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Polarity of response to transforming growth factor-beta1 in proximal tubular epithelial cells is regulated by beta-catenin.
J Biol Chem. 2007 Sep 28; 282(39):28639-47.JB

Abstract

Transforming growth factor-beta1 (TGF-beta1)-mediated loss of proximal tubular epithelial cell-cell interaction is regulated in a polarized fashion. The aim of this study was to further explore the polarity of the TGF-beta1 response and to determine the significance of R-Smad-beta-catenin association previously demonstrated to accompany adherens junction disassembly. Smad3 signaling response to TGF-beta1 was assessed by activity of the Smad3-responsive reporter gene construct (SBE)(4)-Lux and by immunoblotting for phospho-Smad proteins. Similar results were obtained with both methods. Apical application of TGF-beta1 led to increased Smad3 signaling compared with basolateral stimulation. Association of Smad proteins with beta-catenin was greater following basolateral TGFbeta-1 stimulation, as was the expression of cytoplasmic Triton-soluble beta-catenin. Inhibition of beta-catenin expression by small interfering RNA augmented Smad3 signaling. Lithium chloride, a GSK-3 inhibitor, increased expression of beta-catenin and attenuated TGF-beta1-dependent Smad3 signaling. Lithium chloride did not influence degradation of Smad3 but resulted in decreased nuclear translocation. Smad2 activation as assessed by Western blot analysis and activity of the Smad2-responsive reporter constructs ARE/MF1 was also greater following apical as compared with basolateral TGFbeta-1 stimulation, suggesting that this is a generally applicable mechanism for the regulation of TGF-beta1-dependent R-Smads. Caco-2 cells are a colonic carcinoma cell line, with known resistance to the anti-proliferative effects of TGF-beta1 and increased expression of beta-catenin. We used this cell line to address the general applicability of our observations. Inhibition of beta-catenin in this cell line by small interfering RNA resulted in increased TGF-beta1-dependent Smad3 phosphorylation and restoration of TGF-beta1 anti-proliferative effects.

Authors+Show Affiliations

Institute of Nephrology, School of Medicine, Heath Park, Cardiff University, Cardiff CF14 4XN, Wales, United Kingdom.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Comparative Study
Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

17623674

Citation

Zhang, Mei, et al. "Polarity of Response to Transforming Growth Factor-beta1 in Proximal Tubular Epithelial Cells Is Regulated By Beta-catenin." The Journal of Biological Chemistry, vol. 282, no. 39, 2007, pp. 28639-47.
Zhang M, Lee CH, Luo DD, et al. Polarity of response to transforming growth factor-beta1 in proximal tubular epithelial cells is regulated by beta-catenin. J Biol Chem. 2007;282(39):28639-47.
Zhang, M., Lee, C. H., Luo, D. D., Krupa, A., Fraser, D., & Phillips, A. (2007). Polarity of response to transforming growth factor-beta1 in proximal tubular epithelial cells is regulated by beta-catenin. The Journal of Biological Chemistry, 282(39), 28639-47.
Zhang M, et al. Polarity of Response to Transforming Growth Factor-beta1 in Proximal Tubular Epithelial Cells Is Regulated By Beta-catenin. J Biol Chem. 2007 Sep 28;282(39):28639-47. PubMed PMID: 17623674.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Polarity of response to transforming growth factor-beta1 in proximal tubular epithelial cells is regulated by beta-catenin. AU - Zhang,Mei, AU - Lee,Chien-Hung, AU - Luo,Dong Dong, AU - Krupa,Aleksandra, AU - Fraser,Donald, AU - Phillips,Aled, Y1 - 2007/07/09/ PY - 2007/7/12/pubmed PY - 2007/11/9/medline PY - 2007/7/12/entrez SP - 28639 EP - 47 JF - The Journal of biological chemistry JO - J. Biol. Chem. VL - 282 IS - 39 N2 - Transforming growth factor-beta1 (TGF-beta1)-mediated loss of proximal tubular epithelial cell-cell interaction is regulated in a polarized fashion. The aim of this study was to further explore the polarity of the TGF-beta1 response and to determine the significance of R-Smad-beta-catenin association previously demonstrated to accompany adherens junction disassembly. Smad3 signaling response to TGF-beta1 was assessed by activity of the Smad3-responsive reporter gene construct (SBE)(4)-Lux and by immunoblotting for phospho-Smad proteins. Similar results were obtained with both methods. Apical application of TGF-beta1 led to increased Smad3 signaling compared with basolateral stimulation. Association of Smad proteins with beta-catenin was greater following basolateral TGFbeta-1 stimulation, as was the expression of cytoplasmic Triton-soluble beta-catenin. Inhibition of beta-catenin expression by small interfering RNA augmented Smad3 signaling. Lithium chloride, a GSK-3 inhibitor, increased expression of beta-catenin and attenuated TGF-beta1-dependent Smad3 signaling. Lithium chloride did not influence degradation of Smad3 but resulted in decreased nuclear translocation. Smad2 activation as assessed by Western blot analysis and activity of the Smad2-responsive reporter constructs ARE/MF1 was also greater following apical as compared with basolateral TGFbeta-1 stimulation, suggesting that this is a generally applicable mechanism for the regulation of TGF-beta1-dependent R-Smads. Caco-2 cells are a colonic carcinoma cell line, with known resistance to the anti-proliferative effects of TGF-beta1 and increased expression of beta-catenin. We used this cell line to address the general applicability of our observations. Inhibition of beta-catenin in this cell line by small interfering RNA resulted in increased TGF-beta1-dependent Smad3 phosphorylation and restoration of TGF-beta1 anti-proliferative effects. SN - 0021-9258 UR - https://www.unboundmedicine.com/medline/citation/17623674/Polarity_of_response_to_transforming_growth_factor_beta1_in_proximal_tubular_epithelial_cells_is_regulated_by_beta_catenin_ L2 - http://www.jbc.org/cgi/pmidlookup?view=long&pmid=17623674 DB - PRIME DP - Unbound Medicine ER -