title: Permeability changes of integrin-containing multivesicular structures triggered by picornavirus entry.
abstract: Cellular uptake of clustered α2β1-integrin induces the formation of membrane compartments that subsequently mature into a multivesicular body (MVB). Enhanced internalization mediated by clustered integrins was observed upon infection by the picornavirus echovirus 1 (EVI). We elucidated the structural features of virus-induced MVBs (vMVBs) in comparison to antibody-induced control MVBs (mock infection) by means of high-pressure cryo fixation of cells followed by immuno electron tomography during early entry of the virus. Three-dimensional tomograms revealed a marked increase in the size and complexity of these vMVBs and the intraluminal vesicles (ILVs) at 2 and 3.5 hours post infection (p.i.), in contrast to the control MVBs without virus. Breakages in the membranes of vMVBs were detected from tomograms after 2 and especially after 3.5 h suggesting that these breakages could facilitate the genome release to the cytoplasm. The in situ neutral-red labeling of viral genome showed that virus uncoating starts as early as 30 min p.i., while an increase of permeability was detected in the vMVBs between 1 and 3 hours p.i., based on a confocal microscopy assay. Altogether, the data show marked morphological changes in size and permeability of the endosomes in the infectious entry pathway of this non-enveloped enterovirus and suggest that the formed breakages facilitate the transfer of the genome to the cytoplasm for replication.
authors.affiliation: Department of Molecular and Cellular Biology, University of California Davis, Davis, California, United States of America; Department of Anatomy, Faculty of Dentistry, Mahidol University, Bangkok, Thailand.
authors.forename: Pan
authors.initials: P
authors.lastname: Soonsawad
authors.affiliation: Department of Biological and Environmental Science/Nanoscience Center, University of Jyväskylä, Jyväskylä, Finland.
authors.forename: Lassi
authors.initials: L
authors.lastname: Paavolainen
authors.affiliation: Department of Biological and Environmental Science/Nanoscience Center, University of Jyväskylä, Jyväskylä, Finland.
authors.forename: Paula
authors.initials: P
authors.lastname: Upla
authors.affiliation: Department of Molecular and Cellular Biology, University of California Davis, Davis, California, United States of America; Department of Anatomy, Faculty of Dentistry, Mahidol University, Bangkok, Thailand.
authors.forename: Wattana
authors.initials: W
authors.lastname: Weerachatyanukul
authors.affiliation: Department of Biological and Environmental Science/Nanoscience Center, University of Jyväskylä, Jyväskylä, Finland.
authors.forename: Nina
authors.initials: N
authors.lastname: Rintanen
authors.affiliation: Department of Molecular and Cellular Biology, University of California Davis, Davis, California, United States of America.
authors.forename: Juan
authors.initials: J
authors.lastname: Espinoza
authors.affiliation: Department of Molecular and Cellular Biology, University of California Davis, Davis, California, United States of America; Department of Biological and Environmental Science/Nanoscience Center, University of Jyväskylä, Jyväskylä, Finland.
authors.forename: Gregory
authors.initials: G
authors.lastname: McNerney
authors.affiliation: Department of Biological and Environmental Science/Nanoscience Center, University of Jyväskylä, Jyväskylä, Finland.
authors.forename: Varpu
authors.initials: V
authors.lastname: Marjomäki
authors.affiliation: Department of Molecular and Cellular Biology, University of California Davis, Davis, California, United States of America.
authors.forename: R Holland
authors.initials: RH
authors.lastname: Cheng
mesh_terms: D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000378:metabolism / Q000502:physiology / Q000821:virology; D003593:Cytoplasm / Q000378:metabolism / Q000502:physiology; D055032:Electron Microscope Tomography / Q000379:methods; D011992:Endosomes / Q000378:metabolism / Q000502:physiology / Q000821:virology; D006801:Humans; D038982:Integrin alpha2beta1 / Q000378:metabolism*; D018613:Microscopy, Confocal; D057146:Multivesicular Bodies / Q000378:metabolism* / Q000502:physiology / Q000821:virology*; D010539:Permeability; D010849:Picornaviridae / Q000378:metabolism* / Q000502:physiology*; D010850:Picornaviridae Infections / Q000378:metabolism* / Q000503:physiopathology* / Q000821:virology
chemical_list: D038982:Integrin alpha2beta1