The Experts below are selected from a list of 4992 Experts worldwide ranked by ideXlab platform
Richard Treisman - One of the best experts on this subject based on the ideXlab platform.
-
ERK-Induced Activation of TCF Family of SRF CoFactors Initiates a Chromatin Modification Cascade Associated with Transcription.
Molecular Cell, 2017Co-Authors: Cyril Esnault, Francesco Gualdrini, Stuart Horswell, Gavin Kelly, Aengus Stewart, Phil East, Nik Matthews, Richard TreismanAbstract:We investigated the relationship among ERK signaling, histone modifications, and transcription Factor activity, focusing on the ERK-regulated Ternary Complex Factor family of SRF partner proteins. In MEFs, activation of ERK by TPA stimulation induced a common pattern of H3K9acS10ph, H4K16ac, H3K27ac, H3K9acK14ac, and H3K4me3 at hundreds of transcription start site (TSS) regions and remote regulatory sites. The magnitude of the increase in histone modification correlated well with changes in transcription. H3K9acS10ph preceded the other modifications. Most induced changes were TCF dependent, but TCF-independent TSSs exhibited the same hierarchy, indicating that it reflects gene activation per se. Studies with TCF Elk-1 mutants showed that TCF-dependent ERK-induced histone modifications required Elk-1 to be phosphorylated and competent to activate transcription. Analysis of direct TCF-SRF target genes and chromatin modifiers confirmed this and showed that H3S10ph required only Elk-1 phosphorylation. Induction of histone modifications following ERK stimulation is thus directed by transcription Factor activation and transcription.
-
MAL and Ternary Complex Factor Use Different Mechanisms To Contact a Common Surface on the Serum Response Factor DNA-Binding Domain
Molecular and cellular biology, 2006Co-Authors: Alexia-ileana Zaromytidou, Francesc Miralles, Richard TreismanAbstract:The transcription Factor serum response Factor (SRF) interacts with its coFactor, MAL/MKL1, a member of the myocardin-related transcription Factor (MRTF) family, through its DNA-binding domain. We define a seven-residue sequence within the conserved MAL B1 region essential and sufficient for Complex formation. The neighboring Q-box sequence facilitates this interaction. The B1 and Q-box regions also have antagonistic effects on MAL nuclear import, but the residues involved are largely distinct. Both MAL and the Ternary Complex Factor (TCF) family of SRF coFactors interact with a hydrophobic groove and pocket on the SRF DNA-binding domain. Unlike the TCFs, however, interaction of MAL with SRF is impaired by SRF alphaI-helix mutations that reduce DNA bending in the SRF-DNA Complex. A clustered SRF alphaI-helix mutation strongly impairs MAL-SRF Complex formation but does not affect DNA distortion in the MAL-SRF Complex. MAL-SRF Complex formation is facilitated by DNA binding. DNase I footprinting indicates that in the SRF-MAL Complex MAL directly contacts DNA. These contacts, which flank the DNA sequences protected from DNase I by SRF, are required for effective MAL-SRF Complex formation in gel mobility shift assays. We propose a model of MAL-SRF Complex formation in which MAL interacts with SRF by the addition of a beta-strand to the SRF DNA-binding domain beta-sheet region, while SRF-induced DNA bending facilitates MAL-DNA contact.
