Project description:Specific regulation of target genes by transforming growth factor-β (TGF-β) in a given cellular context is determined in part by transcription factors and cofactors that interact with the Smad complex. In the present study, we determined Smad2 and Smad3 (Smad2/3) binding regions in the promoters of known genes in HepG2 hepatoblastoma cells, and compared them to those in HaCaT epidermal keratinocytes to elucidate the mechanisms of cell type- and context-dependent regulation of transcription induced by TGF-β. Our results show that 81% of the Smad2/3 binding regions in HepG2 cells were not shared with those found in HaCaT cells. Hepatocyte nuclear factor 4α (HNF4α) is expressed in HepG2 cells, but not in HaCaT cells, and the HNF4α binding motif was identified as an enriched motif in the HepG2-specific Smad2/3 binding regions. ChIP-sequencing analysis of HNF4A binding regions under TGF-β stimulation revealed that 32.5% of the Smad2/3 binding regions overlapped HNF4A bindings. MIXL1 was identified as a new combinatorial target of HNF4A and Smad2/3, and both the HNF4A protein and its binding motif were required for the induction of MIXL1 by TGF-β in HepG2 cells. These findings generalize the importance of binding of HNF4A on Smad2/3 binding genomic regions for HepG2-specific regulation of transcription by TGF-β, and suggest that certain transcription factors expressed in a cell-type-specific manner play important roles in the transcription regulated by the TGF-β-Smad signaling pathway. HepG2 cells were treated with TGF-beta for 1.5 h or left untreated. anti-HNF4A ChIP-seq was performed. One lane was used for each sample.
Project description:Specific regulation of target genes by transforming growth factor-β (TGF-β) in a given cellular context is determined in part by transcription factors and cofactors that interact with the Smad complex. In the present study, we determined Smad2 and Smad3 (Smad2/3) binding regions in the promoters of known genes in HepG2 hepatoblastoma cells, and compared them to those in HaCaT epidermal keratinocytes to elucidate the mechanisms of cell type- and context-dependent regulation of transcription induced by TGF-β. Our results show that 81% of the Smad2/3 binding regions in HepG2 cells were not shared with those found in HaCaT cells. Hepatocyte nuclear factor 4α (HNF4α) is expressed in HepG2 cells, but not in HaCaT cells, and the HNF4α binding motif was identified as an enriched motif in the HepG2-specific Smad2/3 binding regions. ChIP-sequencing analysis of HNF4A binding regions under TGF-β stimulation revealed that 32.5% of the Smad2/3 binding regions overlapped HNF4A bindings. MIXL1 was identified as a new combinatorial target of HNF4A and Smad2/3, and both the HNF4A protein and its binding motif were required for the induction of MIXL1 by TGF-β in HepG2 cells. These findings generalize the importance of binding of HNF4A on Smad2/3 binding genomic regions for HepG2-specific regulation of transcription by TGF-β, and suggest that certain transcription factors expressed in a cell-type-specific manner play important roles in the transcription regulated by the TGF-β-Smad signaling pathway.
Project description:Smad2/3 are transcription factors that engage in TGF-beta-induced transcription. We determined and analyzed HepG2 and Hep3B-specific Smad2/3 binding sites by ChIP-chip. We used expression microarrays to compare the Smad2/3 and HNF4alpha binding sites identified by ChIP-chip or ChIP-seq, respectively, to TGF-beta-induced gene expressions. HepG2 cells were transfected with control or HNF4A siRNAs and treated with 3 ng/ml TGF-beta for 0, 1.5 and 24 h (6 samples in total, no replicates). Total RNA was extracted and expression microarray analysis was performed as described in the protocols.
Project description:Specific regulation of target genes by transforming growth factor-β (TGF-β) in a given cellular context is determined in part by transcription factors and cofactors that interact with the Smad complex. In the present study, we determined Smad2 and Smad3 (Smad2/3) binding regions in the promoters of known genes in HepG2 hepatoblastoma cells, and compared them to those in HaCaT epidermal keratinocytes to elucidate the mechanisms of cell-type- and context-dependent regulation of transcription induced by TGF-β. Our results show that 81% of the Smad2/3 binding regions in HepG2 cells were not shared with those found in HaCaT cells. Hepatocyte nuclear factor 4α (HNF4α) is expressed in HepG2 cells, but not in HaCaT cells, and the HNF4α binding motif was identified as an enriched motif in the HepG2-specific Smad2/3 binding regions. ChIP-sequencing analysis of HNF4α binding regions under TGFα stimulation revealed that 32.5% of the Smad2/3 binding regions overlapped HNF4α bindings. MIXL1 was identified as a new combinatorial target of HNF4α and Smad2/3, and both the HNF4α protein and its binding motif were required for the induction of MIXL1 by TGF-β in HepG2 cells. These findings generalize the importance of binding of HNF4α on Smad2/3 binding genomic regions for HepG2-specific regulation of transcription by TGF-β, and suggest that certain transcription factors expressed in a cell-type-specific manner play important roles in the transcription regulated by the TGF-β-Smad signaling pathway.
Project description:Smad2/3 are transcription factors that engage in TGF-beta-induced transcription. We determined and analyzed HepG2 and Hep3B-specific Smad2/3 binding sites by ChIP-chip. We used expression microarrays to compare the Smad2/3 and HNF4alpha binding sites identified by ChIP-chip or ChIP-seq, respectively, to TGF-beta-induced gene expressions.
Project description:Gene expression profiling was carried out in four (HepG2-shCtrl,HepG2-shPJA1, HepG2/Ctrl and HepG2/TGFb1 cells) different liver cancer cells. PJA1 is an E3 ligase that regulates TGF-beta signaling pathway. In this study, we report a major role of the PJA1-mediated desregulation of TGF-beta/Smad3 in liver cancers . To determine the mechanism for the oncogenic function of PJA1 in TGF-β signaling transduction, we analyzed gene profiles the cells of knockdown PJA1 in HepG2 cells and the cells treated with TGFb1 in HepG2.
Project description:We determined and analyzed the effect of TTF-1/NKX2-1 on Smad3/Smad4 binding sites by ChIP-sequencing. We used expression microarrays to evaluate the effect of TTF-1/NKX2-1 siRNA on TGF-beta-induced gene expressions. H441 cells were transfected with siRNAs and treated with TGF-beta for RNA extraction and hybridization on Affymetrix microarrays. This submission represents transcriptome component of study.