title: Lysosomal-associated transmembrane protein 5 (LAPTM5) is a molecular partner of CD1e.
abstract: The CD1e protein participates in the presentation of lipid antigens in dendritic cells. Its transmembrane precursor is transported to lysosomes where it is cleaved into an active soluble form. In the presence of bafilomycin, which inhibits vacuolar ATPase and consequently the acidification of endosomal compartments, CD1e associates with a 27 kD protein. In this work, we identified this molecular partner as LAPTM5. The latter protein and CD1e colocalize in trans-Golgi and late endosomal compartments. The quantity of LAPTM5/CD1e complexes increases when the cells are treated with bafilomycin, probably due to the protection of LAPTM5 from lysosomal proteases. Moreover, we could demonstrate that LAPTM5/CD1e association occurs under physiological conditions. Although LAPTM5 was previously shown to act as a platform recruiting ubiquitin ligases and facilitating the transport of receptors to lysosomes, we found no evidence that LATPM5 controls either CD1e ubiquitination or the generation of soluble lysosomal CD1e proteins. Notwithstanding these last observations, the interaction of LAPTM5 with CD1e and their colocalization in antigen processing compartments both suggest that LAPTM5 might influence the role of CD1e in the presentation of lipid antigens.
authors.affiliation: Institut National de la Santé et de la Recherche Médicale, Unité Mixte de Recherche S725, Strasbourg, France.
authors.forename: Catherine
authors.initials: C
authors.lastname: Angénieux
authors.forename: François
authors.initials: F
authors.lastname: Waharte
authors.forename: Alexandre
authors.initials: A
authors.lastname: Gidon
authors.forename: François
authors.initials: F
authors.lastname: Signorino-Gelo
authors.forename: Virginie
authors.initials: V
authors.lastname: Wurtz
authors.forename: Rim
authors.initials: R
authors.lastname: Hojeij
authors.forename: Fabienne
authors.initials: F
authors.lastname: Proamer
authors.forename: Christian
authors.initials: C
authors.lastname: Gachet
authors.forename: Alain
authors.initials: A
authors.lastname: Van Dorsselaer
authors.forename: Daniel
authors.initials: D
authors.lastname: Hanau
authors.forename: Jean
authors.initials: J
authors.lastname: Salamero
authors.forename: Henri
authors.initials: H
authors.lastname: de la Salle
mesh_terms: D018949:Antigens, CD1 / Q000378:metabolism*; D002451:Cell Compartmentation / Q000187:drug effects; D045744:Cell Line, Tumor; D003712:Dendrites / Q000187:drug effects / Q000378:metabolism; D011992:Endosomes / Q000187:drug effects / Q000378:metabolism; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D057809:HEK293 Cells; D006207:Half-Life; D006367:HeLa Cells; D006801:Humans; D047468:Immunoprecipitation; D018942:Macrolides / Q000494:pharmacology; D008545:Melanoma / Q000235:genetics; D008565:Membrane Proteins / Q000378:metabolism*; D011485:Protein Binding / Q000187:drug effects; D021381:Protein Transport / Q000187:drug effects; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012995:Solubility / Q000187:drug effects; D014162:Transfection; D054875:Ubiquitination / Q000187:drug effects; D021601:trans-Golgi Network / Q000187:drug effects / Q000378:metabolism
chemical_list: D018949:Antigens, CD1; C417738:CD1e antigen; D018942:Macrolides; D008565:Membrane Proteins; D012333:RNA, Messenger; C100848:LAPTM5 protein, human