title: Ena/VASP regulates mDia2-initiated filopodial length, dynamics, and function.
abstract: Filopodia are long plasma membrane extensions involved in the formation of adhesive, contractile, and protrusive actin-based structures in spreading and migrating cells. Whether filopodia formed by different molecular mechanisms equally support these cellular functions is unresolved. We used Enabled/vasodilator-stimulated phosphoprotein (Ena/VASP)-deficient MV(D7) fibroblasts, which are also devoid of endogenous mDia2, as a model system to investigate how these different actin regulatory proteins affect filopodia morphology and dynamics independently of one another. Filopodia initiated by either Ena/VASP or mDia2 contained similar molecular inventory but differed significantly in parameters such as number, length, F-actin organization, lifetime, and protrusive persistence. Moreover, in the absence of Ena/VASP, filopodia generated by mDia2 did not support initiation of integrin-dependent signaling cascades required for adhesion and subsequent lamellipodial extension, thereby causing a defect in early cell spreading. Coexpression of VASP with constitutively active mDia2(M/A) rescued these early adhesion defects. We conclude that Ena/VASP and mDia2 support the formation of filopodia with significantly distinct properties and that Ena/VASP regulates mDia2-initiated filopodial morphology, dynamics, and function.
authors.affiliation: David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139 melanie.barzik@nih.gov.
authors.forename: Melanie
authors.initials: M
authors.lastname: Barzik
authors.affiliation: David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139.
authors.forename: Leslie M
authors.initials: LM
authors.lastname: McClain
authors.affiliation: Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599.
authors.forename: Stephanie L
authors.initials: SL
authors.lastname: Gupton
authors.affiliation: David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139.
authors.forename: Frank B
authors.initials: FB
authors.lastname: Gertler
mesh_terms: D000818:Animals; D002448:Cell Adhesion; D015815:Cell Adhesion Molecules / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D002478:Cells, Cultured; D003598:Cytoskeletal Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D051379:Mice; D008840:Microfilament Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D008869:Microtubule-Associated Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D009252:NADPH Dehydrogenase / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D011554:Pseudopodia / Q000378:metabolism / Q000502:physiology* / Q000648:ultrastructure; D015398:Signal Transduction; D000098662:Vasodilator-Stimulated Phosphoprotein
chemical_list: D015815:Cell Adhesion Molecules; D003598:Cytoskeletal Proteins; C102176:Enah protein, mouse; D008840:Microfilament Proteins; D008869:Microtubule-Associated Proteins; D010750:Phosphoproteins; D000098662:Vasodilator-Stimulated Phosphoprotein; C508552:Dia2 protein, mouse; D009252:NADPH Dehydrogenase