Project description:Transforming growth factor (TGF)-β plays crucial roles in embryonic development and adult tissue homeostasis by eliciting various cellular responses in target cells. TGF-β signaling is principally mediated through receptor-activated Smad proteins, which regulate expression of target genes in cooperation with other DNA-binding transcriptionfactors (Smad cofactors). In this study, we found that the basic helix-loop-helix transcription factor Olig1 is a Smad cofactor involved in TGF-b-induced cell motility. Knockdown of Olig1 attenuated TGF-β-induced cell motility in chamber migration and wound healing assays. In contrast, Olig1 knockdown had no effect on bone morphogenetic protein-induced cell motility, TGF-β-induced cytostasis or epithelial-mesenchymal transition. Furthermore, we observed that cooperation of Smad2/3 with Olig1 is regulated by a peptidyl-prolyl cis/trans isomerase, Pin1. TGF-b-induced cell motility, induction of Olig1-regulated genes, and physical interaction between Smad2/3 and Olig1 were all inhibited after knockdown of Pin1, indicating a novel mode of regulation of Smad signaling. We also found that Olig1 interacts with the L3 loop of Smad3. Using a synthetic peptide corresponding to the L3 loop of Smad3, we succeeded in selectively inhibiting TGF-b-induced cell motility. These findings may lead to a new strategy for selective regulation of TGF-b-induced cellular responses. NMuMG cells were transfected with siRNAs (siControl, siOlig1 or siPin1) and treated with or without TGF-b for 1h. We compared genes affected by knockdown of Olig1 and that of Pin1.
Project description:Transforming growth factor (TGF)-β plays crucial roles in embryonic development and adult tissue homeostasis by eliciting various cellular responses in target cells. TGF-β signaling is principally mediated through receptor-activated Smad proteins, which regulate expression of target genes in cooperation with other DNA-binding transcriptionfactors (Smad cofactors). In this study, we found that the basic helix-loop-helix transcription factor Olig1 is a Smad cofactor involved in TGF-b-induced cell motility. Knockdown of Olig1 attenuated TGF-β-induced cell motility in chamber migration and wound healing assays. In contrast, Olig1 knockdown had no effect on bone morphogenetic protein-induced cell motility, TGF-β-induced cytostasis or epithelial-mesenchymal transition. Furthermore, we observed that cooperation of Smad2/3 with Olig1 is regulated by a peptidyl-prolyl cis/trans isomerase, Pin1. TGF-b-induced cell motility, induction of Olig1-regulated genes, and physical interaction between Smad2/3 and Olig1 were all inhibited after knockdown of Pin1, indicating a novel mode of regulation of Smad signaling. We also found that Olig1 interacts with the L3 loop of Smad3. Using a synthetic peptide corresponding to the L3 loop of Smad3, we succeeded in selectively inhibiting TGF-b-induced cell motility. These findings may lead to a new strategy for selective regulation of TGF-b-induced cellular responses.
Project description:Activation of the transforming growth factor β (TGF-β) signaling leads to established hallmarks of cancer such as the epithelial-to-mesenchymal transition (EMT), initiating cancer dissemination and increasing chemoresistance. TGF-β signal by binding to its type I and II receptors, leading to parallel activation of SMAD proteins, ubiquitin ligases and protein kinases. Here, using a panel of tumor cells we show that TGF-β activation induces the expression of the mammalian nuclear long non-coding RNA (lncRNA) VIM-AS1 (Vimentin antisense RNA 1) variant 2 (v.2) via the formation of a complex among the transcriptional factors GATA6-SMAD-SPI1. Furthermore, transcriptomic analysis indicated VIM-AS1 enhancing TGF-β signaling and EMT, as further validated by functional gain or loss assays. Mechanistically, the TGF-β-induced VIM-AS1 v.2 enhanced SMAD nucleocytoplasmic shuttling by interacting with the N-terminus domain of the nucleoporin RanBP2 (Nup358), whereby acting as a scaffold molecule, facilitates the binding of RanBP2 with SMAD2/3 and its further nuclear import. Finally, VIM-AS1 increases invasion and motility of tumor cells and emerges as a promising therapeutic target to sensitize cancer cells to chemotherapeutic drugs. Hence, we delineated a novel signaling mechanism for VIM-AS1 v.2 facilitating TGF-β response in tumor cells via SMAD nucleocytoplasmic shuttling.
