XB-ART-37351Biochim Biophys Acta April 1, 2008; 1779 (4): 217-29.
Translational control by cytoplasmic polyadenylation in Xenopus oocytes.
Elongation of the poly(A) tails of specific mRNAs in the cytoplasm is a crucial regulatory step in oogenesis and early development of many animal species. The best studied example is the regulation of translation by cytoplasmic polyadenylation elements (CPEs) in the 3'' untranslated region of mRNAs involved in Xenopus oocyte maturation. In this review we discuss the mechanism of translational control by the CPE binding protein (CPEB) in Xenopus oocytes as follows: 1. The cytoplasmic polyadenylation machinery such as CPEB, the subunits of cleavage and polyadenylation specificity factor (CPSF), symplekin, Gld-2 and poly(A) polymerase (PAP). 2. The signal transduction that leads to the activation of CPE-mediated polyadenylation during oocyte maturation, including the potential roles of kinases such as MAPK, Aurora A, CamKII, cdk1/Ringo and cdk1/cyclin B. 3. The role of deadenylation and translational repression, including the potential involvement of PARN, CCR4/NOT, maskin, pumilio, Xp54 (Ddx6, Rck), other P-body components and isoforms of the cap binding initiation factor eIF4E. Finally we discuss some of the remaining questions regarding the mechanisms of translational regulation by cytoplasmic polyadenylation and give our view on where our knowledge is likely to be expanded in the near future.
PubMed ID: 18316045
PMC ID: PMC2323027
Article link: Biochim Biophys Acta
Genes referenced: camk2g cpeb1 ddx6 eif4a1 eif4e mapk1 parn pum1 tacc3
Article Images: [+] show captions
|Fig. 1. The activation of CPE-mediated cytoplasmic polyadenylation. In immature oocytes, CPE containing mRNAs already contain all the proteins necessary for polyadenylation as well as the deadenylase PARN. During oocyte maturation, phosphorylation of CPEB causes a rearrangement of the complex that leads to the ejection of PARN and the activation of the poly(A) polymerase Gld-2. 4E: eIF4E, 4A: eIF4A. For further description of this process, see the text.|
|Fig. 2. The signal transduction cascade leading to cytoplasmic polyadenylation during oocyte maturation. Schematic representation of the key signalling events in oocyte maturation and the role of cytoplasmic polyadenylation in this process. For a detailed description, see the text.|
|Fig. 3. Four models of translation repression by CPEs. Schematic representation of some of the proposed translational repression mechanisms for CPE containing mRNAs. For a detailed description, see the text.|