title: A novel Rho-dependent pathway that drives interaction of fascin-1 with p-Lin-11/Isl-1/Mec-3 kinase (LIMK) 1/2 to promote fascin-1/actin binding and filopodia stability.
abstract: BACKGROUND
  Fascin-1 is an actin crosslinking protein that is important for the assembly of cell protrusions in neurons, skeletal and smooth muscle, fibroblasts, and dendritic cells. Although absent from most normal adult epithelia, fascin-1 is upregulated in many human carcinomas, and is associated with poor prognosis because of its promotion of carcinoma cell migration, invasion, and metastasis. Rac and Cdc42 small guanine triphosphatases have been identified as upstream regulators of the association of fascin-1 with actin, but the possible role of Rho has remained obscure. Additionally, experiments have been hampered by the inability to measure the fascin-1/actin interaction directly in intact cells. We investigated the hypothesis that fascin-1 is a functional target of Rho in normal and carcinoma cells, using experimental approaches that included a novel fluorescence resonance energy transfer (FRET)/fluorescence lifetime imaging (FLIM) method to measure the interaction of fascin-1 with actin.
  
  
  RESULTS
  Rho activity modulates the interaction of fascin-1 with actin, as detected by a novel FRET method, in skeletal myoblasts and human colon carcinoma cells. Mechanistically, Rho regulation depends on Rho kinase activity, is independent of the status of myosin II activity, and is not mediated by promotion of the fascin/PKC complex. The p-Lin-11/Isl-1/Mec-3 kinases (LIMK), LIMK1 and LIMK2, act downstream of Rho kinases as novel binding partners of fascin-1, and this complex regulates the stability of filopodia.
  
  
  CONCLUSIONS
  We have identified a novel activity of Rho in promoting a complex between fascin-1 and LIMK1/2 that modulates the interaction of fascin-1 with actin. These data provide new mechanistic insight into the intracellular coordination of contractile and protrusive actin-based structures. During the course of the study, we developed a novel FRET method for analysis of the fascin-1/actin interaction, with potential general applicability for analyzing the activities of actin-binding proteins in intact cells.
authors.affiliation: Randall Division of Cell and Molecular Biophysics, King's College London, Guy's Campus, London SE1 1UL, UK.
authors.forename: Asier
authors.initials: A
authors.lastname: Jayo
authors.forename: Maddy
authors.initials: M
authors.lastname: Parsons
authors.forename: Josephine C
authors.initials: JC
authors.lastname: Adams
mesh_terms: D000199:Actins / Q000378:metabolism*; D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism*; D002460:Cell Line; D002465:Cell Movement; D004789:Enzyme Activation; D031541:Fluorescence Resonance Energy Transfer; D006801:Humans; D007527:Isoenzymes / Q000378:metabolism; D054461:Lim Kinases / Q000378:metabolism*; D051379:Mice; D008840:Microfilament Proteins / Q000378:metabolism*; D018613:Microscopy, Confocal; D008954:Models, Biological; D009218:Myosins / Q000378:metabolism; D011485:Protein Binding; D011493:Protein Kinase C / Q000378:metabolism; D011554:Pseudopodia / Q000378:metabolism*; D015398:Signal Transduction; D059008:Time-Lapse Imaging; D054460:rho-Associated Kinases / Q000378:metabolism; D020742:rhoA GTP-Binding Protein / Q000037:antagonists & inhibitors / Q000378:metabolism*
chemical_list: D000199:Actins; D002352:Carrier Proteins; D007527:Isoenzymes; D008840:Microfilament Proteins; C020324:fascin; C515892:LIMK1 protein, human; C102895:LIMK2 protein, human; D054461:Lim Kinases; D054460:rho-Associated Kinases; D011493:Protein Kinase C; D009218:Myosins; D020742:rhoA GTP-Binding Protein