Project description:Imbalances in glucose and energy homeostasis are at the core of the worldwide epidemic of obesity and diabetes. Here, we illustrate an important role of the TGF-beta/Smad3 signaling pathway in regulating glucose and energy homeostasis. Smad3 deficient mice are protected from diet-induced obesity and diabetes. Interestingly, the metabolic protection is accompanied by Smad3-/- white adipose tissue acquiring the bioenergetic and gene expression profile of brown fat/skeletal muscle. Smad3-/- adipocytes demonstrate a marked increase in mitochondrial biogenesis, with a corresponding increase in basal respiration, and Smad3 acts as a repressor of PGC-alpha1 expression. We observe significant correlation between TGF-beta1 levels and adiposity in rodents and humans. Further, systemic blockade of TGF-beta1 signaling protects mice from obesity, diabetes and hepatic steatosis. Together, these results demonstrate that TGF-beta signaling regulates glucose tolerance and energy homeostasis and suggest that modulation of TGF-beta1 activity might be an effective treatment strategy for obesity and diabetes. Smad3-/- and WT mice were fed with regular diet (RD) and high fat diet (HFD), and diet induced obese (DIO) mice were treated with IgG and anti-TGF-b1 antibody
Project description:Imbalances in glucose and energy homeostasis are at the core of the worldwide epidemic of obesity and diabetes. Here, we illustrate an important role of the TGF-beta/Smad3 signaling pathway in regulating glucose and energy homeostasis. Smad3 deficient mice are protected from diet-induced obesity and diabetes. Interestingly, the metabolic protection is accompanied by Smad3-/- white adipose tissue acquiring the bioenergetic and gene expression profile of brown fat/skeletal muscle. Smad3-/- adipocytes demonstrate a marked increase in mitochondrial biogenesis, with a corresponding increase in basal respiration, and Smad3 acts as a repressor of PGC-alpha1 expression. We observe significant correlation between TGF-beta1 levels and adiposity in rodents and humans. Further, systemic blockade of TGF-beta1 signaling protects mice from obesity, diabetes and hepatic steatosis. Together, these results demonstrate that TGF-beta signaling regulates glucose tolerance and energy homeostasis and suggest that modulation of TGF-beta1 activity might be an effective treatment strategy for obesity and diabetes.
Project description:Investigation of transcript level modulation in unstimulated and TGF-beta treated (with or without superimposed T-cell receptor and CD28 stimulation) naive CD4 T cells from wild type or Smad3-deficient littermate mice. Smad3 is a critical signaling molecule and transcription factor downstream of TGF-beta and mediates several of the TGF-beta dependent tolerogenic effects in T cells. This study was undertaken to unveil the transcriptionnal program controled by the TGF-b/Smad3 axis. Microarray study using RNA recovered after 6 hours of culture in either serum free media, serum-free media + TGF-beta (2.5ng/ml) or serum-free media + TGF-beta and anti-CD3e and anti-CD28 stimulation (3 conditions). Naive CD4 T cells (TCRb+, CD4+, CD62L+ and CD44-) were sorted from either wild type or Smad3 deficient littermates and submitted to the 3 culture conditions. Three biological replicates were obtained (each from at least 2 different mice). Thus a total of 18 Nimblegen 365K chip were used.
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:We sought to explore whether BAF45D regulates PAX6 expression through cooperating with TGF-beta/SMAD signaling in RA treated P19 cells. Here we identified BAF45D is required for expression of phosphorylated SMAD3 and PAX6 induced by RA. Genome-wide analysis revealed that during RA-induced early neural differentiation, BAF45D knockdown failed to activate TGF-beta/SMAD signaling and induce expression of Stat3 and Smad7, two negative regulators of TGF-beta/SMAD signaling. Moreover, BAF45D was immunoprecipited with BRG1and phosphorylated SMAD3. In addition, Smad3 siRNA abolished RA-indueced expression of phosphorylated SMAD3, PAX6, STAT3 and SMAD7. Finally, overexpression of BAF45D directly induced expression of PAX6 and phosphorylated SMAD3.These results suggest that a novel effect of BAF45D cooperating with TGF-beta/SMAD signaling pathway on PAX6 level control, which may shed new light on neural differentiation of P19 cells.
