1
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van Wieringen T, Kimani SG, Hultgård-Ekwall AK, Forsberg J, Reyhani V, Engström Å, Rubin K. Opposite effects of PDGF-BB and prostaglandin E1 on cell-motility related processes are paralleled by modifications of distinct actin-binding proteins. Exp Cell Res 2009; 315:1745-58. [DOI: 10.1016/j.yexcr.2009.02.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2008] [Revised: 01/30/2009] [Accepted: 02/04/2009] [Indexed: 01/27/2023]
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2
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Wang HH, Tanaka H, Qin X, Zhao T, Ye LH, Okagaki T, Katayama T, Nakamura A, Ishikawa R, Thatcher SE, Wright GL, Kohama K. Blebbistatin inhibits the chemotaxis of vascular smooth muscle cells by disrupting the myosin II-actin interaction. Am J Physiol Heart Circ Physiol 2008; 294:H2060-8. [PMID: 18296570 DOI: 10.1152/ajpheart.00970.2007] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Blebbistatin is a myosin II-specific inhibitor. However, the mechanism and tissue specificity of the drug are not well understood. Blebbistatin blocked the chemotaxis of vascular smooth muscle cells (VSMCs) toward sphingosylphosphorylcholine (IC(50) = 26.1 +/- 0.2 and 27.5 +/- 0.5 microM for GbaSM-4 and A7r5 cells, respectively) and platelet-derived growth factor BB (IC(50) = 32.3 +/- 0.9 and 31.6 +/- 1.3 muM for GbaSM-4 and A7r5 cells, respectively) at similar concentrations. Immunofluorescence and fluorescent resonance energy transfer analysis indicated a blebbistatin-induced disruption of the actin-myosin interaction in VSMCs. Subsequent experiments indicated that blebbistatin inhibited the Mg(2+)-ATPase activity of the unphosphorylated (IC(50) = 12.6 +/- 1.6 and 4.3 +/- 0.5 microM for gizzard and bovine stomach, respectively) and phosphorylated (IC(50) = 15.0 +/- 0.6 microM for gizzard) forms of purified smooth muscle myosin II, suggesting a direct effect on myosin II motor activity. It was further observed that the Mg(2+)-ATPase activities of gizzard myosin II fragments, heavy meromyosin (IC(50) = 14.4 +/- 1.6 microM) and subfragment 1 (IC(50) = 5.5 +/- 0.4 microM), were also inhibited by blebbistatin. Assay by in vitro motility indicated that the inhibitory effect of blebbistatin was reversible. Electron-microscopic evaluation showed that blebbistatin induced a distinct conformational change (i.e., swelling) of the myosin II head. The results suggest that the site of blebbistatin action is within the S1 portion of smooth muscle myosin II.
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Affiliation(s)
- Hong Hui Wang
- Department of Molecular and Cellular Pharmacology, Faculty of Medicine, Gunma University Graduate School of Medicine, 3-39-22 Showa-Machi, Maebashi, Gunma, Japan
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3
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Jiang H, Rhee S, Ho CH, Grinnell F. Distinguishing fibroblast promigratory and procontractile growth factor environments in 3-D collagen matrices. FASEB J 2008; 22:2151-60. [PMID: 18272655 DOI: 10.1096/fj.07-097014] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Understanding growth factor function during wound repair is necessary for the development of therapeutic interventions to improve healing outcomes. In the current study, we compare the effects of serum and purified growth factors on human fibroblast function in three different collagen matrix models: cell migration in nested matrices, floating matrix contraction, and stressed-released matrix contraction. The results of these studies indicate that platelet-derived growth factor (PDGF) is unique in its capacity to promote cell migration. Serum, lysophosphatidic acid, sphingosine-1-phophate (S1P), and endothelin-1 promote stressed-released matrix contraction but not cell migration. In addition, we found that S1P inhibits fibroblast migration and treatment of serum to remove lipid growth factors or treatment of cells to interfere with S1P(2) receptor function increases serum promigratory activity. Our findings suggest that different sets of growth factors generate promigratory and procontractile tissue environments for fibroblasts and that the balance between PDGF and S1P is a key determinant of fibroblast promigratory activity.
