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Loss of γ-cytoplasmic actin triggers myofibroblast transition of human epithelial cells.

Lechuga S, Baranwal S, Li C, Naydenov NG, Kuemmerle JF, Dugina V, Chaponnier C, Ivanov AI - Mol. Biol. Cell (2014)

Bottom Line: Such epithelial plasticity is accompanied by dramatic reorganizations of the actin cytoskeleton, although mechanisms underlying cytoskeletal effects on epithelial transdifferentiation remain poorly understood.Induction of EMyT in γ-CYA-depleted cells depended on activation of serum response factor and its cofactors, myocardial-related transcriptional factors A and B.Loss of γ-CYA stimulated formin-mediated actin polymerization and activation of Rho GTPase, which appear to be essential for EMyT induction.

View Article: PubMed Central - PubMed

Affiliation: Department of Human and Molecular Genetics, Virginia Commonwealth University, Richmond, VA 23298.

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Rho activation is essential for EMyT induction in γ-CYA–depleted cells. (A, B) Level of total and GTP-bound active RhoA in control and γ-CYA–depleted A549 cells was determined by a rhotekin pull-down assay and immunoblotting. (C–E) Control and γ-CYA–depleted A549 cells were treated for 24 h with either vehicle or ROCK inhibitor, Y27632, and assembly of stress fibers (C), as well as expression of different EMyT markers (D, E), was examined by fluorescence analysis and immunoblotting. Data are presented as mean ± SE (n = 3); **p < 0.005, ***p < 0.0005.
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Figure 8: Rho activation is essential for EMyT induction in γ-CYA–depleted cells. (A, B) Level of total and GTP-bound active RhoA in control and γ-CYA–depleted A549 cells was determined by a rhotekin pull-down assay and immunoblotting. (C–E) Control and γ-CYA–depleted A549 cells were treated for 24 h with either vehicle or ROCK inhibitor, Y27632, and assembly of stress fibers (C), as well as expression of different EMyT markers (D, E), was examined by fluorescence analysis and immunoblotting. Data are presented as mean ± SE (n = 3); **p < 0.005, ***p < 0.0005.

Mentions: Formin-dependent actin polymerization is controlled by a small GTPase, RhoA (Goode and Eck, 2007). Furthermore, RhoA was shown to be essential for activation of an SRF/MRTF-dependent transcriptional program (Sotiropoulos et al., 1999; Mack et al., 2001; Miralles et al., 2003). Thus we next investigated the involvement of this GTPase in the observed EMyT response by using a Rho activation assay and inhibition of Rho signaling. Loss of γ-CYA resulted in a more than threefold increase in the amount of active RhoA without significant changes in total Rho expression (Figure 8, A and B). Furthermore Y27632, which is known to inhibit Rho-associated kinase (ROCK), suppressed induction of contractile proteins and assembly of F-actin bundles in γ-CYA–depleted A549 cells (Figure 8, C–E). Overall these results strongly suggest that Rho activation is essential for the EMyT induction caused by γ-CYA deficiency.


Loss of γ-cytoplasmic actin triggers myofibroblast transition of human epithelial cells.

Lechuga S, Baranwal S, Li C, Naydenov NG, Kuemmerle JF, Dugina V, Chaponnier C, Ivanov AI - Mol. Biol. Cell (2014)

Rho activation is essential for EMyT induction in γ-CYA–depleted cells. (A, B) Level of total and GTP-bound active RhoA in control and γ-CYA–depleted A549 cells was determined by a rhotekin pull-down assay and immunoblotting. (C–E) Control and γ-CYA–depleted A549 cells were treated for 24 h with either vehicle or ROCK inhibitor, Y27632, and assembly of stress fibers (C), as well as expression of different EMyT markers (D, E), was examined by fluorescence analysis and immunoblotting. Data are presented as mean ± SE (n = 3); **p < 0.005, ***p < 0.0005.
© Copyright Policy - creative-commons
Related In: Results  -  Collection

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Figure 8: Rho activation is essential for EMyT induction in γ-CYA–depleted cells. (A, B) Level of total and GTP-bound active RhoA in control and γ-CYA–depleted A549 cells was determined by a rhotekin pull-down assay and immunoblotting. (C–E) Control and γ-CYA–depleted A549 cells were treated for 24 h with either vehicle or ROCK inhibitor, Y27632, and assembly of stress fibers (C), as well as expression of different EMyT markers (D, E), was examined by fluorescence analysis and immunoblotting. Data are presented as mean ± SE (n = 3); **p < 0.005, ***p < 0.0005.
Mentions: Formin-dependent actin polymerization is controlled by a small GTPase, RhoA (Goode and Eck, 2007). Furthermore, RhoA was shown to be essential for activation of an SRF/MRTF-dependent transcriptional program (Sotiropoulos et al., 1999; Mack et al., 2001; Miralles et al., 2003). Thus we next investigated the involvement of this GTPase in the observed EMyT response by using a Rho activation assay and inhibition of Rho signaling. Loss of γ-CYA resulted in a more than threefold increase in the amount of active RhoA without significant changes in total Rho expression (Figure 8, A and B). Furthermore Y27632, which is known to inhibit Rho-associated kinase (ROCK), suppressed induction of contractile proteins and assembly of F-actin bundles in γ-CYA–depleted A549 cells (Figure 8, C–E). Overall these results strongly suggest that Rho activation is essential for the EMyT induction caused by γ-CYA deficiency.

Bottom Line: Such epithelial plasticity is accompanied by dramatic reorganizations of the actin cytoskeleton, although mechanisms underlying cytoskeletal effects on epithelial transdifferentiation remain poorly understood.Induction of EMyT in γ-CYA-depleted cells depended on activation of serum response factor and its cofactors, myocardial-related transcriptional factors A and B.Loss of γ-CYA stimulated formin-mediated actin polymerization and activation of Rho GTPase, which appear to be essential for EMyT induction.

View Article: PubMed Central - PubMed

Affiliation: Department of Human and Molecular Genetics, Virginia Commonwealth University, Richmond, VA 23298.

Show MeSH
Related in: MedlinePlus