Chen Peili, Tong,
DNA methylation is one of the most important ways of genome transformation in eukaryotes, and it is involved in the regulation of gene expression. Complexes involving methylated binding proteins play an important role in inhibiting gene expression. The maintenance of DNA methylation phenotype requires DNA methyltransferase to catalyze the methylation of "semi-methylated" DNA. The methylation level of cells decreased obviously during the aging process, which may have a certain regulatory effect on gene expression in this process.
Authors: Department of Biochemistry and Molecular Biology, School of Basic Medicine, Peking University; Department of biochemistry and molecular biology; Basic medical college; Peking University; Department of Biochemistry and Molecular Biology, School of Basic Medicine, Peking University, Beijing100083; Beijing100083; Beijing 100083
Key words: DNA methylation; DNA methyltransferase; cell senescence
Fund: National Key Basic Research and Development Plan (G 20000517001); Key Project of National Natural Science Foundation of China (No.:39930 170)
Classification number: Q75
DOI:CNKI:ISSN: 100 1- 1080 . 0 . 2000-03-006
Text snapshot:
DNA methylation is an important regulation mode of genetic and extragenetic modification in mammals, which mainly occurs in C base of symmetric CpG sequence. In the mammalian genome, except for some genes, such as CpG islands in the regulatory regions of housekeeping genes and tissue-specific genes, most CpG sites have been methylated. The modified C _ (5 MC) is more unstable than C, and it is easy to deamino spontaneously to form T. In double-stranded DNA, the speed of this reaction is about 5.8 f10' 3/s. If the total number is calculated according to the protection site of 3.8 F 1 CpG, each cell will produce about two T' G mismatches every day. If it cannot be repaired effectively, that is, C~T transformation mutation is formed in the daughter cells, which may be the reason why the number of CpG loci in mammalian genome is lower than expected. In the study of p53 gene mutation, it is confirmed that smC is a hot spot of mutation, and its mutation rate is 100%.