DFG Research Training Group "TJ-Train" (GRK 2318)
Clostridium perfringens enterotoxin (CPE) causes one of the most common food borne illnesses. CPE binds to tight junction (TJ) proteins (e.g. claudin-3 and -4) and subsequently forms pores in the membrane leading to damage of epithelial cells. Due to its cytotoxicity, CPE is used for targeting of claudin-overexpressing tumor cells. In contrast, the c-terminal domain cCPE of CPE is non-toxic and contains the claudin binding domain. cCPE is used as a TJ modulator to increase paracellular drug delivery. Previously, we elucidated in structure-based studies the molecular mechanism of the CPE-claudin interaction and designed CPE- or cCPE-variants with shifted claudin subtypespecificity (e.g. binding to claudin-1 or -5).
Aim of this project are expanded structure-function studies to design and to test variants of cCPE and CPE as claudin subtype-specific and in turn tissue-specific biologicals for (i) improved drug delivery by TJ-modulation, (ii) molecular diagnosis or (iii) cytotoxic treatment of carcinomas.
Methods: Molecular modelling, site-directed mutagenesis, expression and purification of recombinant proteins, protein-protein interaction assays, cell culture of differentiated epithelial and carcinoma cells, immunocytochemistry and confocal microscopy. Activity of cCPE- and CPE-variants will be tested by measurements of transepithelial resistance and paracellular solute permeability as well as imaging and cytotoxicity assays with cell lines and in vivo xenotransplant tumor models.
PhD doctoral student