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Proc Natl Acad Sci U S A. Oct 24, 1995; 92(22): 10252–10256.

Contraction due to microtubule disruption is associated with increased phosphorylation of myosin regulatory light chain.


Microtubules have been proposed to function as rigid struts which oppose cellular contraction. Consistent with this hypothesis, microtubule disruption strengthens the contractile force exerted by many cell types. We have investigated alternative explanation for the mechanical effects of microtubule disruption: that microtubules modulate the mechanochemical activity of myosin by influencing phosphorylation of the myosin regulatory light chain (LC20). We measured the force produced by a population of fibroblasts within a collagen lattice attached to an isometric force transducer. Treatment of cells with nocodazole, an inhibitor of microtubule polymerization, stimulated an isometric contraction that reached its peak level within 30 min and was typically 30-45% of the force increase following maximal stimulation with 30% fetal bovine serum. The contraction following nocodazole treatment was associated with a 2- to 4-fold increase in LC20 phosphorylation. The increases in both force and LC20 phosphorylation, after addition of nocodazole, could be blocked or reversed by stabilizing the microtubules with paclitaxel (former generic name, taxol). Increasing force and LC20 phosphorylation by pretreatment with fetal bovine serum decreased the subsequent additional contraction upon microtubule disruption, a finding that appears inconsistent with a load-shifting mechanism. Our results suggest that phosphorylation of LC20 is a common mechanism for the contractions stimulated both by microtubule poisons and receptor-mediated agonists. The modulation of myosin activity by alterations in microtubule assembly may coordinate the physiological functions of these cytoskeletal components.

