组蛋白的泛素化与去泛素化修饰

泛素在真核生物体内广泛存在,泛素化修饰是转录后的修饰方式之一;组蛋白是染色质的主要成分之一,与基因的表达有密切关系。组蛋白的泛素化修饰与经典的蛋白质的泛素调节途径不同,不会导致蛋白质的降解,但是能够招募核小体到染色体、参与X染色体的失活、影响组蛋白的甲基化和基因的转录。组蛋白的去泛素化修饰同样与染色质的结构及基因表达密切相关。组蛋白的泛素化和磷酸化、乙酰化、甲基化修饰之间还存在协同和级联效应。     

High-resolution profiling of histone methylations in the human genome

Histone modifications are implicated in influencing gene expression. We have generated high-resolution maps for the genome-wide distribution of 20 histone lysine and arginine methylations as well as histone variant H2A.Z, RNA polymerase II, and the insulator binding protein CTCF across the human genome using the Solexa 1G sequencing technology. Typical patterns of histone methylations exhibited at promoters, insulators, enhancers, and transcribed regions are identified. The monomethylations of H3K27, H3K9, H4K20, H3K79, and H2BK5 are all linked to gene activation, whereas trimethylations of H3K27, H3K9, and H3K79 are linked to repression. H2A.Z associates with functional regulatory elements, and CTCF marks boundaries of histone methylation domains. Chromosome banding patterns are correlated with unique patterns of histone modifications. Chromosome breakpoints detected in T cell cancers frequently reside in chromatin regions associated with H3K4 methylations. Our data provide new insights into the function of histone methylation and chromatin organization in genome function.