Local Chromatin Mobility is Independent of Transcriptional Activity

The dynamics of chromatin in live cells is characterized by high mobility on a sub-micrometer scale and strict constraints on larger scales. While there is ample evidence that chromatin loci can move within the nucleus in response to transcriptional activation, chromatin loci expressed at a steady state are confined to small intranuclear volumes, which they do not leave for hours. Previous work has shown, using in-vivo tagging of chromatin loci, that chromatin at the nuclear periphery has lower mobility and is more strictly constrained than chromatin in more internal nuclear positions. It appeared plausible that this difference was because of differences in local transcriptional activity and association of peripheral chromatin loci with heterochromatin. We here provide evidence that chromatin mobility is in fact independent of local transcriptional activity.