Loss of alpha I type I collagen gene expression in rat clonal bone cell lines is accompanied by DNA methylation

Four clonal cell lines subcloned from a clonal population of fetal rat calvaria cells show a loss of type I collagen synthesis. Northem blot analysis showed that the level of α1(I) collagen mRNA expression in each of the clonal populations parallels the level of collagen protein expression in each of these cell lines. The methylation pattern of the collagen gene in these clonal cell lines was determined using the restriction endonucleases MspI and HpaII. It was found that the loss in collagen type I expression correlated positively with the degree of methylation of α1(I) procollagen genes, indicating that methylation of CpG may be an important mechanism of collagen gene regulation.