Thyroxine preferentially stimulates transcription by isolated neuronal nuclei in the developing rat brain cortex

Lindholm, Dan

doi:10.1016/0014-5793(84)80495-0

Cited by 6 publications

(4 citation statements)

References 28 publications

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“…Nuclei were prepared from brain cortices pooled from three or four animals using discontinuous sucrose gradient centrifugation and separated into neuronal and glial cell-enriched nuclear fractions (Austoker et al, 1972). The two nuclear fractions have been shown to exhibit differences in morphology and nucleosomal spacing (Thomas and Thompson, 1977;Brown, 1978) as well as in RNA synthesis in vitro (Thomas and Thompson, 1977;Lindholm, 1984~;Stoykova et al, 1985). Cross-contamination between the two types of nuclei was -10% and was unaffected by the age ofthe rats (cf.…”

Section: Methodsmentioning

confidence: 99%

“…In some experiments, a-amanitin (1 pg/ml) was added to the reaction mixture to inhibit the activity of RNA polymerase 11. The remaining activity is mainly due to RNA polymerase I in both types of brain nuclei (Lindholm, 1984~;Stoykova et al, 1985). The activity of "free RNA polymerase" in nuclei was determined with use of 20 pg of polyd[A-TI (Boehringer, Mannheim, F.R.G.)…”

Section: Methodsmentioning

confidence: 99%

“…Ribonuclease activity was measured by incubation of brain nuclei for 30 min at 35°C in the presence of 50 nCi of [3H]polyuridylic acid. The reaction was stopped by addition of 5% trichloroacetic acid, and the amount of radioactivity released into the acid soluble fraction was then determined (Lindholm, 1984~).…”

Section: Methodsmentioning

confidence: 99%

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Decreased Transcription of Neuronal Polyadenylated RNA During Senescence in Nuclei from Rat Brain Cortex

Lindholm

1986

Journal of Neurochemistry

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Neuronal and glial cell-enriched nuclei were prepared from the brain cortex of rats of different ages for study of alterations in the synthesis of cellular RNA with age. RNA synthesis by isolated neuronal nuclei was substantially reduced in senescent rats, whereas that of glial nuclei remained constant throughout development. The nuclear content of polyadenylic acid-containing RNA in neurons was particularly decreased in old rats. The results show that the activity of the chromatin-bound neuronal RNA polymerase declines during senescence, an observation indicating an age-related reduction in template activity in neuronal nuclei. The activity of nuclear poly(adenylate) polymerase also progressively decreases in aging neurons. The decrease in the transcription and polyadenylation of nuclear RNA may contribute to the decline in neuronal protein synthesis observed in old animals.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Decreased Transcription of Neuronal Polyadenylated RNA During Senescence in Nuclei from Rat Brain Cortex

Lindholm

1986

Journal of Neurochemistry

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“…Nuclear preparations from mammalian brain have proven to be a good model for studies involving different aspects of protein synthesis and RNA metabolism under cell-free conditions (Dutton and Mahler, 1968; Burdman and Journey, 1969;Austoker et al, 1972; Fleischer-Lambropoulos and Reinsch, 197 1 ; Gozes et al, 1977;Lindholm, 1984). Brain cell nuclei can be separated into neuron-and glia-rich fractions using sucrose gradients (L~vtrup-Rein and McEwen, 1966;Austoker et al, 1972; Thompson, 1973;Stoykova et al, 1979).…”

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confidence: 99%

Rapid Isolation of Rat Brain Nuclei on Percoll Gradients

Vakakis

Hearn

Veitch

et al. 1991

Journal of Neurochemistry

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A rapid isotonic method for fractionation of nuclei from rat brain is described. This procedure is based on the use of discontinuous colloidal silica gel (Percoll) gradients. We start from a 63,000-g purified nuclear pellet (fraction P3) isolated from gray matter and white matter separately. This is followed by fractionation of fraction P3 in an initial differential centrifugation step on five-step Percoll gradients producing six nuclear fractions designated 1, 2, 3 (gray matter) and 4, 5, 6 (white matter). Fractions 2, 4, and 5 obtained from this centrifugation are heterogeneous. These fractions are subfractionated further under isopycnic conditions using five-step Percoll gradients to yield subfractions 2b, 4b, and 5c. Three methods were used to characterize the nuclear types. First, light and electron microscopic examination was used to identify the nuclei in each preparation and to assess the purity of each preparation. Second, the activities of RNA polymerase I and II were monitored. Third, the protein/DNA ratios of the nuclear fractions were determined. Fraction 1 was enriched in neuronal nuclei; fractions 2b and 4b in astrocytic nuclei; and fractions 3, 5c, and 6 in nuclei of oligodendrocytes. RNA polymerase I and II activity was highest in fraction 1, which also displayed the highest protein/DNA ratio. Electron microscopy showed that the various classes of nuclei are congruent to 90% pure. Therefore, the procedure described here is suitable for obtaining highly purified neuronal and three types of glial nuclei from rat brain.

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Effects of hypothyroidism on RNA synthesis in the adult rat brain

Yiannakouris

Valcana

1994

Neurochem Res

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In this study we investigated the effects of hypothyroidism on adult brain RNA synthesis. Our data show that in the cerebral hemispheres of hypothyroid rats there is a decrease in microsomal RNA content and microsomal [3H]uridine incorporation. Sucrose gradient analysis revealed that these changes are mainly associated with free ribosomes and subunits and reflect changes in rRNA. The above changes are accompanied by a decrease in RNA polymerase I activity. All of the above mentioned changes returned to normal after thyroxine (T4) treatment. In contrast to RNA polymerase I, RNA polymerase II activity was not affected. However, electrophoretic analysis of the in vitro poly(A)+RNA translation products revealed that hypothyroidism affects a few mRNAs. These results indicate that thyroid hormones have a role in adult brain tissue metabolism.

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Thyroxine preferentially stimulates transcription by isolated neuronal nuclei in the developing rat brain cortex

Cited by 6 publications

References 28 publications

Decreased Transcription of Neuronal Polyadenylated RNA During Senescence in Nuclei from Rat Brain Cortex

Decreased Transcription of Neuronal Polyadenylated RNA During Senescence in Nuclei from Rat Brain Cortex

Rapid Isolation of Rat Brain Nuclei on Percoll Gradients

Effects of hypothyroidism on RNA synthesis in the adult rat brain

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