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Affiliation(s)
- Hongmei Jiang
- Department of Cell Biology, University of Texas Southwestern Medical School, 5323 Harry Hines Boulevard, Dallas, TX 75390-9039, USA
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4
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Watterson KR, Lanning DA, Diegelmann RF, Spiegel S. Regulation of fibroblast functions by lysophospholipid mediators: Potential roles in wound healing. Wound Repair Regen 2007; 15:607-16. [DOI: 10.1111/j.1524-475x.2007.00292.x] [Citation(s) in RCA: 92] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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5
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Petroll WM. Dynamic assessment of cell-matrix mechanical interactions in three-dimensional culture. Methods Mol Biol 2007; 370:67-82. [PMID: 17416988 DOI: 10.1007/978-1-59745-353-0_6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Cell-matrix mechanical interactions play a defining role in a range of biological processes such as developmental morphogenesis and wound healing. Despite current agreement that fibroblasts exert mechanical forces on the extracellular matrix (ECM) to promote structural organization of the collagen architecture, the underlying mechanisms of force generation and transduction to the ECM are not completely understood. Investigation of these processes has been limited, in part, by the technical challenges associated with simultaneous imaging of cell activity and fibrillar collagen organization. To overcome these limitations, we have developed an experimental model in which cells expressing proteins tagged with enhanced green fluorescent protein are plated inside fibrillar collagen matrices, and high magnification time-lapse differential interference contrast and fluorescent imaging is then performed. Using this system, focal adhesion movement and reorganization in isolated cells can be directly correlated with collagen matrix deformation and changes in the mechanical behavior of fibroblasts can be assessed over time.
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Affiliation(s)
- W Matthew Petroll
- Department of Ophthalmology, University of Texas Southwestern Medical Center, Dallas, TX, USA
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6
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Rhee S, Grinnell F. P21-activated kinase 1: convergence point in PDGF- and LPA-stimulated collagen matrix contraction by human fibroblasts. ACTA ACUST UNITED AC 2006; 172:423-32. [PMID: 16449192 PMCID: PMC2063651 DOI: 10.1083/jcb.200505175] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Fibroblast three-dimensional collagen matrix culture provides a tissue-like model that can be used to analyze cell form and function. The physiological agonists platelet-derived growth factor (PDGF) and lysophosphatidic acid (LPA) both stimulate human fibroblasts to contract floating collagen matrices. In this study, we show that the PDGF and LPA signaling pathways required for matrix contraction converge on p21-activated kinase 1 (PAK1) and its downstream effector cofilin1 and that contraction depends on cellular ruffling activity, rather than on the protrusion and retraction of cellular dendritic extensions. We also show that, depending on the agonist, different Rho effectors cooperate with PAK1 to regulate matrix contraction, Rho kinase in the case of PDGF and mDia1 in the case of LPA. These findings establish a unified framework for understanding the cell signaling pathways involved in fibroblast contraction of floating collagen matrices.
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Affiliation(s)
- Sangmyung Rhee
- Department of Cell Biology, University of Texas Southwestern Medical School, Dallas, TX 75390, USA
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7
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Masamune A, Satoh M, Kikuta K, Suzuki N, Shimosegawa T. Endothelin-1 stimulates contraction and migration of rat pancreatic stellate cells. World J Gastroenterol 2005; 11:6144-51. [PMID: 16273641 PMCID: PMC4436631 DOI: 10.3748/wjg.v11.i39.6144] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
AIM: To examine the ability of ET-1 to affect the cell functions of PSCs and the underlying molecular mechanisms.
METHODS: PSCs were isolated from the pancreas of male Wistar rats after perfusion with collagenase, and cells between passages two and five were used. Expression of ET-1 and ET receptors was assessed by reverse transcription-PCR and immunostaining. Phosphorylation of myosin regulatory light chain (MLC), extracellular-signal regulated kinase (ERK), and Akt was examined by Western blotting. Contraction of PSCs was assessed on hydrated collagen lattices. Cell migration was examined using modified Boyden chambers. Cell proliferation was assessed by measuring the incorporation of 5-bromo-2×deoxyuridine.
RESULTS: Culture-activated PSCs expressed ETA and ETB receptors, and ET-1. ET-1 induced phosphorylation of MLC and ERK, but not Akt. ET-1 induced contraction and migration, but did not alter proliferation of PSCs. ET-1-induced contraction was inhibited by an ETA receptor antagonist BQ-123 and an ETB receptor antagonist BQ-788, whereas migration was inhibited by BQ-788 but not by BQ-123. A Rho kinase inhibitor Y-27632 abolished both contraction and migration.
