title: Thrombomodulin-mediated cell adhesion: involvement of its lectin-like domain.
abstract: Thrombomodulin (TM) is an integral membrane glycoprotein that is a potent anticoagulant factor. TM may also possess functions distinct from its anticoagulant activity. Here the influence of TM on cell adhesion was studied in TM-negative melanoma A2058 cells transfected with green fluorescent protein-tagged TM (TMG) or lectin domain-deleted TM (TMG(DeltaL)). Confocal microscopy demonstrated that both TMG and TMG(DeltaL) were distributed in the plasma membrane. TMG-expressed cells grew as closely clustered colonies, with TM localized prominently in the intercellular boundaries. TMG(DeltaL)-expressed cells grew singly. Overexpression of TMG, but not TMG(DeltaL), decreased monolayer permeability in vitro and tumor growth in vivo. The cell-to-cell adhesion in TMG-expressed cells was Ca2+-dependent and was inhibited by monoclonal antibody against the lectin-like domain of TM. The effects of TM-mediated cell adhesion were abolished by the addition of mannose, chondroitin sulfate A, or chondroitin sulfate C. In addition, anti-lectin-like domain antibody disrupted the close clustering of the endogenous TM-expressed keratinocyte HaCaT cell line derived from normal human epidermis. Double-labeling immunofluorescence staining revealed similar distributions of TM and actin filament in the cortex region of the TMG-expressed cells. Thus, TM can function as a Ca2+-dependent cell-to-cell adhesion molecule. Binding of specific carbohydrates to the lectin-like domain is essential for this specific function.
authors.affiliation: Department of Biochemistry, College of Medicine, National Cheng Kung University, Tainan, Taiwan 701, Republic of China.
authors.forename: Huey-Chun
authors.initials: HC
authors.lastname: Huang
authors.forename: Guey-Yueh
authors.initials: GY
authors.lastname: Shi
authors.forename: Shinn-Jong
authors.initials: SJ
authors.lastname: Jiang
authors.forename: Chung-Sheng
authors.initials: CS
authors.lastname: Shi
authors.forename: Chun-Mei
authors.initials: CM
authors.lastname: Wu
authors.forename: Hsi-Yuan
authors.initials: HY
authors.lastname: Yang
authors.forename: Hua-Lin
authors.initials: HL
authors.lastname: Wu
mesh_terms: D002118:Calcium / Q000494:pharmacology; D002448:Cell Adhesion; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000378:metabolism; D002809:Chondroitin Sulfates / Q000494:pharmacology; D006801:Humans; D037102:Lectins / Q000378:metabolism*; D008358:Mannose / Q000494:pharmacology; D018613:Microscopy, Confocal; D017434:Protein Structure, Tertiary; D017384:Sequence Deletion; D018180:Thrombomodulin / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D014162:Transfection
chemical_list: D037102:Lectins; D018180:Thrombomodulin; D002809:Chondroitin Sulfates; D008358:Mannose; D002118:Calcium