Identification of a small subfraction of hnRNA with the characteristics of a precursor to mRNA

Price, Richard; Ransom, Laura J.; Penman, Sheldon

doi:10.1016/0092-8674(74)90019-1

Cited by 32 publications

(12 citation statements)

References 10 publications

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“…This suggests that there may be more than one class of polyadenylated nuclear RNA molecules, in agreement with other observations (20,30). Since there is a lag in attainment of a maximum rate of accumulation of polyadenylated mRNA in the cytoplasm (4,31), this poly(A) would be attached to precursors of mRNA just before they pass into the cytoplasm but after they had resided in the nucleus an average of several minutes.…”

Section: Figuresupporting

confidence: 77%

“…This agrees with the half-life observed for unstable RNA 25 min, and all serves as the only source of poly(A) in the cytoplasm. In the cytoplasm, half decays with a half-life of 30 min and the other half with a half-life of 10 hr. (C) About 45% of the nuclear poly(A) synthesized decays in the nucleus with a half-life of 25 min, but accounts for most of the nuclear poly(A) at steady state.…”

Section: Figurementioning

confidence: 99%

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Relationship between nuclear and cytoplasmic poly(adenylic acid).

Brandhorst¹,

McConkey²

1975

Proc. Natl. Acad. Sci. U.S.A.

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The kinetics of accumulation of radioactive poly(A) in the nucleus and cytoplasm of mouse L cells have been determined using labeling conditions in which the cellular ATP pool is shown to have a nearly constant specific radioactivity. Most or all nuclear poly(A) accumulates with kinetics very similar to those of heterogeneous nuclear RNA, having a half-time of about 25 min. There is little or no lag before attainment of a maximal rate of accumulation of cytoplasmic poly(A). These data are consistent with a variety of models in which nuclear poly(A) does or does not all serve as a precursor of cytoplasmic poly(A). In either type of model there must be a class of poly(A) either synthesized in the cytoplasm or passing through a small nuclear pool separate from the main pool of nuclear poly(A). The T3' ends of many messenger RNA (mRNA) and heterogeneous nuclear RNA (hnRNA) molecules are polyadenylated posttranscriptionally. This observation has led to the suggestion that polyadenylated hnRNA molecules serve as precursors of mRNA (1). If the 3' ends of all polyadenylated hnRNA molecules were precursors of mRNA, these nuclear precursors could easily be selected from total hnRNA by affinity chromatography (2). If some polyadenylated hnRNA molecules decay entirely in the nucleus, such selection would not serve to isolate only precursors of mRNA. In the latter instance, some poly(A) would be expected to decay in the nucleus.Jelinek et al. (3) have presented evidence that most or all cytoplasmic poly(A) is derived from nuclear poly(A), and suggest that nuclear poly(A) may be conserved. More recently Perry, Kelley, and LaTorre (4) reported on their investigations of the kinetics of accumulation of poly(A) in the nucleus and cytoplasm of L cells and concluded that some nuclear poly(A) must decay in the nucleus and that substantial synthesis of cytoplasmic poly(A) may occur. Our investigations of ATP pools and nuclear RNA in L cells (5, 6) gave us reason to think that there might be sources of error in the investigations of Perry et al. (4). Perry et al. demonstrated that total cellular RNA labeled with tritiated adenosine at high concentration accumulates with kinetics indicating that it is synthesized via an ATP pool of constant specific radioactivity. Whereas, this appears to be valid over the long term, their argument cannot be convincingly applied over the first few hours, because it does not take into account the rapid initial accumulation of highly unstable hnRNA and nuclear precursors of ribosomal RNA, nor the extensive conversion of adenine nutleotides to guanine nucleotides under the labeling conditions used (5, 6). In the investigations of Perry et al. (4) the cellular ATP pool would not reach a constant specific radioactivity until as late as 2 hr after the addition of exogenous label (Brandhorst, unpublished observations); this could seriously distort the actual kinetics of accumulation of poly(A). As explained previously (4, 6), rapid establishment of constant specific activity of the ATP pool facilita...

