Chondroitin sulfate-mediated N-cadherin/β-catenin signaling is associated with basal-like breast cancer cell invasion.

Tumor metastasis involves cancer cell invasion across basement membranes and interstitial tissues. The initial invasion step consists of adherence of the tumor cell to the extracellular matrix (ECM), and this binding transduces a variety of signals from the ECM to the tumor cell. Accordingly, it is critical to establish the mechanisms by which extracellular cues influence the intracellular activities that regulate tumor cell invasion.

Histone deacetylase-mediated regulation of chondroitin 4-O-sulfotransferase-1 (Chst11) gene expression by Wnt/β-catenin signaling.

Chondroitin sulfate (CS) proteoglycans are abundant extracellular and cell surface molecules that consist of a protein core to which highly sulfated CS chains are covalently attached. The CS backbone is composed of repeating disaccharide units [-GlcA-GalNAc-], and during synthesis the CS chains acquire structural variability due to the action of sulfotransferases. Specific sulfation patterns are recognized by a large variety of proteins, including growth factors, morphogens, and extracellular matrix proteins, and these interactions regulate key events in development and normal physiology.

Surface Plasmon Resonance Assay of Binding Properties of Antisense Oligonucleotides to Serum Albumins and Lipoproteins.

In the present study, we developed an assay to evaluate the kinetic binding properties of the unconjugated antisense oligonucleotide (ASO) and lipophilic and hydrophilic ligands conjugated ASOs to mouse and human serum albumin, and lipoproteins using surface plasmon resonance (SPR). The lipophilic ligands conjugated ASOs showed clear affinity to the albumins and lipoproteins, while the unconjugated and hydrophilic ligand conjugated ASOs showed no interaction. The SPR method showed reproducible immobilization of albumins and lipoproteins as ligands on the sensor chip, and reproducible affinity kinetic parameters of interaction of ASOs conjugated with the ligands could be obtained.

Surface plasmon resonance assay of inhibition by pharmaceuticals for thyroxine hormone binging to transport proteins.

We developed a surface plasmon resonance (SPR) assay to estimate the competitive inhibition by pharmaceuticals for thyroxine (T4) binding to thyroid hormone transport proteins, transthyretin (TTR) and thyroxine binding globulin (TBG). In this SPR assay, the competitive inhibition of pharmaceuticals for introducing T4 into immobilized TTR or TBG on the sensor chip can be estimated using a running buffer containing pharmaceuticals. The SPR assay showed reproducible immobilization of TTR and TBG, and the kinetic binding parameters of T4 to TTR or TBG were estimated.

Binding properties of antimicrobial agents to lipid membranes using surface plasmon resonance.

In the present study, we examined the interaction of antimicrobial agents with four model lipid membranes that mimicked mammalian cell membranes and Gram-positive and -negative bacterial membranes and analyzed the binding kinetics using our surface plasmon resonance (SPR) technique. The selective and specific binding characteristics of antimicrobial agents to the lipid membranes were estimated, and the kinetic parameters were analyzed by application of a two-state reaction model. Reproducible analysis of binding kinetics was observed.

Binding properties of antimicrobial agents to dipeptide terminal of lipid II using surface plasmon resonance.

We developed a surface plasmon resonance (SPR) assay to estimate the interactions of antimicrobial agents with the dipeptide terminal of lipid II (D-alanyl-D-alanine) and its analogous dipeptides (L-alanyl-L-alanine and D-alanyl-D-lactate) as ligands. The established SPR method showed the reproducible immobilization of ligands on sensor chip and analysis of binding kinetics of antimicrobial agents to ligands. The ligand-immobilized chip could be used repeatedly for at least 200 times for the binding assay of antimicrobial agents, indicating that the ligand-immobilized chip is sufficiently robust for the analysis of binding kinetics.

Lipid membrane-binding properties of daptomycin using surface plasmon resonance.

In the present study, we developed an assay of interactions of daptomycin with four model lipid membranes that mimicked mammal cell membranes and gram-positive and negative bacteria membranes. We also analyzed the binding kinetics of the gram-positive bacteria membranes using surface plasmon resonance (SPR). Daptomycin showed a higher affinity for the model gram-positive bacteria membrane than those of the model mammal cell and gram-negative bacteria membranes, and the binding selectivity of daptomycin in the presence of calcium could be represented by this SPR system.

Down-regulation of chondroitin 4-O-sulfotransferase-1 by Wnt signaling triggers diffusion of Wnt-3a.

During metazoan development, Wnt molecules are secreted from Wnt-producing cells, diffuse to target cells, and determine cell fates; therefore, Wnt secretion is tightly regulated. However, the molecular mechanisms controlling Wnt diffusion are not fully elucidated. The specific chondroitin sulfate (CS) structure synthesized by chondroitin-4-O-sulfotransferase-1 (C4ST-1) binds to Wnt-3a with high affinity (Nadanaka, S.