title: ForC, a novel type of formin family protein lacking an FH1 domain, is involved in multicellular development in Dictyostelium discoideum.
abstract: Formins are highly conserved regulators of cytoskeletal organization and share three regions of homology: the FH1, FH2 and FH3 domains. Of the nine known formin genes or pseudogenes carried by Dictyostelium, forC is novel in that it lacks an FH1 domain. Mutant Dictyostelium lacking forC (DeltaforC) grew normally during the vegetative phase and, when starved, migrated normally and formed tight aggregates. Subsequently, however, DeltaforC cells made aberrant fruiting bodies with short stalks and sori that remained unlifted. DeltaforC aggregates were also unable to migrate as slugs, suggesting forC is involved in mediating cell movement during multicellular stages of Dictyostelium development. Consistent with this idea, expression of forC was increased significantly in aggregates of wild-type cells. GFP-ForC expressed in DeltaforC cells was localized at the crowns, which are macropinocytotic structures rich in F-actin, suggesting that, like other formin isoforms, ForC functions in close relation with the actin cytoskeleton. Truncation analysis of GFP-ForC revealed that the FH3 domain is required for ForC localization; moreover, localization of a truncated GFP-ForC mutant at the site of contacts between cells on substrates and along the cortex of cells within a multicellular culminant suggests that ForC is involved in the local actin cytoskeletal reorganization mediating cell-cell adhesion.
authors.affiliation: Japan Society for the Promotion of Science, National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki 305-8562, Japan. c.kitayama@aist.go.jp
authors.forename: Chikako
authors.initials: C
authors.lastname: Kitayama
authors.forename: Taro Q P
authors.initials: TQ
authors.lastname: Uyeda
mesh_terms: D008841:Actin Cytoskeleton / Q000378:metabolism*; D000818:Animals; D002448:Cell Adhesion / Q000235:genetics*; D002449:Cell Aggregation / Q000235:genetics; D002451:Cell Compartmentation / Q000235:genetics; D002462:Cell Membrane / Q000235:genetics / Q000378:metabolism; D004023:Dictyostelium / Q000235:genetics / Q000378:metabolism*; D005326:Fetal Proteins / Q000235:genetics / Q000378:metabolism; D000080865:Formins; D005786:Gene Expression Regulation / Q000235:genetics; D008840:Microfilament Proteins; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D017434:Protein Structure, Tertiary / Q000235:genetics; D015800:Protozoan Proteins / Q000235:genetics / Q000302:isolation & purification*; D012333:RNA, Messenger / Q000378:metabolism; D011993:Recombinant Fusion Proteins; D017386:Sequence Homology, Amino Acid; D012689:Sequence Homology, Nucleic Acid; D015854:Up-Regulation / Q000235:genetics
chemical_list: D005326:Fetal Proteins; D000080865:Formins; D008840:Microfilament Proteins; D009687:Nuclear Proteins; D015800:Protozoan Proteins; D012333:RNA, Messenger; D011993:Recombinant Fusion Proteins