title: Critical roles of actin-interacting protein 1 in cytokinesis and chemotactic migration of mammalian cells.
abstract: Cofilin regulates actin filament dynamics by stimulating actin filament disassembly and plays a critical role in cytokinesis and chemotactic migration. Aip1 (actin-interacting protein 1), also called WDR1 (WD-repeat protein 1), is a highly conserved WD-repeat protein in eukaryotes and promotes cofilin-mediated actin filament disassembly in vitro; however, little is known about the mechanisms by which Aip1 functions in cytokinesis and cell migration in mammalian cells. In the present study, we investigated the roles of Aip1 in cytokinesis and chemotactic migration of human cells by silencing the expression of Aip1 using siRNA (small interfering RNA). Knockdown of Aip1 in HeLa cells increased the percentage of multinucleate cells; this effect was reversed by expression of an active form of cofilin. In Aip1-knockdown cells, the cleavage furrow ingressed normally from anaphase to early telophase; however, an excessive accumulation of actin filaments was observed on the contractile ring in late telophase. These results suggest that Aip1 plays a crucial role in the completion of cytokinesis by promoting cofilin-mediated actin filament disassembly in telophase. We have also shown that Aip1 knockdown significantly suppressed chemokine-induced chemotactic migration of Jurkat T-lymphoma cells, and this was blocked by expression of an active form of cofilin. Whereas control cells mostly formed a single lamellipodium in response to chemokine stimulation, Aip1 knockdown cells abnormally exhibited multiple protrusions around the cells before and after cell stimulation. This indicates that Aip1 plays an important role in directional cell migration by restricting the stimulus-induced membrane protrusion to one direction via promoting cofilin activity.
authors.affiliation: Department of Biomolecular Sciences, Graduate School of Life Sciences, Tohoku University, Sendai, Miyagi 980-8578, Japan.
authors.forename: Asuka
authors.initials: A
authors.lastname: Kato
authors.forename: Souichi
authors.initials: S
authors.lastname: Kurita
authors.forename: Aya
authors.initials: A
authors.lastname: Hayashi
authors.forename: Noriko
authors.initials: N
authors.lastname: Kaji
authors.forename: Kazumasa
authors.initials: K
authors.lastname: Ohashi
authors.forename: Kensaku
authors.initials: K
authors.lastname: Mizuno
mesh_terms: D051339:Actin Depolymerizing Factors / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D001692:Biological Transport / Q000187:drug effects; D002462:Cell Membrane / Q000378:metabolism; D002465:Cell Movement / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D002478:Cells, Cultured; D054377:Chemokine CXCL12 / Q000494:pharmacology; D002633:Chemotaxis / Q000187:drug effects / Q000235:genetics / Q000502:physiology; D048749:Cytokinesis / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D003593:Cytoplasm / Q000187:drug effects / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D019169:Jurkat Cells; D008840:Microfilament Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D008938:Mitosis / Q000187:drug effects / Q000235:genetics / Q000502:physiology
chemical_list: D051339:Actin Depolymerizing Factors; D054377:Chemokine CXCL12; D008840:Microfilament Proteins; C115237:actin interacting protein 1