An mRNA Stability Complex Functions with Poly(A)-Binding Protein To Stabilize mRNA In Vitro

Wang, Zuoren; Day, Nancy A.; Trifillis, Panayiota; Kiledjian, Megerditch

doi:10.1128/mcb.19.7.4552

Cited by 238 publications

(221 citation statements)

References 69 publications

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“…In humans, at least four separate PABPC genes and four pseudogenes have been identified (40). PABPC1 influences mRNA translation and decay (18,20,23,27,29,30,50,(54)(55)(56), and it shuttles between the nucleus and cytoplasm of at least some mammalian cells (1,57,58). Consistent with the preferential compartmentalization of PABPN1 to the nucleus and PABPC1 to the cytoplasm, a physical interaction has been detected between PAP and PABPN1 but not PABPC1 (28).…”

mentioning

confidence: 61%

Evidence that Poly(A) Binding Protein C1 Binds Nuclear Pre-mRNA Poly(A) Tails

Hosoda

Lejeune

Maquat

2006

Molecular and Cellular Biology

103

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In mammalian cells, poly(A) binding protein C1 (PABP C1) has well-known roles in mRNA translation and decay in the cytoplasm. However, PABPC1 also shuttles in and out of the nucleus, and its nuclear function is unknown. Here, we show that PABPC1, like the major nuclear poly(A) binding protein PABPN1, associates with nuclear pre-mRNAs that are polyadenylated and intron containing. PABPC1 does not bind nonpolyadenylated histone mRNA, indicating that the interaction of PABPC1 with pre-mRNA requires a poly(A) tail. Consistent with this conclusion, UV cross-linking results obtained using intact cells reveal that PABPC1 binds directly to pre-mRNA poly(A) tails in vivo. We also show that PABPC1 immunopurifies with poly(A) polymerase, suggesting that PABPC1 is acquired by polyadenylated transcripts during poly(A) tail synthesis. Our findings demonstrate that PABPC1 associates with polyadenylated transcripts earlier in mammalian mRNA biogenesis than previously thought and offer insights into the mechanism by which PABPC1 is recruited to newly synthesized poly(A). Our results are discussed in the context of pre-mRNA processing and stability and mRNA trafficking and the pioneer round of translation.The 3Ј ends of almost all eukaryotic mRNAs and their precursors consist of homopolymeric tails of adenosine, or poly(A), that are added by poly(A) polymerase (PAP) during the process of 3Ј end formation. There are two classes of poly(A) binding proteins (PABPs) in mammalian cells (32,40). One class is exemplified by PABPN1, formerly called PABP2. PABPN1 is primarily nuclear and plays a role in the synthesis of poly(A) tails, but it also shuttles between the nucleus and cytoplasm (5,8,9,31,53). The other class consists of the primarily cytoplasmic PABPs, of which PABPC1, formerly called PABI or PABP1, is the major form in mammalian somatic cells (40). In humans, at least four separate PABPC genes and four pseudogenes have been identified (40). PABPC1 influences mRNA translation and decay (18,20,23,27,29,30,50,(54)(55)(56), and it shuttles between the nucleus and cytoplasm of at least some mammalian cells (1,57,58). Consistent with the preferential compartmentalization of PABPN1 to the nucleus and PABPC1 to the cytoplasm, a physical interaction has been detected between PAP and PABPN1 but not PABPC1 (28). Furthermore, PABPN1 associates with RNA polymerase II during transcription and accompanies the released transcript to the nuclear pore (2). Given that PABPC1 can exist within nuclei, a key issue is whether PABPC1 binds to transcripts inside the nucleus, and if it does, at which step in mRNA maturation.The 5Ј ends of eukaryotic mRNAs and their precursors are capped, and the cap is initially bound by the mostly nuclear cap binding protein (CBP) heterodimer of CBP80 and CBP20 (25, 35, 38), which will be called CBP80/CBP20. CBP80/CBP20 is detectably replaced by the mostly cytoplasmic eukaryotic translation initiation factor 4E (eIF4E) only after introns have been removed by splicing (35). Evidence indicates that PABPC1 is a component...