Project description:Investigation of transcript level modulation in unstimulated and TGF-beta treated (with or without superimposed T-cell receptor and CD28 stimulation) naive CD4 T cells from wild type or Smad3-deficient littermate mice. Smad3 is a critical signaling molecule and transcription factor downstream of TGF-beta and mediates several of the TGF-beta dependent tolerogenic effects in T cells. This study was undertaken to unveil the transcriptionnal program controled by the TGF-b/Smad3 axis.
Project description:Transforming growth factor-beta (TGF-beta) transmits signals that facilitate cancer progression. Especially, epithelial-mesenchymal transition (EMT) induced by TGF-beta is considered to crucially contribute to the malignant phenotype of cancer cells. Here we report that the EMT-associated cellular responses induced by TGF-beta are mediated through distinct signaling pathways that diverge at Smad3; cell motility and epithelial marker downregulation are Smad3-dependent while mesenchymal marker induction is not. Furthermore, using a chimeric protein approach in SMAD3 knockout A549 cells, we found that the beta 4 region in the MH1 domain of Smad3 is indispensable for TGF-beta–induced cell motility, but not for epithelial marker downregulation. A transcriptome analysis was performed using A549 cells expressing Smad3 mutant of the MH1 domain.
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:TGF-βs regulate macrophage responses, by activating Smad2/3. We have previously demonstrated that macrophage-specific Smad3 stimulates phagocytosis and mediates anti-inflammatory macrophage transition in the infarcted heart. However, the role of macrophage Smad2 signaling in myocardial infarction remains unknown. We studied the role of macrophage-specific Smad2 signaling in the healing infarct, and we explored the basis for the distinct effects of Smad2 and Smad3. Infarct macrophages exhibited both Smad2 and Smad3 activation. In contrast to the effects of Smad3 loss, myeloid cell-specific Smad2 disruption had no effects on mortality, ventricular dysfunction and adverse remodeling, after myocardial infarction. Phagocytic removal of dead cells, macrophage and myofibroblast infiltration, collagen deposition, angiogenesis and scar remodeling were not affected by macrophage Smad2 loss. In isolated macrophages, TGF-β1, -β2 and -β3, activated both Smad2 and Smad3, whereas BMP6 triggered only Smad3 activation. Smad2 and Smad3 had similar patterns of nuclear translocation in response to TGF-β1. Smad3, and not Smad2, was the main mediator of transcriptional effects of TGF-β on macrophages and Smad3 loss resulted in enrichment of genes associated with RAR/RXR signaling, cholesterol biosynthesis and lipid metabolism. In conclusion, the in vivo and in vitro effects of TGF-β on macrophage function involve Smad3, and not Smad2.
Project description:TGF-β is involved in various biological processes, including development, differentiation, growth regulation, and epithelial-mesenchymal transition (EMT). In TGF-β/Smad signaling, receptor-activated Smad complexes activate or repress their target gene promoters. Smad cofactors are a group of Smad-binding proteins that promote recruitment of Smad complexes to these promoters. Long noncoding RNAs (lncRNAs), that behave as Smad cofactors have thus far not been identified. Here, we characterize a novel lncRNA EMT-associated lncRNA induced by TGF-β-1(ELIT-1). ELIT-1 was induced by TGF-β-stimulation via the TGF-β/Smad pathway in TGF-β-responsive cell lines. ELIT-1-depletion abrogated TGF-β-mediated EMT progression and expression of TGF-β target genes including Snail, a transcription factor critical for EMT. A positive correlation between high expression of ELIT-1 and poor prognosis in lung adenocarcinoma and gastric cancer patients suggests that ELIT-1 may be useful as a prognostic and therapeutic target. RIP assays revealed that ELIT-1 bound to Smad3, but not Smad2. In conjunction with Smad3, ELIT-1 enhanced Smad-responsive promoter activities by recruiting Smad3 to the promoters of its target genes including Snail, other TGF-β-target genes, and ELIT-1 itself. Collectively, these data show that ELIT-1 is a novel trans-acting lncRNA that forms a positive feedback loop to enhance TGF-β/Smad3 signaling and promote EMT progression.