-
mal and Ternary Complex Factor use different mechanisms to contact a common surface on the serum response Factor dna binding domain
Molecular and Cellular Biology, 2006Co-Authors: Alexia-ileana Zaromytidou, Francesc Miralles, Richard TreismanAbstract:Serum response Factor (SRF) is a prototype of the MADS (Mcm1, Agamous, Deficiens, SRF) family of eukaryotic transcription Factors, which play important roles in the specification of cell identity during development and differentiation (22, 31). SRF interacts directly with at least two families of signal-regulated coFactors. The Ternary Complex Factor (TCF) family of Ets domain proteins, Elk-1, SAP-1, and Net, which respond to mitogen-activated protein kinase signaling, bind to both SRF and adjacent DNA sequences (34). In contrast, members of the myocardin-related transcription Factor (MRTF) coactivator family (MAL/MKL1/MRTFa, MAL16/MKL2/MRTFb, and myocardin) apparently bind SRF without making specific DNA contacts (17, 21, 27, 36, 37). MAL and MAL16 respond to Rho-actin signaling, while activation by myocardin is apparently constitutive (5, 23, 28, 36). The best-characterized MADS box regulatory Complexes are those formed by SRF and its Saccharomyces cerevisiae relative, Mcm1. In each case, the MADS protein forms a three-layered structure comprising the 56-residue MADS box motif and its C-terminal flanking sequences (8, 26, 32). A long coiled-coil at the core of the MADS box dimer straddles the DNA minor groove, making sequence-specific major groove contacts at each side, and inserting its N-terminal extension into the minor groove. Above lies a four-stranded antiparallel β-sheet platform derived from the C-terminal sequences of each MADS motif. The third layer is structurally variable, being formed from subfamily-specific sequences C terminal to the MADS box and is required for high-affinity dimerization. Interaction of TCF with SRF is mediated by the 20-residue B-box sequence (6, 9, 15, 30), while the MATα2-Mcm1 interaction involves an unrelated eight-residue sequence (20, 35). Each coFactor adds an extra β-strand to the MADS box β-sheet platform, albeit in opposite polarity in the two Complexes, inserting an aromatic side chain into a hydrophobic pocket in the third layer of the DNA binding structure (8, 16, 32). The mechanism of MRTF-SRF interaction is poorly understood. Complex formation requires the basic B1 region, also important for nuclear import, and the Q-box, a glutamine-rich sequence C terminal to it (23, 36, 39). Functional and biochemical assays suggest that the SRF surfaces contacted by the MRTFs and TCFs overlap (23, 24, 39), and it has been proposed that the Q box mediates myocardin-SRF interaction via the same mechanism as TCF (39). Two observations suggest that MRTF-SRF and TCF-SRF interactions differ significantly, however: an altered DNA binding specificity SRF derivative can recruit TCF, but not MAL, to DNA (9, 23), and functional studies suggest that the SRF DNA-binding domain must contact DNA to respond to Rho signaling (10). In this paper we analyze MAL-SRF Complex formation in detail and identify a short sequence within the B1 region necessary and sufficient for specific interaction with SRF. We show that DNA binding and distortion is necessary for optimal interaction between SRF and MAL, which directly contacts DNA flanking the SRF binding site in the Complex.
-
Ternary Complex Factor SAP-1 is required for Erk-mediated thymocyte positive selection
Nature Immunology, 2004Co-Authors: Patrick S Costello, Robert H Nicolas, Yasuyuki Watanabe, Ian Rosewell, Richard TreismanAbstract:Thymocyte selection and differentiation requires extracellular signal–regulated kinase (Erk) signaling, but transcription Factor substrates of Erk in thymocytes are unknown. We have characterized the function of SAP-1 ( Elk4 ), an Erk-regulated transcription Factor, in thymocyte development. Early thymocyte development was normal, but single-positive thymocyte and peripheral T cell numbers were reduced, reflecting a T cell–autonomous defect. T cell receptor–induced activation of SAP-1 target genes such as Egr1 was substantially impaired in double-positive thymocytes, although Erk activation was normal. Analysis of T cell receptor transgenes showed that positive selection was reduced by 80–90% in SAP-1-deficient mice; heterozygous mice showed a moderate defect. Negative selection was unimpaired. SAP-1 thus directly links Erk signaling to the transcriptional events required for thymocyte positive selection.
-
the p38 and erk map kinase pathways cooperate to activate Ternary Complex Factors and c fos transcription in response to uv light
The EMBO Journal, 1996Co-Authors: M A Price, F H Cruzalegui, Richard TreismanAbstract:We investigated the activation of c-fos transcription following UV irradiation, a 'stress' stimulus. In both HeLa TK- and NIH 3T3 cells the Serum Response Element is required for efficient UV-induced c-fos transcription, and in HeLa TK- cells the Ternary Complex Factor (TCF) binding site contributes substantially to activation. Consistent with this, UV irradiation activates LexA-TCF fusion proteins more strongly in HeLa TK- than in NIH 3T3 cells. The TCF C-termini of the TCFs are substrates for UV-induced MAP kinases: both the Elk-1 and SAP-1a C-termini are efficiently phosphorylated by the p38 MAPK, but only the Elk-1 C-terminus is a good substrate for the SAPK/JNKs. The specificity and activation kinetics of TCF C-terminal kinases, and the susceptibility of transcriptional activation by LexA-TCF fusion proteins to specific inhibitors of different MAPK pathways, show that both the ERK and p38 MAPK pathways contribute to TCF activation in response to UV irradiation. Activity of both these pathways is also required for the response of the c-fos gene itself to UV stimulation.
Bohdan Wasylyk - One of the best experts on this subject based on the ideXlab platform.
-
Complexity in transcription control at the activation domain-mediator interface.
