TG-interacting factor1 (Tgif1) maintains the identity of mouse ES cells by counterbalancing the expression of core pluripotency factors and ES cell core factors
Ontology highlight
ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE55437 | GEO | 2015/09/26
SECONDARY ACCESSION(S): PRJNA239582
REPOSITORIES: GEO
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Project description:TG-interacting factor1 (Tgif1) is well-known as a transcriptional repressor in transforming growth factor beta (TGFβ) signaling pathway. Target mapping of ES cell core factors in mouse embryonic stem (ES) cells revealed that Tgif1 is occupied by Oct4 and Nanog. Moreover, recent interactome study of mouse gene regulatory regions showed a preferential regulation of Tgif1 by mouse ES cell specific enhancers. However, the detailed role and mode of actions of Tgif1 in stem cell maintenance and development remains elusive. We show that Tgif1 is indispensable for self-renewal and pluripotency of mouse embryonic stem (ES) cells. Aberrant expression of Tgif1 promotes differentiation of ES cells even in the presence of LIF in part by deregulation of pluripotency factors. Intriguingly, we find that Tgif1 level is a critical factor to determine specific lineage commitment in a dosage-dependent manner. We further show that Tgif1 interacts with ES cell core factors and co-localizes at their binding sites, which eventually restricts expression of ES cell core factors including Oct4, Sox2, and Nanog. Taken together, we provide new insights into the roles of Tgif1 in maintenance as well as differentiation of ES cells.
2015-09-26 | GSE55404 | GEO
Project description:TG-interacting factor1 (Tgif1) is well-known as a transcriptional repressor in transforming growth factor beta (TGFβ) signaling pathway. Target mapping of ES core factors in mouse embryonic stem (ES) cells revealed that Tgif1 is occupied by Oct4 and Nanog. Moreover, recent interactome study of mouse gene regulatory regions showed a preferential regulation of Tgif1 by mouse ES cell specific enhancers. However, the detailed role and mode of actions of Tgif1 in stem cell maintenance and development remains elusive. We show that Tgif1 is indispensable for self-renewal and pluripotency of mouse embryonic stem (ES) cells. Aberrant expression of Tgif1 promotes differentiation of ES cells even in the presence of LIF in part by deregulation of pluripotency factors. Intriguingly, we find that Tgif1 level is a critical factor to determine specific lineage commitment in a dosage-dependent manner. We further show that Tgif1 interacts with ES cell core factors and co-localizes at their binding sites, which eventually restricts expression of ES cell core factors including Oct4, Sox2, and Nanog. Taken together, we provide new insights into the roles of Tgif1 in maintenance as well as differentiation of ES cells.
2015-09-26 | GSE55401 | GEO
Project description:Osteoporosis is caused by increased bone resorption and decreased bone formation. Intermittent administration of a fragment of Parathyroid hormone (PTH) activates osteoblast-mediated bone formation and is used in patients with severe osteoporosis. However, the mechanisms by which PTH elicits its anabolic effect are not fully elucidated. Here we show that the absence of the homeodomain protein TG-interacting factor 1 (Tgif1) impairs osteoblast differentiation and activity, leading to a reduced bone formation. Deletion of Tgif1 in osteoblasts and osteocytes decreases bone resorption due to an increased secretion of Semaphorin 3E (Sema3E), an osteoclast-inhibiting factor. Tgif1 is a PTH target gene and PTH treatment failed to increase bone formation and bone mass in Tgif1-deficient mice. Thus, our study identifies Tgif1 as a novel regulator of bone remodeling and an essential component of the PTH anabolic action. These insights contribute to a better understanding of bone metabolism and the anabolic function of PTH.
