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Beta-catenin and transforming growth factor beta have distinct roles regulating fibroblast cell motility and the induction of collagen lattice contraction.

Poon R, Nik SA, Ahn J, Slade L, Alman BA - BMC Cell Biol. (2009)

Bottom Line: Treating wild-type cells or primary human fibroblasts with dickkopf-1, which inhibits beta-catenin, or lithium, which stimulates beta-catenin produced similar results.Scratch wound assays and Boyden chamber motility studies using these same cells found that beta-catenin positively regulated cell motility, while transforming growth factor beta had little effect.Cell motility and the induction of collagen lattice contraction are not always coupled, and are likely regulated by different intracellular mechanisms.

View Article: PubMed Central - HTML - PubMed

Affiliation: Program in Developmental and Stem Cell Biology, Hospital for Sick Children, University of Toronto, Toronto, ON, Canada. Raymond.poon@sickkids.ca

ABSTRACT

Background: beta-catenin and transforming growth factor beta signaling are activated in fibroblasts during wound healing. Both signaling pathways positively regulate fibroblast proliferation during this reparative process, and the effect of transforming growth factor beta is partially mediated by beta-catenin. Other cellular processes, such as cell motility and the induction of extracellular matrix contraction, also play important roles during wound repair. We examined the function of beta-catenin and its interaction with transforming growth factor beta in cell motility and the induction of collagen lattice contraction.

Results: Floating three dimensional collagen lattices seeded with cells expressing conditional and stabilized beta-catenin alleles, showed a modest negative relationship between beta-catenin level and the degree of lattice contraction. Transforming growth factor beta had a more dramatic effect, positively regulating lattice contraction. In contrast to the situation in the regulation of cell proliferation, this effect of transforming growth factor beta was not mediated by beta-catenin. Treating wild-type cells or primary human fibroblasts with dickkopf-1, which inhibits beta-catenin, or lithium, which stimulates beta-catenin produced similar results. Scratch wound assays and Boyden chamber motility studies using these same cells found that beta-catenin positively regulated cell motility, while transforming growth factor beta had little effect.

Conclusion: This data demonstrates the complexity of the interaction of various signaling pathways in the regulation of cell behavior during wound repair. Cell motility and the induction of collagen lattice contraction are not always coupled, and are likely regulated by different intracellular mechanisms. There is unlikely to be a single signaling pathway that acts as master regulator of fibroblast behavior in wound repair. beta-catenin plays dominant role regulating cell motility, while transforming growth factor beta plays a dominant role regulating the induction of collagen lattice contraction.

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Dkk-1 and lithium have a minimal effect on collagen lattice contraction. A. Means and 95% confidence intervals for collagen lattice average diameters as observed over seven days are given for fibroblasts from mice expressing the wild type fibroblasts treated with either an adenovirus expressing Dkk-1 or a control adenovirus. Cultures were also treated with either transforming growth factor β or a carrier. There is a statistically significant difference for transforming growth factor β treatment compared to carrier after day three. For Dkk-1 and lithium treatment there is a minimal change in lattice contraction rate. B. Representative photographs of the collagen lattices at day seven. C. Western analysis for β-catenin showing how Dkk-1 and lithium regulates the protein level of β-catenin.
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Figure 4: Dkk-1 and lithium have a minimal effect on collagen lattice contraction. A. Means and 95% confidence intervals for collagen lattice average diameters as observed over seven days are given for fibroblasts from mice expressing the wild type fibroblasts treated with either an adenovirus expressing Dkk-1 or a control adenovirus. Cultures were also treated with either transforming growth factor β or a carrier. There is a statistically significant difference for transforming growth factor β treatment compared to carrier after day three. For Dkk-1 and lithium treatment there is a minimal change in lattice contraction rate. B. Representative photographs of the collagen lattices at day seven. C. Western analysis for β-catenin showing how Dkk-1 and lithium regulates the protein level of β-catenin.

Mentions: Lithium will elevate β-catenin level through its regulation of GSK3β [25,26], and dickkopf-1 (Dkk-1) ligand will inhibit Wnt receptor binding, preventing the activation of β-catenin catenin mediated signaling by receptor activation [27,28]. We treated fibroblasts with an adenovirus expressing Dkk-1 [29] and observed their ability of TGF-β to induce lattice contraction. Cell cultures infected with Ad-Dkk-1 demonstrated the same behavior as fibroblasts expressing conditional alleles of β-catenin (Fig. 4). To determine if lithium could induce fibroblasts to cause lattice contraction, we treated wild type and β-catenin cells with lithium. Lithium treatment induced β-catenin protein, and inhibited lattice contraction in wild type cell, in a similar manner to that observed in cells expressing β-catenin stabilized conditional alleles (Fig. 4). Lithium and Dkk-1 treatment had no effect on cells expressing alleles of β-catenin. Using densitometry there was an increase to 195% of baseline β-catenin protein level with lithium treatment (p < 0.01) and a decrease to 45% of control levels with Dkk-1 treatment (P < 0.005).


