Stabilities of Avian Sarcoma Virus RNAs: Comparison of Subgenomic and Genomic Species with Cellular mRNAs

Cm, Stoltzfus; Dimock, Kenneth; Horikami, Sandra M.; Ta, Ficht

doi:10.1099/0022-1317-64-10-2191

Cited by 24 publications

(21 citation statements)

References 26 publications

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“…Instead HIV-1 unspliced RNA constitutes a single functional pool that can function interchangeably as mRNA and as vpRNA. Our results are similar to results with ASV and RSV in which Stoltzfus et al (23) and Sonstegard and Hackett (22) concluded that a single metabolic pool of viral RNA exists that functions as both mRNA and vpRNA. Contrasting results in the MLV system suggested that there are two nonequilibrating pools of MLV RNA, each functioning as either mRNA or vpRNA (11).…”

Section: Discussionsupporting

confidence: 91%

“…These data implied that MLV transcripts segregate into two functionally distinct populations of mRNA for translation or vpRNA for encapsidation (11). Stoltzfus et al (23) applied isotopic equilibrium assay to cells infected with avian sarcoma virus (ASV) and observed not two but rather a single RNA population that functions as both ASV mRNA and vpRNA. Sonstegard and Hackett (22) came to similar conclusions in their studies of Rous sarcoma virus (RSV) vector RNAs.…”

mentioning

confidence: 99%

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Translation Is Not Required To Generate Virion Precursor RNA in Human Immunodeficiency Virus Type 1-Infected T Cells

Butsch¹,

Boris‐Lawrie

2000

J Virol

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The retroviral primary transcription product is a multifunctional RNA that is utilized as pre-mRNA, mRNA, and genomic RNA. The relationship between human immunodeficiency virus type 1 (HIV-1) unspliced transcripts used as mRNA for viral protein synthesis and as virion precursor RNA (vpRNA) for encapsidation remains an important question. We developed a biochemical assay to evaluate the hypothesis that prior utilization as mRNA template for protein synthesis is necessary to generate vpRNA. HIV-1-infected T cells were treated with translation inhibitors under conditions that maintain virus production. Immunoprecipitation of newly synthesized HIV-1 Gag protein revealed that de novo translation is not necessary to sustain assembly, release, or processing of Gag structural protein. Both newly synthesized protein and steady-state Gag are competent for assembly, and the extracellular accumulation of Gag is proportional to the intracellular abundance of Gag. As early as 2 h after transcription, newly synthesized RNA is detectable in cell-free virions and encapsidation is sustained upon inhibition of host cell translation. Results of both [ 3 H]uridine incorporation assays and HIV-1-specific RNase protection assays (RPAs) indicate that translation inhibition reduces the absolute amounts of both cytoplasmic and virion-associated RNA. Evaluation of encapsidation efficiency by RPA revealed that the cytoplasmic availability of vpRNA is increased, indicating that HIV-1 unspliced mRNA can be rerouted to function as vpRNA. Our data contrast with results from the HIV-2 and murine leukemia virus systems and indicate that HIV-1 unspliced RNA constitutes a single functional pool that can function interchangeably as mRNA and as vpRNA.

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Section: Discussionsupporting

confidence: 91%

mentioning

confidence: 99%

Translation Is Not Required To Generate Virion Precursor RNA in Human Immunodeficiency Virus Type 1-Infected T Cells

Butsch¹,

Boris‐Lawrie

2000

J Virol

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“…It is possible that U6 snRNA associates with multiple sites on the RSV genome. Evidence that RSV virion RNA can be translated prior to packaging (Stoltzfus et al 1983; J. LeBlanc and K. Beemon, unpubl. ) suggests that U6 snRNA is not associated with the efficiently translated leader region or the gag gene.…”

Section: Discussionmentioning

confidence: 99%

Packaging and reverse transcription of snRNAs by retroviruses may generate pseudogenes

Giles¹,

Caputi²,

Beemon³

2004

RNA

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Retroviruses specifically package two copies of their RNA genome in each viral particle, along with some small cellular RNAs, including tRNAs and 7S L RNA. We show here that Rous sarcoma virus (RSV) also packages U6 snRNA at approximately one copy per virion. In addition, trace amounts of U1 and U2 snRNAs were detected in purified virus by Northern blotting. U6 snRNA comigrated with the RSV 70S genomic RNA dimer on sucrose gradients. We observed reverse transcription of U6 snRNA in an endogenous reaction in which RSV particles were the source of both reverse transcriptase and RNA substrates. This finding led us to examine mammalian genomic sequences for the presence of snRNA pseudogenes. A survey of the human, mouse, and rat genomes revealed a high number of spliceosomal snRNA pseudogenes. U6 pseudogenes were the most abundant, with approximately 200 copies in each genome. In the human genome, 67% of U6 snRNA pseudogenes, and a significant number of the other snRNA pseudogenes, were associated with LINE, SINE, or retroviral LTR repeat sequences. We propose that the packaging of snRNAs in retroviral particles leads to their reverse transcription in an infected cell and the integration of snRNA/viral recombinants into the host genome.

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“…Through actD treatment of cells containing radiolabeled RNAs, Stoltzfus et al (44) determined the half-life of unspliced RSV RNAs to be 7.5 h both in the cytoplasm and in virions. Thus, they propose that RSV also employs a single population of RNAs to serve as genomic RNAs as well as mRNAs.…”

mentioning

confidence: 99%

Unspliced Rous Sarcoma Virus Genomic RNAs Are Translated and Subjected to Nonsense-Mediated mRNA Decay before Packaging

LeBlanc

Beemon

2004

J Virol

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Retroviruses package full-length, unspliced RNAs into progeny virions as dimerized RNA genomes. They also use unspliced RNAs as mRNAs to produce the gag and pol gene products. We asked whether a single Rous sarcoma virus (RSV) RNA can be translated and subsequently packaged or whether genomic packaging requires a nontranslated population of RNAs. We addressed this issue by utilizing the translation-dependent nonsense-mediated mRNA decay (NMD) pathway. NMD is the selective destruction of mRNAs bearing premature termination codons (PTCs). The pathway has been shown to be associated with splicing in higher eukaryotes. Here, we demonstrate that both translation and the cellular factor Upf1 are required for the decay of unspliced, PTC-bearing RSV RNA by the NMD pathway. To address the relationship between RNA translation and packaging, we examined virus produced in cells cotransfected with PTC-bearing retroviral clones and wild-type viral clones. We observed that PTC-bearing transcripts are packaged into viral particles at levels three-to fivefold less than those of control RNAs. Since PTC-mediated degradation requires translation, we conclude that RSV can package progeny virion particles using previously translated RNAs.

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Stabilities of Avian Sarcoma Virus RNAs: Comparison of Subgenomic and Genomic Species with Cellular mRNAs

Cited by 24 publications

References 26 publications

Translation Is Not Required To Generate Virion Precursor RNA in Human Immunodeficiency Virus Type 1-Infected T Cells

Translation Is Not Required To Generate Virion Precursor RNA in Human Immunodeficiency Virus Type 1-Infected T Cells

Packaging and reverse transcription of snRNAs by retroviruses may generate pseudogenes

Unspliced Rous Sarcoma Virus Genomic RNAs Are Translated and Subjected to Nonsense-Mediated mRNA Decay before Packaging

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