A general transcription co-factor, Smad3, potentiates master transcription factor mediated cell identity conversions
Ontology highlight
ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE85178 | GEO | 2017/11/02
SECONDARY ACCESSION(S): PRJNA336438
REPOSITORIES: GEO
Similar Datasets
Project description:We have identified that expression of constitutive active Smad3 (Smad3CA) significantly enhanced reprogramming by Oct4, Sox2, Klf4, c-Myc. Smad3 is known to interact with several master transcription factors and boost their activity during development. Therefore, we hypothesized that Smad3CA is recruited to Oct4 binding sites during reprogramming. To test this hypothesis, we investigated genome-wide Smad3 binding sites in the presence and absence of reprogramming factor expression.
2017-11-03 | GSE85177 | GEO
Project description:We have identified that expression of constitutive active Smad3 (Smad3CA) significantly enhanced reprogramming by Oct4, Sox2, Klf4, c-Myc. To investigate how Smad3CA expression impacts on chromatin opening, we performed ATAC-seq on day 3 of reprogramming in the presence or absence of Smad3CA expression.
2017-11-03 | GSE85175 | GEO
Project description:A general transcription co-factor, Smad3, potentiates master transcription factor mediated cell identity conversions
| PRJNA336438 | ENA
Project description:The exogenous expression of master transcription factors (TFs) is a powerful and exciting approach to convert cellular identity. Yet, the generation of desired cell types is often plagued by inefficiency, slow kinetics and inability to produce mature cell types. Through investigations of the molecular mechanisms of induced plurpipotent stem cell generation, we discovered that expression of constitutively active Smad2/3 (Smad2CA/3CA), together with the Yamanaka factors, could dramatically improve the efficiency and kinetics of reprogramming. Mechanistically, SMAD3 interacted with both co-activators and reprogramming factors, bridging their interaction during reprogramming. Fascinatingly, SMAD2/3 interact with a multitude of master TFs in different cell types, and conversions of B cells to macrophages, myoblasts to adipocytes, and human fibroblasts to neurons were also markedly enhanced when their master TFs were co-expressed with Smad3CA. These results revealed the existence of shared molecular mechanisms underlying diverse TF-mediated cellular conversions, and demonstrated SMAD2/3 as a widely applicable booster.
2017-11-03 | GSE72596 | GEO
Project description:BackgroundHIV-1 does not encode a helicase and hijacks those of the cell for efficient replication. We and others previously showed that the DEAD box helicase, DDX5, is an essential HIV dependency factor. DDX5 was recently shown to be associated with the 7SK snRNP. Cellular positive transcription elongation factor b (P-TEFb) is bound in an inactive form with HEXIM1/2 on 7SK snRNP. The Tat/P-TEFb complex is essential for efficient processivity of Pol II in HIV-1 transcription elongation and Tat competes with HEXIM1/2 for P-TEFb. We investigated the precise role of DDX5 in HIV replication using siRNA mediated knockdown and rescue with DDX5 mutants which prevent protein-protein interactions and RNA and ATP binding.ResultsWe demonstrate a critical role for DDX5 in the Tat/HEXIM1 interaction. DDX5 acts to potentiate Tat activity and can bind both Tat and HEXIM1 suggesting it may facilitate the dissociation of HEXIM1/2 from the 7SK-snRNP complex, enhancing Tat/P-TEFb availability. We show knockdown of DDX5 in a T cell line significantly reduces HIV-1 infectivity and viral protein production. This activity is unique to DDX5 and cannot be substituted by its close paralog DDX17. Overexpression of DDX5 stimulates the Tat/LTR promoter but suppresses other cellular and viral promoters. Individual mutations of conserved ATP binding, RNA binding, helicase related or protein binding motifs within DDX5 show that the N terminal RNA binding motifs, the Walker B and the glycine doublet motifs are essential for this function. The Walker A and RNA binding motifs situated on the transactivation domain are however dispensable.ConclusionDDX5 is an essential cellular factor for efficient HIV transcription elongation. It interacts with Tat and may potentiate the availability of P-TEFb through sequestering HEXIM1.
| S-EPMC7106839 | biostudies-literature
Project description:Tissue-specific gene expression requires modulation of nucleosomes, allowing transcription factors to occupy cis elements that are accessible only in selected tissues. Master transcription factors control cell-specific genes and define cellular identities, but it is unclear if they possess special abilities to regulate cell-specific chromatin and if such abilities might underlie lineage determination and maintenance. One prevailing view is that several transcription factors enable chromatin access in combination. The homeodomain protein CDX2 specifies the embryonic intestinal epithelium, through unknown mechanisms, and partners with transcription factors such as HNF4A in the adult intestine. We examined enhancer chromatin and gene expression following Cdx2 or Hnf4a excision in mouse intestines. HNF4A loss did not affect CDX2 binding or chromatin, whereas CDX2 depletion modified chromatin significantly at CDX2-bound enhancers, disrupted HNF4A occupancy, and abrogated expression of neighboring genes. Thus, CDX2 maintains transcription-permissive chromatin, illustrating a powerful and dominant effect on enhancer configuration in an adult tissue. Similar, hierarchical control of cell-specific chromatin states is probably a general property of master transcription factors.