CONCLUSION: ET-1 induced contraction and migration of PSCs through ET receptors and activation of Rho-Rho kinase. ETA and ETB receptors play different roles in the regulation of these cellular functions in response to ET-1.
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Affiliation(s)
- Atsushi Masamune
- Division of Gastro-enterology, Tohoku University Graduate School of Medicine, 1-1 Seiryo-machi, Aoba-ku, Sendai 980-8574, Japan.
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8
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Goeckeler ZM, Wysolmerski RB. Myosin phosphatase and cofilin mediate cAMP/cAMP-dependent protein kinase-induced decline in endothelial cell isometric tension and myosin II regulatory light chain phosphorylation. J Biol Chem 2005; 280:33083-95. [PMID: 16055445 DOI: 10.1074/jbc.m503173200] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
This study determined the effects of increased intracellular cAMP and cAMP-dependent protein kinase activation on endothelial cell basal and thrombin-induced isometric tension development. Elevation of cAMP and maximal cAMP-dependent protein kinase activation induced by 10 microm forskolin, 40 microm 3-isobutyl-1-methylxanthine caused a 50% reduction in myosin II regulatory light chain (RLC) phosphorylation and a 35% drop in isometric tension, but it did not inhibit thrombin-stimulated increases in RLC phosphorylation and isometric tension. Elevation of cAMP did not alter myosin light chain kinase catalytic activity. However, direct inhibition of myosin light chain kinase with KT5926 resulted in a 90% decrease in RLC phosphorylation and only a minimal decrease in isometric tension, but it prevented thrombin-induced increases in RLC phosphorylation and isometric tension development. We showed that elevated cAMP increases phosphorylation of RhoA 10-fold, and this is accompanied by a 60% decrease in RhoA activity and a 78% increase in RLC phosphatase activity. Evidence is presented that it is this inactivation of RhoA that regulates the decrease in isometric tension through a pathway involving cofilin. Activated cofilin correlates with increased F-actin severing activity in cell extracts from monolayers treated with forskolin/3-isobutyl-1-methylxanthine. Pretreatment of cultures with tautomycin, a protein phosphatase type 1 inhibitor, blocked the effect of cAMP on 1) the dephosphorylation of cofilin, 2) the decrease in RLC phosphorylation, and 3) the decrease in isometric tension. Together, these data provide in vivo evidence that elevated intracellular cAMP regulates endothelial cell isometric tension and RLC phosphorylation through inhibition of RhoA signaling and its downstream pathways that regulate myosin II activity and actin reorganization.
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Affiliation(s)
- Zoe M Goeckeler
- Department of Pathology, St. Louis University School of Medicine, St. Louis, Missouri 63104, USA
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9
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Bhadriraju K, Hansen LK. Extracellular matrix-dependent myosin dynamics during G1-S phase cell cycle progression in hepatocytes. Exp Cell Res 2004; 300:259-71. [PMID: 15474992 DOI: 10.1016/j.yexcr.2004.06.033] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2003] [Revised: 06/09/2004] [Indexed: 12/31/2022]
Abstract
Cell spreading and proliferation are tightly coupled in anchorage-dependent cells. While adhesion-dependent proliferation signals require an intact actin cytoskeleton, and some of these signals such as ERK activation have been characterized, the role of myosin in spreading and cell cycle progression under different extracellular matrix (ECM) conditions is not known. Studies presented here examine changes in myosin activity in freshly isolated hepatocytes under ECM conditions that promote either proliferation (high fibronectin density) or growth arrest (low fibronectin density). Three different measures were obtained and related to both spreading and cell cycle progression: myosin protein levels and association with cytoskeleton, myosin light chain phosphorylation, and its ATPase activity. During the first 48 h in culture, corresponding with transit through G1 phase, there was a six-fold increase in both myosin protein levels and myosin association with actin cytoskeleton. There was also a steady increase in myosin light chain phosphorylation and ATPase activity with spreading, which did not occur in non-spread, growth-arrested cells on low density of fibronectin. Myosin-inhibiting drugs blocked ERK activation, cyclin D1 expression, and S phase entry. Overexpression of the cell cycle protein cyclin D1 overcame both ECM-dependent and actomyosin-dependent inhibition of DNA synthesis, suggesting that cyclin D1 is a key event downstream of myosin-dependent cell cycle regulation.