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Section: Figuresupporting

confidence: 77%

Section: Figurementioning

confidence: 99%

Relationship between nuclear and cytoplasmic poly(adenylic acid).

Brandhorst¹,

McConkey²

1975

Proc. Natl. Acad. Sci. U.S.A.

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“…The HnRNA we obtained appears to be substantially intact, not aggregated, and is recovered in over 80% yield from nuclei. When 2M-LiCl was used to avoid DNAase incubation, large losses ensued, presumably because of the attachment of HnRNA to DNA (Price et al, 1974). Essential to the success of the method using proteinase and sodium dodecyl sulphate was the extraction of hydrophilic lipids (Suzuki 1975).…”

Section: Isolation Ofhnrnamentioning

confidence: 99%

The effect of convulsions induced by flurothyl on ribonucleic acid synthesis in rat cerebral cortex during the recovery phase

Wynter

Ioannou

Mathias

1975

Biochemical Journal

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The effect of convulsions, induced by flurothyl, on RNA synthesis in purified unfractionated nuclei and the cytoplasm of rat cerebral cortex was studied by using a double-label technique involving injection of [3H]- and [14C]-orotate intracisternally. 2. Intact RNA was extracted in 80% yield by an enzymic method by using a proteinase in the presence of sodium dodecyl sulphate followed by deoxyribonuclease. Electrophoresis on 1.5% polyacrylamide-0.5% agarose gels revealed the presence of giant nuclear RNA of size up to approx. 300X 10(6) daltons and mRNA of maximal mol.wt. 9 X 10(6)-16 X 10(6). 3. Nuclear RNA synthesis was decreased to 27% in the first 15 min after convulsions but rapidly increased, so that at 1 1/2 h it was 124% of the control, and at 6 h 147%. 4. Labelling of cytoplasmic RNA was decreased to 15% at 15 min after convulsions but had not recovered to control values by 6 h. 5. Analysis of radioactive gel patterns and the 3H/14C ratio at six time-points (15 min-6h) showed that the major effect was inhibition of the processing of heterogeneous nuclear RNA resulting in a sharp decline in the export of newly synthesized RNA from the nucleus. 6. Cytoplasmic RNA patterns indicated that specific messengers were synthesized at different times during the recovery of the cell after convulsions.

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“…This fact makes one suspect a tight association of RNA with some intranuclear structures. Secondly, Price et al (1974) have shown that all hnRNA of HeLa cells is pelleted with the chromatin when nuclei are lysed and most of the ribonucleoprotein particles, up to 90 %, stay associated with the chromatin even at 0.7M-(NH4)2SO4. That a significant portion of chromatinassociated RNA was polyadenylated indicates that this RNA fraction consisted of not only nascent but also completed RNA transcripts.…”

mentioning

confidence: 98%

A model for cytoplasm-governed gene regulation

Lichtenstein¹,

Shapot²

1976

Biochemical Journal

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A model of cytoplasm-governed transcription is presented. The nuclear membrane has a selective permeability towards nuclear pre-mRNA molecules which are provided with group-specific non-translated "passwords". RNA transcription on the chromatin proceeds under a dual control. One of them is gene regulation according to the Britten-Davidson and Georgiev models. The other is cytoplasm-governed regulation mediated through the selective transport of mRNA from nucleus to cytoplasm. Pre-mRNA molecules which are not "in immediate demand" by the cytoplasm and therefore accumulating the nucleus repress their own synthesis by end-product inhibition. The interrelationship of the two types of regulation in the course of cell development is discussed.

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Identification of a small subfraction of hnRNA with the characteristics of a precursor to mRNA

Cited by 32 publications

References 10 publications

Relationship between nuclear and cytoplasmic poly(adenylic acid).

Relationship between nuclear and cytoplasmic poly(adenylic acid).

The effect of convulsions induced by flurothyl on ribonucleic acid synthesis in rat cerebral cortex during the recovery phase

A model for cytoplasm-governed gene regulation

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