Role of epimorphin in bile duct formation of rat liver epithelial stem-like cells: Involvement of small G protein RhoA and C/EBPβ
ABSTRACT Epimorphin/syntaxin 2 is a high conserved and very abundant protein involved in epithelial morphogenesis in various organs. We have shown recently that epimorphin (EPM), a protein exclusively expressed on the surface of hepatic stellate cells and myofibroblasts of the liver, induces bile duct formation of hepatic stem-like cells (WB-F344 cells) in a putative biophysical way. Therefore, the aim of this study was to present some of the molecular mechanisms by which EPM mediates bile duct formation. We established a biliary differentiation model by co-culture of EPM-overexpressed mesenchymal cells (PT67(EPM)) with WB-F344 cells. Here, we showed that EPM could promote WB-F344 cells differentiation into bile duct-like structures. Biliary differentiation markers were also elevated by EPM including Yp, Cx43, aquaporin-1, CK19, and gamma glutamyl transpeptidase (GGT). Moreover, the signaling pathway of EPM was analyzed by focal adhesion kinase (FAK), extracellular regulated kinase 1/2 (ERK1/2), and RhoA Western blot. Also, a dominant negative (DN) RhoA-WB-F344 cell line (WB(RhoA-DN)) was constructed. We found that the levels of phosphorylation (p) of FAK and ERK1/2 were up-regulated by EPM. Most importantly, we also showed that RhoA is necessary for EPM-induced activation of FAK and ERK1/2 and bile duct formation. In addition, a dual luciferase-reporter assay and CHIP assay was performed to reveal that EPM regulates GGT IV and GGT V expression differentially, possibly mediated by C/EBPβ. Taken together, these data demonstrated that EPM regulates bile duct formation of WB-F344 cells through effects on RhoA and C/EBPβ, implicating a dual aspect of this morphoregulator in bile duct epithelial morphogenesis.
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ABSTRACT: An essential function of the liver is the formation and secretion of bile, a complex aqueous solution of organic and inorganic compounds essential as route for the elimination of body cholesterol as unesterified cholesterol or as bile acids. In bile, a considerable amount of otherwise insoluble cholesterol is solubilized by carriers including two other classes of lipids, namely phospholipid and bile acids. Formation of bile and generation of bile flow are driven by the active secretion of bile acids, lipids and electrolytes into the canalicular and bile duct lumens followed by the parallel movement of water. Thus, water has to cross rapidly into and out of the cell interior driven by osmotic forces. Bile as a fluid, results from complicated interplay of hepatocyte and cholangiocyte uptake and secretion, concentration, by involving a number of transporters of lipids, anions, cations, and water. The discovery of the aquaporin water channels, has clarified the mechanisms by which water, the major component of bile (more than 95%), moves across the hepatobiliary epithelia. This review is focusing on novel acquisitions in liver membrane lipidic and water transport and functional participation of aquaporin water channels in multiple aspects of hepatobiliary fluid balance. Involvement of aquaporins in a series of clinically relevant hepatobiliary disorders are also discussed.Molecular Aspects of Medicine 04/2012; 33(5-6):651-64. DOI:10.1016/j.mam.2012.03.010 · 10.30 Impact Factor
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ABSTRACT: CD41 (αIIb integrin), a specific marker for megakaryocytes and platelets, was recently shown to mark the initiation of definitive hematopoiesis in mouse embryos. However, whether embryonic CD41(+) populations have a nonhematopoietic potential remains elusive. Here, we report that the CD41(+) cells from the mouse E11.0 aorta-gonad-mesonephros (AGM) region and yolk sac (YS) expressed a set of mesenchymal markers (as revealed by reverse transcriptase-polymerase chain reaction), displayed myofibroblastic/fibroblastic potential in vitro under mesenchymal culture conditions, and differentiated into α-SMA(+)/epimorphin(+)/vimentin(+) cells in the lungs of adult recipients after systemic transplantation. This unique cell population with fibroblastic potential expressed intermediate rather than high levels of CD41 and was negative for CD34 in the AGM region. In contrast, circulating CD41(+) cells in the embryonic blood stream harbored no similar fibroblastic potential. Compared with the YS, the AGM-derived CD41(+) cells had a more robust fibroblastic potential, as revealed by higher in vitro growth rates. Interestingly, the AGM-derived CD41(+) cells demonstrated a stronger response to the chemotaxin of circulating blood plasma than the YS-derived CD41(+) cells. We are the first group that illustrates the fibroblastic potential of an embryonic CD41(+) population in vitro and in vivo, reflecting the close association between blood and mesenchyme development during mouse mid-gestation. The precise origin of these mesenchymal populations needs further clarification.Stem cells and development 04/2012; 21(14):2592-605. DOI:10.1089/scd.2011.0572 · 4.20 Impact Factor
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ABSTRACT: Studies have shown that the expression of CD133, leucine-rich-repeat-containing G-protein-coupled receptor 5 (Lgr5), and ATP binding cassette (ABC)G2 proteins is associated with malignancy and poor prognosis in colon cancer. However, molecular regulation mechanism of the three proteins has not been elucidated. Here, we report that microRNA-142-3p (miR-142-3p) inhibits the expression of CD133, Lgr5, and ABCG2 in colon cancer cells by binding to both the 3'-untranslated region and the coding sequences of the three genes. The miR-142-3p was markedly decreased in colon cancer specimens, in which it was negatively correlated with the expression of CD133, Lgr5, and ABCG2. Reduction of miR-142-3p corresponds to poor differentiation and bigger tumor size in colon cancers. Moreover, miR-142-3p levels were reduced in cells that formed spheres compared to cells that were cultured in regular media. Transfection of miR-142-3p mimics in colon cancer cells downregulated cyclin D1 expression, induced G1 phase cell cycle arrest, and elevated the sensitivity of the cells to 5-fluorouracil. Furthermore, OCT4 suppressed miR-142-3p, and hypomethylation of the OCT4 promoter was associated with a reduction in miR-142-3p. Finally, the miR-142-3p inhibited the growth of colon cancer cells in vivo, which was accompanied by the downregulation of CD133, Lgr5, and ABCG2 in tumor tissues. Our results elucidate a novel regulation pathway in colon cancer cells and suggest a potential therapeutic approach for colon cancer therapy.Journal of Molecular Medicine 04/2013; 91(8). DOI:10.1007/s00109-013-1037-x · 4.74 Impact Factor