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Affiliation(s)
- Kiran Bhadriraju
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, MN 55455, USA
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10
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Carlson MA, Longaker MT. The fibroblast-populated collagen matrix as a model of wound healing: a review of the evidence. Wound Repair Regen 2004; 12:134-47. [PMID: 15086764 DOI: 10.1111/j.1067-1927.2004.012208.x] [Citation(s) in RCA: 121] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The fibroblast-populated collagen matrix (FPCM) has been utilized as an in vitro model of wound healing for more than 2 decades. It offers a reasonable approximation of the healing wound during the phases of established granulation tissue and early scar. The gross and microscopic morphology of the FPCM and the healing wound are similar at analogous phases. The processes of proliferation, survival/apoptosis, protein synthesis, and contraction act in similar directions in these two models, and the response to exogenous agents also is consistent between them. If its limitations are respected, then the FPCM can be used as a model of the healing wound.
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Affiliation(s)
- Mark A Carlson
- Department of Surgery, University of Nebraska Medical Center and the Omaha VA Medical Center, Omaha, Nebraska 68105, USA.
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11
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Emmert DA, Fee JA, Goeckeler ZM, Grojean JM, Wakatsuki T, Elson EL, Herring BP, Gallagher PJ, Wysolmerski RB. Rho-kinase-mediated Ca2+-independent contraction in rat embryo fibroblasts. Am J Physiol Cell Physiol 2004; 286:C8-21. [PMID: 12967916 PMCID: PMC2823795 DOI: 10.1152/ajpcell.00428.2002] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Thus far, determining the relative contribution of Ca2+/calmodulin-dependent myosin light chain kinase (MLCK) and Ca2+-independent Rho-kinase pathways to myosin II activation and contraction has been difficult. In this study, we characterize the role of Rho-kinase in a rat embryo fibroblast cell line (REF-52), which contains no detectable MLCK. No endogenous MLCK could be detected in REF-52 cells by either Western or Northern blot analysis. In the presence or absence of Ca2+, thrombin or lysophosphatidic acid (LPA) increased RhoA activity and Rhokinase activity, correlating with isometric tension development and myosin II regulatory light chain (RLC) phosphorylation. Resting tension is associated with a basal phosphorylation of 0.31 +/- 0.02 mol PO4/mol RLC, whereas upon LPA or thrombin treatment myosin II RLC phosphorylation increases to 1.08 +/- 0.05 and 0.82 +/- 0.05 mol PO4/mol RLC, respectively, within 2.5 min. Ca2+ chelation has minimal effect on the kinetics and magnitude of isometric tension development and RLC phosphorylation. Treatment of REF-52 cells with the Rho-kinase-specific inhibitor Y-27632 abolished thrombin- and LPA-stimulated contraction and RLC phosphorylation. These results suggest that Rho-kinase is sufficient to activate myosin II motor activity and contraction in REF-52 cells.
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Affiliation(s)
- Daniel A Emmert
- Department of Pathology, Saint Louis University School of Medicine, 1402 S. Grand Blvd., St. Louis, MO 63104, USA
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12
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Rosenfeldt HM, Amrani Y, Watterson KR, Murthy KS, Panettieri RA, Spiegel S. Sphingosine-1-phosphate stimulates contraction of human airway smooth muscle cells. FASEB J 2003; 17:1789-99. [PMID: 14519658 DOI: 10.1096/fj.02-0836com] [Citation(s) in RCA: 102] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The bioactive sphingolipid sphingosine-1-phosphate (S1P) that is increased in airways of asthmatic subjects markedly induced contraction of human airway smooth muscle (HASM) cells embedded in collagen matrices in a Gi-independent manner. Dihydro-S1P, which binds to S1P receptors, also stimulated contractility. S1P induced formation of stress fibers, contraction of individual HASM cells, and stimulated myosin light chain phosphorylation, which was inhibited by the Rho-associated kinase inhibitor Y-27632. S1P-stimulated HASM cell contractility was independent of the ERK1/2 and PKC signaling pathways, important regulators of airway smooth muscle contraction. However, removal of extracellular calcium completely blocked S1P-mediated contraction and Y-27632 reduced it. S1P also induced calcium mobilization that was not desensitized by repeated additions. Pretreatment with thapsigargin to deplete InsP3-sensitive calcium stores partially blocked increases in [Ca2+]i induced by S1P, yet did not inhibit S1P-stimulated contraction. In sharp contrast, the L-type calcium channel blocker verapamil markedly decreased S1P-induced HASM cell contraction, supporting a role for calcium influx from extracellular sources. Collectively, our results suggest that S1P may regulate HASM contractility, important in the pathobiology of asthma.
