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Publications de l’équipe Imagerie spatio-temporelle de la dynamique des organelles et des endomembranes Année de publication : 2002 Ray Mc Dermott, Umit Ziylan, Danièle Spehner, Huguette Bausinger, Dan Lipsker, Mieke Mommaas, Jean-Pierre Cazenave, Graça Raposo, Bruno Goud, Henri de la Salle, Jean Salamero, Daniel Hanau (2002 Jan 26) Birbeck granules are subdomains of endosomal recycling compartment in human epidermal Langerhans cells, which form where Langerin accumulates. Molecular biology of the cell : 317-35 Résumé Birbeck granules are unusual rod-shaped structures specific to epidermal Langerhans cells, whose origin and function remain undetermined. We investigated the intracellular location and fate of Langerin, a protein implicated in Birbeck granule biogenesis, in human epidermal Langerhans cells. In the steady state, Langerin is predominantly found in the endosomal recycling compartment and in Birbeck granules. Langerin internalizes by classical receptormediated endocytosis and the first Birbeck granules accessible to endocytosed Langerin are those connected to recycling endosomes in the pericentriolar area, where Langerin accumulates. Drug-induced inhibition of endocytosis results in the appearance of abundant open-ended Birbeck granule-like structures appended to the plasma membrane, whereas inhibition of recycling induces Birbeck granules to merge with a tubular endosomal network. In mature Langerhans cells, Langerin traffic is abolished and the loss of internal Langerin is associated with a concomitant depletion of Birbeck granules. Our results demonstrate an exchange of Langerin between early endosomal compartments and the plasma membrane, with dynamic retention in the endosomal recycling compartment. They show that Birbeck granules are not endocytotic structures, rather they are subdomains of the endosomal recycling compartment that form where Langerin accumulates. Finally, our results implicate ADP-ribosylation factor proteins in Langerin trafficking and the exchange between Birbeck granules and other endosomal membranes. Dan Lipsker, Umit Ziylan, Danièle Spehner, Fabienne Proamer, Huguette Bausinger, Pascale Jeannin, Jean Salamero, Alain Bohbot, Jean-Pierre Cazenave, Robert Drillien, Yves Delneste, Daniel Hanau, Henri de la Salle (2002 Jan 25) Heat shock proteins 70 and 60 share common receptors which are expressed on human monocyte-derived but not epidermal dendritic cells. European journal of immunology : 322-32 Résumé Priming of CTL by means of heat shock proteins (hsp) is dependent on antigen-presenting cells (APC), which present the hsp-associated peptides, via their cell surface MHC class I molecules, toCD8(+) T cells. It has not yet been established how human (hu) hsp70 interacts with the major (hu)APC, the dendritic cells (DC). Here we show that (hu)hsp70 is specifically internalized intoCD14(-), Toll-like receptor 4(-) monocyte-derived (hu)DC by receptormediated endocytosis. We further demonstrate that (hu)hsp70 and (hu)hsp60 share the INSTITUT CURIE, 20 rue d’Ulm, 75248 Paris Cedex 05, France | 1 Publications de l’équipe Imagerie spatio-temporelle de la dynamique des organelles et des endomembranes same receptors on (hu)monocyte-derived DC. Both molecules as well as MHC class I molecules are spontaneously internalized and reach the MHC class II-enriched compartments. Finally, freshly isolated (hu) epidermal Langerhans cells (LC), the DC of the skin, as well as CD34(+)-derived LC do not bind hsp60 or hsp70. Given the likely importance of the internalization of hsp70 by APC in the induction of the immune responses, the finding that hsp60 and hsp70 are internalized through the same receptor(s) may explain why microbial hsp60 represents a major T cell antigen. This may rationalize the use of microbial hsp60 to prime immune responses against microbes. The lack of hsp60/70 receptors on epidermal LC raises the crucial question as to whether absence of priming of the skin and mucosal immune systems by hsp-polypeptide complexes could account for some tissuespecific diseases. This work also points to a potential advantage of using monocyte-derived DC in human immunotherapeutic applications of hsp60/70. Année de publication : 2001 Isabelle Le Blanc, Vincent Blot, Isabelle Bouchaert, Jean Salamero, Bruno Goud, Arielle R Rosenberg, Marie-Christine Dokhélar (2001 Dec 26) Intracellular distribution of human T-cell leukemia virus type 1 Gag proteins is independent of interaction with intracellular membranes. Journal of virology : 905-11 Résumé Retrovirus Gag proteins are synthesized on free ribosomes, and are sufficient to govern the assembly and release of virus particles. Like type C retroviruses, human T-cell leukemia virus type 1 (HTLV-1) assembles and buds at the plasma membrane. After immunofluorescence staining, HTLV-1 Gag proteins appear as punctuated intracellular clusters, which suggests that they are associated either with intracellular membranes or with the plasma membrane. However, colocalization experiments using a panel of markers demonstrated that Gag proteins were not associated with the membranes involved in the secretory or endocytosis pathway. Small amounts of Gag proteins were detected at the plasma membrane and colocalized with the envelope glycoproteins. Moreover, Gag proteins were excluded from streptolysin-O permeabilized cells and in this respect behaved like cytoplasmic proteins. This suggests that the trafficking of HTLV-1 Gag proteins through the cytoplasm of the host cell is independent of any cell membrane system. Année de publication : 2014 Sofia Traikov, Christoph Stange, Thomas Wassmer, Perrine Paul-Gilloteaux, Jean Salamero, Graça Raposo, Bernard Hoflack (1970 Jan 1) Septin6 and Septin7 GTP binding proteins regulate AP-3- and ESCRT-dependent multivesicular body biogenesis. PloS one : e109372 : DOI : 10.1371/journal.pone.0109372 INSTITUT CURIE, 20 rue d’Ulm, 75248 Paris Cedex 05, France | 2 Publications de l’équipe Imagerie spatio-temporelle de la dynamique des organelles et des endomembranes Résumé Septins (SEPTs) form a family of GTP-binding proteins implicated in cytoskeleton and membrane organization, cell division and host/pathogen interactions. The precise function of many family members remains elusive. We show that SEPT6 and SEPT7 complexes bound to F-actin regulate protein sorting during multivesicular body (MVB) biogenesis. These complexes bind AP-3, an adapter complex sorting cargos destined to remain in outer membranes of maturing endosomes, modulate AP-3 membrane interactions and the motility of AP-3-positive endosomes. These SEPT-AP interactions also influence the membrane interaction of ESCRT (endosomal-sorting complex required for transport)-I, which selects ubiquitinated cargos for degradation inside MVBs. Whereas our findings demonstrate that SEPT6 and SEPT7 function in the spatial, temporal organization of AP-3- and ESCRT-coated membrane domains, they uncover an unsuspected coordination of these sorting machineries during MVB biogenesis. This requires the E3 ubiquitin ligase LRSAM1, an AP-3 interactor regulating ESCRT-I sorting activity and whose mutations are linked with Charcot-Marie-Tooth neuropathies. INSTITUT CURIE, 20 rue d’Ulm, 75248 Paris Cedex 05, France | 3