INIMEC - CONICET   05467
INSTITUTO DE INVESTIGACION MEDICA MERCEDES Y MARTIN FERREYRA
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
The Giardial ENTH Protein Participates in Lysosomal Protein Trafficking and Endocytosis
Autor/es:
FELIZIANI C; ROPOLO AS; LANFREDI-RANGEL; WENDLAND B; TOUZ MC
Reunión:
Congreso; 23rd International Congress of the IUBMB and 44th Annual SBBq Meeting; 2015
Resumen:
In this work, we have identified a single gene in Giardia encoding a protein containing an ENTH domain that defines monomeric adaptor proteins of the epsin family. This domain is present in the epsin or epsin-related (epsinR) adaptor proteins, which are implicated in endocytosis and Golgi-to-endosome protein trafficking, respectively, in other eukaryotic cells. We found that GlENTHp (for Giardia lamblia ENTH protein) localized in the cytosol and, like epsin, was associated with the alpha subunit of AP-2, clathrin and ubiquitin, strongly interacted with PI3,4,5P3, and was involved in receptor-mediated endocytosis. It also bonded the gamma subunit of AP-1 and PI4P, and was implicated in ER-to-PV trafficking, like epsinR proteins. Alteration of the GlENTHp function severely affected trophozoite growth showing an unusual accumulation of dense material in the lysosome-like peripheral vacuoles (PVs), indicating that GlENTHp might be implicated in the maintenance of PV homeostasis. Because many components of the endocytic machinery are structurally and functionally conserved between eukaryotes, the yeast system was used to explore the similarities as well as the particularities of GlENTHp as a member of the epsin family. The yeast S. cerevisiae expresses two homologues of epsin, Ent1 and Ent2, and two orthologous of epsinR, Ent3 and Ent5. Although the expression of GlENTHp (or its ENTH domain alone) neither complemented growth in ent1Δent2Δ mutant nor restored GFP-CPS1 vacuolar protein trafficking defect in ent3Δent5Δ, it resulted in an Ent3/5 dominant non-functional phenotype in a wild type strain. This phenotype is linked to a defect in CPS1 localization and α-factor mating pheromone maturation. The finding that GlENTHp acts as an non- functional epsinR in yeast cells reinforce the phylogenetic data showing that GlENTHp belongs to the epsinR subfamily present in eukaryotes prior to its evolution in different taxa.