Loss of type I procollagen gene expression in SV40-transformed human fibroblasts is accompanied by hypermethylation of these genes.
Transformation of human lung fibroblasts (WI-38) by Simian Virus 40 (SV40) resulted in a decline of 25-30% in the amount of secreted collagen. The collagen produced by the transformed fibroblasts contained no type I collagen (i.e. alpha 1(I) and alpha 2 chains), which was the major collagen component produced by untransformed fibroblasts. Measurement of the procollagen mRNA levels by dot hybridization with nick-translated procollagen-cDNA clones showed that the absence of type I collagen was due to the absence of alpha 1(I) and alpha 2 procollagen mRNAs. This result was confirmed by hybridization of cDNA to total RNA with southern blots of the procollagen clones. To clarify the mechanism by which type I procollagen gene transcription is abolished in transformed cells, the methylation patterns of the alpha 1(I) and alpha 2 procollagen genes in normal and SV40-transformed fibroblasts were compared, using the chicken alpha 1(I) and alpha 2 procollagen-cDNA clones as probes. Methylated sites were detected by means of the restriction endonuclease isoschizomers HpaII and MspI. Methylation of the procollagen alpha 1(I) and alpha 2 genes was increased in the SV40-transformed fibroblasts, concurrently with the loss of type I collagen synthesis. DNA methylation may thus contribute to altered regulation of gene expression upon cell transformation.
D002460:Cell Line; D002472:Cell Transformation, Viral; D004247:DNA / Q000235:genetics*; D004262:DNA Restriction Enzymes; D004279:DNA, Viral / Q000235:genetics; D005796:Genes; D006801:Humans; D008168:Lung; D008745:Methylation; D009693:Nucleic Acid Hybridization; D011347:Procollagen / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics; D013539:Simian virus 40 / Q000235:genetics*
D004279:DNA, Viral; D011347:Procollagen; D012333:RNA, Messenger; D004247:DNA; D004262:DNA Restriction Enzymes