Alpha-smooth muscle actin expression enhances cell traction force.

Using an established corneal stromal cell differentiation model, we manipulated alpha-smooth muscle actin (alpha-SMA) protein expression levels in fibroblasts by treating them with TGF-beta1, bFGF, TGF-beta type I receptor inhibitor (SB-431542), and siRNA against alpha-SMA. The corresponding cell traction forces (CTFs) were determined by cell traction force microscopy. With all these treatments, we found that alpha-SMA is not required for CTF induction, but its expression upregulates CTF. This upregulation involves the modification of stress fibers but does not appear to relate to non-muscle myosin II expression or beta-actin expression. Moreover, there exists a linear relationship between alpha-SMA protein expression level and CTF magnitude. Finally, CTFs were found to vary among a population of myofibroblasts, suggesting that alpha-SMA protein expression levels of individual cells also vary.

[1]  A. Harris,et al.  Silicone rubber substrata: a new wrinkle in the study of cell locomotion. , 1980, Science.

[2]  Henrik Lindberg,et al.  Transforming Growth Factor-β1 Specifically Induce Proteins Involved in the Myofibroblast Contractile Apparatus* , 2004, Molecular & Cellular Proteomics.

[3]  J. Molloy,et al.  Contractility of single human dermal myofibroblasts and fibroblasts. , 2002, Cell motility and the cytoskeleton.

[4]  C. McCulloch,et al.  Dependence of collagen remodelling on α‐smooth muscle actin expression by fibroblasts , 1994 .

[5]  T. Komuro.  Re-evaluation of fibroblasts and fibroblast-like cells , 2004, Anatomy and Embryology.

[6]  E Bell,et al.  Production of a tissue-like structure by contraction of collagen lattices by human fibroblasts of different proliferative potential in vitro. , 1979, Proceedings of the National Academy of Sciences of the United States of America.

[7]  B. Hinz,et al.  Alpha-smooth muscle actin is crucial for focal adhesion maturation in myofibroblasts. , 2003, Molecular biology of the cell.

[8]  P. Janmey,et al.  The specific NH2-terminal sequence Ac-EEED of alpha-smooth muscle actin plays a role in polymerization in vitro and in vivo , 1995, The Journal of cell biology.

[9]  Guoxiong Xu,et al.  Cellular retinol-binding protein-1 is transiently expressed in granulation tissue fibroblasts and differentially expressed in fibroblasts cultured from different organs. , 1997, The American journal of pathology.

[10]  G. Gabbiani,et al.  The myofibroblast in wound healing and fibrocontractive diseases , 2003, The Journal of pathology.

[11]  T. Leung,et al.  Rho-mediated assembly of stress fibers is differentially regulated in corneal fibroblasts and myofibroblasts. , 2003, Experimental cell research.

[12]  B. Hinz,et al.  The NH2-terminal peptide of α–smooth muscle actin inhibits force generation by the myofibroblast in vitro and in vivo , 2002, The Journal of cell biology.

[13]  M. Dembo,et al.  Stresses at the cell-to-substrate interface during locomotion of fibroblasts. , 1999, Biophysical journal.

[14]  Frederick Grinnell,et al.  Fibroblasts, myofibroblasts, and wound contraction , 1994, The Journal of cell biology.

[15]  B. Hinz,et al.  The N-terminal Ac-EEED sequence plays a role in α-smooth-muscle actin incorporation into stress fibers , 2005, Journal of Cell Science.

[16]  K. Beningo,et al.  Flexible substrata for the detection of cellular traction forces. , 2002, Trends in cell biology.

[17]  R. Silver,et al.  Contractile activity and smooth muscle alpha-actin organization in thrombin-induced human lung myofibroblasts. , 2003, American journal of physiology. Lung cellular and molecular physiology.

[18]  F. Gabbiani,et al.  Action of general and alpha-smooth muscle-specific actin antibody microinjection on stress fibers of cultured smooth muscle cells. , 1990, Experimental cell research.

[19]  M. Kurabayashi,et al.  Basic Fibroblast Growth Factor Antagonizes Transforming Growth Factor-β1–Induced Smooth Muscle Gene Expression Through Extracellular Signal–Regulated Kinase 1/2 Signaling Pathway Activation , 2004, Arteriosclerosis, thrombosis, and vascular biology.

[20]  G. Gabbiani,et al.  Focal adhesion features during myofibroblastic differentiation are controlled by intracellular and extracellular factors. , 2001, Journal of cell science.

[21]  A. Desmoulière,et al.  Transforming growth factor-beta 1 induces alpha-smooth muscle actin expression in granulation tissue myofibroblasts and in quiescent and growing cultured fibroblasts , 1993, The Journal of cell biology.

[22]  B. Hinz,et al.  Myofibroblasts and mechano-regulation of connective tissue remodelling , 2002, Nature Reviews Molecular Cell Biology.

[23]  K. Beningo,et al.  Flexible polyacrylamide substrata for the analysis of mechanical interactions at cell-substratum adhesions. , 2002, Methods in cell biology.

[24]  Jeen-Shang Lin,et al.  Determining substrate displacement and cell traction fields--a new approach. , 2006, Journal of theoretical biology.

[25]  Ben Fabry,et al.  Traction fields, moments, and strain energy that cells exert on their surroundings. , 2002, American journal of physiology. Cell physiology.

[26]  E. Howard,et al.  Transforming growth factor-beta1 promotes the morphological and functional differentiation of the myofibroblast. , 2000, Experimental cell research.

[27]  G. Gabbiani,et al.  Rat fibroblasts cultured from various organs exhibit differences in alpha-smooth muscle actin expression, cytoskeletal pattern, and adhesive structure organization. , 1998, Experimental cell research.

[28]  D. Bigner,et al.  SB-431542, a small molecule transforming growth factor-beta-receptor antagonist, inhibits human glioma cell line proliferation and motility. , 2004, Molecular cancer therapeutics.

[29]  B. Hinz,et al.  Alpha-smooth muscle actin expression upregulates fibroblast contractile activity. , 2001, Molecular biology of the cell.

[30]  Ning Wang,et al.  Spatial and temporal traction response in human airway smooth muscle cells. , 2002, American journal of physiology. Cell physiology.

[31]  S. Numazawa,et al.  Atypical protein kinase C mediates activation of NF-E2-related factor 2 in response to oxidative stress. , 2003, American journal of physiology. Cell physiology.

[32]  G. Gabbiani,et al.  Mechanisms of myofibroblast activity and phenotypic modulation. , 1999, Experimental cell research.