Publication

Abstract : The vertebrate reticuloendothelial system (RES) functions to remove potentially damaging macromolecules, such as excess hormones, immune-peptides and -complexes, bacterial-endotoxins, microorganisms and tumor cells. Insect hemocytes and nephrocytes – which include pericardial cells (PCs) and garland cells – are thought to be functionally equivalent to the RES. Although the ability of both vertebrate scavenger endothelial cells (SECs) and {PCs} to sequester colloidal and soluble macromolecules has been demonstrated the molecular mechanism of this function remains to be investigated. We report here the functional characterization of Drosophila larval {PCs} with important insights into their cellular uptake pathways. We demonstrate the nephrocyte function of {PCs} in live animals. We also develop and use live-cell assays to show that {PCs} take up soluble macromolecules in a Dynamin-dependent manner and colloids by a Dynamin-independent pathway. We had earlier identified Drosophila rudhira (Drudh) as a specific marker for PCs. Using {RNAi} mediated knock-down we show that Drudh regulates macropinocytic uptake in PCs. Our study establishes important functions for Drosophila PCs, describes methods to identify and study them, provides a genetic handle for further investigation of their role in maintaining homeostasis and demonstrates that they perform key subsets of the roles played by the vertebrate RES.