Alternative Pathways for Lipid Transfer in the Hematophagous Panstrongylus megistus: Putative Proteins Mediating Lipophorin-Tissue Interaction

FRUTTERO, L.L.; CARLINI, C.R.; RUBIOLO, E.R.; CANAVOSO, L.E.

Foz do Iguazu- Brasil

Otro; XXXIX Reunion Anual da Sociedade Brasileira de Bioquimica e Biologia Molecular; 2010

Sociedade Brasileira de Bioquimica e Biologia Molecular

Lipophorin (Lp), the main insect lipoprotein, is a “reusable shuttle” that takes up or delivers lipids to tissues without being internalized and degraded. Although an endocytic Lp receptor has been characterized, its physiological role is unclear. Therefore, it has been proposed that non-endocytic proteins located at the plasma membrane could be involved in Lp-tissue interaction. In this context, the aims of this work were: (a) to identify Lp-binding proteins in the plasma membrane of the midgut and (b) to explore the pathways by which Lp transfers lipids to the midgut and ovary. These aims were assessed using Panstrongylus megistus, a vector of Chagas’ disease. The experimental design included immunoprecipitation (IP), bidimensional electrophoresis (2D), tandem mass spectrometry (MS) and in vivo assays with fluorescently labeled Lp. The IP/2D/MS identified several Lp-binding proteins including â-ATP synthase. Results showed that Lp interacted reversibly with the midgut at the sub-epithelial layer. In the ovary, Lp followed different pathways to transfer lipids to oocytes including endocytosis and posterior co-localization with vitellogenin. These findings allowed us to identify a novel protein, â-ATP synthase, as a putative non-endocytic receptor involved in Lp-midgut interaction. Results also demonstrated for the first time in triatomines that endocytosis of Lp is an alternative pathway by which the ovarian tissue builds lipid resources in developing oocytes. Key words: Lipophorin, lipid transport, Panstrongylus megistus, binding proteins, tandem mass spectrometry.