Science Signaling, 2009Co-Authors: Michael Balamotis, Bohdan Wasylyk, Mario Pennella, Jennitte Stevens, Andrew Belmont, Arnold BerkAbstract:Transcript elongation by polymerase II paused at the Egr1 promoter is activated by mitogen-activated protein kinase phosphorylation of the Ternary Complex Factor (TCF) ELK1 bound at multiple upstream sites and subsequent phospho-ELK1 interaction with mediator through the MED23 subunit. Consequently, Med23 knockout (KO) nearly eliminates Egr1 (early growth response Factor 1) transcription in embryonic stem (ES) cells, leaving a paused polymerase at the promoter. Med23 KO did not, however, eliminate Egr1 transcription in fibroblasts. Chromatin immunoprecipitation analysis and direct visualization of fluorescently labeled TCF derivatives and mediator subunits revealed that three closely related TCFs bound to the same control regions. The relative amounts of these TCFs, which responded differently to the loss of MED23, differed in ES cells and fibroblasts. Transcriptome analysis suggests that most genes expressed in both cell types, such as Egr1, are regulated by alternative transcription Factors in the two cell types that respond differently to the same signal transduction pathways.
-
the Ternary Complex Factor net elk 3 participates in the transcriptional response to hypoxia and regulates hif 1α
Oncogene, 2008Co-Authors: Christian E. Gross, H Duboispot, Bohdan WasylykAbstract:The Ternary Complex Factor Net/Elk3 is downregulated in hypoxia and participates in the induction by hypoxia of several genes, including c-fos, vascular endothelial growth Factor and egr-1. However, the global role of Net in hypoxia remains to be elucidated. We have identified, in a large-scale analysis of RNA expression using microarrays, more than 370 genes that are regulated by Net in hypoxia. In order to gain insights into the role of Net in hypoxia, we have analysed in parallel the genes regulated by HIF-1α, the classical Factor involved in the response to hypoxia. We identified about 190 genes that are regulated by HIF-1α in hypoxia. Surprisingly, when we compare the genes induced by hypoxia that require either Net or HIF-1α, the majority are the same (75%), suggesting that the functions of both Factors are closely linked. Interestingly, in hypoxia, Net regulates the expression of several genes known to control HIF-1α stability, including PHD2, PHD3 and Siah2, suggesting that Net regulates the stability of HIF-1α. We found that inhibition of Net by RNAi leads to decreased HIF-1α expression at the protein level in hypoxia. These results indicate that Net participates in the transcriptional response to hypoxia by regulation of HIF-1α protein stability.
-
The Ternary Complex Factor Net/Elk-3 participates in the transcriptional response to hypoxia and regulates HIF-1α
Oncogene, 2007Co-Authors: Christian E. Gross, H Dubois-pot, Bohdan WasylykAbstract:The Ternary Complex Factor Net/Elk3 is downregulated in hypoxia and participates in the induction by hypoxia of several genes, including c-fos, vascular endothelial growth Factor and egr-1. However, the global role of Net in hypoxia remains to be elucidated. We have identified, in a large-scale analysis of RNA expression using microarrays, more than 370 genes that are regulated by Net in hypoxia. In order to gain insights into the role of Net in hypoxia, we have analysed in parallel the genes regulated by HIF-1α, the classical Factor involved in the response to hypoxia. We identified about 190 genes that are regulated by HIF-1α in hypoxia. Surprisingly, when we compare the genes induced by hypoxia that require either Net or HIF-1α, the majority are the same (75%), suggesting that the functions of both Factors are closely linked. Interestingly, in hypoxia, Net regulates the expression of several genes known to control HIF-1α stability, including PHD2, PHD3 and Siah2, suggesting that Net regulates the stability of HIF-1α. We found that inhibition of Net by RNAi leads to decreased HIF-1α expression at the protein level in hypoxia. These results indicate that Net participates in the transcriptional response to hypoxia by regulation of HIF-1α protein stability.
-
The Ternary Complex Factor net is downregulated by hypoxia and regulates hypoxia-responsive genes.
