title: RhoD activated by fibroblast growth factor induces cytoneme-like cellular protrusions through mDia3C.
abstract: The small GTPase RhoD regulates actin cytoskeleton to collapse actin stress fibers and focal adhesions, resulting in suppression of cell migration and cytokinesis. It also induces alignment of early endosomes along actin filaments and reduces their motility. We show here that a constitutively activated RhoD generated two types of actin-containing thin peripheral cellular protrusions distinct from Cdc42-induced filopodia. One was longer, almost straight, immotile, and sensitive to fixation, whereas the other was shorter, undulating, motile, and resistant to fixation. Moreover, cells expressing wild-type RhoD extended protrusions toward fibroblast growth factor (FGF) 2/4/8-coated beads. Stimulation of wild-type RhoD-expressing cells with these FGFs also caused formation of cellular protrusions. Nodules moved through the RhoD-induced longer protrusions, mainly toward the cell body. Exogenously expressed FGF receptor was associated with these moving nodules containing endosome-like vesicles. These results suggest that the protrusions are responsible for intercellular communication mediated by FGF and its receptor. Accordingly, the protrusions are morphologically and functionally equivalent to cytonemes. RhoD was activated by FGF2/4/8. Knockdown of RhoD interfered with FGF-induced protrusion formation. Activated RhoD specifically bound to mDia3C and facilitated actin polymerization together with mDia3C. mDia3C was localized to the tips or stems of the protrusions. In addition, constitutively activated mDia3C formed protrusions without RhoD or FGF stimulation. Knockdown of mDia3 obstructed RhoD-induced protrusion formation. These results imply that RhoD activated by FGF signaling forms cytoneme-like protrusions through activation of mDia3C, which induces actin filament formation.
authors.affiliation: Department of Biology, Graduate School of Science, Yayoicho, Inageku, Chiba 263-8522, Japan.
authors.forename: Kazuhisa
authors.initials: K
authors.lastname: Koizumi
authors.forename: Kazunori
authors.initials: K
authors.lastname: Takano
authors.forename: Akiko
authors.initials: A
authors.lastname: Kaneyasu
authors.forename: Haruko
authors.initials: H
authors.lastname: Watanabe-Takano
authors.forename: Emi
authors.initials: E
authors.lastname: Tokuda
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Abe
authors.forename: Naoki
authors.initials: N
authors.lastname: Watanabe
authors.forename: Tadaomi
authors.initials: T
authors.lastname: Takenawa
authors.forename: Takeshi
authors.initials: T
authors.lastname: Endo
mesh_terms: D008841:Actin Cytoskeleton / Q000378:metabolism / Q000648:ultrastructure; D000818:Animals; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D002465:Cell Movement / Q000235:genetics; D002478:Cells, Cultured; D048749:Cytokinesis / Q000235:genetics; D005346:Fibroblast Growth Factors / Q000378:metabolism / Q000494:pharmacology; D022001:Focal Adhesions / Q000235:genetics / Q000378:metabolism; D000080865:Formins; D059630:Mesenchymal Stem Cells / Q000166:cytology / Q000378:metabolism; D051379:Mice; D011554:Pseudopodia / Q000378:metabolism / Q000648:ultrastructure; D020741:rho GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D002352:Carrier Proteins; C491463:Diap2 protein, mouse; D000080865:Formins; D005346:Fibroblast Growth Factors; C491334:Rhod protein, mouse; D020741:rho GTP-Binding Proteins