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Regulated polyadenylation controls mRNA translation during meiotic maturation of mouse oocytes
J D Vassalli1, J Huarte, D Belin
1Institute of Histology and Embryology, University of Geneva Medical School, Switzerland.
Abstract:
The translational activation of dormant tissue-type plasminogen activator mRNA during meiotic maturation of mouse oocytes is accompanied by elongation of its 3'-poly(A) tract. Injected RNA fragments that correspond to part of the 3'-untranslated region (3'UTR) of this mRNA are also subject to regulated polyadenylation. Chimeric mRNAs containing part of this 3'UTR are polyadenylated and translated following resumption of meiosis. Polyadenylation and translation of chimeric mRNAs require both specific sequences in the 3'UTR and the canonical 3'-processing signal AAUAAA. Injection of 3'-blocked mRNAs and in vitro polyadenylated mRNAs shows that the presence of a long poly(A) tract is necessary and sufficient for translation. These results establish a role for regulated polyadenylation in the post-transcriptional control of gene expression.
Insights
Regulated polyadenylation of tissue-type plasminogen activator mRNA, involving its 3'-untranslated region (3'UTR), is crucial for translational activation during mouse oocyte maturation. A long poly(A) tail is necessary and sufficient for this translation.
Area of Science:
- Molecular Biology
- Developmental Biology
- Gene Expression
Background:
- Meiotic maturation of mouse oocytes involves translational activation of dormant mRNAs.
- Tissue-type plasminogen activator (tPA) mRNA undergoes 3 poly(A) tract elongation during this process.
Purpose of the Study:
- To investigate the role of regulated polyadenylation in controlling gene expression during oocyte maturation.
- To identify the sequences and signals required for polyadenylation and translation of tPA mRNA.
Main Methods:
- Injection of RNA fragments and chimeric mRNAs into mouse oocytes.
- Analysis of polyadenylation status and translation of injected constructs.
- Use of 3 -blocked and in vitro polyadenylated mRNAs to assess poly(A) tract function.
Main Results:
- Specific sequences within the 3 -untranslated region (3 UTR) and the AAUAAA signal are required for polyadenylation and translation.
- Elongation of the poly(A) tract is essential for translational activation.
- A long poly(A) tract is both necessary and sufficient for translation.
Conclusions:
- Regulated polyadenylation plays a critical role in the post-transcriptional control of gene expression.
- The 3 UTR of tPA mRNA contains regulatory elements controlling polyadenylation and translation during oocyte maturation.