains elements critical for controlling gene expression in response to extracellular signals and DNA damage.