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Purpose. The objective of this work is to evaluate the ability of peptides derived from the bulge (HAV-peptides) and groove (ADT-peptides) regions of E-cadherin EC1-domain to increase the paracellular porosity of the intercellular junctions of Madin-Darby canine kidney (MDCK) cell monolayers. Methods. Peptides were synthesized using a solid-phase method and were purified using semi-preparative HPLC. MDCK monolayers were used to evaluate the ability of cadherin peptides to modulate cadherin-cadherin interactions in the intercellular junctions. The increase in intercellular junction porosity was determined by the change in transepithelial electrical resistance (TEER) values and the paracellular transport of [sup 14]C-mannitol. Results. HAV- and ADT-peptides can lower the TEER value of MDCK cell monolayers and enhance the paracellular permeation of [sup 14]C-mannitol. HAV- and ADT-decapeptides can modulate the intercellular junctions when they are added from the basolateral side but not from the apical side; on the other hand, HAV- and ADT-hexapeptides increase the paracellular porosity of the monolayers when added from either side. Conjugation of HAV- and ADT-peptides using ω-aminocaproic acid can only work to modulate the paracellular porosity when ADT-peptide is at the N-terminus and HAV-peptide is at the C-terminus; because of its size, the conjugate can only modulate the intercellular junction when added from the basolateral side. Conclusions. Peptides from the bulge and groove regions of the EC1 domain of E-cadherin can inhibit cadherin-cadherin interactions, resulting in the opening of the paracellular junctions. These peptides may be used to improve paracellular permeation of peptides and proteins. Furthermore, this work suggests that both groove and bulge regions of EC-domain are important for cadherin-cadherin interactions. [ABSTRACT FROM AUTHOR]

Purpose. The objective of this work is to understand the sequence specificity of HAV peptides and to improve their selectivity in regulating E-cadherin-E-cadherin interactions in the intercellular junctions. Methods. Peptide 1 was modified using an alanine scanning method to give peptides 2-6. The ability of these peptides to modulate intercellular junctions was evaluated using Madin-Darby Canine Kidney (MDCK) cell monolayers on Transwell™ membranes from either the apical (AP) or the basolateral (BL) side. Modulation of the intercellular junctions was measured by the ability to lower the transepithelial electrical resistance (TEER) of MDCK monolayers and by the increase in mannitol flux. Molecular docking experiments were performed to model the binding properties of these peptides to the EC1 domain of E-cadherin. Results. Peptides 5 (Ac-SHAVAS-NH2) and 6 (Ac-SHAVSA-NH2) were found to be more effective than the parent peptide 1 in decreasing the resistance of the cell monolayer. Furthermore, comparative studies with the control and the weak inhibitor peptide 2 indicate that peptide 5 displayed a significant increase in mannitol flux. Molecular docking of peptides 1, 2 and 5 to the EC1 domain suggests that peptide 5 has the lowest binding energy. Conclusions. HAV peptides have the ability to modulate E-cadherin-E-cadherin interactions in the intercellular junctions of the MDCK cell monolayer, thus indirectly increasing the permeability of the tight junctions. This observation indicates that residues flanking the HAV sequence are important in the binding selectivity of HAV peptides to E-cadherin. Molecular docking can further aid in the design of peptides with better selectivity to the EC1 domain of E-cadherin. [ABSTRACT FROM AUTHOR]