Wnt/β-catenin signaling is important for blood-brain barrier (BBB) development and is implicated in BBB breakdown under various pathophysiological conditions. In the present study, a comprehensive characterization of the relevant genes, transport and permeability processes influenced by both the autocrine and external activation of Wnt signaling in human brain endothelial cells was examined using hCMEC/D3 culture model. The hCMEC/D3 expressed a full complement of Wnt ligands and receptors. Preventing Wnt ligand release from hCMEC/D3 produced minimal changes in brain endothelial function, while inhibition of intrinsic/autocrine Wnt/β-catenin activity through blocking β-catenin binding to Wnt transcription factor caused more modest changes. In contrast, activation of Wnt signaling using exogenous Wnt ligand (Wnt3a) or LiCl (GSK3 inhibitor) improved the BBB phenotypes of the hCMEC/D3 culture model, resulting in reduced paracellular permeability, and increased P-glycoprotein (P-gp) and breast cancer resistance associated protein (BCRP) efflux transporter activity. Further, Wnt3a reduced plasmalemma vesicle associated protein (PLVAP) and vesicular transport activity in hCMEC/D3. Our data suggest that this in vitro model of the BBB has a more robust response to exogenous activation of Wnt/β-catenin signaling compared to autocrine activation, suggesting that BBB regulation may be more dependent on external activation of Wnt signaling within the brain microvasculature.

One of the major hurdles in developing therapeutic agents is the difficulty in delivering drugs through the intestinal mucosa and blood-brain barriers (BBB). The goal here is to describe the general structures of the biological barriers and the strategies to enhance drug delivery across these barriers. Prodrug methods used to improve drug penetration via the transcellular pathway have been successfully developed, and some prodrugs have been used to treat patients. The use of transporters to improve absorption of some drugs (e.g., antiviral agents) has also been successful in treating patients. Other methods, including (a) blocking the efflux pumps to improve transcellular delivery and (b) modulation of cell-cell adhesion in the intercellular junctions to improve paracellular delivery across biological barriers are still in the investigational stage.

It is challenging to deliver molecules to the brain for diagnosis and treatment of brain diseases. This is primarily due to the presence of the blood-brain barrier (BBB), which restricts the entry of many molecules into the brain. In this study, cyclic ADT peptides (ADTC1, ADTC5, and ADTC6) have been shown to modify the BBB to enhance the delivery of marker molecules (e.g., 14C-mannitol, Gd-DTPA) to the brain via the paracellular pathways of the BBB. The hypothesis is that these peptides modulate cadherin interactions in the adherens junctions of the vascular endothelial cells forming the BBB to increase paracellular drug permeation. In vitro studies indicated that ADTC5 had the best profile to inhibit adherens junction resealing in MDCK cell monolayers in a concentration-dependent manner (IC50 = 0.3 mM) with a maximal response at 0.4 mM. Under the current experimental conditions, ADTC5 improved the delivery of 14C-mannitol to the brain about twofold compared to the negative control in the in situ rat brain perfusion model. Furthermore, ADTC5 peptide increased in vivo delivery of Gd-DTPA to the brain of Balb/c mice when administered intravenously (i.v.). In conclusion, ADTC5 has the potential to improve delivery of diagnostic and therapeutic agents to the brain.

A r t i c l e I n f o A b s t r a c t Keywords:ADTC3, E-cadherin domain EC1, Gromacs, dockingThe treatment of diseases that attack the brain is very difficult, because the delivery of drug molecules to the brain is often hindered by the molecules of blood-brain barrier (BBB). Thus, it was developed the new method using synthetic peptide which derived from the amino acids sequence of cadherin and ADTC3 predicted able to modulate the intercellular junction peptide. The intermolecular interaction between ADTC3 and Ecadherin is hypothesized as the driving force of modulation. In this research have been calculated the interaction energy between ADTC3 and E-cadherin. The method used in this research is molecular dynamics (MD) and molecular docking. The results show that cyclic peptide ADTC3 (Ac-CADTPC-NH2) simulated for 20 ns (20,000 ps) has considerable interaction with EC1 domain of E-cadherin which have the binding energies -31.55 kJ.mol -1 and inhibition constant Ki 2.96 μM at the 4487 conformation. This highly interaction energy was predicted as the driving force in modulating intercellular junctions. The binding site of E-cadherin reside on amino acid residues Asp1, Trp2, Val3, Ile4, Lys25, Met92 in the adhesion arm-acceptor pocket region. A b s t r a kKata kunci: ADTC3, E-cadherin domain EC1, Gromacs, docking Pengobatan penyakit yang menyerang otak sangat sulit dilakukan karena penghantaran molekul obat menuju otak terhalang oleh molekul-molekul blood-brain barrier (BBB). Untuk mengatasinya telah dikembangkan metode baru dengan memodulasi junction antar sel menggunakan peptida. Salah satu peptida yang diperkirakan mampu memodulasi adalah ADTC3, yang diturunkan dari susunan asam amino kadherin. Modulasi terjadi diduga karena interaksi antara ADTC3 dengan E-kadherin. Pada penelitian ini telah dihitung energi interaksi antara ADTC3 dengan E-kadherin. Metode yang digunakan adalah dinamika molekul (DM) dan molecular docking. Hasil penelitian menunjukkan bahwa peptida siklik ADTC3 (Ac-CADTPC-NH2) hasil simulasi 20 ns (20.000 ns) berinteraksi kuat dengan domain EC1 E-kadherin dengan energy binding sebesar -31,55 kJ.mol -1 dan tetapan inhibisi Ki sebesar 2,96 µM pada konformasi ke-4487. Interaksi yang kuat ini diperkirakan sebagai daya penggerak memodulasi junction antar sel. Interaksi antara ADTC3 dengan E-kadherin terjadi pada situs residu Ekadherin Asp1, Trp2, Val3, Ile4, Lys25, Met92 yang berada pada daerah adhesion armacceptor pocket.