Molecular and Cellular Biology, 2007Co-Authors: Christian Gross, Gilles Buchwalter, Hélène Dubois-pot, Emilie Cler, Hong Zheng, Bohdan WasylykAbstract:Hypoxia and the Net Ternary Complex Factor (TCF) regulate similar processes (angiogenesis, wound healing, and cellular migration) and genes (PAI-1, c-fos, erg-1, NOS-2, HO-1, and vascular endothelial growth Factor genes), suggesting that they are involved in related pathways. We show here that hypoxia regulates Net differently from the other TCFs and that Net plays a role in the hypoxic response in vivo in mice and in cells. Hypoxia induces Net depletion from target promoters, nuclear export, ubiquitylation, and proteasomal degradation. Key mediators of the hypoxic response, the prolyl-4-hydroxylases containing domain proteins (PHDs), regulate Net. PHD downregulation in normoxia leads to Net degradation, and PHD overexpression delays Net downregulation by hypoxia. Net inhibition by RNA interference or mutation leads to altered regulation by hypoxia of the Net targets PAI-1, c-fos, and egr-1. We propose that hypoxia stimulates transcription of target promoters through removal of the repressor function of Net. Interestingly, the hematocrit response to a chemical inducer of hypoxia-like responses (cobalt chloride) is strongly altered in Net mutant mice. Our results show that the Net TCF is part of the biological response to hypoxia, adding a new component to an important pathological and physiological process.
-
The Ternary Complex Factor Net regulates cell migration through inhibition of PAI-1 expression.
Molecular and Cellular Biology, 2005Co-Authors: Gilles Buchwalter, Christian Gross, Bohdan WasylykAbstract:Net, Elk-1, and Sap-1 are members of the Ternary Complex Factor (TCF) subfamily of Ets transcription Factors. They form Ternary Complexes with serum response Factor (SRF) on serum response elements of immediate early genes such as c-fos and egr-1 and mediate responses to growth Factors and mitogen-activated protein kinase signaling. Although the TCFs have been extensively studied as intermediates in signaling cascades, surprisingly little is known about their different target genes and physiological functions. We report that Net homozygous mutant mouse embryonic fibroblasts have a defect in cell migration. This defect results at least in part from increased expression of plasminogen activator inhibitor type 1 (PAI-1), a serine protease inhibitor (serpin) that controls extracellular proteolysis and cell matrix adhesion. The defect in cell migration can be reverted by the addition of a PAI-1 blocking antibody. Net represses PAI-1 promoter activity and binds to a specific region of the promoter containing Ets binding sites in the absence of SRF. We conclude that Net is a negative regulator of PAI-1 expression and is thereby involved in cell migration.
Gerald Thiel - One of the best experts on this subject based on the ideXlab platform.
-
the super cooling compound icilin stimulates c fos and egr 1 expression and activity involving trpm8 channel activation ca2 ion influx and activation of the Ternary Complex Factor elk 1
Biochemical Pharmacology, 2020Co-Authors: Myriam Ulrich, Ulrich Wissenbach, Gerald ThielAbstract:The TRPM8 cation channel can be activated by the cooling compound icilin. Recently, we showed that stimulation of TRPM8 channels induces a signaling cascade leading to the activation of the transcription Factor AP-1. Additionally, expression of the AP-1 constituent c-Fos has been shown to be induced following TRPM8 stimulation. c-Fos is frequently used as a marker for neuronal activity. Here, we have analyzed the mechanism connecting TRPM8 stimulation and c-Fos expression. Furthermore, we analyzed the expression of the neuronal activity-responsive transcription Factor Egr-1 following TRPM8 activation. The results show that icilin-induced stimulation of TRPM8 channels increased c-Fos promoter activity and induced c-Fos expression. Moreover, icilin stimulation increased Egr-1 promoter activity and induced the expression of Egr-1. Pharmacological inhibition of TRPM8 blocked the icilin-induced expression of Egr-1 and c-Fos. An influx of Ca2+ ions into the cells via TRPM8 was necessary to stimulate Egr-1 and c-Fos expression following icilin treatment. Genetic experiments revealed that serum response elements within the Egr-1 and c-Fos promoters are crucial to couple TRPM8 stimulation with enhanced transcription of both the Egr-1 and c-Fos genes. These data were corroborated by experiments showing that TRPM8 stimulation increased the transcriptional activation potential of Elk-1, a SRE binding protein. c-Fos is important for neuronal excitability and survival. Egr-1 plays an important role in synaptic plasticity, consolidation and reconsolidation of long-term memory. Elk-1 may preserve neurons against toxic insults but may also induce depressive behaviour. The fact that TRPM8 stimulation activates the transcription Factors c-Fos, Egr-1, and Elk-1 connects TRPM8 signaling with maintaining important brain functions.
-
Ternary Complex Factor regulates pancreatic islet size and blood glucose homeostasis in transgenic mice.
