Structural basis of competition between PINCH1 and PINCH2 for binding to the ankyrin repeat domain of integrin-linked kinase.
Formation of a heterotrimeric IPP complex composed of integrin-linked kinase (ILK), the LIM domain protein PINCH, and parvin is important for signaling through integrin adhesion receptors. Mammals possess two PINCH genes that are expressed simultaneously in many tissues. PINCH1 and PINCH2 have overlapping functions and can compensate for one another in many settings; however, isoform-specific functions have been reported and it is proposed that association with a PINCH1- or PINCH2-containing IPP complex may provide a bifurcation point in integrin signaling promoting different cellular responses. Here we report that the LIM1 domains of PINCH1 and PINCH2 directly compete for the same binding site on the ankyrin repeat domain (ARD) of ILK. We determined the 1.9A crystal structure of the PINCH2 LIM1 domain complexed with the ARD of ILK, and show that disruption of this interface by point mutagenesis reduces binding in vitro and alters localization of PINCH2 in cells. These studies provide further evidence for the role of the PINCH LIM1 domain in association with ILK and highlight direct competition as one mechanism for regulating which PINCH isoform predominates in IPP complexes. Differential regulation of PINCH1 and PINCH2 expression may therefore provide a means for altering cellular integrin signaling pathways.
Chiswell
Brian P
BP
Department of Pharmacology, 333 Cedar Street, Yale University School of Medicine, New Haven, CT 06520, USA.
Stiegler
Amy L
AL
Razinia
Ziba
Z
Nalibotski
Elina
E
Boggon
Titus J
TJ
Calderwood
David A
DA
D048868:Adaptor Proteins, Signal Transducing; D000595:Amino Acid Sequence; D017089:Ankyrin Repeat / Q000235:genetics; D001667:Binding, Competitive; D003460:Crystallization; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000235:genetics; D060588:LIM Domain Proteins; D008565:Membrane Proteins; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016296:Mutagenesis; D011485:Protein Binding; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000235:genetics*; D000099200:Scaffold Protein ILK
D048868:Adaptor Proteins, Signal Transducing; D004268:DNA-Binding Proteins; D060588:LIM Domain Proteins; D008565:Membrane Proteins; D017346:Protein Serine-Threonine Kinases; D000099200:Scaffold Protein ILK; C088088:LIMS1 protein, human; C490235:LIMS2 protein, human