De Franceschi Nicola, Arjonen Antti, Elkhatib Nadia, Denessiouk Konstantin, Wrobel Antoni G, Wilson Thomas A, Pouwels Jeroen, Montagnac Guillaume, Owen David J, Ivaska Johanna
Turku Centre for Biotechnology, University of Turku, Turku, Finland.
Institut Gustave Roussy, Villejuif, France.
Nat Struct Mol Biol. 2016 Feb;23(2):172-9. doi: 10.1038/nsmb.3161. Epub 2016 Jan 18.
Integrins are heterodimeric cell-surface adhesion molecules comprising one of 18 possible α-chains and one of eight possible β-chains. They control a range of cell functions in a matrix- and ligand-specific manner. Integrins can be internalized by clathrin-mediated endocytosis (CME) through β subunit-based motifs found in all integrin heterodimers. However, whether specific integrin heterodimers can be selectively endocytosed was unknown. Here, we found that a subset of α subunits contain an evolutionarily conserved and functional YxxΦ motif directing integrins to selective internalization by the most abundant endocytic clathrin adaptor, AP2. We determined the structure of the human integrin α4-tail motif in complex with the AP2 C-μ2 subunit and confirmed the interaction by isothermal titration calorimetry. Mutagenesis of the motif impaired selective heterodimer endocytosis and attenuated integrin-mediated cell migration. We propose that integrins evolved to enable selective integrin-receptor turnover in response to changing matrix conditions.
整合素是异二聚体细胞表面粘附分子,由18种可能的α链之一和8种可能的β链之一组成。它们以基质和配体特异性的方式控制一系列细胞功能。整合素可以通过网格蛋白介导的内吞作用(CME)内化,通过在所有整合素异二聚体中发现的基于β亚基的基序。然而,特定的整合素异二聚体是否可以被选择性内吞尚不清楚。在这里,我们发现一部分α亚基包含一个进化上保守且功能正常的YxxΦ基序,该基序引导整合素通过最丰富的内吞网格蛋白衔接蛋白AP2进行选择性内化。我们确定了与AP2 C-μ2亚基复合的人整合素α4尾部基序的结构,并通过等温滴定量热法证实了这种相互作用。该基序的诱变损害了选择性异二聚体内吞作用,并减弱了整合素介导的细胞迁移。我们提出,整合素的进化是为了在基质条件变化时实现选择性整合素受体周转。