Pharmacological research, 2020Co-Authors: Andrea Lesch, Oliver G. Rössler, Tobias M. Backes, Daniel S. Langfermann, Matthias W. Laschke, Gerald ThielAbstract:Abstract A hallmark of diabetes mellitus is the inability of pancreatic β-cells to secrete sufficient amounts of insulin for maintaining normoglycemia. The formation of smaller islets may underlie the development of a diabetic phenotype, as a decreased β-cell mass will produce an insufficient amount of insulin. For a pharmacological intervention it is crucial to identify the proteins determining β-cell mass. Here, we identified the Ternary Complex Factor (TCF) Elk-1 as a regulator of the size of pancreatic islets. Elk-1 mediates, together with a dimer of the serum-response Factor (SRF), serum response element-regulated gene transcription. Elk-1 is activated in glucose-treated pancreatic β-cells but the biological functions of this protein in β-cells are so far unknown. Elk-1 and homologous TCF proteins are expressed in islets and insulinoma cells. Gene targeting experiments revealed that the TCF proteins show redundant activities. To solve the problem of functional redundancy of these homologous proteins, we generated conditional transgenic mice expressing a dominant-negative mutant of Elk-1 in pancreatic β-cells. The mutant competes with the wild-type TCFs for DNA and SRF-binding. Expression of the Elk-1 mutant in pancreatic β-cells resulted in the generation of significantly smaller islets and increased caspase-3 activity, indicating that apoptosis was responsible for the reduction of the pancreatic islet size. Glucose tolerance tests revealed that transgenic mice expressing the dominant-negative mutant of Elk-1 in pancreatic β-cells displayed impaired glucose tolerance. Thus, we show here for the first time that TCF controls important functions of pancreatic β-cells in vivo. Elk-1 may be considered as a new therapeutic target for the treatment of diabetes.
-
Stimulation of transient receptor potential M3 (TRPM3) channels increases interleukin-8 gene promoter activity involving AP-1 and extracellular signal-regulated protein kinase
Cytokine, 2017Co-Authors: Sandra Rubil, Andrea Lesch, Naofumi Mukaida, Gerald ThielAbstract:Abstract Stimulation of Ca 2+ permeable TRPM3 (transient receptor potential melastatin-3) channels with the steroid ligand pregnenolone sulfate activates stimulus-responsive transcription Factors, including the transcription Factor AP-1 (activator protein-1). As part of a search for AP-1-regulated target genes we analyzed the gene encoding interleukin-8 (IL-8) in HEK293 cells expressing TRPM3 channels. Here, we show that stimulation of TRPM3 channels activated transcription of an IL-8 promoter-controlled reporter gene that was embedded into the chromatin of the cells. Mutational analysis of the IL-8 promoter revealed that the AP-1 binding site of the IL-8 promoter was essential to connect TRPM3 stimulation with the transcription of the IL-8 gene. Genetic experiments revealed that the basic region leucine zipper proteins c-Jun and ATF2 and the Ternary Complex Factor Elk-1 are essential to couple TRPM3 channel stimulation with the IL-8 gene. Moreover, we identified extracellular signal-regulated protein kinase (ERK1/2) as signal transducer connecting TRPM3 stimulation with enhanced transcription of the IL-8 gene. Furthermore, we show that stimulation of TRPC6 (transient receptor potential canonical-6) channels with its ligand hyperforin also increased IL-8 promoter activity, involving the AP-1 binding site within the IL-8 gene, suggesting that activation of IL-8 gene transcription may be a common theme following TRP channel stimulation.
-
Hyperforin activates gene transcription involving transient receptor potential C6 channels.
Biochemical pharmacology, 2017Co-Authors: Gerald Thiel, Oliver G. RösslerAbstract:Hypericum perforatum is one of the most prominent medical plants. Hyperforin, a main ingredient of H. perforatum, has been shown to activate transient receptor potential canonical C6 (TRPC6) channels. Alternatively, it has been proposed that hyperforin functions as a protonophore in a TRPC6-independent manner. Here, we show that hyperforin stimulation activates the transcription Factor AP-1 in HEK293 cells expressing TRPC6 (T6.11 cells), but did not substantially change the AP-1 activity in HEK293 cells lacking TRPC6. We identified the AP-1 binding site as a hyperforin-responsive element. AP-1 is composed of the transcription Factors c-Jun and c-Fos, or other members of the c-Jun and c-Fos families of proteins. Hyperforin stimulation increased c-Jun and c-Fos promoter activities in T6.11 cells and induced an upregulation of c-Jun and c-Fos biosynthesis. The analysis of the c-Fos promoter revealed that the cAMP-response element also functions as a hyperforin-responsive element. Hyperforin-induced upregulation of AP-1 in T6.11 cells was attenuated by preincubation of the cells with either pregnenolone or progesterone, indicating that gene regulation via TRPC6 is under control of hormones or hormonal precursors. The signal transduction of hyperforin-induced AP-1 gene transcription required an influx of Ca2+ ions into the cells, the activation of MAP kinases, and the activation of the transcription Factors c-Jun and Ternary Complex Factor. We conclude that hyperforin regulates gene transcription via activation of TRPC6 channels, involving stimulus-regulated protein kinases and stimulus-responsive transcription Factors. The fact that hyperforin regulates gene transcription may explain many of the intracellular alterations induced by this compound.
