Mammalian mRNA poly(A) tails, formation removal and function

• Unité de recherche: PCRD EU
• Numéro de projet: 95.0625-1
• Titre du projet anglais: Mammalian mRNA poly(A) tails, formation removal and function

Mots-clé (Anglais)

mRNA; POLY(A); Translation

Programme de recherche (Anglais)

EU-programme: 4. Frame Research Programme - 10.1 Stimulation of training and mobility

Description succincte (Anglais)

See abstract

Partenaires et organisations internationales (Anglais)

Université d'Uppsala, Biozentrum Basel, Justus Liebig University Giessen, Oxford University, University of Glasgow, Saint Savas Hospital Athens

Résumé des résultats (Abstract) (Anglais)

The role of the 3'UTR in controlling the translation of certain mRNAs in mammalian oocytes is now well established. The cis-acting sequences are being characterised, and a search for trans-acting effectors is underway. One important issue that must also be addressed is the range of cell types, in addition to primary and meiotically-maturing oocytes, in which such regulatory mechanisms operate. We are studying the translational regulation of murine tissue-type plasminogen activator (tPA) mRNA: it is partially deadenylated and silenced in primary oocytes, and readenylated and translated during meiotic maturation. The3'UTR determinants that control the extent of polyadenylation and the translational activity of tPA mRNA have been identified in our earlier studies; they have been shown to transfer similar properties to recombinant reporter transcripts injected in the cytoplasm of mouse oocytes. In addition to oocytes, many different cell types contain tPA mRNA; however, no evidence for translational control of tPA mRNA in cells other than oocytes is at present available. A system to investigate this issue has been designed. It relies on the generation of transgenic mouse strains in which a reporter-encoding sequence (Green Fluorescent Protein) is placed downstream of an ubiquitous promoter and is followed by a 3'UTR containing the cis-acting determinants that control the polyadenylation and translation of tPA mRNA. Different such transgenic strains have been prepared, and are presently being analysed. The results available to date identify a subset of tissues in which regulated translation of the transgene-encoded mRNA may operate: GFP levels appear very low as compared to the abundance of the mRNA. Control transgenic mice in which the same promoter-reporter pair is followed by a different 3'UTR (that has been shown not to modulate translation in oocytes) are being analysed in parallel. These preliminary experiments indicate that this approach may be fruitful; they also help establish the difficulties and possible pitfalls of such a strategy. One cell lineage that we are presently investigating is the female germ line: since in primary oocytes tPA mRNA is under translational control, the GFP transgenic mice should reveal at which stage in oocyte differentiation the translational repression machinery becomes operative. Analysis of small primary oocytes suggests that this machinery is present before oocytic transcription of the tPA gene is initiated; primordial germ cells are the next cell type in this lineage that should be examined.

Références bases de données (Anglais)

Swiss Database: Euro-DB of the
State Secretariat for Education and Research
Hallwylstrasse 4
CH-3003 Berne, Switzerland
Tel. [phone]
Swiss Project-Number: 95.0625-1