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Affiliation(s)
- Hans M Rosenfeldt
- Department of Biochemistry, Medical College of Virginia Campus, Virginia Commonwealth University, 2-011 Sanger Hall, 1101 E. Marshall St., Richmond, Virginia 23298-0614, USA
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13
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Saab S, Tam SP, Tran BIN, Melton AC, Tangkijvanich P, Wong H, Yee HF. Myosin mediates contractile force generation by hepatic stellate cells in response to endothelin-1. J Biomed Sci 2003. [PMID: 12432226 DOI: 10.1007/bf02254988] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Although endothelin-1-stimulated contractile force generation by stellate cells is believed to play an important role in hepatic pathophysiology, the molecular signals that mediate this process are incompletely understood. The aim of this study was to test the hypothesis that myosin mediates the contractile force generated by stellate cells in response to endothelin-1. Contractile force generation by primary and immortalized stellate cells was directly and quantitatively measured. Myosin phosphorylation and reorganization, and actin stress fiber formation were investigated in immortalized stellate cells. Endothelin-1 stimulated a rapid and robust generation of contractile force by primary and immortalized stellate cells with a similar dose dependence. Myosin phosphorylation, actin stress fiber assembly, and reorganization of myosin to stress fibers were induced by concentrations of endothelin-1 that also stimulated stellate cell contraction. BQ-123, a selective endothelin receptor antagonist, inhibited myosin phosphorylation and contractile force generation. Y-27632, which selectively inhibits rho-associated kinase, also blocked endothelin-1-stimulated myosin phosphorylation and contractile force generation with a similar dose dependence. These results suggest that endothelin-1-stimulated contractile force generation by stellate cells is mediated by myosin.
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Affiliation(s)
- Sammy Saab
- Department of Medicine, UCLA School of Medicine, Los Angeles, Calif 90095, USA
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14
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Abe M, Ho CH, Kamm KE, Grinnell F. Different molecular motors mediate platelet-derived growth factor and lysophosphatidic acid-stimulated floating collagen matrix contraction. J Biol Chem 2003; 278:47707-12. [PMID: 14504290 DOI: 10.1074/jbc.m306228200] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Fibroblast-collagen matrix contraction has been used as a model system to study how cells organize connective tissue. Previous work showed that lysophosphatidic acid (LPA)-stimulated floating collagen matrix contraction is independent of Rho kinase, whereas platelet-derived growth factor (PDGF)-stimulated contraction is Rho kinase-dependent. The current studies were carried out to learn more about the molecular motors responsible for LPA- and PDGF-stimulated contraction. We found that neither PDGF nor LPA-dependent contractile mechanisms require myosin II regulatory light chain kinase or increased phosphorylation of myosin II regulatory light chain (measured as diphosphorylation). Low concentrations of the specific myosin II inhibitor blebbistatin blocked PDGF-stimulated matrix contraction and LPA-stimulated retraction of fibroblast dendritic extensions but not LPA-stimulated matrix contraction. These data suggest that PDGF- and LPA-stimulated floating matrix contraction utilize myosin II-dependent and -independent mechanisms, respectively. LPA-dependent, Rho kinase-independent force generation also was detected during fibroblast spreading on collagen-coated coverslips.
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Affiliation(s)
- Masatoshi Abe
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9039, USA
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15
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Petroll WM, Ma L. Direct, dynamic assessment of cell-matrix interactions inside fibrillar collagen lattices. CELL MOTILITY AND THE CYTOSKELETON 2003; 55:254-64. [PMID: 12845599 DOI: 10.1002/cm.10126] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Cell mechanical behavior has traditionally been studied using 2-D planar elastic substrates. The goal of this study was to directly assess cell-matrix mechanical interactions inside more physiologic 3-D collagen matrices. Rabbit corneal fibroblasts transfected to express GFP-zyxin were plated at low density inside 100 micro m-thick type I collagen matrices. 3-D datasets of isolated cells were acquired at 1-3-min intervals for up to 5 h using fluorescent and Nomarski DIC imaging. Unlike cells on 2-D substrates, cells inside the collagen matrices had a bipolar morphology with thin pseudopodial processes, and without lamellipodia. The organization of the collagen fibrils surrounding each cell was clearly visualized using DIC. Using time-lapse color overlays of GFP and DIC images, displacement and/or realignment of collagen fibrils by focal adhesions could be directly visualized. During pseudopodial extension, new focal adhesions often formed in a line along collagen fibrils in front of the cell, while existing adhesions moved backward. This process generated tractional forces as indicated by the pulling in of collagen fibrils in front of the cell. Meanwhile, adhesions on both the dorsal and ventral surface of the cell body generally moved forward, resulting in contractile shortening along the pseudopodia and localized extracellular matrix (ECM) compression. Cytochalasin D induced rapid disassembly of focal adhesions, cell elongation, and ECM relaxation. This experimental model allows direct, dynamic assessment of cell-matrix interactions inside a 3-D fibrillar ECM. The data suggest that adhesions organize along actin-based contractile elements that are much less complex than the network of actin filaments that mechanically links lamellar adhesions on 2-D substrates.
