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Updated: Aug 23, 2025

Fluorescent Leakage Assay to Investigate Membrane Destabilization by Cell-Penetrating Peptide
Published on: December 19, 2020
Impact of peptide permeation enhancer on tight junctions opening cellular mechanisms
Joël Brunner1, Domitille Schvartz2, Aurélie Gouiller1
1School of Pharmaceutical Sciences, University of Geneva, Geneva, Switzerland.
Abstract:
The myristoylated pentapeptide, L-R5, contains an amino acid sequence of the zeta inhibitory peptide (ZIP) portion (pseudosubstrate) of protein kinase C zeta (PKC ζ). As PKC ζ is involved in the modulation of epithelial tight junctions (TJs) through the phosphorylation of TJ proteins, L-R5 was suggested to interact with the enzyme resulting in the enhancement of paracellular permeability. This study shows that L-R5 does not bind to the enzyme but interacts directly with TJ proteins. We show here that the binding of PKC ζ to occludin and its successive phosphorylation is prevented by L-R5, which leads to TJ disruption and enhanced epithelial permeability. Although L-R5 did not show any in vitro cytotoxicity, a proteomics study revealed that L-R5 interferes with other regulatory pathways, e.g., apoptosis and immune response. We suggest that structural modification of the peptide may increase the specificity TJ protein-peptide interaction.
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