title: Preliminary characterisation of nanotubes connecting T-cells and their use by HIV-1.
abstract: BACKGROUND
  Cells, especially those of the immune system, can form long and thin connections termed tunnelling nanotubes (TNTs). These structures can reach >100 µm in length and, in T-cells, contain actin but no tubulin and are not open ended. T-cell TNTs were found to form following cell contact and to enable the transfer of HIV-1 from an infected- to a connected-T-cell. TNTs are poorly characterised at molecular level.
  
  
  RESULTS
  We found Rab11 and tetraspanins, especially CD81, all along T-cells TNTs, whereas Rab4 and Rab35 were absent from these structures. Regarding actin cytoskeleton regulators, Exo70, N-WASP and especially ezrin accumulated at the level of the TNT tip that contacts the connected cell. Phosphoinositides such as PI(4,5)P2 were also concentrated at this level together with HIV-1 Gag. Gag spots on cells and TNTs were essentially immobile, and likely correspond to area of Gag multimerisation for budding to form virus-like particles. Mobility of PHPLCδ , a specific probe for PI(4,5)P2 , was reduced > threefold at the level of TNT basis or tip compared with the cell body.
  
  
  CONCLUSIONS
  Our study identified the TNT tip as an active zone of actin cytoskeleton reorganisation with the presence of ezrin, Exo70, N-WASP and PI(4,5)P2 . The latter is also known to enable HIV-1 Gag recruitment for viral budding, and the presence of Gag at this level, contacting the connected cell, indicates that the TNT tip is also a favourite place for HIV-1 assembly and budding.
authors.affiliation: CPBS, UMR 5236 CNRS-Université de Montpellier, Route de Mende, Montpellier, 34293, France.
authors.forename: Simon
authors.initials: S
authors.lastname: Lachambre
authors.forename: Christophe
authors.initials: C
authors.lastname: Chopard
authors.forename: Bruno
authors.initials: B
authors.lastname: Beaumelle
mesh_terms: D000199:Actins / Q000378:metabolism; D002450:Cell Communication / Q000502:physiology; D003598:Cytoskeletal Proteins / Q000378:metabolism; D015658:HIV Infections / Q000378:metabolism; D015497:HIV-1 / Q000378:metabolism*; D006801:Humans; D019169:Jurkat Cells; D043942:Nanotubes / Q000821:virology*; D010716:Phosphatidylinositols / Q000378:metabolism; D013601:T-Lymphocytes / Q000378:metabolism* / Q000821:virology*; D060225:Tetraspanin 28 / Q000378:metabolism; D059470:Tetraspanins / Q000378:metabolism; D014404:Tubulin / Q000378:metabolism; D033921:Vesicular Transport Proteins / Q000378:metabolism; D051317:Wiskott-Aldrich Syndrome Protein, Neuronal / Q000378:metabolism; D054301:gag Gene Products, Human Immunodeficiency Virus / Q000378:metabolism; D020691:rab GTP-Binding Proteins / Q000378:metabolism; D000099149:Ezrin
chemical_list: D000199:Actins; D003598:Cytoskeletal Proteins; D010716:Phosphatidylinositols; D060225:Tetraspanin 28; D059470:Tetraspanins; D014404:Tubulin; D033921:Vesicular Transport Proteins; D051317:Wiskott-Aldrich Syndrome Protein, Neuronal; D054301:gag Gene Products, Human Immunodeficiency Virus; D020691:rab GTP-Binding Proteins; D000099149:Ezrin; C554798:CD81 protein, human; C547754:EXOC7 protein, human; C495771:WASL protein, human
keywords: Ezrin; Gag; HIV-1; Nanotubes; T-cell