Receptor-mediated endocytosis and trafficking between endosomal–lysosomal vacuoles in Giardia lamblia
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The early branching Giardia lamblia has highly polarized vacuoles, located underneath the plasma membrane, which have at least some of the characteristics of endosomes and of lysosomes. These peripheral vacuoles (PVs) are necessary for nutrient uptake and the maintenance of plasma membrane composition, but whether they carry out sorting and segregation of receptors and ligands is a matter of debate. Here, we showed that the internalization of low-density lipoprotein (LDL) to the PVs is highly dynamic in trophozoites with a rate similar to the internalization of the low-density lipoprotein receptor-related protein 1. Moreover, by analyzing receptor-mediated and fluid-phase endocytosis in living cells, we showed that after endocytosis LDL but not dextran moved laterally between the PVs. We speculate on PV functional heterogeneity and maturation in this parasite.
KeywordsGiardia Lamblia Total Internal Reflection Fluorescence Microscopy Chroma Technology Numerical Aperture Objective Giardia Trophozoite
The project was supported by grant number R01TW00724 from the Fogarty International Center. The content is solely the responsibility of the authors and does not necessarily represent the official views of the Fogarty International Center or the National Institutes of Health. This research was also supported in part by the Argentine Agencia Nacional para la Promoción de la Ciencia y Tecnología (FONCyT-PICT698).
Conflict of interest
- Touz MC (2012) The unique endosomal/lysosomal system of Giardia lamblia in molecular regulation of endocytosis, Vol. 1 (ed. Ceresa, B.), InTech, Croatia.pp. http://www.intechopen.com/books/molecular-regulation-of-endocytosis/the-unique-endosomal-lysosomal-system-of-giardia-lamblia. Accessed 6 July 2012