Giardia Lipoprotein Receptor-related Protein: a novel LDLR family member in a primitive eukaryotic cell

RIVERO, MR; MIRAS, SL; ROPOLO, AS; TOUZ, MC

Buzios

Congreso; XIII International Congress of Protistology; 2009

Host cell cholesterol has been implicated in the survival and replication of many pathogens. However, lipid uptake in protozoa parasites has not been widely characterized. The divergent eukaryote Giardia lamblia is unable to synthesize cholesterol de novo, trophozoites colonize the upper part of the human small intestine and they might obtain this compound from the intestinal milieu (1, 2). It had been suggested that a portion of the lipid uptake may be associated with endocytosis of lipoproteins (3). In mammalian cells, the uptake of cholesterol via the internalization of low-density lipoprotein (LDL) is a regulated mechanism involving the LDL receptor (LDLR) and the ARH (autosomal recessive hypercholesterolemia) adaptor protein, an AP2 associated protein (4). In Giardia, we observed that the AP2 adaptor complex is implicated in the internalization of cholesterol from LDL via a regulated AP2-clathrin-dependent pathway in vitro cultures. Nevertheless, no specific lipoprotein receptor has been identified.