title: Distinct kinetic and mechanical properties govern ALCAM-mediated interactions as shown by single-molecule force spectroscopy.
abstract: The activated leukocyte cell adhesion molecule (ALCAM) mediates dynamic homotypic and heterotypic cellular interactions. Whereas homotypic ALCAM-ALCAM interactions have been implicated in the development and maintenance of tissue architecture and tumor progression, heterotypic ALCAM-CD6 interactions act to initiate and stabilize T-cell-dendritic-cell interactions affecting T-cell activation. The ability to resist the forces acting on the individual bonds during these highly dynamic cellular contacts is thought to be crucial for the (patho)physiology of ALCAM-mediated cell adhesion. Here, we used atomic force microscopy to characterize the relationship between affinity, avidity and the stability of ALCAM-mediated interactions under external loading, at the single-molecule level. Disruption of the actin cytoskeleton resulted in enhanced ALCAM binding avidity, without affecting the tensile strength of the individual bonds. Force spectroscopy revealed that the ALCAM-CD6 bond displayed a significantly higher tensile strength, a smaller reactive compliance and an up to 100-fold lower dissociation rate in the physiological force window in comparison to the homotypic interaction. These results indicate that homotypic and heterotypic ALCAM-mediated adhesion are governed by significantly distinct kinetic and mechanical properties, providing novel insight into the role of ALCAM during highly dynamic cellular interactions.
authors.affiliation: Department of Tumour Immunology (278), Nijmegen Centre for Molecular Life Sciences (NCMLS), Radboud University Nijmegen Medical Centre, PO Box 9101, 6500HB Nijmegen, The Netherlands.
authors.forename: Joost
authors.initials: J
authors.lastname: Te Riet
authors.forename: Aukje W
authors.initials: AW
authors.lastname: Zimmerman
authors.forename: Alessandra
authors.initials: A
authors.lastname: Cambi
authors.forename: Ben
authors.initials: B
authors.lastname: Joosten
authors.forename: Sylvia
authors.initials: S
authors.lastname: Speller
authors.forename: Ruurd
authors.initials: R
authors.lastname: Torensma
authors.forename: Frank N
authors.initials: FN
authors.lastname: van Leeuwen
authors.forename: Carl G
authors.initials: CG
authors.lastname: Figdor
authors.forename: Frank
authors.initials: F
authors.lastname: de Lange
mesh_terms: D000199:Actins / Q000378:metabolism; D020410:Activated-Leukocyte Cell Adhesion Molecule / Q000378:metabolism*; D015703:Antigens, CD / Q000378:metabolism; D000945:Antigens, Differentiation, T-Lymphocyte / Q000378:metabolism; D002448:Cell Adhesion; D002470:Cell Survival; D003599:Cytoskeleton / Q000378:metabolism; D006801:Humans; D020014:K562 Cells; D007700:Kinetics; D018625:Microscopy, Atomic Force; D011485:Protein Binding; D013057:Spectrum Analysis; D013314:Stress, Mechanical
chemical_list: D000199:Actins; D020410:Activated-Leukocyte Cell Adhesion Molecule; D015703:Antigens, CD; D000945:Antigens, Differentiation, T-Lymphocyte; C062279:CD6 antigen