DNA methylation is not involved in the structural alterations of Ornithine Decarboxylase or Total Chromatin of c-Ha-rasVal 12 Oncogene-Transformed NIH-3T3 Fibroblasts
✍ Scribed by Jens Laitinen; Per Saris; Erkki Hölttä
- Publisher
- John Wiley and Sons
- Year
- 1995
- Tongue
- English
- Weight
- 978 KB
- Volume
- 57
- Category
- Article
- ISSN
- 0730-2312
No coin nor oath required. For personal study only.
✦ Synopsis
The ornithine decarboxylase (odc) gene is an early response gene, whose increased expression and relaxed chromatin structure is closely coupled to neoplastic growth. In various turnour cells, the odc gene displays hypomethylation at the sequences CCGG. Hypomethylation of genes is believed to correlate with chromatin decondensation and gene expression. Since a given pattern of DNA methylation may not be preserved in neoplastic cells, we studied the methylation status of odc gene at the CCGG sequences in c-Ha-rasVa112 oncogene-transformed NIH-3T3 fibroblasts during the growth cycle and relative to their normal counterparts. We found that the methylation state of the odc gene and its promoter and mid-coding and 3' regions remain unaltered during the cell cycle. We also found that in ras oncogene-transformed cells, which display a more decondensed nucleosomal organization of chromatin than the normal cells, the CCGG sequences in bulk DNA and at the odc gene were methylated to the same extent as in the nontransformed cells. These data suggest that DNA hypomethylation at the CCGG sequences is not a prerequisite for chromatin decondensation and cell transformation by the c-Ha-rasVa' l 2 oncogene.