THE PHYSIOLOGICAL RELEVANCE OF MIDGUT MEMBRANE PROTEINS IN THE PROCESS OF LIPID TRANSFER IN A VECTOR OF CHAGAS? DISEASE

FRUTTERO LL; STARIOLO R; CARLINI CR; RUBIOLO ER; CANAVOSO LE

San Juan, Argentina

Jornada; 2º Reunión Conjunta de Sociedades de Biología de la República Argentina, XVIII Jornadas Científicas de la Sociedad de Biología de Córdoba; 2011

Sociedades de Biología de la República Argentina

In insects, lipid transport through hemolymph is accomplished by lipophorin, the main high-density lipoprotein. It is suggested that lipophorin transfers its lipid cargo to tissues by a process mediated by uncharacterized non-endocytic receptors. In this context, we have analyzed the lipid transfer between circulating lipophorin and the midgut tissue in Panstrongylus megistus, a Chagas? disease vector. We made special focus in the characterization of membrane proteins that interacted with lipophorin. Immunofluorescence and in vivo assays with fluorescently labeled lipophorin showed that this lipoprotein interacted mainly with the sub-epithelial layer of the midgut. No intracellular signal compatible with endocytosis was observed. The use of lipophorin-Bodipy-FA (a fatty acid analog) demonstrated that lipid transfer at the midgut was bidirectional, and showed no dependence with the nutritional status of the insect. By combining ligand blotting, immunoprecipitation, and mass spectrometry approaches, several midgut membrane proteins interacting with lipophorin were identified, including the Beta subunit of the ATP synthase complex (Beta-ATPase), which was pointed out in human cell lines as a lipoprotein receptor. These findings are in agreement with the function of lipophorin as a reusable shuttle and suggest for the first time a novel role for Beta-ATPase as a non-endocytic lipophorin receptor in the midgut of P. megistus.