Demethylation of classical satellite 2 and 3 DNA with chromosomal instability in senescent human fibroblasts.

Abstract

Demethylation of genomic 5-methylcytosine is reported in aged human tissues and senesced human cells, although it is not understood to what extent this phenomenon contributes to replicative senescence. We examined methylation status of satellite 2 and 3 sequences during passages of normal human fibroblasts. These sequences are abundant in the juxtacentromeric heterochromatin of human chromosomes 1, 9 and 16, and heavily methylated in tissues of normal individuals. The decrease in DNA methylation level was two times faster in satellite 3 DNA than in satellite 2 and total DNA. Then we monitored appearance of micronuclei during the passages since they are indicative of heterochromatin decondensation or chromosome breakage. Concomitant with the DNA demethylation, micronuclei containing the heterochromatin of chromosomes 1, 9 or 16, appeared specifically. These results suggest that demethylation of heterochromatin has a role in replicative senescence through chromosome instability.

• Authors: Toshikazu Suzuki, Michihiko Fujii, Dai Ayusawa
• Journal: Experimental gerontology (Exp Gerontol) 2002 Aug-Sep Vol. 37 Issue 8-9 Pg. 1005-14 ISSN: 0531-5565 [Print] England
• PMID: 12213551 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• DNA, Satellite
• Heterochromatin

Topics

• Cell Line
• Cellular Senescence (genetics)
• Chromosome Aberrations
• DNA Methylation
• DNA, Satellite (metabolism)
• Fibroblasts (metabolism)
• Heterochromatin (metabolism)
• Humans
• Micronuclei, Chromosome-Defective