title: Amphiphysin 1 is important for actin polymerization during phagocytosis.
abstract: Amphiphysin 1 is involved in clathrin-mediated endocytosis. In this study, we demonstrate that amphiphysin 1 is essential for cellular phagocytosis and that it is critical for actin polymerization. Phagocytosis in Sertoli cells was induced by stimulating phosphatidylserine receptors. This stimulation led to the formation of actin-rich structures, including ruffles, phagocytic cups, and phagosomes, all of which showed an accumulation of amphiphysin 1. Knocking out amphiphysin 1 by RNA interference in the cells resulted in the reduction of ruffle formation, actin polymerization, and phagocytosis. Phagocytosis was also drastically decreased in amph 1 (-/-) Sertoli cells. In addition, phosphatidylinositol-4,5-bisphosphate-induced actin polymerization was decreased in the knockout testis cytosol. The addition of recombinant amphiphysin 1 to the cytosol restored the polymerization process. Ruffle formation in small interfering RNA-treated cells was recovered by the expression of constitutively active Rac1, suggesting that amphiphysin 1 functions upstream of the protein. These findings support that amphiphysin 1 is important in the regulation of actin dynamics and that it is required for phagocytosis.
authors.affiliation: Department of Neuroscience, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama 700-8558, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Yamada
authors.forename: Emiko
authors.initials: E
authors.lastname: Ohashi
authors.forename: Tadashi
authors.initials: T
authors.lastname: Abe
authors.forename: Norihiro
authors.initials: N
authors.lastname: Kusumi
authors.forename: Shun-Ai
authors.initials: SA
authors.lastname: Li
authors.forename: Yumi
authors.initials: Y
authors.lastname: Yoshida
authors.forename: Masami
authors.initials: M
authors.lastname: Watanabe
authors.forename: Kazuhito
authors.initials: K
authors.lastname: Tomizawa
authors.forename: Yuji
authors.initials: Y
authors.lastname: Kashiwakura
authors.forename: Hiromi
authors.initials: H
authors.lastname: Kumon
authors.forename: Hideki
authors.initials: H
authors.lastname: Matsui
authors.forename: Kohji
authors.initials: K
authors.lastname: Takei
mesh_terms: D000199:Actins / Q000378:metabolism*; D000818:Animals; D002478:Cells, Cultured; D003600:Cytosol / Q000187:drug effects / Q000378:metabolism; D017353:Gene Deletion; D008081:Liposomes; D008297:Male; D021962:Membrane Microdomains / Q000187:drug effects / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D009419:Nerve Tissue Proteins / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D010587:Phagocytosis / Q000187:drug effects; D010718:Phosphatidylserines / Q000494:pharmacology; D051381:Rats; D020744:rac GTP-Binding Proteins / Q000378:metabolism
chemical_list: D000199:Actins; D008081:Liposomes; D009419:Nerve Tissue Proteins; D010718:Phosphatidylserines; C075637:amphiphysin; D020744:rac GTP-Binding Proteins