Regulation of growth and cell fate during tissue regeneration by the two SWI/SNF chromatin-remodeling complexes of Drosophila

To regenerate, damaged tissue must heal the wound, regrow to the proper size, replace the correct cell types, and return to the normal gene-expression program. However, the mechanisms that temporally and spatially control the activation or repression of important genes during regeneration are not fully understood. To determine the role that chromatin modifiers play in regulating gene expression after tissue damage, we induced ablation in Drosophila melanogaster imaginal wing discs, and screened for chromatin regulators that are required for epithelial tissue regeneration. Here, we show that many of these genes are indeed important for promoting or constraining regeneration. Specifically, the two SWI/SNF chromatin-remodeling complexes play distinct roles in regulating different aspects of regeneration. The PBAP complex regulates regenerative growth and developmental timing, and is required for the expression of JNK signaling targets and the growth promoter Myc. By contrast, the BAP complex ensures correct patterning and cell fate by stabilizing the expression of the posterior gene engrailed. Thus, both SWI/SNF complexes are essential for proper gene expression during tissue regeneration, but they play distinct roles in regulating growth and cell fate.