Nephrocyte ageing and endosome maturation

Project Title: Function of metazoan HOPS and CORVET (together with C. Ungermann, Biochemistry Division)

Funding Source: DFG PA517/12-1 (awaits renewal)

Principle Investigator: Achim Paululat with Maren Janz

Drosophila nephrocytes act as scavenger cells and are part of the excretory system of the insect. The have been established as a model for studying endocytosis. We study the role of proteins in the endo-lysosomal maturation pathway. In particular, we are interested in the role of Rabs and GEFs in nephrocyte ageing.

This picture shows a larval heart, triple-stained for nephrocytes (in green)  muscles (in red) and the extracellular matrix around the heart (in white). The nephrocytes act as scavenger cells (sort of litter boxes) in the animal. They are essential for the uptake of metabolites, osmoregulation and the secretion of extracellular matrix proteins, just to mention a few important functions. We are studying the endosomal pathway, its components and their role in nephrocyte physiology and ageing.

The pictures on the right side shows a cross-section through nephrocytes, imaged with an transmission electron microscope to illustrate the ultrastructure of the cells. A shows a nephrocytes isolated  from a one week old fly, B a cell from a six week old animal. Nephrocytes undergo dramatic ultrastructural changes upon ageing. They lose their membrane infolding and filtration apparatus (slit diaphragms) and display an increased number of multilamellar vesicles. One of our recent projects addresses ageing of nephrocytes.