Lysosomal-associated transmembrane protein 5 (LAPTM5) is a molecular partner of CD1e
Résumé
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.
Mots clés
Antigens
CD1/*metabolism
Cell Compartmentation/drug effects
Cell Line
Tumor
Dendrites/drug effects/metabolism
Endosomes/drug effects/metabolism
Gene Expression Regulation
Neoplastic/drug effects
HEK293 Cells
Half-Life
HeLa Cells
Humans
Immunoprecipitation
Macrolides/pharmacology
Melanoma/genetics
Membrane Proteins/*metabolism
Protein Binding/drug effects
Protein Transport/drug effects
RNA
Messenger/genetics/metabolism
Solubility/drug effects
Transfection
Ubiquitination/drug effects
trans-Golgi Network/drug effects/metabolism
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