Interphase movements of a DNA chromosome region modulated by VP16 transcriptional activator

We examined changes in intranuclear chromosome positioning induced by a tra nscriptional activator in a simple experimental system. Targeting the VP16 acidic activation domain (AAD) to an engineered chromosome site resulted in its transcriptional activation and redistribution from a predominantly per ipheral to a more interior nuclear localization. Direct visualization in vi vo revealed that the chromosome site normally moves into the nuclear interi or transiently in early G1 and again in early S phase. In contrast, VP16 AA D targeting induced this site's permanent interior localization in early G1 . A single transcriptional activator therefore can modify the cell-cycle-de pendent programme of intranuclear positioning of chromosome loci.