| 摘要: | Functional Analysis of Human Endosialin Kai-Chims Kuo, Huey-Chun Huang, Chung-Sheng Shi, Guey-Yuen Shi, Hua-Lin Wu Department of Biochemistry and Molecular Biology, College of Medcine, National Cheng Kung University, Tainan, Taiwan, ROC Human endosialin was first discovered in 1992 by immunostaining with a monoclonal antibody FB5 detecting tumor and normal tissues. It was reported to be expressed in tumor endothelium but not in normal endothelium. Human endosialin is a type I membrane protein of 757 amino acids with a reported molecular mass of 165kDa. Structurally, it composed of six distinct domains including a C-type lectin-like domain, one domain with similarity to the Sushi/ccp/scr pattern, and three EGF-like repeats, followed by a mucin-like region, a transmembrane segment, and a short cytoplasmic tail. Subsequent analysis showed that the endosialin carried abundantly sialylated, O-linked oligosaccharides, placing it in the group of sialomucin-like molecules. The N-terminal 360 amino acids of endosialin showed 39% homology to thrombomodulin（TM）, a receptor involved in regulating blood coagulation, and 33% to complement receptor C1qRp. In our recent study, TM can function as a cell-cell adhesion molecule and its EGF-like domain to serine/threonine rich domain could function as an angiogenic factor. This structural kinship indicates a function for endosialin involving in cell adhesion, angiogenesis and tumor progression. In this report, using endosialin stably expressed HaCaT cells, we found that the stable clones expressed endosialin exhibited similar proliferative rate with the vector control. However, using Boyden chamber migration assay, the endosialin stably expressed clones showed suppressed migratory ability compared to the vector control. We also expressed the recombinant human endosialin protein consisting of three EGF-like domains（rhESD2）. rhESD2 slightly enhanced the proliferative rate and significantly induced the chemotatic migration of human u? |