-
Transient Receptor Potential Melastatin-3 (TRPM3)–Induced Activation of AP-1 Requires Ca2+ Ions and the Transcription Factors c-Jun, ATF2, and Ternary Complex Factor
Molecular Pharmacology, 2015Co-Authors: Andrea Lesch, Peter Lipp, Gerald ThielAbstract:The steroid pregnenolone sulfate activates the transcription Factor activator protein-1 (AP-1) via stimulation of transient receptor potential melastatin-3 (TRPM3) channels. Here, we show that the signaling pathway requires an influx of Ca2+ ions into the cells and a rise in the intracellular Ca2+ levels. The upregulation of AP-1 was attenuated in cells that overexpressed mitogen activated protein kinase phosphatase–1, indicating that Ca2+ ions prolong the signaling cascade via activation of mitogen activated protein kinases. On the transcriptional level, expression of a dominant-negative mutant of the basic region leucine zipper protein c-Jun, a major constituent of the AP-1 transcription Factor Complex, or expression of a c-Jun–specific short hairpin RNA attenuated pregnenolone sulfate–induced AP-1 activation. In addition, stimulation of TRPM3 channels increased the transcriptional activation potential of the basic region leucine zipper protein ATF2. Inhibition of ATF2 target gene expression via expression of a dominant-negative mutant of ATF2 or expression of an ATF2-specific short hairpin RNA interfered with TRPM3-mediated stimulation of AP-1. Moreover, we show that a dominant-negative mutant of the Ternary Complex Factor (TCF) Elk-1 attenuated the upregulation of AP-1 following stimulation of TRPM3 channels. Thus, c-Jun, ATF2, and TCFs are required to connect the intracellular signaling cascade elicited by activation of TRPM3 channels with enhanced transcription of AP-1–regulated genes. We conclude that pregnenolone sulfate–induced TRPM3 channel activation changes the gene expression pattern of the cells by activating transcription of c-Jun-, ATF2-, and TCF-controlled genes.
M A Price - One of the best experts on this subject based on the ideXlab platform.
-
the p38 and erk map kinase pathways cooperate to activate Ternary Complex Factors and c fos transcription in response to uv light
The EMBO Journal, 1996Co-Authors: M A Price, F H Cruzalegui, Richard TreismanAbstract:We investigated the activation of c-fos transcription following UV irradiation, a 'stress' stimulus. In both HeLa TK- and NIH 3T3 cells the Serum Response Element is required for efficient UV-induced c-fos transcription, and in HeLa TK- cells the Ternary Complex Factor (TCF) binding site contributes substantially to activation. Consistent with this, UV irradiation activates LexA-TCF fusion proteins more strongly in HeLa TK- than in NIH 3T3 cells. The TCF C-termini of the TCFs are substrates for UV-induced MAP kinases: both the Elk-1 and SAP-1a C-termini are efficiently phosphorylated by the p38 MAPK, but only the Elk-1 C-terminus is a good substrate for the SAPK/JNKs. The specificity and activation kinetics of TCF C-terminal kinases, and the susceptibility of transcriptional activation by LexA-TCF fusion proteins to specific inhibitors of different MAPK pathways, show that both the ERK and p38 MAPK pathways contribute to TCF activation in response to UV irradiation. Activity of both these pathways is also required for the response of the c-fos gene itself to UV stimulation.
-
comparative analysis of the Ternary Complex Factors elk 1 sap 1a and sap 2 erp net
The EMBO Journal, 1995Co-Authors: M A Price, A E Rogers, Richard TreismanAbstract:A transcription Factor Ternary Complex composed of Serum Response Factor (SRF) and Ternary Complex Factor (TCF) mediates the response of the c-fos Serum Response Element (SRE) to growth Factors and mitogens. Three Ets domain proteins, Elk-1, SAP-1 and ERP/NET, have been reported to have the properties of TCF. Here we compare Elk-1 and SAP-1a with the human ERP/NET homologue SAP-2. All three TCF RNAs are ubiquitously expressed at similar relative levels. All three proteins contain conserved regions that interact with SRF and the c-fos SRE with comparable efficiency, but in vitro Complex formation by SAP-2 is strongly inhibited by its C-terminal sequences. Similarly, only Elk-1 and SAP-1a efficiently bind the c-fos SRE in vivo; Ternary Complex formation by SAP-2 is weak and is substantially unaffected by serum stimulation or v-ras co-expression. All three TCFs contain C-terminal transcriptional activation domains that are phosphorylated following growth Factor stimulation. Activation requires conserved S/T-P motifs found in all the TCF family members. Each TCF activation domain can be phosphorylated in vitro by partially purified ERK2, and ERK activation in vivo is sufficient to potentiate transcriptional activation.
