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J. Virol. doi:10.1128/JVI.01612-07
Copyright (c) 2008, American Society for Microbiology and/or the Listed Authors/Institutions. All Rights Reserved.

NPXY Motifs in the 1 Integrin Cytoplasmic Tail Are Required for Functional Reovirus Entry

Departments of Microbiology and Immunology, Pediatrics, and Medicine, and Elizabeth B. Lamb Center for Pediatric Research, Vanderbilt University School of Medicine and Department of Medicine, Veterans Affairs Hospital, Nashville, TN 37232

^* To whom correspondence should be addressed. Email: terry.dermody{at}vanderbilt.edu.

	Abstract

Reovirus cell entry is mediated by attachment to cell-surface carbohydrate and junctional adhesion molecule-A (JAM-A) and internalization by 1 integrin. The 1 integrin cytoplasmic tail contains two NPXY motifs, which function in recruitment of adaptor proteins and clathrin for endocytosis and serve as sorting signals for internalized cargo. As reovirus infection requires disassembly in the endocytic compartment, we investigated the role of the 1 integrin NPXY motifs in reovirus internalization. In comparison to wild-type cells ( 1+/+), reovirus infectivity was significantly reduced in cells expressing mutant 1 integrin in which the NPXY motifs were altered to NPXF ( 1+/+Y783F/Y795F). However, reovirus displayed equivalent binding and internalization following adsorption to 1+/+ cells and 1+/+Y783F/Y795F cells, suggesting that the NPXY motifs are essential for transport of reovirus within the endocytic pathway. Reovirus entry into 1+/+ cells was blocked by chlorpromazine, an inhibitor of clathrin-mediated endocytosis, while entry into 1+/+Y783F/Y795F cells was unaffected. Furthermore, virus was distributed to morphologically distinct endocytic organelles in 1+/+ and 1+/+Y783F/Y795F cells, providing further evidence that the 1 integrin NPXY motifs mediate sorting of reovirus in the endocytic pathway. Thus, NPXY motifs in the 1 integrin cytoplasmic tail are required for functional reovirus entry, which indicates a key role for these sequences in endocytosis of a pathogenic virus.