Scientific article

Alpha-smooth muscle actin is crucial for focal adhesion maturation in myofibroblasts

Published inMolecular biology of the cell, vol. 14, no. 6, p. 2508-2519
Publication date2003

Cultured myofibroblasts are characterized by stress fibers, containing alpha-smooth muscle actin (alpha-SMA) and by supermature focal adhesions (FAs), which are larger than FAs of alpha-SMA-negative fibroblasts. We have investigated the role of alpha-SMA for myofibroblast adhesion and FA maturation. Inverted centrifugation reveals two phases of initial myofibroblast attachment: during the first 2 h of plating microfilament bundles contain essentially cytoplasmic actin and myofibroblast adhesion is similar to that of alpha-SMA-negative fibroblasts. Then, myofibroblasts incorporate alpha-SMA in stress fibers, develop mature FAs and their adhesion capacity is significantly increased. When alpha-SMA expression is induced in 5 d culture by TGFbeta or low serum levels, fibroblast adhesion is further increased correlating with a "supermaturation" of FAs. Treatment of myofibroblasts with alpha-SMA fusion peptide (SMA-FP), which inhibits alpha-SMA-mediated contractile activity, reduces their adhesion to the level of alpha-SMA negative fibroblasts. With the use of flexible micropatterned substrates and EGFP-constructs we show that SMA-FP application leads to a decrease of myofibroblast contraction, shortly followed by disassembly of paxillin- and beta3 integrin-containing FAs; alpha5 integrin distribution is not affected. FRAP of beta3 integrin-EGFP demonstrates an increase of FA protein turnover following SMA-FP treatment. We conclude that the formation and stability of supermature FAs depends on a high alpha-SMA-mediated contractile activity of myofibroblast stress fibers.

  • Actins/ metabolism
  • Animals
  • Cytoplasm/metabolism
  • Fibroblasts/ metabolism
  • Focal Adhesions/ metabolism
  • Muscle, Smooth/ metabolism
  • Rats
Citation (ISO format)
HINZ, Boris et al. Alpha-smooth muscle actin is crucial for focal adhesion maturation in myofibroblasts. In: Molecular biology of the cell, 2003, vol. 14, n° 6, p. 2508–2519. doi: 10.1091/mbc.E02-11-0729
Updates (1)
ISSN of the journal1059-1524

Technical informations

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