B-ATPase AND ITS FUNCTION IN THE TRANSFER OF LIPIDS FROM LIPOPHORIN TO TARGET TISSUES IN Panstrongylus megistus (HEMIPTERA: REDUVIIDAE).

LEYRIA J; FRUTTERO LL; QUINTANILLA MF; CANAVOSO LE

San Miguel de Tucumán

Otro; Tercera Reunión Conjunta de Sociedades de Biología de la República Argentina.; 2015

Sociedades de Biología de la República Argentina

Lipophorin (Lp), a high-density lipoprotein, is the main lipid carrier in the hemolymph of insects. Lp plays a role as a ?reusable shuttle?, cycling among the tissues by loading and unloading its lipid cargo without synthesis or degradation of its apolipoprotein matrix. In order to exchange lipids, Lp must interact with specific binding sites located in the plasma membrane of the target cells. Currently, there are few characterized candidates supporting the functioning of the docking mechanism of Lp-mediated lipid transfer. In this work, we employed a combination of ligand blotting and tandem mass spectrometry to characterize proteins with the property to bind Lp to the midgut and fat body membranes of the hematophagous insect Panstrongylus megistus, a Chagas disease vector. The ß chain of ATP synthase complex (ß-ATPase) was identified as a Lp binding protein and its role in lipid transfer was further assessed at the biochemical and cellular level in different organs. After subcellular fractionation, ß- ATPase was detected by western blot in enriched membrane preparations free of mitochondria of midgut and fat body. By immunofluorescence assays, ß-ATPase was found at the surface of enterocytes and trophocytes, partially co-localizing with Lp. In vivo functional studies injecting an anti- ß-ATPase antibody demonstrated that blocking of ß-ATPase partially impaired Lp binding to midgut and fat body. The blocking of ß-ATPase also diminished Lp-mediated lipid transfer to fat body. Taken together, these findings strongly suggest that ß-ATPase is a docking receptor that mediates Lp lipid transfer to the major lipid target tissues in P. megistus.