Project description:Human intestinal macrophages contribute to tissue homeostasis in noninflamed mucosa through profound down-regulation of pro-inflammatory cytokine release. Here, we show that this down-regulation extends to Toll-like receptor (TLR)-induced cytokine release, as intestinal macrophages expressed TLR3-TLR9 but did not release cytokines in response to TLR-specific ligands. Likely contributing to this unique functional profile, intestinal macrophages expressed markedly down-regulated adapter proteins MyD88 and Toll interleukin receptor 1 domain-containing adapter-inducing interferon beta, which together mediate all TLR MyD88-dependent and -independent NF-kappaB signaling, did not phosphorylate NF-kappaB p65 or Smad-induced IkappaBalpha, and did not translocate NF-kappaB into the nucleus. Importantly, transforming growth factor-beta released from intestinal extracellular matrix (stroma) induced identical down-regulation in the NF-kappaB signaling and function of blood monocytes, the exclusive source of intestinal macrophages. Our findings implicate stromal transforming growth factor-beta-induced dysregulation of NF-kappaB proteins and Smad signaling in the differentiation of pro-inflammatory blood monocytes into noninflammatory intestinal macrophages. Comparison of unstimulated monocytes and macrophages, and flagellin stimulated monocytes and macrophages.
Project description:Transforming growth factor (TGF)-β signaling is a key driver to induce epithelial-to-mesenchymal transition (EMT), a process that enhances cancer cell plasticity and metastatic potential. However, the role of circular RNAs (circRNAs) in TGF-β signaling remains largely unexplored. Here, we identify circTBRII(3-6), a circRNA derived from TGF-β type II receptor (TBRII) pre-mRNA, as a critical enhancer of TGF-β/SMAD signaling in breast cancer cells. Depletion of circTBRII(3-6) inhibits TGF-β-induced EMT, migration, and in vivo extravasation of breast cancer cells. Mechanistically, circTBRII(3-6) acts as a scaffold that facilitates the interaction between the RNA-binding protein insulin-like growth factor 2 mRNA binding protein 3 (IGF2BP3) and TGF-β type I receptor (TBRI) mRNA in an N6-methyladenosine (m6A)-dependent manner, and thereby stabilizes TBRI and promotes its expression. Furthermore, IGF2BP3 knockdown reduces circTBRII(3-6)-mediated enhancement of TGF-β/SMAD signaling, as well as TGF-β-induced EMT and migration. Our findings identify circTBRII(3-6) as a novel enforcer of TGF-β/SMAD signaling at the receptor level and highlight IGF2BP3 as a critical m6A reader that mediates circTBRII(3-6)-driven breast cancer cell plasticity.
Project description:Transforming growth factor- (TGF-) signaling is a critical driver of epithelial–mesenchymal transition (EMT) and cancer progression. However, the regulatory roles of long non-coding RNAs (lncRNAs) in TGF--induced EMT and cancer progression are not well understood. Here, we identified an unannotated nuclear lncRNA LETS1 (LncRNA Enforcing TGF- Signaling 1) as a novel TGF-/SMAD target gene. Loss of LETS1 attenuates TGF--induced EMT, migration and extravasation in breast and lung cancer cells. LETS1 potentiates TGF-/SMAD signaling by stabilizing cell surface TGF- type I receptor (TRI) and thereby forms a positive feedback loop. Mechanistically, LETS1 inhibits TRI polyubiquitination by inducing the orphan nuclear receptor 4A1 (NR4A1) expression, a critical determinant of a destruction complex for inhibitory SMAD7. An unbiased interactome analysis identified the Nuclear Factor of Activated T Cells (NFAT5) as a protein partner of LETS1 to mediate activation of NR4A1 promoter. Overall, our findings characterize LETS1 as an EMT-promoting lncRNA and elucidate the mechanism by which nuclear LETS1 potentiates TGF- receptor signaling.