-
comparative analysis of the Ternary Complex Factors elk 1 sap 1a and sap 2 erp net
The EMBO Journal, 1995Co-Authors: M A Price, A E Rogers, Richard TreismanAbstract:Abstract A transcription Factor Ternary Complex composed of Serum Response Factor (SRF) and Ternary Complex Factor (TCF) mediates the response of the c-fos Serum Response Element (SRE) to growth Factors and mitogens. Three Ets domain proteins, Elk-1, SAP-1 and ERP/NET, have been reported to have the properties of TCF. Here we compare Elk-1 and SAP-1a with the human ERP/NET homologue SAP-2. All three TCF RNAs are ubiquitously expressed at similar relative levels. All three proteins contain conserved regions that interact with SRF and the c-fos SRE with comparable efficiency, but in vitro Complex formation by SAP-2 is strongly inhibited by its C-terminal sequences. Similarly, only Elk-1 and SAP-1a efficiently bind the c-fos SRE in vivo; Ternary Complex formation by SAP-2 is weak and is substantially unaffected by serum stimulation or v-ras co-expression. All three TCFs contain C-terminal transcriptional activation domains that are phosphorylated following growth Factor stimulation. Activation requires conserved S/T-P motifs found in all the TCF family members. Each TCF activation domain can be phosphorylated in vitro by partially purified ERK2, and ERK activation in vivo is sufficient to potentiate transcriptional activation.
-
Comparative analysis of the Ternary Complex Factors Elk-1, SAP-1a and SAP-2 (ERP/NET).
The EMBO journal, 1995Co-Authors: M A Price, A E Rogers, Richard TreismanAbstract:A transcription Factor Ternary Complex composed of Serum Response Factor (SRF) and Ternary Complex Factor (TCF) mediates the response of the c-fos Serum Response Element (SRE) to growth Factors and mitogens. Three Ets domain proteins, Elk-1, SAP-1 and ERP/NET, have been reported to have the properties of TCF. Here we compare Elk-1 and SAP-1a with the human ERP/NET homologue SAP-2. All three TCF RNAs are ubiquitously expressed at similar relative levels. All three proteins contain conserved regions that interact with SRF and the c-fos SRE with comparable efficiency, but in vitro Complex formation by SAP-2 is strongly inhibited by its C-terminal sequences. Similarly, only Elk-1 and SAP-1a efficiently bind the c-fos SRE in vivo; Ternary Complex formation by SAP-2 is weak and is substantially unaffected by serum stimulation or v-ras co-expression. All three TCFs contain C-terminal transcriptional activation domains that are phosphorylated following growth Factor stimulation. Activation requires conserved S/T-P motifs found in all the TCF family members. Each TCF activation domain can be phosphorylated in vitro by partially purified ERK2, and ERK activation in vivo is sufficient to potentiate transcriptional activation.
Alfred Nordheim - One of the best experts on this subject based on the ideXlab platform.
-
Tissue-specific expression of the Ets gene Xsap-1 during Xenopus laevis development.
Mechanisms of development, 2001Co-Authors: Oliver Nentwich, Frank E. Münchberg, Götz Frommer, Alfred NordheimAbstract:We report the cloning of Xenopus laevis Xsap-1 cDNA, encoding a member of the Ternary Complex Factor subfamily of ETS transcription Factors. The expression pattern of Xsap-1 was examined during Xenopus embryogenesis using whole-mount in situ hybridization. Spatial expression of Xsap-1 mRNA is first detected at the animal pole at the mid-blastula stage. During neurulation Xsap-1 is expressed in cells participating in neural tube formation, in the sensorial layer of the epidermal ectoderm, and in an anterior region of the ventral mesoderm. Later, Xsap-1 expression is observed in the eye, ear vesicle, branchial arches, heart, pronephros, in the somites, and the developing nervous system, such as fore-, mid-, and hindbrain as well as in the cranial ganglion X.
