Chromatin dynamics in regeneration epithelia: Lessons from Drosophila imaginal discs.

During the process of regeneration, a switch in the transcription program occurs in cells that contribute to the reconstruction of the missing tissue. Early signals released upon damage are integrated into the chromatin of responding cells to change its activity and function. Changes in chromatin dynamics result in transcriptional reprogramming, this is the coordinated regulation of expression of a specific subset of genes required for the regeneration process. Here we summarize changes in gene expression and chromatin dynamics that occurs during the process of regeneration of Drosophila imaginal discs.

Damage-responsive elements in Drosophila regeneration.

One of the most important questions in regenerative biology is to unveil how and when genes change expression and trigger regeneration programs. The resetting of gene expression patterns during response to injury is governed by coordinated actions of genomic regions that control the activity of multiple sequence-specific DNA binding proteins. Using genome-wide approaches to interrogate chromatin function, we here identify the elements that regulate tissue recovery in Drosophila imaginal discs, which show a high regenerative capacity after genetically induced cell death. Our findings indicate there is global coregulation of gene expression as well as a regeneration program driven by different types of regulatory elements. Novel enhancers acting exclusively within damaged tissue cooperate with enhancers co-opted from other tissues and other developmental stages, as well as with endogenous enhancers that show increased activity after injury. Together, these enhancers host binding sites for regulatory proteins that include a core set of conserved transcription factors that control regeneration across metazoans.