UC Santa Barbara

Apoptosis is the process of highly regulated programmed cell death that utilizes caspase-3 to initiate the executioner phase of apoptosis. However, under certain circumstances, cells are able to survive its activation through a process called “anastasis”. Anastasis has been documented to occur in several cell lines and in Drosophila melanogaster. However, the purpose of anastasis and how it is regulated are currently unknown. In Drosophila, anastasis can be visualized using a previously created biosensor, CasExpress, that permanently marks cells that have survived caspase-3 activation with GFP. CasExpress can detect anastasis in Drosophila wing disc during normal development. Since Drosophila wing discs have been used as a model for studying regeneration, it would be beneficial to use this model to investigate if anastasis occurs during tissue regeneration. Using the CasExpress system, we found that anastasis occurs during regeneration in response to reaper-induced tissue damage. To determine if anastasis is required for regeneration, overexpression of reaper in cells that have undergone caspase-3 activation results in a decrease in the number of CasExpress positive cells. We found that the removal of cells that survive caspase-3 activation during tissue ablation does not manifest in a significant change in wing size, possibly due to the incomplete killing of anastatic cells. To start unraveling how anastasis is regulated, CasExpress was utilized in screening the requirement of several genes known to function in wound healing.