Beta-catenin and transforming growth factor beta have distinct roles regulating fibroblast cell motility and the induction of collagen lattice contraction.

Poon R, Nik SA, Ahn J, Slade L, Alman BA - BMC Cell Biol. (2009)

Dkk-1 and lithium have a minimal effect on collagen lattice contraction. A. Means and 95% confidence intervals for collagen lattice average diameters as observed over seven days are given for fibroblasts from mice expressing the wild type fibroblasts treated with either an adenovirus expressing Dkk-1 or a control adenovirus. Cultures were also treated with either transforming growth factor β or a carrier. There is a statistically significant difference for transforming growth factor β treatment compared to carrier after day three. For Dkk-1 and lithium treatment there is a minimal change in lattice contraction rate. B. Representative photographs of the collagen lattices at day seven. C. Western analysis for β-catenin showing how Dkk-1 and lithium regulates the protein level of β-catenin.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2691404&req=5

Figure 4: Dkk-1 and lithium have a minimal effect on collagen lattice contraction. A. Means and 95% confidence intervals for collagen lattice average diameters as observed over seven days are given for fibroblasts from mice expressing the wild type fibroblasts treated with either an adenovirus expressing Dkk-1 or a control adenovirus. Cultures were also treated with either transforming growth factor β or a carrier. There is a statistically significant difference for transforming growth factor β treatment compared to carrier after day three. For Dkk-1 and lithium treatment there is a minimal change in lattice contraction rate. B. Representative photographs of the collagen lattices at day seven. C. Western analysis for β-catenin showing how Dkk-1 and lithium regulates the protein level of β-catenin.
Mentions: Lithium will elevate β-catenin level through its regulation of GSK3β [25,26], and dickkopf-1 (Dkk-1) ligand will inhibit Wnt receptor binding, preventing the activation of β-catenin catenin mediated signaling by receptor activation [27,28]. We treated fibroblasts with an adenovirus expressing Dkk-1 [29] and observed their ability of TGF-β to induce lattice contraction. Cell cultures infected with Ad-Dkk-1 demonstrated the same behavior as fibroblasts expressing conditional alleles of β-catenin (Fig. 4). To determine if lithium could induce fibroblasts to cause lattice contraction, we treated wild type and β-catenin cells with lithium. Lithium treatment induced β-catenin protein, and inhibited lattice contraction in wild type cell, in a similar manner to that observed in cells expressing β-catenin stabilized conditional alleles (Fig. 4). Lithium and Dkk-1 treatment had no effect on cells expressing alleles of β-catenin. Using densitometry there was an increase to 195% of baseline β-catenin protein level with lithium treatment (p < 0.01) and a decrease to 45% of control levels with Dkk-1 treatment (P < 0.005).

Bottom Line: Treating wild-type cells or primary human fibroblasts with dickkopf-1, which inhibits beta-catenin, or lithium, which stimulates beta-catenin produced similar results.Scratch wound assays and Boyden chamber motility studies using these same cells found that beta-catenin positively regulated cell motility, while transforming growth factor beta had little effect.Cell motility and the induction of collagen lattice contraction are not always coupled, and are likely regulated by different intracellular mechanisms.

View Article: PubMed Central - HTML - PubMed

Affiliation: Program in Developmental and Stem Cell Biology, Hospital for Sick Children, University of Toronto, Toronto, ON, Canada. Raymond.poon@sickkids.ca

ABSTRACT

Background: beta-catenin and transforming growth factor beta signaling are activated in fibroblasts during wound healing. Both signaling pathways positively regulate fibroblast proliferation during this reparative process, and the effect of transforming growth factor beta is partially mediated by beta-catenin. Other cellular processes, such as cell motility and the induction of extracellular matrix contraction, also play important roles during wound repair. We examined the function of beta-catenin and its interaction with transforming growth factor beta in cell motility and the induction of collagen lattice contraction.

Results: Floating three dimensional collagen lattices seeded with cells expressing conditional and stabilized beta-catenin alleles, showed a modest negative relationship between beta-catenin level and the degree of lattice contraction. Transforming growth factor beta had a more dramatic effect, positively regulating lattice contraction. In contrast to the situation in the regulation of cell proliferation, this effect of transforming growth factor beta was not mediated by beta-catenin. Treating wild-type cells or primary human fibroblasts with dickkopf-1, which inhibits beta-catenin, or lithium, which stimulates beta-catenin produced similar results. Scratch wound assays and Boyden chamber motility studies using these same cells found that beta-catenin positively regulated cell motility, while transforming growth factor beta had little effect.

Conclusion: This data demonstrates the complexity of the interaction of various signaling pathways in the regulation of cell behavior during wound repair. Cell motility and the induction of collagen lattice contraction are not always coupled, and are likely regulated by different intracellular mechanisms. There is unlikely to be a single signaling pathway that acts as master regulator of fibroblast behavior in wound repair. beta-catenin plays dominant role regulating cell motility, while transforming growth factor beta plays a dominant role regulating the induction of collagen lattice contraction.

Show MeSH
Related in: MedlinePlus