Investigating cell extrusion and cell death during tissue morphogenesis

Cell removal can have many reasons, from overcrowding to substituting young cell populations with mature ones. Misregulation of cell death can trigger associated diseases. Excessive apoptosis can lead to pathological cell loss, as in Alzheimer’s disease, stroke or myocardial infarction. In turn, failure of old or defective cells to die leads to the accumulation of cell masses triggering tumorigenesis and causing cancer. I propose to study the abdominal epithelial morphogenesis of Drosophila to characterise the factors determining the path a cell can take towards apoptosis. In this system, the larval epithelial cells (LECs) undergo apoptosis before being replaced by adult progenitor cells called histoblasts. Interestingly, the LECs show two distinct apoptotic behaviours. By interfering selectively with genes known to control apoptosis and delamination, and subsequent analysis of cell behaviour by in vivo 4D microscopy, I will investigate the various factors determining extrusion events and apoptotic signals.