| S-EPMC3554120 | biostudies-literature
Project description:Master transcription factors Oct4, Sox2, and Nanog bind enhancer elements and recruit Mediator to activate much of the gene expression program of pluripotent embryonic stem cells (ESCs). We report here that the ESC master transcription factors form unusual enhancer domains at most genes that control the pluripotent state. These domains, which we call super-enhancers, consist of clusters of enhancers that are densely occupied by the master regulators and Mediator. Super-enhancers differ from typical enhancers in size, transcription factor density and content, ability to activate transcription, and sensitivity to perturbation. Reduced levels of Oct4 or Mediator cause preferential loss of expression of super-enhancer-associated genes relative to other genes, suggesting how changes in gene expression programs might be accomplished during development. In other more differentiated cells, super-enhancers containing cell-type-specific master transcription factors are also found at genes that define cell identity. Super-enhancers thus play key roles in the control of mammalian cell identity.
| S-EPMC3653129 | biostudies-literature
Project description:At face value, the Sin3 histone deacetylase (HDAC) complex appears to be a prototypical co-repressor complex, that is, a multi-protein complex recruited to chromatin by DNA bound repressor proteins to facilitate local histone deacetylation and transcriptional repression. While this is almost certainly part of its role, Sin3 stubbornly refuses to be pigeon-holed in quite this way. Genome-wide mapping studies have found that Sin3 localises predominantly to the promoters of actively transcribed genes. While Sin3 knockout studies in various species result in a combination of both up- and down-regulated genes. Furthermore, genes such as the stem cell factor, Nanog, are dependent on the direct association of Sin3 for active transcription to occur. Sin3 appears to have properties of a co-repressor, co-activator and general transcription factor, and has thus been termed a co-regulator complex. Through a series of unique domains, Sin3 is able to assemble HDAC1/2, chromatin adaptors and transcription factors in a series of functionally and compositionally distinct complexes to modify chromatin at both gene-specific and global levels. Unsurprisingly, therefore, Sin3/HDAC1 have been implicated in the regulation of numerous cellular processes, including mammalian development, maintenance of pluripotency, cell cycle regulation and diseases such as cancer.
| S-EPMC6295471 | biostudies-literature
Project description:Several members of the SMAD family of transcription factors have been reported to bind RNA in addition to their canonical double-stranded DNA (dsDNA) ligand. RNA binding by SMAD has the potential to affect numerous cellular functions that involve RNA. However, the affinity and specificity of this RNA binding activity has not been well characterized, which limits the ability to validate and extrapolate functional implications of this activity. Here we perform quantitative binding experiments in vitro to determine the ligand requirements for RNA binding by SMAD3. We find that SMAD3 binds poorly to single- and double-stranded RNA, regardless of sequence. However, SMAD3 binds RNA with large internal loops or bulges with high apparent affinity. This apparent affinity matches that for its canonical dsDNA ligand, suggesting a biological role for RNA binding by SMAD3.
| S-EPMC5714123 | biostudies-literature
Project description:?S is a master transcription initiation factor that protects bacterial cells from various harmful environmental stresses including antibiotic pressure. Although its mechanism remains unclear, it is known that full activation of ?S-mediated transcription requires a ?S-specific activator, Crl. In this study, we determined a 3.80 Å cryo-EM structure of an Escherichia coli transcription activation complex (E. coli Crl-TAC) comprising E. coli ?S-RNA polymerase (?S-RNAP) holoenzyme, Crl, and a nucleic-acid scaffold. The structure reveals that Crl interacts with domain 2 of ?S (?S2) and the RNAP core enzyme, but does not contact promoter DNA. Results from subsequent hydrogen-deuterium exchange mass spectrometry (HDX-MS) indicate that Crl stabilizes key structural motifs within ?S2 to promote the assembly of the ?S-RNAP holoenzyme and also to facilitate formation of an RNA polymerase-promoter DNA open complex (RPo). Our study demonstrates a unique DNA contact-independent mechanism of transcription activation, thereby defining a previously unrecognized mode of transcription activation in cells.
| S-EPMC6917491 | biostudies-literature