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Affiliation(s)
- W Matthew Petroll
- Department of Ophthalmology, University of Texas Southwestern Medical Center, Dallas, TX 75390-9057, USA.
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16
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Vanni S, Lagerholm BC, Otey C, Taylor DL, Lanni F. Internet-based image analysis quantifies contractile behavior of individual fibroblasts inside model tissue. Biophys J 2003; 84:2715-27. [PMID: 12668480 PMCID: PMC1302838 DOI: 10.1016/s0006-3495(03)75077-2] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
In a cell-populated collagen gel, intrinsic fiber structure visible in differential interference contrast images can provide markers for an in situ strain gauge to quantify cell-gel mechanics, while optical sections of fluorescent protein distribution capture cytoskeletal kinematics. Mechanics quantification can be derived automatically from timelapse differential interference contrast images using a Deformation Quantification and Analysis software package accessible online at http://dqa.web.cmu.edu. In our studies, fibroblast contractile machinery was observed to function entirely within pseudopods, while GFP-alpha-actinin concentrated in pseudopod tips and cortex. Complex strain patterns around individual cells showed instances of both elastic and inelastic strain transmission, suggesting a role in observed long-range alignment of cells.
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Affiliation(s)
- Steven Vanni
- Department of Biological Sciences, Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, Pennsylvania 15213, USA
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17
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Seasholtz TM. The RHOad less traveled: the myosin phosphorylation-independent path from Rho kinase to cell contraction. Focus on "Rho kinase mediates serum-induced contraction in fibroblast fibers independent of myosin LC20 phosphorylation". Am J Physiol Cell Physiol 2003; 284:C596-8. [PMID: 12556358 DOI: 10.1152/ajpcell.00530.2002] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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18
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Glenn HL, Jacobson BS. Arachidonic acid signaling to the cytoskeleton: the role of cyclooxygenase and cyclic AMP-dependent protein kinase in actin bundling. CELL MOTILITY AND THE CYTOSKELETON 2002; 53:239-50. [PMID: 12211105 DOI: 10.1002/cm.10072] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Cell adhesion to the extracellular matrix via integrins is a primary regulatory mechanism for numerous aspects of normal cellular function. However, disruption of this interaction can result in pathology. For example, one characteristic of transformed cells is loss of adhesion dependence for viability. Adhesion also is a necessary step in tumor metastasis. It has been shown previously, in HeLa cells, that cell attachment to a gelatin-coated substrate results in the release of arachidonic acid, which is metabolized by lipoxygenase. A subsequent cascade of lipid second messengers activates protein kinase C, which triggers actin polymerization leading to cell spreading. We now demonstrate by inhibitor studies and biochemical analysis, a parallel branch of arachidonic acid signaling that reorganizes the actin cytoskeleton into small bundles. This branch of the pathway is initiated by cyclooxygenase, which generates prostaglandins and causes the downstream activation of cyclic AMP-dependent protein kinase. This work elucidates a system of interacting signals in which arachidonic acid functions at a branch point in cytoskeletal signaling. The lipoxygenase branch provides polymerized actin; these actin filaments act as a substrate for the cylooxygenase branch to generate actin bundles.
