Translation and stability of rat liver messenger RNA for alpha 2 mu-globulin in Xenopus oocyte. The role of terminal poly(A).

Deshpande, A. K.; Chatterjee, Bandana; Roy, Arun K.

doi:10.1016/s0021-9258(19)86791-1

Cited by 54 publications

(8 citation statements)

References 37 publications

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“…The 80S peak, which accumulated in cycloheximide-treated but not untreated extracts (data not shown), is indicated by an arrow. levels of translational initiation than occur in reticulocyte extracts and give support to the notion that the extent of the difference between poly(A)+ and poly(A)-mRNAs will be dependent on the extent of reinitiation (15,16,21,61). Although the differences between poly(A)+ and poly(A)-mRNAs are substantially smaller in vitro than they are in some in vivo systems, we are confident that the differences are significant because (i) the magnitude of the poly(A) effect in vitro is equivalent to that obtained by differences in mRNA capping (Fig.…”

Section: Gradients Arrows Indicate the Position Of The 80s Peak (A) Capped Poly(a)+ Rbg (68 A's) Versus Capped Poly(a)+ Rbg (68 A's); (B)supporting

confidence: 61%

“…Previous experiments have also utilized purified or synthetic mRNAs to evaluate a possible role for poly(A) in translation (15)(16)(17)21). Our experiments differ from these earlier studies in that we used synthetic mRNAs which closely resemble their in vivo counterparts, i.e., (i) the poly(A)+ mRNAs used here contain homogeneous poly(A) tracts equivalent to steady-state lengths, (ii) the poly(A)+ and poly(A)-mRNAs used here differ only in poly(A) sequences and not other mRNA sequences, and (iii) both the poly(A)+ and the poly(A)-mRNAs used in this study lack additional [non-poly(A)] homopolymeric tracts.…”

Section: Resultsmentioning

confidence: 99%

“…The results of several different experimental approaches have provided evidence which indirectly supports this hypothesis. These results include (i) the correlation of specific changes in mRNA poly(A) tail length with translational efficiency following fertilization in Spisula oocytes (72), during early development in Dictyostelium discoideum (61), oocyte maturation in Xenopus laevis (34,55), oocyte activation in mice (33,84,86), salivary gland development in Drosophila melanogaster (67), and in response to physiologic stimuli in the rat hypothalamus (11,69,89); (ii) the higher translational activity of poly(A)+ as opposed to poly(A)-mRNAs in vitro, as demonstrated in systems as diverse as cell extracts derived from rabbit reticulocytes (16,73), Ehrlich ascites tumor cells (31), and wheat germ (73), as well as in microinjected Xenopus oocytes (15,21,34) and electroporated tobacco protoplasts (22); (iii) a correlation between the abundance and stability of PABPs and the rate of translational initiation in developing or heat-shocked Dictyostelium discoideum amoebae (53,54); (iv) the demonstration that exogenous poly(A) is a potent and specific inhibitor of the in vitro translation of poly(A)+ but not poly(A)-mRNAs in rabbit reticulocyte (4,28,37), wheat germ (4), L-cell (49), and pea seed (81) extracts; and (v) the demonstration that purified PABP can stimulate translation in vitro (81).…”

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confidence: 99%

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mRNA Poly (A) Tail, a 3′ Enhancer of Translational Initiation

Munroe

Jacobson

1990

Molecular and Cellular Biology

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To evaluate the hypothesis that the 3' poly(A) tract of mRNA plays a role in translational initiation, we constructed derivatives of pSP65 which direct the in vitro synthesis of mRNAs with different poly(A) tail lengths and compared, in reticulocyte extracts, the relative efficiencies with which such mRNAs were translated, degraded, recruited into polysomes, and assembled into messenger ribonucleoproteins or intermediates in the translational initiation pathway. Relative to mRNAs which were polyadenylated, we found that nonpolyadenylated [poly(A)-]mRNAs had a reduced translational capacity which was not due to an increase in their decay rates, but was attributable to a reduction in their efficiency of recruitment into polysomes. The defect in poly(A)- mRNAs affected a late step in translational initiation, was distinct from the phenotype associated with cap-deficient mRNAs, and resulted in a reduced ability to form 80S initiation complexes. Moreover, poly(A) added in trans inhibited translation from capped polyadenylated mRNAs but stimulated translation from capped poly(A)- mRNAs. We suggest that the presence of a 3' poly(A) tail may facilitate the binding of an initiation factor or ribosomal subunit at the mRNA 5' end.