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Project description:Despite advances in radiation delivery protocols, exposure of normal tissues during the course of radiation therapy remains a limiting factor of cancer treatment. If the canonical TGF-?/Smad pathway has been extensively studied and implicated in the development of radiation damage in various organs, the precise modalities of its activation following radiation exposure remain elusive. In the present study, we hypothesized that TGF-?1 signaling and target genes expression may depend on radiation-induced modifications in Smad transcriptional co-repressors/inhibitors expressions (TGIF1, SnoN, Ski and Smad7). In endothelial cells (HUVECs) and in a model of experimental radiation enteropathy in mice, radiation exposure increases expression of TGF-?/Smad pathway and of its target gene PAI-1, together with the overexpression of Smad co-repressor TGIF1. In mice, TGIF1 deficiency is not associated with changes in the expression of radiation-induced TGF-? pathway-related transcripts following localized small intestinal irradiation. In HUVECs, TGIF1 overexpression or silencing has no influence either on the radiation-induced Smad activation or the Smad3-dependent PAI-1 overexpression. However, TGIF1 genetic deficiency sensitizes mice to radiation-induced intestinal damage after total body or localized small intestinal radiation exposure, demonstrating that TGIF1 plays a role in radiation-induced intestinal injury. In conclusion, the TGF-?/Smad co-repressor TGIF1 plays a role in radiation-induced normal tissue damage by a Smad-independent mechanism.
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Project description:In Arabidopsis thaliana, the basic Helix Loop Helix transcription factor, PHYTOCHROME INTERACTING FACTOR1 (PIF1) is known to orchestrate the seed transcriptome such that, ultimately, proteins repressing the completion of germination are produced in darkness. While PIF1-mediated control of abscisic acid (ABA) and gibberellic acid (GA) anabolism/catabolism is indirect, PIF1 action favors ABA while discriminating against GA, firmly establishing ABA's repressive influence on the completion of germination. The result is tissue that is more sensitive to and producing more ABA; and is less responsive to and deficient in GA. Illumination of the appropriate wavelength activates phytochrome which enters the nucleus, and binds to PIF1, initiating PIF1's phosphorylation by diverse kinases, subsequent polyubiquitination, and hydrolysis. One mechanism by which phosphorylated PIF1 is eliminated from the cells of the seed upon illumination involves an F-BOX protein, COLD TEMPERATURE GERMINATING10 (CTG10). Discovered in an unbiased screen of activation tagged lines hastening the completion of seed germination at 10°C, one indirect consequence of CTG10 action in reducing PIF1 titer, should be to enhance the transcription of genes whose products work to increase bioactive GA titer, shifting the intracellular milieu from one that is repressive to, toward one conducive to, the completion of seed germination. We have tested this hypothesis using a variety of Arabidopsis lines altered in CTG10 amounts. Here we demonstrate using bimolecular fluorescence complementation that PIF1 interacts with CTG10 and show that, in light exposed seeds, PIF1 is more persistent in ctg10 relative to WT seeds while it is less stable in seeds over-expressing CTG10. These results are congruent with the relative transcript abundance from three genes whose products are involved in bioactive GA accumulation. We put forth a model of how PIF1 interactions in imbibed seeds change during germination and how a permissive light signal influences these changes, leading to the completion of germination of these positively photoblastic propagules.
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Project description:TG-interacting factor (TGIF) is a transcriptional co-repressor that directly associates with Smad (Sma- and Mad-related protein) proteins and inhibits Smad-mediated transcriptional activation. By using Affymetrix (Santa Clara, CA, U.S.A.) oligonucleotide microarray analysis, we found that TGIF mRNA level was elevated by transforming-growth-factor-beta (TGF-beta) treatment in a human T-cell line, HuT78. Subsequent reverse-transcription PCR assays indicated that TGF-beta1 and activin were able to induce a rapid and transient increase in the level of TGIF in both HuT78 and HepG2 hepatoma cells. To analyse whether or not the regulation of TGIF mRNA occurs at the transcriptional level, a 2.4 kb human TGIF promoter was isolated. A primer extension assay was performed to localize the putative transcription initiation site of the promoter. When transiently expressed in HepG2 cells, this promoter was stimulated by TGF-beta1 and activin treatment in a time-dependent manner. A series of deletion mutants of the TGIF promoter were also generated to further characterize the TGF-beta responsive region of the promoter. In addition, expression of TGIF was able to cause a dose-dependent inhibition of TGF-beta and activin signalling. Taken together, these experiments indicated that TGIF is a novel transcriptional target of TGF-beta and activin signalling and is likely involved in a negative feedback loop to desensitize TGF-beta/activin action.
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