Project description:To confirm that the SMAD1/5- and SMAD4-associated genes are direct transcriptional regulators in mESCs in response to BMP, we treated undifferentiated R1 ES cells with BMP4 or with the BMP4 antagonist noggin, which can inhibit BMP signaling effectively for 4 h. Undifferentiated R1 ES cells were treated for 4 h with BMP4 or with the BMP4 antagonist noggin, which can inhibit BMP signaling effectively. Untreated R1 ES cells served as the control.
Project description:To confirm that the SMAD1/5- and SMAD4-associated genes are direct transcriptional regulators in mESCs in response to BMP, we treated undifferentiated R1 ES cells with BMP4 or with the BMP4 antagonist noggin, which can inhibit BMP signaling effectively for 4 h.
Project description:To elucidate the Nodal transcriptional network that governs endoderm formation, we used ChIP-Seq to identify genomic targets for SMAD2/3, SMAD3, SMAD4, FOXH1 and the active and repressive chromatin marks, H3K4me3 and H3K27me3, in human embryonic stem cells (hESCs) and derived endoderm. We demonstrate that while SMAD2/3, SMAD4 and FOXH1 target binding is highly dynamic, there is an optimal signature for driving endoderm commitment. Initially, this signature is marked by both H3K4me3 and H3K27me3 as a very broad bivalent domain in hESCs. Within the first 24 hours, at a few select promoters, SMAD2/3 accumulation coincides with H3K27me3 depletion so that these loci become selectively monovalent marked only by H3K4me3. The correlation between SMAD2/3 binding, monovalent formation and transcriptional activation suggests a mechanism by which SMAD proteins coordinate with chromatin at critical promoters to drive endoderm specification. Examination of 2 different histone modifications and 4 different transcription factor associations in 2 cell types. For transcription factor analysis, three biological replicate ChIPs were pooled from each antibody, as well as input controls, for both hESCs and derived endoderm. For histone modifications, two biological replicates for H3K4me3 and three for H3K27me3 were used.
Project description:To elucidate the Nodal transcriptional network that governs endoderm formation, we used ChIP-Seq to identify genomic targets for SMAD2/3, SMAD3, SMAD4, FOXH1 and the active and repressive chromatin marks, H3K4me3 and H3K27me3, in human embryonic stem cells (hESCs) and derived endoderm. We demonstrate that while SMAD2/3, SMAD4 and FOXH1 target binding is highly dynamic, there is an optimal signature for driving endoderm commitment. Initially, this signature is marked by both H3K4me3 and H3K27me3 as a very broad bivalent domain in hESCs. Within the first 24 hours, at a few select promoters, SMAD2/3 accumulation coincides with H3K27me3 depletion so that these loci become selectively monovalent marked only by H3K4me3. The correlation between SMAD2/3 binding, monovalent formation and transcriptional activation suggests a mechanism by which SMAD proteins coordinate with chromatin at critical promoters to drive endoderm specification.
Project description:Gene-specific transcription factors (GSTFs) control of gene transcription by DNA binding and specific protein complex recruitment, which regulates promoter accessibility for transcription initiation by RNA polymerase II. GSTFs that are frequently mutated in colon and rectal carcinomas are Suppressor of Mothers Against Decapentaplegic 2 (SMAD2) and SMAD4, which play an important role in the TGF-β signaling pathways controlling cell fate and proliferation (ref.). The SMAD protein family is a diverse and it can be divided into three subclasses: receptor activated SMADs, inhibitory SMADs and the common SMAD4 co-activator. To study protein interactors of the SMAD protein family we generated a quantitative proteomics pipeline that allows for inducible expression of GFP-tagged SMAD proteins followed by affinity purification and MS analysis. The nuclear importin IPO5 was identified as a novel interacting protein of SMAD1. Overexpression of IPO5 shows forced BMP R-SMAD nuclear localization confirming a functional relationship between BMP but not TGF-β R-SMADs and IPO5. Finally we provide evidence that the length of the lysine stretch in the NLS is involved in importin selection.
