Delivering Signal-Altering Bacterial Effector Proteins to Mammalian Cells Using Cell-Penetrating Peptide Technology

A major role of the mitogen activated protein kinase (MAPK) pathway in eukaryotes is to activate the bacterial pathogen defense response upon the detection of bacterial products in the environment. This defensive signaling results in the induction of inflammation, the transcription of antimicrobial peptides, the modulation of the cell cycle and cell survival. Some Gram-negative bacteria have evolved needle-like structures called Type III Secretion Systems (T3SS) that secrete signal-altering molecules into the host cell to interrupt signaling pathways that would otherwise lead to the elimination of the bacterial infection. These signal-altering molecules are known as bacterial effector proteins (BEPs). Bacterial effectors YopJ and VopA have been shown to interfere with specific signaling molecules in the MAPK pathway; effectively inducing apoptosis in mammalian intestinal endothelial cells. In this study, we deliver these proteins to colon cancer cells to artificially induce cell death, using a novel cell-penetrating peptide (CPP) delivery system called TAT-CaM. Here, we show that the TAT-CaM system is capable of delivering YopJ into mammalian cells and that YopJ is capable of inducing cell death once delivered. Although we encountered issues with reproducibility, we believe that TAT-CaM-YopJ could be effective in inducing cell death in cancer cells in a reproducible manner after experimental adjustments