CPEB: a life in translation

Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA 01605, USA.
Trends in Biochemical Sciences (Impact Factor: 13.52). 07/2007; 32(6):279-85. DOI: 10.1016/j.tibs.2007.04.004
Source: PubMed

ABSTRACT Nearly two decades ago, Xenopus oocytes were found to contain mRNAs harboring a small sequence in their 3' untranslated regions that control cytoplasmic polyadenylation and translational activation during development. This cytoplasmic polyadenylation element (CPE) is the binding platform for CPE-binding protein (CPEB), which promotes polyadenylation-induced translation. Since then, the biochemistry and biology of CPEB has grown rather substantially: mechanistically, CPEB nucleates a complex of factors that regulates poly(A) elongation through, of all things, a deadenylating enzyme; biologically, CPEB mediates many processes including germ-cell development, cell division and cellular senescence, and synaptic plasticity and learning and memory. These observations underscore the growing complexities of CPEB involvement in cell function.

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    • "PAPD1 was also reported to uridylate histone mRNA along with PAPD5 to target it for degradation [123] although the actual PAP that uridylates histone mRNA is somewhat controversial [124]. hGLD2 (PAPD4) is a cytoplasmic PAP that polyadenylates short (A)-tailed mRNAs in the cytoplasm [125] [126] and is involved in diverse functions such as embryonic development, cell cycle, germline maturation, synaptic plasticity, learning and memory [126] [127] [128] [129] [130] [131]. hGLD2 also polyadenylates p53 mRNA in the cytoplasm [128] [132]. "
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    ABSTRACT: Almost all eukaryotic mRNAs acquire a poly(A) tail at the 3′-end by a concerted RNA processing event: cleavage and polyadenylation. The canonical PAP, PAPα, was considered the only nuclear PAP involved in general polyadenylation of mRNAs. A phosphoinositide-modulated nuclear PAP, Star-PAP, was then reported to regulate a select set of mRNAs in the cell. In addition, several non-canonical PAPs have been identified with diverse cellular functions. Further, canonical PAP itself exists in multiple isoforms thus illustrating the diversity of PAPs. In this review, we compare two nuclear PAPs, Star-PAP and PAPα with a general overview of PAP diversity in the cell. Emerging evidence suggests distinct niches of target pre-mRNAs for the two PAPs and that modulation of these PAPs regulates distinct cellular functions.
    FEBS Letters 06/2014; 588(14). DOI:10.1016/j.febslet.2014.05.029 · 3.34 Impact Factor
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    • "Apart from general regulators of eIF4E activity, eukaryotic cells also contain eIF4E-binding proteins that regulate translation of subsets of mRNAs. Among them, it is worth mentioning Cup in Drosophila, Maskin in oocytes of Xenopus laevis and Neuroguidin in neurons (for references see reviews by Darnell & Richter, 2012; Lasko, 2012; Richter, 2007). However, this mode of regulation requires the formation of complexes of eIF4E-binding proteins with additional protein factors which in turn recognize specific RNA-motives within 3 "
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    ABSTRACT: Abstract The conventional paradigm of translation initiation in eukaryotes states that the cap-binding protein complex eIF4F (consisting of eIF4E, eIF4G and eIF4A) plays a central role in the recruitment of capped mRNAs to ribosomes. However, a growing body of evidence indicates that this paradigm should be revised. This review summarizes the data which have been mostly accumulated in a post-genomic era owing to revolutionary techniques of transcriptome-wide analysis. Unexpectedly, these techniques have uncovered remarkable diversity in the recruitment of cellular mRNAs to eukaryotic ribosomes. These data enable a preliminary classification of mRNAs into several groups based on their requirement for particular components of eIF4F. They challenge the widely accepted concept which relates eIF4E-dependence to the extent of secondary structure in the 5' untranslated regions of mRNAs. Moreover, some mRNA species presumably recruit ribosomes to their 5' ends without the involvement of either the 5' m(7)G-cap or eIF4F but instead utilize eIF4G or eIF4G-like auxiliary factors. The long-standing concept of internal ribosome entry site (IRES)-elements in cellular mRNAs is also discussed.
    Critical Reviews in Biochemistry and Molecular Biology 02/2014; 49(2). DOI:10.3109/10409238.2014.887051 · 5.81 Impact Factor
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    • "An in silico analysis of this UTR fragment revealed the presence of a cytoplasmic polyadenylation element (CPE). Previous work has demonstrated that during oocyte maturation CPEs maintain maternal mRNAs in a dormant state and then release these mRNAs when required (Richter, 2007; Zhang and Sheets, 2009). Deletion of the CPE from the sox19b 3Ј UTR fragment abolished the polyadenylation from the 2-cell to 64-cell stages (Fig. 4C). "
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    ABSTRACT: Transcription is an essential component of basic cellular and developmental processes. However, early embryonic development occurs in the absence of transcription and instead relies upon maternal mRNAs and proteins deposited in the egg during oocyte maturation. Although the early zebrafish embryo is competent to transcribe exogenous DNA, factors present in the embryo maintain genomic DNA in a state that is incompatible with transcription. The cell cycles of the early embryo titrate out these factors, leading to zygotic transcription initiation, presumably in response to a change in genomic DNA chromatin structure to a state that supports transcription. To understand the molecular mechanisms controlling this maternal to zygotic transition, it is important to distinguish between the maternal and zygotic transcriptomes during this period. Here we use exome sequencing and RNA-seq to achieve such discrimination and in doing so have identified the first zygotic genes to be expressed in the embryo. Our work revealed different profiles of maternal mRNA post-transcriptional regulation prior to zygotic transcription initiation. Finally, we demonstrate that maternal mRNAs are required for different modes of zygotic transcription initiation, which is not simply dependent on the titration of factors that maintain genomic DNA in a transcriptionally incompetent state.
    Development 05/2013; 140(13). DOI:10.1242/dev.095091 · 6.27 Impact Factor
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