title: Surface-targeted lysosomal membrane glycoprotein-1 (Lamp-1) enhances lysosome exocytosis and cell invasion by Trypanosoma cruzi.
abstract: To gain entry into non-phagocytic cells, Trypanosoma cruzi trypomastigotes recruit lysosomes to the host cell surface. Lysosome fusion at the site of parasite entry leads to the formation of a parasitophorous vacuole with lysosomal properties. Here, we show that increased expression of the lysosomal membrane glycoprotein Lamp-1 at the cell surface renders CHO cells more susceptible to trypomastigote invasion in a microtubule-dependent fashion. Mutation of critical residues in the lysosome-targeting motif of Lamp-1 abolished the enhancement of T. cruzi invasion. This suggests that interactions dependent on Lamp-1 cytoplasmic tail motifs, and not the surface-exposed luminal domain, modulate T. cruzi entry. Measurements of Ca2+-triggered exocytosis of lysosomes in these cell lines revealed an enhancement of beta-hexosaminidase release in cells expressing wild-type Lamp-1 on the plasma membrane; this effect was not observed in cell lines transfected with Lamp-1 cytoplasmic tail mutants. These results also implicate Ca2+-regulated lysosome exocytosis in cell invasion by T. cruzi and indicate a role for the Lamp-1 cytosolic domain in promoting more efficient fusion of lysosomes with the plasma membrane.
authors.affiliation: Section of Microbial Pathogenesis, Boyer Center for Molecular Medicine, Yale University School of Medicine, New Haven, CT 06536, USA.
authors.forename: P E
authors.initials: PE
authors.lastname: Kima
authors.forename: B
authors.initials: B
authors.lastname: Burleigh
authors.forename: N W
authors.initials: NW
authors.lastname: Andrews
mesh_terms: D000818:Animals; D015703:Antigens, CD / Q000235:genetics / Q000378:metabolism*; D016466:CHO Cells; D002118:Calcium / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism; D014355:Chagas Disease / Q000469:parasitology; D006224:Cricetinae; D005089:Exocytosis / Q000502:physiology*; D005455:Fluorescent Antibody Technique; D051907:Lysosomal Membrane Proteins; D008247:Lysosomes / Q000502:physiology*; D008562:Membrane Glycoproteins / Q000235:genetics / Q000378:metabolism*; D008870:Microtubules / Q000378:metabolism; D014162:Transfection; D014349:Trypanosoma cruzi / Q000472:pathogenicity* / Q000502:physiology
chemical_list: D015703:Antigens, CD; D051907:Lysosomal Membrane Proteins; D008562:Membrane Glycoproteins; D002118:Calcium