Bestor T H, Tycko B
Department of Genetics and Development, Columbia University, College of Physicians and Surgeons, New York, New York 10032, USA.
Nat Genet. 1996 Apr;12(4):363-7. doi: 10.1038/ng0496-363.
There are two biological properties of genomic methylation patterns that can be regarded as established. First, methylation of 5'-CpG-3' dinucleotides within promoters represses transcription, often to undetectable levels. Second, in most cases methylation patterns are subject to clonal inheritance. These properties suit methylation patterns for a number of biological roles, although none of the current hypotheses can be regarded as proved or disproved. One hypothesis suggests that the activity of parasitic sequence elements is repressed by selective methylation. Features of invasive sequences that might allow their identification and inactivation are discussed in terms of the genome defense hypothesis. Identification of the cues that direct de novo methylation may reveal the biological role (or roles) of genomic methylation patterns.
基因组甲基化模式有两个生物学特性，可以认为是已确定的。第一，启动子内5'-CpG-3'二核苷酸的甲基化会抑制转录，通常会抑制到无法检测的水平。第二，在大多数情况下，甲基化模式会发生克隆遗传。这些特性使甲基化模式适合多种生物学作用，尽管目前的假设都不能被视为已得到证实或证伪。一种假设认为，寄生序列元件的活性通过选择性甲基化受到抑制。根据基因组防御假说，讨论了可能有助于识别和灭活入侵序列的特征。确定指导从头甲基化的线索可能会揭示基因组甲基化模式的生物学作用。
