title: NPXY motifs in the beta1 integrin cytoplasmic tail are required for functional reovirus entry.
abstract: Reovirus cell entry is mediated by attachment to cell surface carbohydrate and junctional adhesion molecule A (JAM-A) and internalization by beta1 integrin. The beta1 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 beta1 integrin NPXY motifs in reovirus internalization. In comparison to wild-type cells (beta1+/+ cells), reovirus infectivity was significantly reduced in cells expressing mutant beta1 integrin in which the NPXY motifs were altered to NPXF (beta1+/+Y783F/Y795F cells). However, reovirus displayed equivalent binding and internalization levels following adsorption to beta1+/+ cells and beta1+/+Y783F/Y795F cells, suggesting that the NPXY motifs are essential for transport of reovirus within the endocytic pathway. Reovirus entry into beta1+/+ cells was blocked by chlorpromazine, an inhibitor of clathrin-mediated endocytosis, while entry into beta1+/+Y783F/Y795F cells was unaffected. Furthermore, virus was distributed to morphologically distinct endocytic organelles in beta1+/+ and beta1+/+Y783F/Y795F cells, providing further evidence that the beta1 integrin NPXY motifs mediate sorting of reovirus in the endocytic pathway. Thus, NPXY motifs in the beta1 integrin cytoplasmic tail are required for functional reovirus entry, which indicates a key role for these sequences in endocytosis of a pathogenic virus.
authors.affiliation: Departments of Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA.
authors.forename: Melissa S
authors.initials: MS
authors.lastname: Maginnis
authors.forename: Bernardo A
authors.initials: BA
authors.lastname: Mainou
authors.forename: Aaron
authors.initials: A
authors.lastname: Derdowski
authors.forename: Elizabeth M
authors.initials: EM
authors.lastname: Johnson
authors.forename: Roy
authors.initials: R
authors.lastname: Zent
authors.forename: Terence S
authors.initials: TS
authors.lastname: Dermody
mesh_terms: D020816:Amino Acid Motifs; D019943:Amino Acid Substitution; D000818:Animals; D002460:Cell Line; D004705:Endocytosis / Q000502:physiology; D019012:Integrin beta1 / Q000235:genetics / Q000502:physiology*; D051379:Mice; D012087:Reoviridae / Q000502:physiology*; D022161:Transport Vesicles / Q000821:virology*; D053585:Virus Attachment; D053586:Virus Internalization
chemical_list: D019012:Integrin beta1