title: Priming by chemokines restricts lateral mobility of the adhesion receptor LFA-1 and restores adhesion to ICAM-1 nano-aggregates on human mature dendritic cells.
abstract: LFA-1 is a leukocyte specific β2 integrin that plays a major role in regulating adhesion and migration of different immune cells. Recent data suggest that LFA-1 on mature dendritic cells (mDCs) may function as a chemokine-inducible anchor during homing of DCs through the afferent lymphatics into the lymph nodes, by transiently switching its molecular conformational state. However, the role of LFA-1 mobility in this process is not yet known, despite that the importance of lateral organization and dynamics for LFA-1-mediated adhesion regulation is broadly recognized. Using single particle tracking approaches we here show that LFA-1 exhibits higher mobility on resting mDCs compared to monocytes. Lymphoid chemokine CCL21 stimulation of the LFA-1 high affinity state on mDCs, led to a significant reduction of mobility and an increase on the fraction of stationary receptors, consistent with re-activation of the receptor. Addition of soluble monomeric ICAM-1 in the presence of CCL21 did not alter the diffusion profile of LFA-1 while soluble ICAM-1 nano-aggregates in the presence of CCL21 further reduced LFA-1 mobility and readily bound to the receptor. Overall, our results emphasize the importance of LFA-1 lateral mobility across the membrane on the regulation of integrin activation and its function as adhesion receptor. Importantly, our data show that chemokines alone are not sufficient to trigger the high affinity state of the integrin based on the strict definition that affinity refers to the adhesion capacity of a single receptor to its ligand in solution. Instead our data indicate that nanoclustering of the receptor, induced by multi-ligand binding, is required to maintain stable cell adhesion once LFA-1 high affinity state is transiently triggered by inside-out signals.
authors.affiliation: ICFO-Institut de Ciències Fotòniques, Barcelona, Spain.
authors.forename: Kyra J E
authors.initials: KJ
authors.lastname: Borgman
authors.affiliation: ICFO-Institut de Ciències Fotòniques, Barcelona, Spain.
authors.forename: Thomas S
authors.initials: TS
authors.lastname: van Zanten
authors.affiliation: ICFO-Institut de Ciències Fotòniques, Barcelona, Spain.
authors.forename: Carlo
authors.initials: C
authors.lastname: Manzo
authors.affiliation: Department of Gastroenterology, Hospital Clinic de Barcelona, IDIBAPS, Barcelona, Spain.
authors.forename: Raquel
authors.initials: R
authors.lastname: Cabezón
authors.affiliation: Department of Tumor Immunology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands.
authors.forename: Alessandra
authors.initials: A
authors.lastname: Cambi
authors.affiliation: Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBERehd) and Centre Esther Koplowitz, Barcelona, Spain.
authors.forename: Daniel
authors.initials: D
authors.lastname: Benítez-Ribas
authors.affiliation: ICFO-Institut de Ciències Fotòniques, Barcelona, Spain; ICREA-Institució Catalana de Recerca i Estudis Avançats, Barcelona, Spain.
authors.forename: Maria F
authors.initials: MF
authors.lastname: Garcia-Parajo
mesh_terms: D054421:Chemokine CCL21 / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D003713:Dendritic Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D005786:Gene Expression Regulation; D006801:Humans; D018799:Intercellular Adhesion Molecule-1 / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D008024:Ligands; D016169:Lymphocyte Function-Associated Antigen-1 / Q000235:genetics / Q000378:metabolism*; D009000:Monocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D061251:Primary Cell Culture; D066329:Protein Aggregates; D011485:Protein Binding; D021381:Protein Transport; D015398:Signal Transduction; D012995:Solubility
chemical_list: C515478:CCL21 protein, human; D054421:Chemokine CCL21; D008024:Ligands; D016169:Lymphocyte Function-Associated Antigen-1; D066329:Protein Aggregates; D018799:Intercellular Adhesion Molecule-1