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: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:Sma- and Mad-related protein 4 (SMAD4) is closely associated with the development of ovarian follicular. However, current knowledge of the genome-wide view on the role of SMAD4 gene in mammalian follicular granulosa cells (GCs) is still largely unknown. In the present study, RNA-Seq was performed to investigate the effects of SMAD4 knockdown by RNA interference (SMAD4-siRNA) in porcine follicular GCs. A total of 1025 differentially expressed genes (DEGs), including 530 upregulated genes and 495 downregulated genes, were identified in SMAD4-siRNA treated GCs compared with that treated with NC-siRNA. Furthermore, functional enrichment analysis indicated that upregulated DEGs in SMAD4-siRNA treated cells were mainly enriched in cell-cycle related processes, interferon signaling pathway, and immune system process, while downregulated DEGs were mainly involved in extracellular matrix organization/disassembly, pathogenesis, and cell adhesion. In particular, cell cycle and TGF-β signaling pathway were discovered as the canonical pathways changed under the SMAD4 silencing. Taken together, our data reveals SMAD4 knockdown alters the expression of numerous genes involved in key biological processes of the development of follicular GCs and provides a novel global clue of the role of SMAD4 gene in porcine follicular GCs. mRNA profiles of NC-siRNA treated and SMAD4-siRNA treated porcine GCs were generated by RNA sequencing using Ion Torren Proton
Project description:Sma- and Mad-related protein 4 (SMAD4) is closely associated with the development of ovarian follicular. However, current knowledge of the genome-wide view on the role of SMAD4 gene in mammalian follicular granulosa cells (GCs) is still largely unknown. In the present study, RNA-Seq was performed to investigate the effects of SMAD4 knockdown by RNA interference (SMAD4-siRNA) in porcine follicular GCs. A total of 1025 differentially expressed genes (DEGs), including 530 upregulated genes and 495 downregulated genes, were identified in SMAD4-siRNA treated GCs compared with that treated with NC-siRNA. Furthermore, functional enrichment analysis indicated that upregulated DEGs in SMAD4-siRNA treated cells were mainly enriched in cell-cycle related processes, interferon signaling pathway, and immune system process, while downregulated DEGs were mainly involved in extracellular matrix organization/disassembly, pathogenesis, and cell adhesion. In particular, cell cycle and TGF-β signaling pathway were discovered as the canonical pathways changed under the SMAD4 silencing. Taken together, our data reveals SMAD4 knockdown alters the expression of numerous genes involved in key biological processes of the development of follicular GCs and provides a novel global clue of the role of SMAD4 gene in porcine follicular GCs.
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 transforming growth factor beta (TGFβ) related signaling is one of the most important signaling pathways regulating early developmental events. Smad2 and Smad3 are structurally similar and it is mostly considered that they are equally important in mediating TGFβ signals. Here, we show that Smad3 is an insensitive TGFβ transducer as compared with Smad2. Smad3 preferentially localizes within the nucleus and is thus sequestered from membrane signaling. The ability of Smad3 in oligomerization with Smad4 upon agonist stimulation is also impaired given its unique linker region. Smad2 mediated TGFβ signaling plays a crucial role in epiblast development and patterning of three germ layers. However, signaling unrelated nuclear localized Smad3 is dispensable for TGFβ signaling-mediated epiblast specification, but important for early neural development, an event blocked by TGFβ/Smad2 signaling. Both Smad2 and Smad3 bind to the conserved Smads binding element (SBE), but they show nonoverlapped target gene binding specificity. We conclude that Smad2 and Smad3 possess differential sensitivities in relaying TGFβ signaling and have distinct roles in regulating early developmental events. GFP, GFP-Smad2 and GFP-Smad3 constitutively expressed Smad3-/- mouse ESCs were differentiated to day6 neuroepithelia and collected for Chip-Seq with an anti-GFP antibody.
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.