Functional Analysis of Human Endosialin

• Main Authors: Kai-Chims Kuo, 郭凱琪
• Other Authors: Hwa-Lin Wu
• Format: Others
• Language: zh-TW
• Published: 2005
• Online Access: http://ndltd.ncl.edu.tw/handle/39993194712974144266

碩士 === 國立成功大學 === 生物化學研究所 === 93 === 　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 trans-membrane protein of 757 amino acids with a molecular mass of 165 kDa. It is 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 involved in cell adhesion, angiogenesis and tumor progression. In this report, using endosialin stably expressed HaCaT cells, we found that the stable clones expressing endosialin exhibited similar proliferative rate with the vector control. However, using Boyden chamber migration assay and cell spreading assay on collagen type I matrix, the clones stably expressing endosialin showed suppressed migratory, adhesive and spreading ability compared to the vector control. We also expressed the recombinant human endosialin protein consisting of three EGF-like domains（rhESD2）. Recombinant rhESD2 slightly enhanced the proliferative rate and significantly induced the chemotatic migration of human umbilical vein endothelial cells（HUVECs）. These findings revealed that human endosialin might involve not only in the cell-cell interaction and adhesion but also modulate cell migration of endothelial cells.