Objectives

We hypothesize that an EpCAM/claudin-7 protein complex in CD is potentially part of tetraspanin-enriched microdomains (TEMs), plays a role in the maintenance of barrier function and tight junction integrity, and is regulated by proteolytic cleavage of either EpCAM and/or claudin-7. We will use native murine collecting ducts as experimental tissue to account for cellular composition and variability of conditions (cortico-medullary axis). We first want to investigate and describe the given situation (transport physiology, localization, proteolytic manipulation) in the freshly dissected native murine collecting duct under physiological conditions. In a second step a primary cell culture model close to the native situation will be established to assess differentiation, de-differentiation and proliferation in more detail. A variety of pathophysiological conditions as in glomerulonephritis, renal ischemia, bacterial nephritis, or diabetes challenge integrity, differentiation and proliferation of the collecting duct epithelium and can be simulated in native tubules as well as in the cell culture system.

Aim i)   Describe localization and interaction of the claudin-7/EpCAM complex in isolated collecting ducts

Aim ii)  Analyze the function of the native collecting duct in vitro under posttranslational modification of the                claudin-7/EpCAM complex

Aim iii) Generate a 3D-cell culture system to perform genetic cell manipulations and to verify and expand in              sights from previous studies