Gut-enriched Krüppel-like factor interaction with Smad3 inhibits myofibroblast differentiation.

@article{citeulike:2920046, abstract = {Gut-enriched Kr\"{u}ppel-like factor (GKLF) has been reported to partially inhibit alpha-smooth muscle actin (alpha-SMA) gene transcription by competing for binding to the TGF-beta control element (TCE) with known activators such as Sp1 and other Kr\"{u}ppel-like factors. This incomplete inhibition via the TCE suggests an additional mechanism, which was evaluated in this study. The results showed that an alpha-SMA promoter mutated in the TCE remained susceptible to inhibition by GKLF in rat lung fibroblasts consistent with the existence of an additional TCE-independent mechanism. Since TGF-beta- induced alpha-SMA expression is Smad3-dependent, potential interaction between GKLF and Smad3 was examined as a basis for this additional inhibitory mechanism. Co-immunoprecipitation and yeast two-hybrid assays revealed that GKLF could bind Smad3 through the Smad3 MH2 domain. Electrophoretic mobility shift assays and ChIP assay indicated that this GKLF-Smad3 interaction inhibited Smad3 binding to the Smad3-binding element (SBE) in the alpha-SMA promoter, and the activity of an SBE containing artificial promoter. Further analysis using smad3(-/-) fibroblasts confirmed that the TCE-independent inhibition by GKLF was dependent on Smad3. These data taken together suggest that in addition to inhibition via the TCE, GKLF represses alpha-SMA gene expression by interacting with Smad3 to prevent Smad3 binding to the SBE. It represents the first evidence to directly link GKLF with Smad3, a key intracellular mediator of TGF-beta signaling, which should lead to a clearer understanding of the mechanism of how GKLF regulates TGF-beta-induced gene expression.}, address = {Department of Pathology, University of Michigan Medical School, Ann Arbor, MI 48109-0602, USA.}, author = {Hu, B. and Wu, Z. and Liu, T. and Ullenbruch, M. R. and Jin, H. and Phan, S. H. }, citeulike-article-id = {2920046}, doi = {10.1165/rcmb.2006-0043OC}, issn = {1044-1549}, journal = {American journal of respiratory cell and molecular biology}, keywords = {emt, klf, smad, tgfb}, month = {January}, number = {1}, pages = {78--84}, posted-at = {2008-06-24 04:19:55}, priority = {2}, title = {Gut-enriched Kr\"{u}ppel-like factor interaction with Smad3 inhibits myofibroblast differentiation.}, url = {http://dx.doi.org/10.1165/rcmb.2006-0043OC}, volume = {36}, year = {2007} }

TY - JOUR ID - citeulike:2920046 L3 - citeulike-article-id:2920046 TI - Gut-enriched Krüppel-like factor interaction with Smad3 inhibits myofibroblast differentiation. JF - American journal of respiratory cell and molecular biology VL - 36 IS - 1 SP - 78 EP - 84 AD - Department of Pathology, University of Michigan Medical School, Ann Arbor, MI 48109-0602, USA. SN - 1044-1549 N2 - Gut-enriched Krüppel-like factor (GKLF) has been reported to partially inhibit alpha-smooth muscle actin (alpha-SMA) gene transcription by competing for binding to the TGF-beta control element (TCE) with known activators such as Sp1 and other Krüppel-like factors. This incomplete inhibition via the TCE suggests an additional mechanism, which was evaluated in this study. The results showed that an alpha-SMA promoter mutated in the TCE remained susceptible to inhibition by GKLF in rat lung fibroblasts consistent with the existence of an additional TCE-independent mechanism. Since TGF-beta- induced alpha-SMA expression is Smad3-dependent, potential interaction between GKLF and Smad3 was examined as a basis for this additional inhibitory mechanism. Co-immunoprecipitation and yeast two-hybrid assays revealed that GKLF could bind Smad3 through the Smad3 MH2 domain. Electrophoretic mobility shift assays and ChIP assay indicated that this GKLF-Smad3 interaction inhibited Smad3 binding to the Smad3-binding element (SBE) in the alpha-SMA promoter, and the activity of an SBE containing artificial promoter. Further analysis using smad3(-/-) fibroblasts confirmed that the TCE-independent inhibition by GKLF was dependent on Smad3. These data taken together suggest that in addition to inhibition via the TCE, GKLF represses alpha-SMA gene expression by interacting with Smad3 to prevent Smad3 binding to the SBE. It represents the first evidence to directly link GKLF with Smad3, a key intracellular mediator of TGF-beta signaling, which should lead to a clearer understanding of the mechanism of how GKLF regulates TGF-beta-induced gene expression. KW - emt KW - klf KW - smad KW - tgfb AU - Hu, B AU - Wu, Z AU - Liu, T AU - Ullenbruch, MR AU - Jin, H AU - Phan, SH PY - 2007/01// UR - http://dx.doi.org/10.1165/rcmb.2006-0043OC ER -