Análisis de las diferencias entre células progenitoras y no progenitoras en el sistema traqueal de Drosophila melanogaster

Abstract

In the Drosophila larva, most of the juvenile tissues are made up of large polyploid cells fated to die during metamorphosis stage. The dorsal trunk of the tracheal system is composed mainly of these cells, apart from the second metamere, that is formed by the Differentiated Adult Progenitor (DAP) cells. These cells remain diploid during the larval stages, survive metamorphosis and contribute to the formation of the adult respiratory system. Both the DAPs and the rest of the cells that form the tracheal system, are exposed to the same nutritional and hormonal cues during development, suggesting that there must be different molecular components in each, that lead them to the acquisition of opposing cell fates during the metamorphosis. The initial objective of this thesis was to establish a differential gene expression profile between progenitor and non-progenitor cells of the dorsal trunk, that would allow us to detect specific functions and processes that determine the development of each group. Through this analysis, components of the autophagic pathway were found differentially expressed between DAPs and the rest of the dorsal trunk cells. We confirmed these results using the appropriate markers, and we analyzed the effects of altering the autophagic pathway in the last larval stage and during metamorphosis. These results allowed us to conclude that autophagy is required for the degradation of the larval dorsal trunk during the pupal stage. In parallel, we examined the relationship between the progressive increase in autophagy levels along the dorsal trunk and the degree of polyploidy in non-progenitor cells. Through experiments that allowed us to increase the replication cycles of these cells, we were able to conclude that there is a correlation between the degree of polyploidy and the level of autophagy. Finally, we studied the effect of nutritional and oxidative stress in the progenitor cells of the tracheal system. We found that the nutritional restriction of amino acids inhibits the mitotic cycle, which can be reactivated when standard nutrition conditions are restored.