title: Formin3 is required for assembly of the F-actin structure that mediates tracheal fusion in Drosophila.
abstract: During tracheal development in Drosophila, some branches join to form a continuous luminal network. Specialized cells at the branch tip, called fusion cells, extend filopodia to make contact and become doughnut shaped to allow passage of the lumen. These morphogenetic processes accompany the highly regulated cytoskeletal reorganization of fusion cells. We identified the Drosophila formin3 (form3) gene that encodes a novel formin and plays a role in tracheal fusion. Formins are a family of proteins characterized by highly conserved formin homology (FH) domains. The formin family functions in various actin-based processes, including cytokinesis and cell polarity. During embryogenesis, form3 mRNA is expressed mainly in the tracheal system. In form3 mutant embryos, the tracheal fusion does not occur at some points. This phenotype is rescued by the forced expression of form3 in the trachea. We used live imaging of GFP-moesin during tracheal fusion to show that an F-actin structure that spans the adjoining fusion cells and mediates the luminal connection does not form at abnormal anastomosis sites in form3 mutants. These results suggested that Form3 plays a role in the F-actin assembly, which is essential for cellular rearrangement during tracheal fusion.
authors.affiliation: Department of Physics, Graduate School of Science, University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan.
authors.forename: Hiromasa
authors.initials: H
authors.lastname: Tanaka
authors.forename: Etsuko
authors.initials: E
authors.lastname: Takasu
authors.forename: Toshiro
authors.initials: T
authors.lastname: Aigaki
authors.forename: Kagayaki
authors.initials: K
authors.lastname: Kato
authors.forename: Shigeo
authors.initials: S
authors.lastname: Hayashi
authors.forename: Akinao
authors.initials: A
authors.lastname: Nose
mesh_terms: D000199:Actins / Q000737:chemistry / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D030801:Animals, Genetically Modified; D001369:Axons / Q000378:metabolism; D015820:Cadherins / Q000378:metabolism; D002459:Cell Fusion; D003599:Cytoskeleton / Q000378:metabolism; D029721:Drosophila Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000033:anatomy & histology / Q000196:embryology* / Q000378:metabolism; D000080865:Formins; D017403:In Situ Hybridization; D008840:Microfilament Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D009024:Morphogenesis; D010641:Phenotype; D010802:Phylogeny; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D000199:Actins; D015820:Cadherins; D029721:Drosophila Proteins; D000080865:Formins; D008840:Microfilament Proteins; D011993:Recombinant Fusion Proteins; C467520:esg protein, Drosophila; C493288:form3 protein, Drosophila; C071058:moesin