Similar Datasets
Project description:DNMT3b mediates TGFβ-Smad2/3 action to maintain Epiblast homeostasis upon Smad4 Loss
| PRJNA1005240 | ENA
Project description:Androgens and androgen-related molecules exert a plethora of functions across different tissues, mainly through binding to the transcription factor androgen receptor (AR). Despite widespread therapeutic use and misuse of androgens as potent anabolic agents, the molecular mechanisms of this effect on skeletal muscle are currently unknown. Muscle mass in adulthood is mainly regulated by the bone morphogenetic protein (BMP) axis of the transforming growth factor (TGF)-β pathway via recruitment of mothers against decapentaplegic homolog 4 (SMAD4) protein. Here we show that, upon activation, AR forms a transcriptional complex with SMAD4 to orchestrate a muscle hypertrophy programme by modulating SMAD4 chromatin binding dynamics and enhancing its transactivation activity. We challenged this mechanism of action using spinal and bulbar muscular atrophy (SBMA) as a model of study. This adult-onset neuromuscular disease is caused by a polyglutamine expansion (polyQ) in AR and is characterized by progressive muscle weakness and atrophy secondary to a combination of lower motor neuron degeneration and primary muscle atrophy. Here we found that the presence of an elongated polyQ tract impairs AR cooperativity with SMAD4, leading to an inability to mount an effective anti-atrophy gene expression programme in skeletal muscle in response to denervation. Furthermore, adeno-associated virus, serotype 9 (AAV9)-mediated muscle-restricted delivery of BMP7 is able to rescue the muscle atrophy in SBMA mice, supporting the development of treatments able to fine-tune AR-SMAD4 transcriptional cooperativity as a promising target for SBMA and other conditions associated with muscle loss.
| S-EPMC9107400 | biostudies-literature
Project description:The role of the transforming growth factor (TGF)-? pathway in myocardial fibrosis is well recognized. However, the precise role of this signaling axis in cardiomyocyte (CM) biology is not defined. In TGF-? signaling, SMAD4 acts as the central intracellular mediator. To investigate the role of TGF-? signaling in CM biology, the authors deleted SMAD4 in adult mouse CMs. We demonstrate that CM-SMAD4-dependent TGF-? signaling is critical for maintaining cardiac function, sarcomere kinetics, ion-channel gene expression, and cardiomyocyte survival. Thus, our findings raise a significant concern regarding the therapeutic approaches that rely on systemic inhibition of the TGF-? pathway for the management of myocardial fibrosis.
| S-EPMC6390466 | biostudies-literature
Project description:Insulin is critical for glucose homeostasis, and insulin deficiency or resistance leads to the development of diabetes. Recent evidence suggests that diabetes can be remitted independent of insulin. However, the underlying mechanism remains largely elusive. In this study, we utilized metabolic surgery as a tool to identify the non-insulin determinant mechanism. Here, we report that the most common metabolic surgery, Roux-en-Y gastric bypass (RYGB), reduced insulin production but persistently maintained euglycemia in healthy Sprague-Dawley (SD) rats and C57 mice. This reduction in insulin production was associated with RYGB-mediated inhibition of pancreatic preproinsulin and polypyrimidine tract-binding protein 1. In addition, RYGB also weakened insulin sensitivity that was evaluated by hyperinsulinemic-euglycemic clamp test and downregulated signaling pathways in insulin-sensitive tissues. The mechanistic evidence suggests that RYGB predominately shifted the metabolic profile from glucose utilization to fatty acid oxidation, enhanced the energy expenditure and activated multiple metabolic pathways through reducing gut energy uptake. Importantly, the unique effect of RYGB was extended to rats with islet disruption and patients with type 2 diabetes. These results demonstrate that compulsory rearrangement of the gastrointestinal tract can initiate non-insulin determinant pathways to maintain glucose homeostasis. Based on the principle of RYGB action, the development of a noninvasive intervention of the gastrointestinal tract is a promising therapeutic route to combat disorders characterized by energy metabolism dysregulation.
| S-EPMC6155125 | biostudies-literature
Project description:The goal of this study was to determine the mechanism of androgne in driving muscle hypertrophy programmes. CONCLUSION: AR transcriptionally cooperates with SMAD4 and this affect is lost in the presence of expansion of the polyglutamine repeat in the AR gene.
