title: Cell migration without a lamellipodium: translation of actin dynamics into cell movement mediated by tropomyosin.
abstract: The actin cytoskeleton is locally regulated for functional specializations for cell motility. Using quantitative fluorescent speckle microscopy (qFSM) of migrating epithelial cells, we previously defined two distinct F-actin networks based on their F-actin-binding proteins and distinct patterns of F-actin turnover and movement. The lamellipodium consists of a treadmilling F-actin array with rapid polymerization-dependent retrograde flow and contains high concentrations of Arp2/3 and ADF/cofilin, whereas the lamella exhibits spatially random punctae of F-actin assembly and disassembly with slow myosin-mediated retrograde flow and contains myosin II and tropomyosin (TM). In this paper, we microinjected skeletal muscle alphaTM into epithelial cells, and using qFSM, electron microscopy, and immunolocalization show that this inhibits functional lamellipodium formation. Cells with inhibited lamellipodia exhibit persistent leading edge protrusion and rapid cell migration. Inhibition of endogenous long TM isoforms alters protrusion persistence. Thus, cells can migrate with inhibited lamellipodia, and we suggest that TM is a major regulator of F-actin functional specialization in migrating cells.
authors.affiliation: Department of Cell Biology, The Scripps Research Institute, La Jolla, CA 92037, USA.
authors.forename: Stephanie L
authors.initials: SL
authors.lastname: Gupton
authors.forename: Karen L
authors.initials: KL
authors.lastname: Anderson
authors.forename: Thomas P
authors.initials: TP
authors.lastname: Kole
authors.forename: Robert S
authors.initials: RS
authors.lastname: Fischer
authors.forename: Aaron
authors.initials: A
authors.lastname: Ponti
authors.forename: Sarah E
authors.initials: SE
authors.lastname: Hitchcock-DeGregori
authors.forename: Gaudenz
authors.initials: G
authors.lastname: Danuser
authors.forename: Velia M
authors.initials: VM
authors.lastname: Fowler
authors.forename: Denis
authors.initials: D
authors.lastname: Wirtz
authors.forename: Dorit
authors.initials: D
authors.lastname: Hanein
authors.forename: Clare M
authors.initials: CM
authors.lastname: Waterman-Storer
mesh_terms: D051339:Actin Depolymerizing Factors; D051378:Actin-Related Protein 3; D000199:Actins / Q000378:metabolism*; D000818:Animals; D002448:Cell Adhesion / Q000502:physiology; D002465:Cell Movement / Q000502:physiology*; D002478:Cells, Cultured; D003598:Cytoskeletal Proteins / Q000378:metabolism; D004847:Epithelial Cells / Q000378:metabolism / Q000502:physiology*; D006801:Humans; D008840:Microfilament Proteins / Q000378:metabolism; D008855:Microscopy, Electron, Scanning; D018482:Muscle, Skeletal / Q000378:metabolism; D009218:Myosins / Q000378:metabolism; D011554:Pseudopodia / Q000378:metabolism / Q000502:physiology*; D014335:Tropomyosin / Q000378:metabolism*
chemical_list: C495928:ACTR3 protein, human; D051339:Actin Depolymerizing Factors; D051378:Actin-Related Protein 3; D000199:Actins; D003598:Cytoskeletal Proteins; D008840:Microfilament Proteins; D014335:Tropomyosin; D009218:Myosins
references.citation: J Mol Biol. 1995 Aug 11;251(2):191-6
references.pmid: 7643394
references.citation: J Cell Sci. 1980 Apr;42:81-116
references.pmid: 7400245
references.citation: J Biol Chem. 1990 Dec 5;265(34):21323-9
references.pmid: 2250026
references.citation: J Cell Biol. 1995 Oct;131(1):179-89
references.pmid: 7559774
references.citation: Curr Biol. 2002 Jan 8;12(1):79-84
references.pmid: 11790308
references.citation: J Cell Biol. 1991 Aug;114(3):503-13
references.pmid: 1860882
references.citation: Cell. 2002 May 17;109(4):509-21
references.pmid: 12086607
references.citation: Neuron. 1996 Apr;16(4):769-82
references.pmid: 8607995
references.citation: Curr Opin Cell Biol. 2004 Feb;16(1):99-105