Project description:Human intestinal macrophages contribute to tissue homeostasis in noninflamed mucosa through profound down-regulation of pro-inflammatory cytokine release. Here, we show that this down-regulation extends to Toll-like receptor (TLR)-induced cytokine release, as intestinal macrophages expressed TLR3-TLR9 but did not release cytokines in response to TLR-specific ligands. Likely contributing to this unique functional profile, intestinal macrophages expressed markedly down-regulated adapter proteins MyD88 and Toll interleukin receptor 1 domain-containing adapter-inducing interferon beta, which together mediate all TLR MyD88-dependent and -independent NF-kappaB signaling, did not phosphorylate NF-kappaB p65 or Smad-induced IkappaBalpha, and did not translocate NF-kappaB into the nucleus. Importantly, transforming growth factor-beta released from intestinal extracellular matrix (stroma) induced identical down-regulation in the NF-kappaB signaling and function of blood monocytes, the exclusive source of intestinal macrophages. Our findings implicate stromal transforming growth factor-beta-induced dysregulation of NF-kappaB proteins and Smad signaling in the differentiation of pro-inflammatory blood monocytes into noninflammatory intestinal macrophages.
Project description:Activation of the transforming growth factor β (TGF-β) signaling leads to established hallmarks of cancer such as the epithelial-to-mesenchymal transition (EMT), initiating cancer dissemination and increasing chemoresistance. TGF-β signal by binding to its type I and II receptors, leading to parallel activation of SMAD proteins, ubiquitin ligases and protein kinases. Here, using a panel of tumor cells we show that TGF-β activation induces the expression of the mammalian nuclear long non-coding RNA (lncRNA) VIM-AS1 (Vimentin antisense RNA 1) variant 2 (v.2) via the formation of a complex among the transcriptional factors GATA6-SMAD-SPI1. Furthermore, transcriptomic analysis indicated VIM-AS1 enhancing TGF-β signaling and EMT, as further validated by functional gain or loss assays. Mechanistically, the TGF-β-induced VIM-AS1 v.2 enhanced SMAD nucleocytoplasmic shuttling by interacting with the N-terminus domain of the nucleoporin RanBP2 (Nup358), whereby acting as a scaffold molecule, facilitates the binding of RanBP2 with SMAD2/3 and its further nuclear import. Finally, VIM-AS1 increases invasion and motility of tumor cells and emerges as a promising therapeutic target to sensitize cancer cells to chemotherapeutic drugs. Hence, we delineated a novel signaling mechanism for VIM-AS1 v.2 facilitating TGF-β response in tumor cells via SMAD nucleocytoplasmic shuttling.
Project description:Several long non-coding RNAs (lncRNAs) are differentially expressed in oral cancer, contributing to Oral squamous cell carcinoma (OSCC), an aggressive cancer of the head and neck region. A dysregulated Transforming growth factor-beta (TGF-β) pathway is often observed in OSCC, leading to increased proliferation, migration, invasion, and chemoresistance in OSCC cells. The role of TGF-β regulated lncRNAs in promoting malignancy has already been established in multiple cancers. Such differentially expressed lncRNA involved in cross-talks with the TGF-β pathway is also reported in OSCC. We suspect many such lncRNAs function downstream of the TGF-β pathway in OSCC. We use whole transcriptomic sequencing to identify lncRNAs which are induced upon TGF-β treatment in OSCC via SMAD dependent or SMAD independent pathways to promote OSCC pathogenesis.