Loss of Genes coding for Ribosomal RNA in Ageing Brain Cells

Johnson, Roger W.; Strehler, Bernard L.

doi:10.1038/240412a0

Cited by 128 publications

(48 citation statements)

References 16 publications

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“…Previously, an ageassociated loss of rDNA repeats was observed in mouse brain tissues, probably due to increased homologous recombination among the tandem rDNA repeats (174). Recent studies showed that mammalian cells undergo DNA methylation drift across the genome, which involves global hypomethylation and locus-specific hypermethylation of CpG sites (169,175).…”

Section: Cellular Agingmentioning

confidence: 99%

The Epigenetic Pathways to Ribosomal DNA Silencing

Srivastava

Ahn

2016

Microbiol Mol Biol Rev

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SUMMARYHeterochromatin is the transcriptionally repressed portion of eukaryotic chromatin that maintains a condensed appearance throughout the cell cycle. At sites of ribosomal DNA (rDNA) heterochromatin, epigenetic states contribute to gene silencing and genome stability, which are required for proper chromosome segregation and a normal life span. Here, we focus on recent advances in the epigenetic regulation of rDNA silencing inSaccharomyces cerevisiaeand in mammals, including regulation by several histone modifications and several protein components associated with the inner nuclear membrane within the nucleolus. Finally, we discuss the perturbations of rDNA epigenetic pathways in regulating cellular aging and in causing various types of diseases.

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Section: Cellular Agingmentioning

confidence: 99%

The Epigenetic Pathways to Ribosomal DNA Silencing

Srivastava

Ahn

2016

Microbiol Mol Biol Rev

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“…rDNA has been associated with stress response to DNA damage and with aging, the pioneering studies of this going back several decades (Johnson and Strehler, 1972). rDNA copies are multiplied by repeated recombination, and their homogeneity is maintained by gene conversion events between the tandem repeats (Kobayashi, 2008).…”

Section: The Nucleolus Stress and Dna Damage Sensingmentioning

confidence: 99%

Nucleoli: Composition, Function, and Dynamics

2011

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“…In mammalian cells there have been reports of quantitative changes in nuclear ribosomal DNA associated with the aging process (12). Therefore we used nuclear ribosomal specific probes to determine whether any such changes occurred in the nuclear DNAs from the liquid cultures.…”

Section: Resultsmentioning

confidence: 99%

Podospora anserina does not senesce when serially passaged in liquid culture

Turker

Cummings

1987

J Bacteriol

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A procedure was developed for the prolonged growth of the ascomycete fungus Podospora anserina in liquid culture to determine the effects of such growth on the senescence phenotype. Senescence In P. anserina, which is maternally inherited and associated with the excision and amplification of specific mitochondrial plasmids, occurs when this species is grown on solid -medium. In two independent experiments no evidence of senescence was observed as mycelia were The ascomycete fungus Podospora anserina provides a model system for the study of senescence at the molecular level. When mycelial plugs are placed on corn meal agar in race tubes, growth occurs at a constant rate for a genetically determined distance (19,20). The sudden cessation in vegetative growth which follows is termed senescence. Age is therefore measured as a function of the distance grown in centimeters. There are at least 10 different races of P. anserina, each with a characteristic longevity when grown in race tubes (14).Early investigations of senescence in P. anserina demonstrated that senescence is maternally inherited (19, 20). Ensuing studies have demonstrated that senescence is associated with the excision and amplification of specific mitochondrial DNA sequences and mitochondrial DNA rearrangements (5, 22). The resultant plasmids, termed senDNAs, were found in cultures derived from senescent mycelium. At least six different senDNAs have been reported (1, 5-7, 11, 22, 28), but one particular 2.6-kilobasepair plasmid, asenDNA, is the most common senDNA found in senescent cultures. The other senDNAs occur relatively infrequently, and some have only been reported once. Unlike the other senDNA plasmids, the asenDNA plasmid is also found in young, nonsenescent mycelia of race A, although in lesser amounts (26). This plasmid consists of a complete group II intron of the highly mosaic COI gene, and it possesses an open reading frame with extensive homology to retroviral reverse transcriptase (18). A second class of mitochondrial plasmids, termed sMt-DNAs, have recently been described in P. anserina (M. S. Turker, J. M. Domenico, and D. J.Cummings, J. Biol. Chem., in press).These plasmids are associated with longevity mutants, which are defined as strains capable of growth renewal after one or more senescent crises on solid medium. Similar to senescent cultures, such mutants usually yield mitochondrial DNAs with extensive rearrangements (2, 15; D. J. Cummings, M. S. Turker, and J. M. Domenico, in press). Figure 1 shows the most current restriction map for P. anserina mitochondrial DNA and the locations from which several of the excision amplification plasmids are derived.For this study we investigated the kinetics of P. anserina senescence in liquid culture by developing a procedure for the serial passage of homogenized mycelia. The most striking observation was that P. anserina did not senesce when grown continuously in liquid culture. Fqrther, when small masses of the liquid culture-grown mycelia, termed puff balls, were returned to growth on ...

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Loss of Genes coding for Ribosomal RNA in Ageing Brain Cells

Cited by 128 publications

References 16 publications

The Epigenetic Pathways to Ribosomal DNA Silencing

The Epigenetic Pathways to Ribosomal DNA Silencing

Nucleoli: Composition, Function, and Dynamics

Podospora anserina does not senesce when serially passaged in liquid culture

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