Project description:Smad2, Smad3, Smad4 and Foxh1 ChIPseq performed in pluripotent mESC and embryonic bodies (EBs). RNAseq were performed in WT mESCs and Ebs of WT, Smad2KO, Smad3KO and Smad2/3DKO.
Project description:TGF-beta treatment leads to SMAD1/5 phosphorylation. However, the ability of SMAD1/5 to bind chromatin downstream of TGF-beta signalling is unknown. We performed ChIP-sequencing for pSMAD1/5 and SMAD3 to identify binding sites for pSMAD1/5 upon TGF-beta stimulation and identified preferential pSMAD1/5 binding at SMAD1/5:SMAD4 consensus sites.
Project description:TGF-β signaling is known to be very much dependent on the formation of Smad2/3-Smad4 transcription regulatory complexes. However, the signaling functions of Smad2/3-Smad4 in TGF-β-induced responses are obscure as TGF-β also initiates a number of other signaling pathways. In this study, we systematically assessed the contribution of TGF-β-Smad2/3-Smad4 signaling to target gene transcription. Individual Smads were selectively knocked down in Hep3B cells by stable RNA interference (RNAi). We identified TGF-β-responsive genes using genome-wide oligonucleotide microarrays and confirmed their dependency on Smad2, Smad3 or Smad4 by the combination of RNAi and microarray assay. The major finding from our microarray analysis was that of the 2039 target genes seen to be regulated via TGF-β induction, 190 were differentially transcriptionally controlled by Smad2-Smad4 and Smad3-Smad4 signaling and the latter control mechanism appeared to be functionally more important. We also found evidence of competition between Smad2 and Smad3 for their activation when controlling the transcription of target genes. Keywords: cell type comparison
Project description:The tumor suppressive effects of TGF-β are classically associated with the activation of the “canonical” SMAD-mediated pathway, whereas its oncogenic effects are largely attributed to its “non-canonical signaling”. We herein provide evidence of an oncogenic effect for SMAD2 and 3 in response to TGF-β in SMAD4-null cancer cells. Using the CRISPR/Cas9 technology, we report that simultaneous knockout of Smad2 and 3 in Smad4-negative pancreatic ductal adenocarcinoma (PDAC) cells compromises TGF-β-driven collective migration mediated by FAK and Rho/Rac signaling. Moreover, RNA-sequencing analyses highlight a TGF-β gene signature related to aggressiveness mediated by SMAD2 and 3 in the absence of SMAD4. Using PDAC patients cohorts, we reveal that SMAD4-negative tumors with high levels of (phospho)-SMAD2 are more aggressive and have a poorer prognosis. Thus, loss of SMAD4 tumor suppressive activity in PDAC is associated with oncogenic gain-of-function of SMAD2 and 3 and the onset of associated deleterious effects.
Project description:The FOXL2 mutant C134W occurs in virtually all adult ovarian granulosa cell tumors (AGCT), and is considered a driver of oncogenesis in this disease. However, the mechanism by which FOXL2C134W contributes to tumorigenesis is not known. Here, we show that mutant FOXL2C134W acquires the ability to bind SMAD4, forming a FOXL2C134W/SMAD4/SMAD2/3 complex that binds a novel hybrid DNA motif AGHCAHAA, unique to the FOXL2C134W mutant. This binding induces an enhancer-like chromatin state leading to transcription of nearby genes, many of which are characteristic of stemness and epithelial-to-mesenchymal transition. Importantly, primary AGCT tumors display a strong FOXL2C134W enrichment at hybrid loci. Ablation of SMAD4 or SMAD2/3 inhibits FOXL2C134W binding at hybrid sites and decreases transcription of associated genes. Accordingly, TGFβ-inhibition mitigates the transcriptional effect of FOXL2C134W.