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Alpha-smooth muscle actin expression upregulates fibroblast contractile activity

Celetta, G.
Tomasek, J. J.
Published in Molecular Biology of the Cell. 2001, vol. 12, no. 9, p. 2730-2741
Abstract To evaluate whether alpha-smooth muscle actin (alpha-SMA) plays a role in fibroblast contractility, we first compared the contractile activity of rat subcutaneous fibroblasts (SCFs), expressing low levels of alpha-SMA, with that of lung fibroblasts (LFs), expressing high levels of alpha-SMA, with the use of silicone substrates of different stiffness degrees. On medium stiffness substrates the percentage of cells producing wrinkles was similar to that of alpha-SMA-positive cells in each fibroblast population. On high stiffness substrates, wrinkle production was limited to a subpopulation of LFs very positive for alpha-SMA. In a second approach, we measured the isotonic contraction of SCF- and LF-populated attached collagen lattices. SCFs exhibited 41% diameter reduction compared with 63% by LFs. TGFbeta1 increased alpha-SMA expression and lattice contraction by SCFs to the levels of LFs; TGFbeta-antagonizing agents reduced alpha-SMA expression and lattice contraction by LFs to the level of SCFs. Finally, 3T3 fibroblasts transiently or permanently transfected with alpha-SMA cDNA exhibited a significantly higher lattice contraction compared with wild-type 3T3 fibroblasts or to fibroblasts transfected with alpha-cardiac and beta- or gamma-cytoplasmic actin. This took place in the absence of any change in smooth muscle or nonmuscle myosin heavy-chain expression. Our results indicate that an increased alpha-SMA expression is sufficient to enhance fibroblast contractile activity.
Keywords Actins/genetics/ metabolismAnimalsBlotting, WesternCell Size/drug effectsCells, CulturedCollagen/metabolismFibroblasts/ cytology/drug effects/ metabolismGelsMiceMicroscopy, FluorescenceMuscle, Smooth/ metabolismProtein Isoforms/genetics/metabolismRatsSilicon/metabolismTransfectionTransforming Growth Factor beta/pharmacologyUp-Regulation
PMID: 11553712
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HINZ, Boris et al. Alpha-smooth muscle actin expression upregulates fibroblast contractile activity. In: Molecular Biology of the Cell, 2001, vol. 12, n° 9, p. 2730-2741. https://archive-ouverte.unige.ch/unige:11300

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Deposited on : 2010-08-27

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