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Affiliation(s)
- Honor L Glenn
- Department of Biochemistry and Molecular Biology, University of Massachusetts, Amherst, 01003, USA
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19
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Han YP, Nien YD, Garner WL. Recombinant human platelet-derived growth factor and transforming growth factor-beta mediated contraction of human dermal fibroblast populated lattices is inhibited by Rho/GTPase inhibitor but does not require phosphatidylinositol-3' kinase. Wound Repair Regen 2002; 10:169-76. [PMID: 12100378 DOI: 10.1046/j.1524-475x.2002.10801.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Matrix reorganization and tissue contraction are essential for wound healing. However, the intracellular signals that mediate these processes are largely unknown. We investigated cytokine-induced signaling and its potential role in contraction of adult human dermal fibroblast populated collagen lattices. The results document that recombinant human platelet-derived growth factor-BB and transforming growth factor-1 individually stimulate contraction of fibroblast populated collagen lattices, while a combination of the two cytokines leads to increased contraction. Although recombinant human platelet-derived growth factor-BB promoted collagen contraction, it failed to stimulate phosphatidylinositol-3' kinase in the human dermal fibroblasts. An inhibitor for phosphatidylinositol 3' kinase, wortmannin, had no effect on the cytokine-mediated collagen contraction. In addition, this failed activation of phosphatidylinositol 3' kinase is consistent with absence of tyrosine phosphorylation of the platelet-derived growth factor receptor when the cells are in a collagen matrix. In contrast, tyrosine phosphorylation of the platelet-derived growth factor receptor was readily detected in the dermal fibroblasts in monolayers. We also probed the potential role of Rho/GTPase in the cytokine-mediated contraction of fibroblast populated collagen lattices. Toxin B from Clostridium difficile at picomolar concentrations blocked both recombinant human platelet-derived growth factor and transforming growth factor-5 induced contraction. Further, this inhibition was correlated with the inhibition of cell spreading in collagen, which suggests the formation of actin fibers inside the cells is essential for cytokine-mediated contraction of fibroblast populated collagen lattices. Taken together, these results imply that Rho/GTPase signaling but not phosphoinositol-3' kinase is involved in the cytokine-mediated contraction of fibroblasts populated collagen lattice. These findings suggest a potential mechanism for these signaling components during human wound contraction.
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Affiliation(s)
- Yuan-Ping Han
- Division of Plastic and Reconstructive Surgery, University of Southern California, Los Angeles, CA 90033, USA
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Allen FD, Asnes CF, Chang P, Elson EL, Lauffenburger DA, Wells A. Epidermal growth factor induces acute matrix contraction and subsequent calpain-modulated relaxation. Wound Repair Regen 2002; 10:67-76. [PMID: 11983008 DOI: 10.1046/j.1524-475x.2002.10701.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
During wound healing, dermal fibroblasts switch from a migratory, repopulating phenotype to a contractile, matrix-reassembling phenotype. The mechanisms controlling this switch are unknown. A possible explanation is suggested by the finding that chemokines that appear late in wound repair prevent growth factor-induced cell-substratum de-adhesion by blocking calpain activation. In this study, we tested the specific hypothesis that fibroblast contraction of the matrix is promoted by a pro-repair growth factor, epidermal growth factor, and is modulated by calpain-mediated release of adhesions. We employed an isometric force transduction system designed to measure the contraction of a collagen matrix under tension by a population of NR6 fibroblasts transfected with the human epidermal growth factor receptor. By maintaining a fixed level of strain, we could monitor both the initial contraction and subsequent relaxation of the matrix. Epidermal growth factor stimulated a transient, dose-dependent increase in matrix contraction that peaked within 60 minutes and then decayed over the ensuing 3 to 6 hours. Calpain inhibitor I (ALLN) prevented epidermal growth factor-stimulated cell de-adhesion and resulted in a significantly slower decay of matrix contraction, with only a slight decrease of the peak magnitude of contraction. The mitogen-activated protein kinase kinase-1-selective inhibitor PD 98059 that blocks signaling through the extracellular signal-regulated kinase/mitogen-activated protein kinase pathway, required for epidermal growth factor receptor-mediated activation of calpain and de-adhesion, does not significantly affect the magnitude of matrix contraction within minutes of epidermal growth factor addition, but slows the decay similarly to calpain inhibition. Epidermal growth factor receptor signaling thus stimulates the complementary mechanisms of intracellular contractile force generation and calpain-mediated de-adhesion, which are known to coordinately facilitate cell migration. These findings suggest that calpain can act as a functional switch for transmission of intracellular contractile force to the surrounding matrix, with calpain-mediated de-adhesion reducing this transmission and corresponding matrix contraction. Countervailing processes that down-regulate calpain activation can, accordingly, direct the transition of cell function from locomotion to matrix contraction.
