title: Lipid transfer particle mediates the delivery of diacylglycerol from lipophorin to fat body in larval Manduca sexta.
abstract: This work analyzed the process of lipid storage in fat body of larval Manduca sexta, focusing on the role of lipid transfer particle (LTP). Incubation of fat bodies with [(3)H]diacylglycerol-labeled lipophorin resulted in a significant accumulation of diacylglycerol (DAG) and triacylglycerol (TAG) in the tissue. Transfer of DAG to fat body and its storage as TAG was significantly inhibited (60%) by preincubating the tissue with anti-LTP antibody. Lipid transfer was restored to control values by adding LTP to fat body. Incubation of fat body with dual-labeled DAG lipophorin or its treatment with ammonium chloride showed that neither a membrane-bound lipoprotein lipase nor lipophorin endocytosis is a relevant pathway to transfer or to storage lipids into fat body, respectively. Treatment of fat body with suramin caused a 50% inhibition in [(3)H]DAG transfer from lipophorin. Treatment of [(3)H]DAG-labeled fat body with lipase significantly reduced the amount of [(3)H]DAG associated with the tissue, suggesting that the lipid is still on the external surface of the membrane. Whether this lipid represents irreversibly adsorbed lipophorin or a DAG lipase-sensitive pool is unknown. Nevertheless, these results indicate that the main pathway for DAG transfer from lipophorin to fat body is via LTP and receptor-mediated processes.
authors.affiliation: Department of Biochemistry and Molecular Biophysics and Center for Insect Science, Biological Sciences West, University of Arizona, Tucson, AZ 85721-0088, USA.
authors.forename: Lilian E
authors.initials: LE
authors.lastname: Canavoso
authors.forename: Hwa Kyung
authors.initials: HK
authors.lastname: Yun
authors.forename: Zeina E
authors.initials: ZE
authors.lastname: Jouni
authors.forename: Michael A
authors.initials: MA
authors.lastname: Wells
mesh_terms: D000818:Animals; D001692:Biological Transport; D004075:Diglycerides / Q000378:metabolism*; D005216:Fat Body / Q000737:chemistry / Q000378:metabolism*; D007814:Larva / Q000378:metabolism*; D008074:Lipoproteins / Q000378:metabolism*; D018402:Manduca / Q000254:growth & development / Q000378:metabolism*; D014316:Tritium
chemical_list: C011439:1,2-diacylglycerol; D004075:Diglycerides; D008074:Lipoproteins; C032830:lipophorin; D014316:Tritium