Chromosome positional effects of gene expressions after cellular senescence

Normal human fibroblasts stop dividing after a limited number of cell divisions termed cellular senescence. Telomere shortening has been shown to be the main factor that causes cellular senescence, however, the molecular mechanism of how telomere shortening causes cellular senescence is unclear. Here we analyze the relationship between gene expressions and their chromosomal locations during cellular senescence. It appears that the expression of genes located in chromosome 4 is preferentially altered after senescence. Moreover, we identify four chromosomal loci in which gene expressions are affected by senescence. Finally, we show that there is no preferential alteration of telomere-proximal genes during cellular senescence, implying that cellular senescence is not caused by derepression of telomere-proximal genes. (C) 2003 Elsevier Inc. All rights reserved.