Lipophorin receptor-mediated lipoprotein endocytosis in insect fat body cells

• Published in: Journal of lipid research Vol. 44; no. 8; pp. 1431 - 1440
• Main Authors: Van Hoof, Dennis, Rodenburg, Kees W., Van der Horst, Dick J.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.08.2003; Elsevier
• Subjects: Animals; Carrier Proteins - metabolism; Endocytosis; Fat Body - cytology; Fat Body - metabolism; Female; Fluorescent Antibody Technique; Grasshoppers - metabolism; high-density lipophorin; Humans; insect lipophorin receptor; Larva - metabolism; Ligands; lipid; Lipoproteins - metabolism; Lipoproteins, HDL - metabolism; Locusta migratoria; low density lipoprotein receptor; Male; Molecular Chaperones - metabolism; receptor-associated protein; receptor-mediated endocytosis; Receptors, Cytoplasmic and Nuclear - metabolism; recycling; very low density lipoprotein receptor; receptor-mediated endocytosis; very low density lipoprotein receptor; insect lipophorin receptor; recycling; low density lipoprotein receptor; Locusta migratoria; receptor-associated protein; lipid; high-density lipophorin
• ISSN: 0022-2275; 1539-7262
• DOI: 10.1194/jlr.M300022-JLR200

High-density lipophorin (HDLp) in the circulation of insects is able to selectively deliver lipids to target tissues in a nonendocytic manner. In Locusta migratoria, a member of the LDL receptor family has been identified and shown to mediate endocytosis of HDLp in mammalian cells transfected with the cDNA of this receptor. This insect lipophorin receptor (iLR) is temporally expressed in fat body tissue of young adult as well as larval locusts, as shown by Western blot analysis. Fluorescence microscopy revealed that fat body cells internalize fluorescently labeled HDLp and human receptor-associated protein only when iLR is expressed. Expression of iLR is down-regulated on Day 4 after an ecdysis. Consequently, HDLp is no longer internalized. By starving adult locusts immediately after ecdysis, we were able to prolong iLR expression. In addition, expression of the receptor was induced by starving adults after down-regulation of iLR. These results suggest that iLR mediates endocytosis of HDLp in fat body cells, and that expression of iLR is regulated by the demand of fat body tissue for lipids.