Exosomal sorting of the cytoplasmic domain of bovine leukemia virus TM Env protein.
Exosomes are small membrane vesicles that are released into the extracellular compartment as a consequence of fusion of multivesicular endosomes with the plasma membrane. To unravel the molecular basis of protein sorting into exosomes, we have made a chimeric protein containing the cytosolic domain of the transmembrane subunit of the viral Env protein of BLV and the ectodomain of CD8 (CDTM-BLV-CD8). When expressed in K562 cells known to constitutively secrete exosomes, the chimera was found to be very efficiently targeted to the released vesicles. Very interestingly, the cytosolic domain of the Env protein contains peptide motifs potentially recognized by components of the ESCRT machinery that could be related to chimera sorting into the vesicles. Then, quantifying the chimera secretion, we investigated the site of exosome biogenesis in K562 cells using a pharmacological approach. We present different arguments indicating that CDTM-BLV-CD8-containing exosomes are likely formed from a recycling endosomal/TGN compartment.
De Gassart
Aude
A
UMR 5235 CNRS-Université Montpellier II et I, place E. Bataillon, cc107, 34095 Montpellier cedex 05, France.
Trentin
Bernadette
B
Martin
Marianne
M
Hocquellet
Agnès
A
Bette-Bobillo
Pascale
P
Mamoun
Robert
R
Vidal
Michel
M
D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D002417:Cattle; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000502:physiology; D005089:Exocytosis; D055354:Exosomes / Q000378:metabolism*; D019085:Fluorescent Antibody Technique, Direct; D015686:Gene Products, env / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D020014:K562 Cells; D001909:Leukemia Virus, Bovine; D008969:Molecular Sequence Data; D021381:Protein Transport; D051381:Rats; D011948:Receptors, Antigen, T-Cell / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000187:drug effects / Q000378:metabolism; D021601:trans-Golgi Network / Q000378:metabolism
C067361:CD8 receptor; D015686:Gene Products, env; D011948:Receptors, Antigen, T-Cell; D011993:Recombinant Fusion Proteins