Gerasimova T I, Corces V G
Department of Biology, The Johns Hopkins University, Baltimore, Maryland 21218, USA.
Cell. 1998 Feb 20;92(4):511-21. doi: 10.1016/s0092-8674(00)80944-7.
Chromatin boundaries or insulator elements affect the interaction between enhancers and promoters. The gypsy insulator contains two proteins, Su(Hw) and Mod(mdg4). Both proteins colocalize on several hundred sites on polytene chromosomes and are distributed in a punctated pattern in the nuclear matrix. Mutations in mod(mdg4) have properties characteristic of a trxG gene. In addition, mutations in trxG genes enhance insulator effects on adjacent enhancers, whereas mutations in Pc have the opposite result. These alterations correlate with changes in the pattern of nuclear localization of insulator components. The results suggest a model in which PcG and TrxG proteins regulate insulator function by establishing higher order domains of chromatin organization required for the assembly of functional insulators at the nuclear matrix.
染色质边界或绝缘子元件会影响增强子与启动子之间的相互作用。吉普赛绝缘子包含两种蛋白质，即Su(Hw)和Mod(mdg4)。这两种蛋白质在多线染色体上的数百个位点共定位，并以点状模式分布在核基质中。mod(mdg4)中的突变具有trxG基因的特征性质。此外，trxG基因中的突变会增强绝缘子对相邻增强子的作用，而Pc中的突变则产生相反的结果。这些改变与绝缘子成分的核定位模式变化相关。结果提示了一种模型，即PcG和TrxG蛋白通过建立染色质组织的高阶结构域来调节绝缘子功能，而这种高阶结构域是在核基质中组装功能性绝缘子所必需的。
