Integrin αpS3/β-mediated Phagocytosis of Apoptotic Cells and Bacteria in Drosophila

Abstract

Integrins exert a variety of cellular functions as heterodimers of two transmembrane subunits named α and β. Integrin, β a β-subunit of Drosophila integrin, is involved in the phagocytosis of apoptotic cells and bacteria. Here, we searched for an α-subunit that forms a complex and cooperates withβ Examinations of RNAi-treated animals suggested thatαPS3, but not any of four other -subunits, is required for the effective phagocytosis of apoptotic cells in Drosophila embryos. The mutation of αPS3-encoding scb, deficiency, insertion of P-element, or alteration of nucleotide sequences, brought about a reduction in the level of phagocytosis. The defect in phagocytosis by deficiency was reverted by the forced expression of scb. Furthermore, flies in which the expression of both αPS3 and β was inhibited by RNAi showed a level of phagocytosis almost equal to that observed in flies with RNAi for either subunit alone. A loss of αPS3 also decreased the activity of larval hemocytes in the phagocytosis of Staphylococcus aureus. Finally, a co-immunoprecipitation analysis using a Drosophila cell line treated with a chemical cross-linker suggested a physical association between αPS3 and β. These results collectively indicated that integrin αPS3/β serves as a receptor in the phagocytosis of apoptotic cells and bacteria by Drosophila phagocytes.© 2013 by The American Society for Biochemistry and Molecular Biology, Inc.