The Fat Body of the Hematophagous Insect, Panstrongylus megistus (Hemiptera: Reduviidae): Histological Features and Participation of the β-Chain of ATP Synthase in the Lipophorin-Mediated Lipid Transfer

FRUTTERO, LEONARDO L; LEYRIA, JIMENA; MOYETTA, NATALIA R; RAMOS, FABIAN O; SETTEMBRINI, BEATRIZ P; CANAVOSO, LILIÁN E

JOURNAL OF INSECT SCIENCE

UNIV ARIZONA

Lugar: Arizona; Año: 2019 vol. 19

1536-2442

In insects, lipid transfer to the tissues is mediated by lipophorin, the major circulating lipoprotein, mainly througha nonendocytic pathway involving docking receptors. Currently, the role of such receptors in lipid metabolismremains poorly understood. In this work, we performed a histological characterization of the fat body of the Chagas?disease vector, Panstrongylus megistus (Burmeister), subjected to different nutritional conditions. In addition, weaddressed the role of the β-chain of ATP synthase (β-ATPase) in the process of lipid transfer from lipophorin to the fatbody. Fifth-instar nymphs in either fasting or fed condition were employed in the assays. Histological examinationrevealed that the fat body was composed by diverse trophocyte phenotypes. In the fasting condition, the cells weresmaller and presented a homogeneous cytoplasmic content. The fat body of fed insects increased in size mainly dueto the enlargement of lipid stores. In this condition, trophocytes contained abundant lipid droplets, and the roughendoplasmic reticulum was highly developed and mitochondria appeared elongated. Immunofluorescence assaysshowed that the β-ATPase, a putative lipophorin receptor, was located on the surface of fat body cells colocalizingpartially with lipophorin, which suggests their interaction. No changes in β-ATPase expression were found in fastingand fed insects. Blocking the lipophorin?β-ATPase interaction impaired the lipophorin-mediated lipid transfer to thefat body. The results showed that the nutritional status of the insect influenced the morphohistological features ofthe tissue. Besides, these findings suggest that β-ATPase functions as a lipophorin docking receptor in the fat body.