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Section: Gradients Arrows Indicate the Position Of The 80s Peak (A) Capped Poly(a)+ Rbg (68 A's) Versus Capped Poly(a)+ Rbg (68 A's); (B)supporting

confidence: 61%

Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

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mRNA Poly (A) Tail, a 3′ Enhancer of Translational Initiation

Munroe

Jacobson

1990

Molecular and Cellular Biology

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“….~~~~~~~-w 13 _~~~~-1.25 250 350 45 The possibility that poly(A) tail lengths directly determine mRNA stabilities has been suggested by microinjection experiments with adenylated and deadenylated mRNAs (17,29,46,56) and by experiments with cordycepin-treated cells (90). However, similar microinjection experiments with different poly(A)+ and poly(A)-mRNAs (16,27,48,73) and other experimental approaches (38,58,71,84) do not support this hypothesis. Our measurements of the poly(A) tail lengths associated with individual stable and unstable D. discoideum mRNAs (Fig.…”

Section: Discussionmentioning

confidence: 78%

“…mRNA decay rates versus poly(A) tail length. The possibility that poly(A) tail lengths directly determine mRNA stabilities has been suggested by some experiments (28,56,86,90), but not by others (16,38,58,71,84). To evaluate whether poly(A) tail lengths influence mRNA decay rates in D. discoideum amoebae, we have compared the steady-state poly(A) tail length of seven mRNAs with different half-lives (Fig.…”

Section: Resultsmentioning

confidence: 99%

Determinants of mRNA Stability in Dictyostelium discoideum Amoebae: Differences in Poly(A) Tail Length, Ribosome Loading, and mRNA Size Cannot Account for the Heterogeneity of mRNA Decay Rates

Shapiro

Herrick

Manrow

et al. 1988

Molecular and Cellular Biology

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As an approach to understanding the structures and mechanisms which determine mRNA decay rates, we have cloned and begun to characterize cDNAs which encode mRNAs representative of the stability extremes in the poly(A)+ RNA population of Dictyostelium discoideum amoebae. The cDNA clones were identified in a screening procedure which was based on the occurrence of poly(A) shortening during mRNA aging. mRNA half-lives were determined by hybridization of poly(A)+ RNA, isolated from cells labeled in a 32PO4 pulse-chase, to dots of excess cloned DNA. Individual mRNAs decayed with unique first-order decay rates ranging from 0.9 to 9.6 h, indicating that the complex decay kinetics of total poly(A)+ RNA in D. discoideum amoebae reflect the sum of the decay rates of individual mRNAs. Using specific probes derived from these cDNA clones, we have compared the sizes, extents of ribosome loading, and poly(A) tail lengths of stable, moderately stable, and unstable mRNAs. We found (i) no correlation between mRNA size and decay rate; (ii) no significant difference in the number of ribosomes per unit length of stable versus unstable mRNAs, and (iii) a general inverse relationship between mRNA decay rates and poly(A) tail lengths. Collectively, these observations indicate that mRNA decay in D. discoideum amoebae cannot be explained in terms of random nucleolytic events. The possibility that specific 3'-structural determinants can confer mRNA instability is suggested by a comparison of the labeling and turnover kinetics of different actin mRNAs. A correlation was observed between the steady-state percentage of a given mRNA found in polysomes and its degree of instability; i.e., unstable mRNAs were more efficiently recruited into polysomes than stable mRNAs. Since stable mRNAs are, on average, "older" than unstable mRNAs, this correlation may reflect a translational role for mRNA modifications that change in a time-dependent manner. Our previous studies have demonstrated both a time-dependent shortening and a possible translational role for the 3' poly(A) tracts of mRNA. We suggest, therefore, that the observed differences in the translational efficiency of stable and unstable mRNAs may, in part, be attributable to differences in steady-state poly(A) tail lengths.

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