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: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:New findings demonstrate that transcriptional factors alternative to Smad4 can bind to Smad2/3 and mediate different transcriptional effects. In this study, we detected constitutively phosphorylation of Smad2/3 in Smad4-null pancreatic cancer cell line BxPC-3. Both pan-specific TGF-β-neutralizing antibody and specific TGF-β type I receptor (TβR-I) inhibitor, SB-431542, can decrease steady-state p-Smad2/3 levels. Moreover, exogenous TGF-β strongly stimulated translocation of phosphorylated Smad2/3 (p-Smad2/3) into the nucleus. Therefore, we identified TGF-β-responsive genes using genome-wide oligonucleotide microarrays and confirmed their dependency on Smad2/3 by the combination of RNA interference (RNAi) and microarray assay. The major finding from our microarray analysis was that of the 262 target genes seen to be regulated via TGF-β induction, 87 were differentially transcriptionally controlled by Smad2/3 signaling and 175 were Smad2/3-independent. Our results showed that integrin β6 was transcriptionally up-regulated via TGF-β induction in a Smad3-dependent manner, which was validated by real-time RT-PCR and western blot. We also provide evidence that αVβ6 integrin can activate TGF-β-Smad2/3 signaling. Thus, we for the first time suggest the positive feedback loop compose of TGF-β-Smad3 signaling and integrin β6. Functional analysis revealed that exogenous TGF-β can amplify the invasive property of Smad4-deficient pancreatic cancer cells; however, TGF-β-neutralizing antibody, specific TβR-I inhibitor, and anti-αVβ6 integrin antibody can reduce it. Therefore, integrin β6 mediated the invasion of BxPC-3 cells induced by TGF-β signaling. Keywords: cell type comparison
Project description:The vertebrate homologues of Drosophila dachsund, DACH1 and DACH2, have been implicated as important regulatory genes in development. DACH1 plays a role in retinal and pituitary precursor cell proliferation and DACH2 plays a specific role in myogenesis. DACH proteins contain a domain (DS-domain) that is conserved with the proto-oncogenes Ski and Sno. Since the Ski/Sno proto-oncogenes repress AP-1 and SMAD signaling, we hypothesized that DACH1 might play a similar cellular function. Herein, DACH1 was found to be expressed in breast cancer cell lines and to inhibit TGF-beta induced apoptosis. DACH1 repressed TGF-beta induction of AP-1 and Smad signaling in gene reporter assays and repressed endogenous TGF-beta responsive genes by microarray analyses. DACH1 bound to endogenous NCoR and Smad4 in cultured cells and DACH1 co-localized with NCoR in nuclear dot-like structures. NCoR enhanced DACH1 repression and the repression of TGF-beta-induced AP-1 or Smad-signaling by DACH1 required the DACH1 DS domain. The DS-domain of DACH was sufficient for NCoR-binding at a Smad4-binding site. Smad4 was required for DACH1 repression of Smad signaling. In Smad4 null HTB-134 cells, DACH1 inhibited the activation of SBE-4 reporter activity induced by Smad2 or Smad3 only in the presence of Smad4. DACH1 participates in the negative regulation of TGF-beta signaling by interacting with NCoR and Smad4. Keywords: other
Project description:Smad2 and Smad3 (Smad2/3) primarily mediates the transforming growth factor-β (TGF-β) signaling that drives cell proliferation, differentiation, and migration. The dynamics of the Smad2/3 phosphorylation provides the key mechanism for regulating the TGF-β signaling pathway. Here we identified NLK as a novel regulator of TGF-β signaling pathway via modulating the phosphorylation of Smad2/3 in the linker region.
Project description:To understand the genome wide binding profile of SMAD2/3 when SMAD4 is lost, Smad2/3 ChIPseq was performed in SMAD4 knockout (S4KO) mouse embryonic stem cells (mESC) or in S4KO embryonic bodies (EBs). To figure out the effect of Dnmt3b on SMAD2/3 binding ability in the absence of SMAD4, we further performed SMAD2/3 CUT&Tag in EBs of S4KO and S4KO with Dnmt3b konckdown, as well as in mesendoderm (ME) stage of WT and S4KO. The binding sites of Dnmt3a and Dnmt3b were explored by Dnmt3a or Dnmt3b ChIP-seq and Dnmt3b CUT&Tag in WT EBs and S4KO EBs. WT with Dnmt3b knockdown and S4KO with Dnmt3b knockdown were used to as a control for the Dnmt3b CUT&Tag. Besides, we inserted a 3xFlag-tag at the C-terminus of Dnmt3a or Dnmt3b and then carried out Flag CUT&Tag in EBs.
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.
Project description:Smad2/3 are transcription factors that engage in TGF-beta-induced transcription. Here we analyzed the effect of identified Smad2/3 binding sites to transcription. We used expression microarrays to compare the Smad2/3 binding sites identified by ChIP-chip to TGF-beta-induced gene expressions. Keywords: time course We also examined the effect of either ETS1/TFAP2A/SMAD2/SMAD3 siRNAs on TGF-beta-induced gene expression change.
Project description:By performing oligonucleotide microarray analysis the role of Smad4 in response to TGF-ß was evaluated in established MDA-MB-468 Smad4 negative and positive clones that were treated with TGF-ß for different time points. Keywords: time-course
Project description:To dissected the roles of SMAD2/3 and SMAD4 in mouse embryonic stem cells (mESC), knockouts of SMAD2/3 (SMAD2 and SMAD3 double knockout, S2/3DKO) and SMAD4 (SMAD4 knockout, S4KO) were used to conduct RNAseq in ES and EB conditions.