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mentioning

confidence: 61%

Evidence that Poly(A) Binding Protein C1 Binds Nuclear Pre-mRNA Poly(A) Tails

Hosoda

Lejeune

Maquat

2006

Molecular and Cellular Biology

103

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“…The presence of PCBP2 in the P-body in cells at rest may help explain the protein's translational silencing activity (Ostareck-Lederer et al 1998;Perrotti et al 2002). Meanwhile, involvement of PCBP2 in IRES-mediated translation initiation and its mRNA-stabilizing function (Wang et al 1999) point to the possibility that PCBP2 plays a part in rapidly shifting certain untranslated mRNAs into the translationally active state.…”

Section: Discussionmentioning

confidence: 99%

Identification of PCBP2, a facilitator of IRES-mediated translation, as a novel constituent of stress granules and processing bodies

Fujimura¹,

Kano²,

Murata³

2008

RNA

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Recent advances in microscopic techniques have shed light on the roles of specific subcellular structures in the regulation of gene expression. One such structure is the stress granule (SG), which is engaged in stress-triggered translational arrest by sequestering pre-initiation complexes of translation. Recent studies revealed the spatial, compositional, and functional linkage of the SG to the processing body (P-body), another cytoplasmic structure that has been implicated in mRNA degradation and siRNA-or miRNA-mediated gene silencing. In this study, we report that PCBP2, a facilitator of IRES (Internal Ribosomal Entry Site)-mediated translation, is a novel constituent of the SG and P-body. Immunofluorescence studies revealed that while PCBP2 is diffusely distributed throughout the nucleoplasm and the cytoplasm, the protein is enriched in a subset of P-bodies under normal conditions. Upon exposure to heat and arsenic stress, PCBP2 became predominantly accumulated at the SG, but was still present in Dcp1a-positive P-bodies. Live-cell imaging revealed the dynamic association of PCBP2-enriched P-bodies and the SG, and FRAP experiments demonstrated that PCBP2 actively moves in and out of the SG and P-body. Taken together, these results suggest that PCBP2 shuttles between the cytoplasm and the two structures under stress. We propose that PCBP2 may be involved in stress-induced remodeling of mRNP complexes and that it may also play a role in the rapid transition of certain silenced mRNAs into a translationally active state. Additionally, given the property of PCBP2 as a nuclear-cytoplasmic shuttling protein, PCBP2 may play a role in directly targeting nascent mRNPs to specific P-bodies for storage.

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“…PABP acts as a deadenylation inhibitor in mammalian cell extracts (Bernstein et al 1989;Ford et al 1997) and when overexpressed in Xenopus oocytes (Wormington et al 1996). In the case of the ␣-globin mRNA, PABP interacts with the ␣CP complex that binds to the 3Ј-UTR of this transcript, and slows the rate of its deadenylation (Wang et al 1999). A more complex picture arises in the case of the c-fos mCRD (major coding region determinant), a sequence element that specifies rapid deadenylation and decay of the c-fos transcript in a manner that is dependent on translation (Grosset et al 2000).…”

Section: Introductionmentioning

confidence: 99%

Evidence that poly(A) binding protein has an evolutionarily conserved function in facilitating mRNA biogenesis and export

Chekanova

Belostotsky²

2003

RNA

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Eukaryotic poly(A) binding protein (PABP) is a ubiquitous, essential cellular factor with well-characterized roles in translational initiation and mRNA turnover. In addition, there exists genetic and biochemical evidence that PABP has an important nuclear function. Expression of PABP from Arabidopsis thaliana, PAB3, rescues an otherwise lethal phenotype of the yeast pab1⌬ mutant, but it neither restores the poly(A) dependent stimulation of translation, nor protects the mRNA 5 cap from premature removal. In contrast, the plant PABP partially corrects the temporal lag that occurs prior to the entry of mRNA into the decay pathway in the yeast strains lacking Pab1p. Here, we examine the nature of this lag-correction function. We show that PABP (both PAB3 and the endogenous yeast Pab1p) act on the target mRNA via physically binding to it, to effect the lag correction. Furthermore, substituting PAB3 for the yeast Pab1p caused synthetic lethality with rna15-2 and gle2-1, alleles of the genes that encode a component of the nuclear pre-mRNA cleavage factor I, and a factor associated with the nuclear pore complex, respectively. PAB3 was present physically in the nucleus in the complemented yeast strain and was able to partially restore the poly(A) tail length control during polyadenylation in vitro, in a poly(A) nuclease (PAN)-dependent manner. Importantly, PAB3 in yeast also promoted the rate of entry of mRNA into the translated pool, rescued the conditional lethality, and alleviated the mRNA export defect of the nab2-1 mutant when overexpressed. We propose that eukaryotic PABPs have an evolutionarily conserved function in facilitating mRNA biogenesis and export.

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An mRNA Stability Complex Functions with Poly(A)-Binding Protein To Stabilize mRNA In Vitro

Cited by 238 publications

References 69 publications

Evidence that Poly(A) Binding Protein C1 Binds Nuclear Pre-mRNA Poly(A) Tails

Evidence that Poly(A) Binding Protein C1 Binds Nuclear Pre-mRNA Poly(A) Tails

Identification of PCBP2, a facilitator of IRES-mediated translation, as a novel constituent of stress granules and processing bodies

Evidence that poly(A) binding protein has an evolutionarily conserved function in facilitating mRNA biogenesis and export

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