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Interference with the contractile machinery of the fibroblastic chondrocyte cytoskeleton induces re-expression of the cartilage phenotype through involvement of PI3K, PKC and MAPKs.
Journal article

Interference with the contractile machinery of the fibroblastic chondrocyte cytoskeleton induces re-expression of the cartilage phenotype through involvement of PI3K, PKC and MAPKs.

  • Rottmar M Laboratory for Materials-Biology Interactions, Empa, St. Gallen, Switzerland.
  • Mhanna R Cartilage Engineering+Regeneration Laboratory, ETH Zurich, Zurich, Switzerland.
  • Guimond-Lischer S Laboratory for Materials-Biology Interactions, Empa, St. Gallen, Switzerland.
  • Vogel V Laboratory of Applied Mechanobiology, ETH Zurich, Zurich, Switzerland.
  • Zenobi-Wong M Cartilage Engineering+Regeneration Laboratory, ETH Zurich, Zurich, Switzerland. Electronic address: marcy.zenobi@hest.ethz.ch.
  • Maniura-Weber K Laboratory for Materials-Biology Interactions, Empa, St. Gallen, Switzerland. Electronic address: katharina.maniura@empa.ch.
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  • 2013-11-20
Published in:
  • Experimental cell research. - 2014
Actin cytoskeleton
Cell contractility
Chondrocyte
ERK
GAG
ILK
MAPK
MEK
PI3K
PI3K, PKC, MAPK, ILK
PKC
Re-differentiation
Staurosporine
extracellular signaling regulated kinase
glycosaminoglycan
integrin-linked kinase
mitogen-activated protein kinase
mitogen-activated protein kinase kinase
phosphoinositide-3-kinase
protein kinase C
Actinin
Animals
Cartilage
Cattle
Cell Differentiation
Cells, Cultured
Chondrocytes
Cytochalasin D
Cytoskeleton
Extracellular Signal-Regulated MAP Kinases
Fibroblasts
Gene Expression Regulation
Myosins
Phenotype
Phosphatidylinositol 3-Kinases
Protein Kinase C
Staurosporine
English Chondrocytes rapidly lose their phenotypic expression of collagen II and aggrecan when grown on 2D substrates. It has generally been observed that a fibroblastic morphology with strong actin-myosin contractility inhibits chondrogenesis, whereas chondrogenesis may be promoted by depolymerization of the stress fibers and/or disruption of the physical link between the actin stress fibers and the ECM, as is the case in 3D hydrogels. Here we studied the relationship between the actin-myosin cytoskeleton and expression of chondrogenic markers by culturing fibroblastic chondrocytes in the presence of cytochalasin D and staurosporine. Both drugs induced collagen II re-expression; however, renewed glycosaminoglycan synthesis could only be observed upon treatment with staurosporine. The chondrogenic effect of staurosporine was augmented when blebbistatin, an inhibitor of myosin/actin contractility, was added to the staurosporine-stimulated cultures. Furthermore, in 3D alginate cultures, the amount of staurosporine required to induce chondrogenesis was much lower compared to 2D cultures (0.625 nM vs. 2.5 nM). Using a selection of specific signaling pathway inhibitors, it was found that PI3K-, PKC- and p38-MAPK pathways positively regulated chondrogenesis while the ERK-pathway was found to be a negative regulator in staurosporine-induced re-differentiation, whereas down-regulation of ILK by siRNA indicated that ILK is not determining for chondrocyte re-differentiation. Furthermore, staurosporine analog midostaurin displayed only a limited chondrogenic effect, suggesting that activation/deactivation of a specific set of key signaling molecules can control the expression of the chondrogenic phenotype. This study demonstrates the critical importance of mechanobiological factors in chondrogenesis suggesting that the architecture of the actin cytoskeleton and its contractility control key signaling molecules that determine whether the chondrocyte phenotype will be directed along a fibroblastic or chondrogenic path.
Language
  • English
Open access status
closed
Identifiers
Persistent URL
https://sonar.ch/global/documents/267170
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