2022-05-27 | GSE185977 | GEO
Project description:To improve cartilage formation by bone marrow-derived mesenchymal stem cells (BMSCs), the signaling mechanism governing chondrogenic differentiation requires better understanding. We previously showed that the transforming growth factor-β (TGFβ) receptor ALK5 is crucial for chondrogenesis induced by TGFβ. ALK5 phosphorylates SMAD2 and SMAD3 proteins, which then form complexes with SMAD4 to regulate gene transcription. By modulating the expression of SMAD2, SMAD3 and SMAD4 in human BMSCs, we investigated their role in TGFβ-induced chondrogenesis. Activation of TGFβ signaling, represented by SMAD2 phosphorylation, was decreased by SMAD2 knockdown and highly increased by SMAD2 overexpression. Moreover, TGFβ signaling via the alternative SMAD1/5/9 pathway was strongly decreased by SMAD4 knockdown. TGFβ-induced chondrogenesis of human BMSCs was strongly inhibited by SMAD4 knockdown and only mildly inhibited by SMAD2 knockdown. Remarkably, both knockdown and overexpression of SMAD3 blocked chondrogenic differentiation. Chondrogenesis appears to rely on a delicate balance in the amount of SMAD3 and SMAD4 as it was not enhanced by SMAD4 overexpression and was inhibited by SMAD3 overexpression. Furthermore, this study reveals that TGFβ-activated phosphorylation of SMAD2 and SMAD1/5/9 depends on the abundance of SMAD4. Overall, our findings suggest a more dominant role for SMAD3 and SMAD4 than SMAD2 in TGFβ-induced chondrogenesis of human BMSCs.
| S-EPMC5327413 | biostudies-literature
Project description:Cells are subjected to oxidative stress during the initiation and progression of tumors, and this imposes selective pressure for cancer cells to adapt mechanisms to tolerate these conditions. Here, we examined the dependency of cancer cells on glutathione (GSH), the most abundant cellular antioxidant. While cancer cell lines displayed a broad range of sensitivities to inhibition of GSH synthesis, the majority were resistant to GSH depletion. To identify cellular pathways required for this resistance, we carried out genetic and pharmacologic screens. Both approaches revealed that inhibition of deubiquitinating enzymes (DUBs) sensitizes cancer cells to GSH depletion. Inhibition of GSH synthesis, in combination with DUB inhibition, led to an accumulation of polyubiquitinated proteins, induction of proteotoxic stress, and cell death. These results indicate that depletion of GSH renders cancer cells dependent on DUB activity to maintain protein homeostasis and cell viability and reveal a potentially exploitable vulnerability for cancer therapy.
| S-EPMC6506399 | biostudies-literature
Project description:Implantation is a hallmark of mammalian embryogenesis during which embryos establish their contacts with the maternal endometrium, remodel, and undertake growth and differentiation. The mechanisms and sequence of events through which embryos change their shape during this transition are largely unexplored. Here, we show that the first extraembryonic lineage, the polar trophectoderm, is the key regulator for remodeling the embryonic epiblast. Loss of its function after immuno-surgery or inhibitor treatments prevents the epiblast shape transitions. In the mouse, the polar trophectoderm exerts physical force upon the epiblast, causing it to transform from an oval into a cup shape. In human embryos, the polar trophectoderm behaves in the opposite manner, exerting a stretching force. By mimicking this stretching behavior in mouse embryogenesis, we could direct the epiblast to adopt the disc-like shape characteristic of human embryos at this stage. Thus, the polar trophectoderm acts as a conserved regulator of epiblast shape.
| S-EPMC7816124 | biostudies-literature
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.
2024-10-21 | GSE240786 | GEO
Project description:The transition from the fed to the fasted state necessitates a shift from carbohydrate to fat metabolism that is thought to be mostly orchestrated by reductions in plasma insulin concentrations. Here, we show in awake rats that insulinopenia per se does not cause this transition but that both hypoleptinemia and insulinopenia are necessary. Furthermore, we show that hypoleptinemia mediates a glucose-fatty acid cycle through activation of the hypothalamic-pituitary-adrenal axis, resulting in increased white adipose tissue (WAT) lipolysis rates and increased hepatic acetyl-coenzyme A (CoA) content, which are essential to maintain gluconeogenesis during starvation. We also show that in prolonged starvation, substrate limitation due to reduced rates of glucose-alanine cycling lowers rates of hepatic mitochondrial anaplerosis, oxidation, and gluconeogenesis. Taken together, these data identify a leptin-mediated glucose-fatty acid cycle that integrates responses of the muscle, WAT, and liver to promote a shift from carbohydrate to fat oxidation and maintain glucose homeostasis during starvation.
| S-EPMC5766366 | biostudies-literature