title: Integrin-mediated cell adhesion and spreading engage different sources of reactive oxygen species.
abstract: The tightly regulated production of intracellular reactive oxygen species (ROS) participates in several biologic processes such as cellular growth, programmed cell death, senescence, and adhesion. It is increasingly evident that the same enzymatic processes that were originally linked to ROS generation during host defence or apoptosis execution are also involved in redox-mediated signal transduction. We investigated in murine NIH3T3 fibroblasts the contribution of a variety of redox-dependent events during signal transduction initiated by integrin engagement due to fibronectin stimulation and report that a mitochondrial ROS release occurs, strictly confined to the early phase of extracellular matrix (ECM) contact (10 min). Besides, 5-lipoxygenase (5-LOX) is engaged by integrin receptor ligation as another ROS source, contributing to the more-intense, second ROS burst (45 min), possibly orchestrating the spreading of cells in response to ECM contact. To define a potential mechanism for ROS signaling, we demonstrate that on integrin recruitment, the Src homology-2 domain-containing phosphatase 2 (SHP-2) undergoes a reversible oxidization/inactivation to which mitochondrial and 5-lipoxygenase ROS contribute differentially. In keeping with a key role of oxidants during integrin signaling, the inactivation of SHP-2 prevents the dephosphorylation and inactivation of SHP-2 substrates (p125FAK and SHPS-1), thus enabling the continued propagation of the signal arising by integrin engagement.
authors.affiliation: Department of Biochemical Sciences, University of Florence, Florence, Italy.
authors.forename: Maria Letizia
authors.initials: ML
authors.lastname: Taddei
authors.forename: Matteo
authors.initials: M
authors.lastname: Parri
authors.forename: Tommaso
authors.initials: T
authors.lastname: Mello
authors.forename: Alfonso
authors.initials: A
authors.lastname: Catalano
authors.forename: Alan D
authors.initials: AD
authors.lastname: Levine
authors.forename: Giovanni
authors.initials: G
authors.lastname: Raugei
authors.forename: Giampietro
authors.initials: G
authors.lastname: Ramponi
authors.forename: Paola
authors.initials: P
authors.lastname: Chiarugi
mesh_terms: D000818:Animals; D001094:Arachidonate 5-Lipoxygenase; D015153:Blotting, Western; D002448:Cell Adhesion / Q000502:physiology; D002465:Cell Movement / Q000502:physiology; D005109:Extracellular Matrix / Q000378:metabolism; D005353:Fibronectins / Q000378:metabolism; D007150:Immunohistochemistry; D047468:Immunoprecipitation; D016023:Integrins / Q000378:metabolism / Q000502:physiology*; D051379:Mice; D008928:Mitochondria / Q000378:metabolism; D041681:NIH 3T3 Cells; D010084:Oxidation-Reduction; D054648:Protein Phosphatase 2; D017027:Protein Tyrosine Phosphatases / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism*
chemical_list: D005353:Fibronectins; D016023:Integrins; D017382:Reactive Oxygen Species; D001094:Arachidonate 5-Lipoxygenase; D054648:Protein Phosphatase 2; D017027:Protein Tyrosine Phosphatases