Impact of oncogene expression in the respiratory system of Drosophila melanogaster

The ectopic expression of several oncogenes targeted to the tracheal system of the fruit fly induced structural changes comprising meta- and hyperplasia of the epithelium. The ectopic expression of a constitutively active isoform of the epidermal growth factor receptor (EgfrCA) led to thickening of the epithelium and obvious changes in the cellular structure and death of the larvae. A test system with the ability to identify substances that rescue this lethal phenotype was developed. Moreover, activation of different components of the Ras/ MAPK pathway in a specialized cell type of the tracheal system that is devoted to the direct oxygen supply of the tissue, the so called terminal cells, resulted in enlargement and an increased number of branches of these cells. In contrast, activation of the local innate immune system, triggered by overexpression of the immune-activating receptor PGRP-LCx led to death of these cells.