1132 Investigation of the target protein of imatinib’s inhibitory effect on IgG translocation in human endothelial cells

We have previously reported that imatinib, a c-Abl inhibitor, reduces caveolae-mediated endocytosis of endothelial cells and inhibits the extravasation IgG in steady state. However, target signaling pathway behind this mechanism remains unclear. Here, we established an vitro culture system using human dermal microvascular (HDMEC) to mimic IgG. Thrombin histamine increased translocation through HDMEC sheet, whereas imatinib GNF-2 (another inhibitor) reduced effects thrombin histamine. Next, conducted protein phosphorylation analysis mass spectrometry on sheets stimulated with or without inhibitors. The conditions examined were as follows. (1) no stimulation, (2) (3) GNF-2, (4) thrombin, (5) (6) (7) histamine, (8) (9) GNF-2. phosphopeptide profiles subjected multiple analyses Kyoto Encyclopedia Genes Genomes, Gene Ontology enrichment analysis, Set Enrichment Analysis. two inhibitors inhibited pathways correlated with: Adherens junction, including p120-catenin, alpha-catenin, beta-catenin, LM07, afadin; Focal adhesion, RTK, ZYK, paxillin, FAK, MLC; Tight junction including, PAR3, TJP1/2, PALS1, MUPP1, claudin; leukocyte transepithelial migration, CAMs, MLC. These results suggest thrombin- histamine-dependent enhancement is inhibition involved cell adhesion cytoskeleton. Our findings are expected lead discovery therapeutic agents for treatment antibody-dependent autoimmune diseases.