V8 protease

For the V8 proteolysis assay, 6 μg of Prc was incubated with 0.6 μg of V8 protease (Roche) in 0.1 M Tris (pH 7.4) at 25°C. Samples were incubated, and the reactions were stopped at different time points by adding 5× SDS-PAGE loading dye. After being heated at 98°C, samples were loaded onto a 4 to 12% bis-Tris gel. Protein bands were then detected and analyzed by Coomassie blue staining.

The following materials and antibodies were purchased: LPS from Escherichia coli 0128:B12 (Sigma-Aldrich); LPS from P. gingivalis (InvivoGen); recombinant human HSP70 (Stressgen; endotoxin activity, <0.05 endotoxin units (EU)/μg); recombinant bovine HSC70 (Stressgen; <0.05 EU/μg); recombinant bovine HSC70 ATPase fragment (Enzo Life Sciences; 0.1 EU/μg); V8 protease (Roche); 15-deoxyspergualin (DSG) (Spanidin® Inj.; Nippon Kayaku); mouse monoclonal anti-TLR4 (HTA125) and anti-TLR2 (TL2.1) antibodies (Hycult Biotechnology); mouse monoclonal anti-CD14 (MY4) antibody (Beckman Coulter); rabbit polyclonal anti-p44/42, anti-p38, anti-phosphorylated p38, anti-phosphorylated IκB-α, mouse monoclonal anti-phosphorylated p44/42 antibodies (Cell Signaling); mouse monoclonal anti-JUN-N-terminal protein kinase (JNK) (D-2), anti-phosphorylated JNK (G-7), anti-IκB-α (H-4) antibodies (Santa Cruz Biotechnology); and mouse monoclonal anti-β-actin antibody (Abcam). Endotoxin levels of all materials used were determined using a ToxinSensor chromogenic LAL endotoxin assay kit (GenScript), and the resultant level was low (~0.1 EU/μg). The LPS, bovine serum albumin (BSA), HSP70, HSC70, and the HSC70 ATPase fragment were heated at 95°C for 20 min.