references.pmid: 15037312
references.citation: Int Rev Cytol. 1993;144:85-127
references.pmid: 8320063
references.citation: Cell. 2004 Oct 29;119(3):419-29
references.pmid: 15507212
references.citation: J Cell Biol. 1997 Mar 24;136(6):1307-22
references.pmid: 9087445
references.citation: Proc Natl Acad Sci U S A. 1998 May 26;95(11):6181-6
references.pmid: 9600938
references.citation: J Cell Biol. 1996 Jun;133(6):1403-15
references.pmid: 8682874
references.citation: Hybridoma. 1985 Fall;4(3):223-42
references.pmid: 3899907
references.citation: J Neurosci. 1996 Nov 1;16(21):6853-63
references.pmid: 8824324
references.citation: J Cell Biol. 1997 Jul 28;138(2):375-84
references.pmid: 9230079
references.citation: J Supramol Struct. 1976;5(4):531(383)-563(415)
references.pmid: 800620
references.citation: Biophys J. 2003 Mar;84(3):1591-605
references.pmid: 12609863
references.citation: Cell Motil. 1982;2(1):1-8
references.pmid: 6890875
references.citation: J Microsc. 2003 Sep;211(Pt 3):191-207
references.pmid: 12950468
references.citation: Curr Biol. 2002 Nov 19;12(22):1891-9
references.pmid: 12445381
references.citation: Annu Rev Biophys Biomol Struct. 2000;29:545-76
references.pmid: 10940259
references.citation: Neuron. 2004 Apr 8;42(1):37-49
references.pmid: 15066263
references.citation: Methods. 2003 Jan;29(1):29-41
references.pmid: 12543069
references.citation: J Microsc. 1975 Jul;104(2):107-20
references.pmid: 1104850
references.citation: Proc Natl Acad Sci U S A. 1994 Dec 20;91(26):12962-6
references.pmid: 7809155
references.citation: Curr Biol. 1998 Nov 5;8(22):1227-30
references.pmid: 9811609
references.citation: Curr Protoc Cell Biol. 2002 Feb;Chapter 4:Unit 4.10
references.pmid: 18228403
references.citation: Cell Motil Cytoskeleton. 1998;40(4):393-407
references.pmid: 9712268
references.citation: J Cell Biol. 1995 Nov;131(4):989-1002
references.pmid: 7490299
references.citation: J Clin Chem Clin Biochem. 1983 Sep;21(9):535-44
references.pmid: 6631336
references.citation: J Cell Biol. 1999 May 31;145(5):1009-26
references.pmid: 10352018
references.citation: J Cell Sci. 2002 Dec 1;115(Pt 23):4649-60
references.pmid: 12415009
references.citation: Nat Cell Biol. 2004 Feb;6(2):154-61
references.pmid: 14743221
references.citation: J Cell Sci. 1994 Jun;107 ( Pt 6):1633-9
references.pmid: 7962203
references.citation: Science. 2004 Sep 17;305(5691):1782-6
references.pmid: 15375270
references.citation: J Cell Biol. 2004 Apr 26;165(2):233-42
references.pmid: 15117967
references.citation: Phys Rev E Stat Nonlin Soft Matter Phys. 2002 May;65(5 Pt 1):051505
references.pmid: 12059562
references.citation: J Cell Biol. 2002 Jul 8;158(1):31-7
references.pmid: 12105180
references.citation: Biophys J. 2003 Aug;85(2):1289-306
references.pmid: 12885672
references.citation: Int Rev Cytol. 1997;170:1-38
references.pmid: 9002235
references.citation: Biophys J. 2000 Aug;79(2):1095-106
references.pmid: 10920039
references.citation: J Cell Biol. 2003 Jun 9;161(5):845-51
references.pmid: 12796474
references.citation: Neuron. 2004 Jul 8;43(1):81-94
references.pmid: 15233919
references.citation: J Cell Biol. 1981 Aug;90(2):485-94
references.pmid: 7197276
references.citation: Mol Biol Cell. 2003 Mar;14(3):1002-16
references.pmid: 12631719
references.citation: Biophys J. 2002 Dec;83(6):3162-76
references.pmid: 12496086
references.citation: J Cell Biol. 1999 Apr 19;145(2):331-45
references.pmid: 10209028
references.citation: Curr Biol. 2001 Aug 21;11(16):1300-4
references.pmid: 11525747
references.citation: Biophys J. 2003 May;84(5):3336-52
references.pmid: 12719263
references.citation: Biochem J. 1948;43(2):271-9
references.pmid: 16748400
references.citation: Science. 2002 Feb 8;295(5557):1083-6
references.pmid: 11834838
references.citation: Mol Biol Cell. 2004 Jul;15(7):3475-84
references.pmid: 15146061