Shmookler Reis R J, Goldstein S
Nucleic Acids Res. 1982 Jul 24;10(14):4293-304. doi: 10.1093/nar/10.14.4293.
A mass culture of human diploid fibroblasts, and eight clones isolated from that mass culture, were examined for methylation patterns in several regions of DNA. Plasmid-inserted cDNA sequences were used as probes for alpha-hCG, beta-globin, A gamma- and G gamma-globin, and beta- and gamma-actin gene regions. Each probe revealed a different clone-specific pattern of DNA methylation, indicating a striking degree of inter-clonal heterogeneity, for those gene regions which are not normally expressed in diploid fibroblasts (alpha-hCG, gamma-globin and beta-globin). Intra-clonal variation was also evident in many instances, implying that heterogeneity could arise de novo in pure cell clones during serial passage. Thus methylation patterns, in particular for repressed genes, appear to be unstably inherited in these cells, and this instability may lead to random derepression in some cell lineages during mitotic growth.
对人二倍体成纤维细胞的大规模培养物以及从该大规模培养物中分离出的八个克隆进行了DNA若干区域甲基化模式的检测。插入质粒的cDNA序列被用作α-人绒毛膜促性腺激素、β-珠蛋白、Aγ-和Gγ-珠蛋白以及β-和γ-肌动蛋白基因区域的探针。每个探针都揭示了不同的克隆特异性DNA甲基化模式，这表明对于那些在二倍体成纤维细胞中通常不表达的基因区域（α-人绒毛膜促性腺激素、γ-珠蛋白和β-珠蛋白），克隆间存在显著程度的异质性。在许多情况下，克隆内变异也很明显，这意味着在连续传代过程中，纯细胞克隆中可能会重新出现异质性。因此，甲基化模式，特别是对于受抑制基因，在这些细胞中似乎是不稳定遗传的，这种不稳定性可能导致在有丝分裂生长过程中某些细胞谱系的随机去抑制。
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