Abstract
Transforming growth factor-beta (TGF-beta) is a cytokine implicated in differentiation of smooth muscle cells and other mesenchymal-derived cells. During hepatic fibrogenesis, TGF-beta has a pivotal role in the initiation, promotion, and progression of transdifferentiation of hepatic stellate cells into myofibroblasts that play a central role in the synthesis of extracellular matrix components. Both, smooth muscle and activated hepatic stellate cells, express smooth muscle alpha-actin, the calponin-related protein SM22alpha, and CSRP2 encoding the cysteine- and glycine-rich LIM domain protein 2 (CRP2). The aim of the present study was to determine whether the expression of CSRP2 is influenced by TGF-beta. Stimulation as well as sequestering experiments demonstrated that TGF-beta markedly influences CSRP2 gene activity. Inhibition experiments using the ALK5 inhibitor SB-431542 further reveal that the transcriptional stimulation of the CSRP2 gene is mediated via the ALK5/Smad2/Smad3 signalling pathway. By use of bisulfite genomic analysis of CpG islands within the 5' regulatory regions we could exclude methylation-associated silencing, previously found to be responsible for the transcriptional inactivity of CSRP2 in a variety of human cancer cells and in a multistage carcinogenesis model, as a cause for CSRP2 inactivity in hepatocytes or fully transdifferentiated myofibroblasts.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Activin Receptors, Type I / antagonists & inhibitors
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Activin Receptors, Type I / physiology
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Animals
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Base Sequence
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Benzamides / pharmacology
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Blotting, Northern
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Blotting, Western
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Cell Line
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Cells, Cultured
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DNA Methylation
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Dioxoles / pharmacology
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Gene Expression / drug effects
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Immunohistochemistry
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LIM Domain Proteins
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Liver / cytology
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Liver / drug effects*
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Liver / metabolism
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Liver Cirrhosis / genetics
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Liver Cirrhosis / metabolism
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Liver Cirrhosis / pathology
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Male
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Molecular Sequence Data
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Muscle Proteins / genetics
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Muscle Proteins / metabolism*
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Muscle, Smooth, Vascular / cytology
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Muscle, Smooth, Vascular / drug effects*
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Muscle, Smooth, Vascular / metabolism
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Nuclear Proteins / genetics
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Nuclear Proteins / metabolism*
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Promoter Regions, Genetic / genetics
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Protein Serine-Threonine Kinases
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RNA, Messenger / genetics
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RNA, Messenger / metabolism
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Rats
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Rats, Sprague-Dawley
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Receptor, Transforming Growth Factor-beta Type I
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Receptors, Transforming Growth Factor beta / antagonists & inhibitors
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Receptors, Transforming Growth Factor beta / physiology
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Signal Transduction / drug effects
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Transforming Growth Factor beta / pharmacology*
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Transforming Growth Factor beta1
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Up-Regulation / genetics
Substances
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4-(5-benzo(1,3)dioxol-5-yl-4-pyridin-2-yl-1H-imidazol-2-yl)benzamide
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Benzamides
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Csrp2 protein, rat
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Dioxoles
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LIM Domain Proteins
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Muscle Proteins
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Nuclear Proteins
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RNA, Messenger
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Receptors, Transforming Growth Factor beta
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TGFB1 protein, human
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Tgfb1 protein, rat
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Transforming Growth Factor beta
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Transforming Growth Factor beta1
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Protein Serine-Threonine Kinases
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Activin Receptors, Type I
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Receptor, Transforming Growth Factor-beta Type I
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TGFBR1 protein, human
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Tgfbr1 protein, rat