Screening for new serine proteases involved in Drosophila melanogaster immunity -

Abstract

Drosophila melanogaster is simple model organism used to study the innate immune system. Research focused for the past few decades on the two arms of the immune system: the cellular and the humoral arms. The humoral immune response of Drosophila melanogaster relies mostly on activation of melanization cascades and anti-microbial peptides (AMP) production. Two different pathways control the AMP production: the immune deficiency pathway (Imd) and the toll pathway. Considering that most of the intra-cellular players of the toll pathway have been characterized, our focus was on the extracellular players in the toll pathway. Previous studies demonstrated the presence of a serine protease (SP) cascade that results in cleavage of spatzle, the ligand of the toll receptor. However, among the 200 SPs encoded by Drosophila melanogaster genome, researchers found that only five were implicated in the activation of the toll pathway. Using an RNA interference screen we searched for candidate SP implicated for the activation of toll pathway, we showed that six SPs are implicated in the extracellular cascade of the toll pathway.