Binding of Transcriptional Activator to Silent Loci Causes Their Detachment from the Nuclear Lamina in Drosophila Neurons and Salivary Gland Cells

In mammals, the binding of transcriptional activators leads to the repositioning of silent loci from the nuclear periphery to the nuclear interior. However, it remained unknown whether the same mechanism functions in <i>Drosophila</i>. Here, using FISH and DamID, we have shown that binding the GAL4 activator to the silent loci causes weakening of their interactions with the nuclear lamina and relocalization inside nuclei in <i>Drosophila</i> salivary gland cells and neurons. This mimics the removal from the nuclear periphery of a neuron-specific gene upon its activation in neurons. Salivary gland cells contain polytene chromosomes with mechanical properties, different from chromosomes of diploid cells, while neurons represent predominantly non-dividing cell type. Our results indicate a causal relationship between transcriptional activator binding and changes in the intranuclear position of loci in <i>Drosophila</i>. They also point to the similarity in general chromatin dynamics in mammals and <i>Drosophila</i>, thus strengthening the role of model organisms in studying genome architecture.