Uncovering the Relationship between Endocytosis and Awd, the Drosophila Homolog of Nme Metastasis Suppressor Proteins

The work presented in this PhD thesis focuses on the study of awd (abnormal wing discs) gene function during the development of Drosophila melanogaster. awd gene product is the ortholog of Nme1 and Nme2 (non-metastatic cell expression 1 and 2, respectively), which display metastasis suppressor abilities. In the first part, the main purpose of my research plan is to investigate the requirement of awd gene function for the correct activation of Notch (N) signalling pathway. N signalling is a highly conserved cell-cell communication pathway that mediates critical cell fate decision events occurring both in insects and vertebrates. Results presented in this PhD thesis clearly show that awd loss of function impairs N receptor trafficking, resulting in defective N signal transduction. In the second part, the issue of my work concern the investigation of Awd dynamics inside and outside cells. Nme1 is found in human body fluids and its protein level correlates with prognosis in cancer patients. This prompted me to gain further insights into the mechanisms through which intracellular and extracellular Awd amounts are controlled. Through molecular genetic approaches, I found that conditional block of Shi activity reduces Awd intracellular amount, indicating that Shi controls intracellular level of Awd. Finally, in the third part, I direct my research towards the study of dVHL, a well-known Awd interactor. The haploinsuffcient dVHL (von-Hippel Lindau) gene is the Drosophila homolog of the human VHL tumour suppressor gene. By applying omics approaches, I found that reduced dVHL gene dosage alters the expression levels of genes involved in chromatin organisation and cell metabolism. Alteration in these cellular activities are recurrently found in cancer cells.