title: Kindlin-2 (Mig-2): a co-activator of beta3 integrins.
abstract: Integrin activation is essential for dynamically linking the extracellular environment and cytoskeletal/signaling networks. Activation is controlled by integrins' short cytoplasmic tails (CTs). It is widely accepted that the head domain of talin (talin-H) can mediate integrin activation by binding to two sites in integrin beta's CT; in integrin beta(3) this is an NPLY(747) motif and the membrane-proximal region. Here, we show that the C-terminal region of integrin beta(3) CT, composed of a conserved TS(752)T region and NITY(759) motif, supports integrin activation by binding to a cytosolic binding partner, kindlin-2, a widely distributed PTB domain protein. Co-transfection of kindlin-2 with talin-H results in a synergistic enhancement of integrin alpha(IIb)beta(3) activation. Furthermore, siRNA knockdown of endogenous kindlin-2 impairs talin-induced alpha(IIb)beta(3) activation in transfected CHO cells and blunts alpha(v)beta(3)-mediated adhesion and migration of endothelial cells. Our results thus identify kindlin-2 as a novel regulator of integrin activation; it functions as a coactivator.
authors.affiliation: Department of Molecular Cardiology, Cleveland Clinic, Cleveland, OH 44195, USA.
authors.forename: Yan-Qing
authors.initials: YQ
authors.lastname: Ma
authors.forename: Jun
authors.initials: J
authors.lastname: Qin
authors.forename: Chuanyue
authors.initials: C
authors.lastname: Wu
authors.forename: Edward F
authors.initials: EF
authors.lastname: Plow
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002460:Cell Line; D006224:Cricetinae; D006801:Humans; D039302:Integrin alphaVbeta3 / Q000235:genetics / Q000378:metabolism*; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008969:Molecular Sequence Data; D009363:Neoplasm Proteins / Q000235:genetics / Q000378:metabolism*; D010455:Peptides / Q000235:genetics / Q000378:metabolism; D019039:Platelet Glycoprotein GPIIb-IIIa Complex / Q000235:genetics / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D015398:Signal Transduction / Q000502:physiology*; D016608:Talin / Q000235:genetics / Q000378:metabolism
chemical_list: C477322:FERMT3 protein, human; D039302:Integrin alphaVbeta3; D008565:Membrane Proteins; D009363:Neoplasm Proteins; D010455:Peptides; D019039:Platelet Glycoprotein GPIIb-IIIa Complex; D034741:RNA, Small Interfering; D011993:Recombinant Fusion Proteins; D016608:Talin