Appearance of extrachromosomal circular DNAs during in vivo and in vitro ageing of mammalian cells

• Published in: Mechanisms of ageing and development Vol. 29; no. 1; pp. 89 - 99
• Main Authors: Kunisada, Takahiro, Yamagishi, Hideo, Ogita, Zen-ichi, Kirakawa, Tadashi, Mitsui, Youji
• Format: Journal Article
• Language: English
• Published: Shannon Elsevier Ireland Ltd 1985; Elsevier Science
• Subjects: Ageing, cell death; Aging; Animals; Biological and medical sciences; Cell physiology; Cell Survival; Chemical Phenomena; Chemistry; Circular DNA amplification; DNA, Circular; Female; Fetus; Fibroblasts - ultrastructure; Fundamental and applied biological sciences. Psychology; Human fibroblasts; Humans; In vivo and in vitro ageing; Lymphocytes - ultrastructure; Mica-press-adsorption; Microscopy, Electron - methods; Middle Aged; Molecular and cellular biology; Rat lymphocytes; Rats; Rats, Inbred Strains; Skin - cytology; Skin - pathology; Werner Syndrome - pathology; Rat lymphocytes; Mica-press-adsorption; Human fibroblasts; In vivo and in vitro ageing; Circular DNA amplification; Human; Cell culture; Extrachromosomal DNA; Rat; Ageing; Rodentia; Circular DNA; Vertebrata; Gene amplification; Mammalia; Cell; Fibroblast; Lymphocyte
• ISSN: 0047-6374; 1872-6216
• DOI: 10.1016/0047-6374(85)90050-8

Appearance of extrachromosomal circular DNAs with in vivo and in vitro cellular ageing was examined by using a new technique of mica-press-adsorption for electron microscopy. The size distribution and the copy number of circular DNA complexes varied, depending on the cellular age. Extrachromosomal circular DNA complexes of variable length of more than 0.5 μm or 1.5 kilobase (kb) appeared during in vivo ageing of rat lymphocytes and in vitro ageing of cultured human lung fibroblasts. A restricted size class of circular forms of less than 0.5 μm in contour length was amplified in human skin fibroblasts from aged normal or Werner's syndrome subjects. These circular DNA molecules are suggested to be products of DNA rearrangements or gene amplification occurring in the chromosome.