title: Inside-out, outside-in, and inside-outside-in: G protein signaling in integrin-mediated cell adhesion, spreading, and retraction.
abstract: The integrin family of cell adhesion receptors mediates bi-directional signaling: 'inside-out' signaling activates the ligand binding function of integrins and 'outside-in' signaling mediates cellular responses induced by ligand binding to integrins leading to cell spreading, retraction, migration, and proliferation. Integrin signaling requires both heterotrimeric G proteins and monomeric small G proteins. This review focuses on recent development in the roles of G proteins in integrin outside-in signaling. The finding of direct interaction between the heterotrimeric G protein subunit Gα13 and integrin β subunits reveals a new mechanism for integrin signaling, and also uncovers a crosstalk between the signaling pathways initiated by G protein-coupled receptors (GPCRs) and integrins. This crosstalk, which may be referred to as 'inside-outside-in' signaling, dynamically regulates contractility and greatly promotes integrin outside-in signaling.
authors.affiliation: Department of Pharmacology, University of Illinois at Chicago, Chicago, IL 60612, United States.
authors.forename: Bo
authors.initials: B
authors.lastname: Shen
authors.forename: M Keegan
authors.initials: MK
authors.lastname: Delaney
authors.forename: Xiaoping
authors.initials: X
authors.lastname: Du
mesh_terms: D000818:Animals; D002448:Cell Adhesion / Q000502:physiology*; D048429:Cell Size; D022081:Cell Surface Extensions / Q000378:metabolism*; D044365:GTP-Binding Protein alpha Subunits, G12-G13 / Q000378:metabolism; D020962:Heterotrimeric GTP-Binding Proteins / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D016023:Integrins / Q000737:chemistry / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology*
chemical_list: D016023:Integrins; D044365:GTP-Binding Protein alpha Subunits, G12-G13; D020962:Heterotrimeric GTP-Binding Proteins