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  • Danowski BA. Fibroblast contractility and actin organization are stimulated by microtubule inhibitors. J Cell Sci. 1989 Jun;93(Pt 2):255–266. [PubMed]
  • Dennerll TJ, Joshi HC, Steel VL, Buxbaum RE, Heidemann SR. Tension and compression in the cytoskeleton of PC-12 neurites. II: Quantitative measurements. J Cell Biol. 1988 Aug;107(2):665–674. [PMC free article] [PubMed]
  • Madreperla SA, Adler R. Opposing microtubule- and actin-dependent forces in the development and maintenance of structural polarity in retinal photoreceptors. Dev Biol. 1989 Jan;131(1):149–160. [PubMed]
  • Tsutsui H, Ishihara K, Cooper G., 4th Cytoskeletal role in the contractile dysfunction of hypertrophied myocardium. Science. 1993 Apr 30;260(5108):682–687. [PubMed]
  • Buxbaum RE, Heidemann SR. A thermodynamic model for force integration and microtubule assembly during axonal elongation. J Theor Biol. 1988 Oct 7;134(3):379–390. [PubMed]
  • Ingber DE. Cellular tensegrity: defining new rules of biological design that govern the cytoskeleton. J Cell Sci. 1993 Mar;104(Pt 3):613–627. [PubMed]
  • Elson EL. Cellular mechanics as an indicator of cytoskeletal structure and function. Annu Rev Biophys Biophys Chem. 1988;17:397–430. [PubMed]
  • Dugina VB, Svitkina TM, Vasiliev JM, Gelfand IM. Special type of morphological reorganization induced by phorbol ester: reversible partition of cell into motile and stable domains. Proc Natl Acad Sci U S A. 1987 Jun;84(12):4122–4125. [PMC free article] [PubMed]
  • Arakawa T, Frieden C. Interaction of microtubule-associated proteins with actin filaments. Studies using the fluorescence-photobleaching recovery technique. J Biol Chem. 1984 Oct 10;259(19):11730–11734. [PubMed]
  • Ishikawa R, Kagami O, Hayashi C, Kohama K. Characterization of smooth muscle caldesmon as a microtubule-associated protein. Cell Motil Cytoskeleton. 1992;23(4):244–251. [PubMed]
  • Okuhara K, Murofushi H, Sakai H. Binding of kinesin to stress fibers in fibroblasts under condition of microtubule depolymerization. Cell Motil Cytoskeleton. 1989;12(2):71–77. [PubMed]
  • Sattilaro RF, Dentler WL, LeCluyse EL. Microtubule-associated proteins (MAPs) and the organization of actin filaments in vitro. J Cell Biol. 1981 Aug;90(2):467–473. [PMC free article] [PubMed]
  • Selden SC, Pollard TD. Phosphorylation of microtubule-associated proteins regulates their interaction with actin filaments. J Biol Chem. 1983 Jun 10;258(11):7064–7071. [PubMed]
  • Leiber D, Jasper JR, Alousi AA, Martin J, Bernstein D, Insel PA. Alteration in Gs-mediated signal transduction in S49 lymphoma cells treated with inhibitors of microtubules. J Biol Chem. 1993 Feb 25;268(6):3833–3837. [PubMed]
  • Shinohara-Gotoh Y, Nishida E, Hoshi M, Sakai H. Activation of microtubule-associated protein kinase by microtubule disruption in quiescent rat 3Y1 cells. Exp Cell Res. 1991 Mar;193(1):161–166. [PubMed]
  • Scott CW, Caputo CB, Salama AI. Properties of a microtubule-associated cofactor-independent protein kinase from pig brain. Biochem J. 1989 Oct 1;263(1):207–214. [PMC free article] [PubMed]
  • Serrano L, Hernández MA, Díaz-Nido J, Avila J. Association of casein kinase II with microtubules. Exp Cell Res. 1989 Mar;181(1):263–272. [PubMed]
  • Vallee RB, DiBartolomeis MJ, Theurkauf WE. A protein kinase bound to the projection portion of MAP 2 (microtubule-associated protein 2). J Cell Biol. 1981 Sep;90(3):568–576. [PMC free article] [PubMed]
  • Kolodney MS, Elson EL. Correlation of myosin light chain phosphorylation with isometric contraction of fibroblasts. J Biol Chem. 1993 Nov 15;268(32):23850–23855. [PubMed]
  • Lamb NJ, Fernandez A, Conti MA, Adelstein R, Glass DB, Welch WJ, Feramisco JR. Regulation of actin microfilament integrity in living nonmuscle cells by the cAMP-dependent protein kinase and the myosin light chain kinase. J Cell Biol. 1988 Jun;106(6):1955–1971. [PMC free article] [PubMed]
  • Broschat KO, Stidwill RP, Burgess DR. Phosphorylation controls brush border motility by regulating myosin structure and association with the cytoskeleton. Cell. 1983 Dec;35(2 Pt 1):561–571. [PubMed]
  • Cande WZ, Ezzell RM. Evidence for regulation of lamellipodial and tail contraction of glycerinated chicken embryonic fibroblasts by myosin light chain kinase. Cell Motil Cytoskeleton. 1986;6(6):640–648. [PubMed]
  • Craig R, Smith R, Kendrick-Jones J. Light-chain phosphorylation controls the conformation of vertebrate non-muscle and smooth muscle myosin molecules. Nature. 302(5907):436–439. [PubMed]
  • Giuliano KA, Kolega J, DeBiasio RL, Taylor DL. Myosin II phosphorylation and the dynamics of stress fibers in serum-deprived and stimulated fibroblasts. Mol Biol Cell. 1992 Sep;3(9):1037–1048. [PMC free article] [PubMed]
  • Wysolmerski RB, Lagunoff D. Involvement of myosin light-chain kinase in endothelial cell retraction. Proc Natl Acad Sci U S A. 1990 Jan;87(1):16–20. [PMC free article] [PubMed]
  • Kolodney MS, Wysolmerski RB. Isometric contraction by fibroblasts and endothelial cells in tissue culture: a quantitative study. J Cell Biol. 1992 Apr;117(1):73–82. [PMC free article] [PubMed]
  • Tomasek JJ, Haaksma CJ, Eddy RJ, Vaughan MB. Fibroblast contraction occurs on release of tension in attached collagen lattices: dependency on an organized actin cytoskeleton and serum. Anat Rec. 1992 Mar;232(3):359–368. [PubMed]
  • Taylor DA, Stull JT. Calcium dependence of myosin light chain phosphorylation in smooth muscle cells. J Biol Chem. 1988 Oct 5;263(28):14456–14462. [PubMed]
  • De Brabander M, Geuens G, Nuydens R, Willebrords R, De Mey J. Taxol induces the assembly of free microtubules in living cells and blocks the organizing capacity of the centrosomes and kinetochores. Proc Natl Acad Sci U S A. 1981 Sep;78(9):5608–5612. [PMC free article] [PubMed]
  • Jay PY, Pham PA, Wong SA, Elson EL. A mechanical function of myosin II in cell motility. J Cell Sci. 1995 Jan;108(Pt 1):387–393. [PubMed]
  • Mabuchi I, Okuno M. The effect of myosin antibody on the division of starfish blastomeres. J Cell Biol. 1977 Jul;74(1):251–263. [PMC free article] [PubMed]
  • Gundersen GG, Bulinski JC. Selective stabilization of microtubules oriented toward the direction of cell migration. Proc Natl Acad Sci U S A. 1988 Aug;85(16):5946–5950. [PMC free article] [PubMed]
  • Rappaport R. Cytokinesis in animal cells. Int Rev Cytol. 1971;31:169–213. [PubMed]
  • Rappaport R, Rappaport BN. Establishment of cleavage furrows by the mitotic spindle. J Exp Zool. 1974 Aug;189(2):189–196. [PubMed]

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