-
regulation of the c fos promoter by the Ternary Complex Factor sap 1a and its coactivator cbp
Oncogene, 1996Co-Authors: Ralf Janknecht, Alfred NordheimAbstract:The c-fos proto-oncogene is activated by a plethora of signals via the transcription Factors Sap-1a and CREB. Recently, the coactivator CBP has been demonstrated to act in concert with CREB when CREB is phosphorylated by protein kinase A. We show that CBP also binds directly to Sap-1a. While phosphorylation of Sap-1a by mitogen-activated protein kinases is not necessary for CBP/Sap-1a interaction, functional cooperation between these two proteins requires Sap-1a to become phosphorylated. CBP-antagonists impair Sap-1a-mediated transactivation. Similarly, the CBP antagonist E1A suppresses c-fos upregulation by phosphorylated CREB, indicating that CBP is a central component of c-fos regulation. Furthermore, CBP is phosphorylated by protein kinase A in vitro and the transactivation potential of the carboxy-terminal region of CBP is enhanced in the presence of active protein kinase A in vivo. Thus, CBP, in addition to CREB, is a target for cAMP-dependent signaling. However, combined phosphorylation of CBP by protein kinase A and mitogen-activated protein kinases appears to be non-cooperative, suggesting that CBP serves the function of a dampening integrator of two different signaling pathways.
-
The Transcription Factor TCF/Elk-1
Advances in Experimental Medicine and Biology, 1996Co-Authors: Judith M. Müller, Alfred Nordheim, Michael A. Cahill, Patrick A. BaeuerleAbstract:The Ternary Complex Factor (TCF) and the serum response Factor (SRF) are nuclear transcription Factors which are essential for efficient signal transduction via the serum response element SRE in the c-fos promoter. Their activation leads to a rapid induction of c-fos gene expression. Activation of mitogen-activated protein kinases (MAPK) by signalling cascades and subsequent TCF phosphorylation are known to be essential steps in this transcriptional activation.
-
activation of Ternary Complex Factor elk 1 by map kinases
The EMBO Journal, 1993Co-Authors: Ralf Janknecht, Wolfram H Ernst, Vera Pingoud, Alfred NordheimAbstract:Ternary Complex Factors (TCFs), one of which is Elk-1, have been implicated in mediation of c-fos induction. They have been shown to be phosphorylated by mitogen-activated protein kinases (MAPKs) in vitro. We demonstrate that recombinant Elk-1 is hyperphosphorylated in vivo upon joint overexpression of MAPKs and constitutively activated Raf-1 kinase, the latter serving as an indirect in vivo activator of MAPKs. This phosphorylation is accompanied by a conformational change and results in an elevated transactivation potential of Elk-1. Mutation of mapped in vivo phosphorylation sites, which are potential targets for MAPKs, reduced Elk-1-mediated transcription. Thus, MAPKs are very probably controlling Elk-1 activity by direct phosphorylation in vivo. Furthermore, Elk-1 was shown to stimulate transcription from both the c-fos serum response element and also from an Ets binding site. While binding of TCFs to the c-fos promoter is dependent on the serum response Factor, TCFs can autonomously interact with Ets binding sites. This indicates that TCFs may participate in the transcriptional regulation of two different sets of genes.
-
ets related protein elk 1 is homologous to the c fos regulatory Factor p62tcf
Nature, 1991Co-Authors: R A Hipskind, V N Rao, Christopher G Mueller, E S P Reddy, Alfred NordheimAbstract:A KEY event in the response of cells to proliferative signals is the rapid, transient induction of the c-fos proto-oncogene, which is mediated through the serum response element (SRE) in the fos promoter1–4. Genomic footprinting5,6 and transfection experi-ments7–9 suggest that this activation occurs through a Ternary Complex that includes the serum response Factor (SRF)10 and the Ternary Complex Factor p62 (ref. 7). Interaction of p62TCF with the SRF-SRE binary Complex requires a CAGGA tract immediately upstream of the SRE (ref. 7). Proteins of the ets proto-oncogene family bind to similar sequences11–13and we have found that a member of this family, Elk-1 (ref. 14), forms SRF-dependent Ternary Complexes with the SRE. Elk-1 and p62TCF have the same DNA sequence requirements and antibodies against Elk-1 block the binding of both proteins. Furthermore, we show that like p62TCF, Elk-1 forms Complexes with the yeast SRF-homologue MCM1 but not with yeast ARG80 (ref. 15). But ARG80 mutants that convey interaction with p62TCF can also form Complexes with Elk-1. The similarity, or even identity, between Elk-1 and p62TCF suggests a novel regulatory role for Ets proteins that is effected through interaction with other proteins, such as SRF. Furthermore, the possible involvement of an Ets protein in the control of c-fos has interesting implications for proto-oncogene cooperation in cellular growth control16.