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Affiliation(s)
- Fred D Allen
- Division of Bioengineering and Environmental Health, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
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21
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Takayama Y, Mizumachi K. Effects of lactoferrin on collagen gel contractile activity and myosin light chain phosphorylation in human fibroblasts. FEBS Lett 2001; 508:111-6. [PMID: 11707279 DOI: 10.1016/s0014-5793(01)03041-1] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
When fibroblasts are plated on a type I collagen gel they reduce the size of the gel and the extent of collagen gel contraction reflects the motile activity of the fibroblasts. We found that both bovine and human lactoferrin (Lf) enhanced the collagen gel contractile activity of WI-38 human fibroblasts. Rho inhibitor (exoenzyme C3), Rho kinase inhibitor (Y-27632), myosin light chain kinase inhibitor (ML-7), MEK inhibitor (PD98059) and Src family tyrosine kinase inhibitor inhibited the Lf-enhanced collagen gel contraction. Treatment of fibroblasts with Lf induced the phosphorylation of myosin light chain (MLC) within 30 min. Lf-enhanced MLC phosphorylation was inhibited by Y-27632 and ML-7. These results suggest that Lf promotes the motility of fibroblasts by regulating MLC phosphorylation.
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Affiliation(s)
- Y Takayama
- National Institute of Livestock and Grassland Science, 2 Ikenodai, Kukizaki, Inashiki, Ibaraki 305-0901, Japan.
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22
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Panetti TS, Magnusson MK, Peyruchaud O, Zhang Q, Cooke ME, Sakai T, Mosher DF. Modulation of cell interactions with extracellular matrix by lysophosphatidic acid and sphingosine 1-phosphate. Prostaglandins Other Lipid Mediat 2001; 64:93-106. [PMID: 11324710 DOI: 10.1016/s0090-6980(01)00102-2] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Lysophosphatidic acid (LPA) and sphingosine 1-phosphate (SPP) are lipid mediators released upon platelet activation. The concentration of LPA in serum is estimated at 1-10 microM whereas the concentration in plasma is considerably less. The SPP concentration in serum is 0.5 microM, approximately two-fold higher than the plasma concentration. The lipids are present during tissue injury and promote cellular processes involved in wound repair. LPA and SPP have multiple effects on cells, many of which are pertinent to wound healing and require that the cells interact in some fashion with components of the extracellular matrix. This review focuses on modulation of cell adhesion, cell migration, collagen gel contraction, and fibronectin matrix assembly by LPA and SPP.
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Affiliation(s)
- T S Panetti
- Department of Medicine, University of Wisconsin, Madison 53706, USA
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Yee HF, Melton AC, Tran BN. RhoA/rho-associated kinase mediates fibroblast contractile force generation. Biochem Biophys Res Commun 2001; 280:1340-5. [PMID: 11162676 DOI: 10.1006/bbrc.2001.4291] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The intracellular signals governing contractile force generation by non-muscle cells remain uncertain. Our aim was to test the hypothesis that the rhoA/rho-associated kinase signaling pathway is a principal mediator of contractile force generation in non-muscle cells. We measured myosin II regulatory light chain (MLC) phosphorylation and directly quantitated force generation by chicken embryo fibroblasts in the absence and presence of selective inhibitors of rhoA, and its downstream effector, rho-associated kinase. Inactivation of rhoA, with C3 transferase, inhibited serum-stimulated MLC phosphorylation and contractile force generation. Y-27632, an inhibitor of rho-associated kinase, reduced basal contractile tension, and inhibited both serum and endothelin-1 stimulated MLC phosphorylation and contractile force generation. The results of this study provide novel evidence indicating that the rhoA/rho-associated kinase signaling pathway is a principal mediator of MLC phosphorylation and consequent contractile force generation by non-muscle cells.
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Affiliation(s)
- H F Yee
- Department of Medicine, University of California Los Angeles School of Medicine, Los Angeles, California 90095, USA
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24
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Abstract
Fibroblast-collagen-matrix contraction provides a unique way to study reciprocal geometric and mechanical interactions between fibroblasts and extracellular matrix. Such interactions are difficult to appreciate or examine in routine cell culture because the culture surface is usually fixed in place. Forces exerted on collagen fibrils by cells cause isometric tension to develop in the cells if the collagen resists deformation; by contrast, the cells remain mechanically unloaded in the absence of matrix resistance. Recent evidence suggests that the state of cellular mechanical loading determines the mechanism that cells use to regulate contraction.
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Affiliation(s)
- F Grinnell
- Dept of Cell Biology, UT Southwestern Medical School, Dallas, TX 75235-9039, USA.
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