The urokinase-type plasminogen activator receptor (uPAR) is a non-integrin vitronectin (VN) cell adhesion receptor linked to the plasma membrane by a glycolipid anchor. Through structure-function analyses of uPAR, VN and integrins, we document that uPAR-mediated cell adhesion to VN triggers a novel type of integrin signalling that is independent of integrin-matrix engagement. The signalling is fully active on VN mutants deficient in integrin binding site and is also efficiently transduced by integrins deficient in ligand binding. Although integrin ligation is dispensable, signalling is crucially dependent upon an active conformation of the integrin and its association with intracellular adaptors such as talin. This non-canonical integrin signalling is not restricted to uPAR as it poses no structural constraints to the receptor mediating cell attachment. In contrast to canonical integrin signalling, where integrins form direct mechanical links between the ECM and the cytoskeleton, the molecular mechanism enabling the crosstalk between non-integrin adhesion receptors and integrins is dependent upon membrane tension. This suggests that for this type of signalling, the membrane represents a critical component of the molecular clutch.

The interaction between uPAR and vitronectin triggers ligand-independent adhesion signalling by integrins / G.M.S. Ferraris, C. Schulte, V. Buttiglione, V. De Lorenzi, A. Piontini, M. Galluzzi, A. Podestà, C.D. Madsen, N. Sidenius. - In: EMBO JOURNAL. - ISSN 0261-4189. - 33:21(2014 Nov 03), pp. 2458-2472. [10.15252/embj.201387611]

The interaction between uPAR and vitronectin triggers ligand-independent adhesion signalling by integrins

C. Schulte;V. De Lorenzi;M. Galluzzi;A. Podestà;
2014-11-03

Abstract

The urokinase-type plasminogen activator receptor (uPAR) is a non-integrin vitronectin (VN) cell adhesion receptor linked to the plasma membrane by a glycolipid anchor. Through structure-function analyses of uPAR, VN and integrins, we document that uPAR-mediated cell adhesion to VN triggers a novel type of integrin signalling that is independent of integrin-matrix engagement. The signalling is fully active on VN mutants deficient in integrin binding site and is also efficiently transduced by integrins deficient in ligand binding. Although integrin ligation is dispensable, signalling is crucially dependent upon an active conformation of the integrin and its association with intracellular adaptors such as talin. This non-canonical integrin signalling is not restricted to uPAR as it poses no structural constraints to the receptor mediating cell attachment. In contrast to canonical integrin signalling, where integrins form direct mechanical links between the ECM and the cytoskeleton, the molecular mechanism enabling the crosstalk between non-integrin adhesion receptors and integrins is dependent upon membrane tension. This suggests that for this type of signalling, the membrane represents a critical component of the molecular clutch.
integrin; membrane tension; signalling; uPAR; vitronectin; cell adhesion; HEK293 cells; humans; integrins; mutation; receptors, urokinase plasminogen activator; signal transduction; vitronectin
Settore FIS/03 - Fisica della Materia
Centro Interdisciplinare Materiali ed Interfacce Nanostrutturati - CIMAINA
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/2434/258158
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