Regulation and composition of activator protein 1 (AP-1) transcription factors controlling collagenase and c-Jun promoter activities

2001 ◽  
Vol 360 (3) ◽  
pp. 599-607 ◽  
Author(s):  
Lars STEINMÜLLER ◽  
Giuseppe CIBELLI ◽  
Jonathan R. MOLL ◽  
Charles VINSON ◽  
Gerald THIEL
Keyword(s):  
Transcription Factor ◽  
Transcription Factors ◽  
Promoter Activity ◽  
Leucine Zipper ◽  
Dominant Negative ◽  
Activator Protein 1 ◽  
Activator Protein ◽  
Extracellular Signal ◽  
Enhancer Binding Protein ◽  
Activating Transcription Factor

The activator protein 1 (AP-1) transcription factor is composed of heterodimers of the Fos/activating transcription factor (ATF) and Jun subfamilies of basic-region leucine-zipper (B-ZIP) proteins. In order to determine the identities of individual B-ZIP proteins in various AP-1 complexes we tested the effect of dominant-negative mutants to the B-ZIP proteins c-Fos, ATF2, ATF4 and CCAAT-enhancer-binding protein (C/EBP) on the activities of the collagenase and c-Jun promoters. These dominant-negative mutants inhibit DNA binding of wild-type B-ZIP proteins in a leucine-zipper-dependent fashion. Transcription of a collagenase promoter/reporter gene was induced in HepG2 hepatoma cells by expression of c-Fos and c-Jun, administration of PMA (‘TPA’) or by expression of a truncated form of MEK (mitogen-activated/extracellular-signal-regulated kinase kinase) kinase-1, MEKK1Δ. In all cases, the dominant-negative mutants A-Fos and A-ATF2 decreased collagenase promoter activity. However, A-ATF4 and A-C/EBP had no effect. A-Fos and A-ATF2 also reduced MEKK1Δ-induced stimulation of the c-Jun promoter. In contrast, constitutive c-Jun promoter activity was blocked solely by A-ATF2, strongly suggesting that ATF2 and/or an ATF2-dimerizing protein are of major importance for c-Jun transcription in unstimulated cells. These results demonstrate that AP-1 transcription factors of different compositions control c-jun gene transcription in resting or stimulated cells.

scholarly journals Phosphorylation of BATF regulates DNA binding: a novel mechanism for AP-1 (activator protein-1) regulation

2003 ◽  
Vol 374 (2) ◽  
pp. 423-431 ◽  
Author(s):  
Christopher D. DEPPMANN ◽  
Tina M. THORNTON ◽  
Fransiscus E. UTAMA ◽  
Elizabeth J. TAPAROWSKY
Keyword(s):  
Transcription Factors ◽  
Dna Binding ◽  
Leucine Zipper ◽  
Binding Domain ◽  
Dna Binding Domain ◽  
Activator Protein 1 ◽  
Basic Leucine Zipper ◽  
Activator Protein

BATF is a member of the AP-1 (activator protein-1) family of bZIP (basic leucine zipper) transcription factors that form transcriptionally inhibitory, DNA binding heterodimers with Jun proteins. In the present study, we demonstrate that BATF is phosphorylated in vivo on multiple serine and threonine residues and at least one tyrosine residue. Reverse-polarity PAGE revealed that serine-43 and threonine-48 within the DNA binding domain of BATF are phosphorylated. To model phosphorylation of the BATF DNA binding domain, serine-43 was replaced by an aspartate residue. BATF(S43D) retains the ability to dimerize with Jun proteins in vitro and in vivo, and the BATF(S43D):Jun heterodimer localizes properly to the nucleus of cells. Interestingly, BATF(S43D) functions like wild-type BATF to reduce AP-1-mediated gene transcription, despite the observed inability of the BATF(S43D):Jun heterodimer to bind DNA. These data demonstrate that phosphorylation of serine-43 converts BATF from a DNA binding into a non-DNA binding inhibitor of AP-1 activity. Given that 40% of mammalian bZIP transcription factors contain a residue analogous to serine-43 of BATF in their DNA binding domains, the phosphorylation event described here represents a mechanism that is potentially applicable to the regulation of many bZIP proteins.

scholarly journals Opposing Roles for ATF2 and c-Fos in c-Jun-Mediated Neuronal Apoptosis

2009 ◽  
Vol 29 (9) ◽  
pp. 2431-2442 ◽  
Author(s):  
Zhongmin Yuan ◽  
Shoufang Gong ◽  
Jingyan Luo ◽  
Zhihao Zheng ◽  
Bin Song ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Neuronal Apoptosis ◽  
Target Genes ◽  
Dominant Negative ◽  
Bimolecular Fluorescence Complementation ◽  
Activator Protein 1 ◽  
Fos Expression ◽  
Activating Transcription Factor ◽  
Living Neurons ◽  
Factor C

ABSTRACT The activator protein 1 (AP-1) transcription factor c-Jun is crucial for neuronal apoptosis. However, c-Jun dimerization partners and the regulation of these proteins in neuronal apoptosis remain unknown. Here we report that c-Jun-mediated neuronal apoptosis requires the concomitant activation of activating transcription factor-2 (ATF2) and downregulation of c-Fos. Furthermore, we have observed that c-Jun predominantly heterodimerizes with ATF2 and that the c-Jun/ATF2 complex promotes apoptosis by triggering ATF activity. Inhibition of c-Jun/ATF2 heterodimerization using dominant negative mutants, small hairpin RNAs, or decoy oligonucleotides was able to rescue neurons from apoptosis, whereas constitutively active ATF2 and c-Jun mutants were found to synergistically stimulate apoptosis. Bimolecular fluorescence complementation analysis confirmed that, in living neurons, c-Fos downregulation facilitates c-Jun/ATF2 heterodimerization. A chromatin immunoprecipitation assay also revealed that c-Fos expression prevents the binding of c-Jun/ATF2 heterodimers to conserved ATF sites. Moreover, the presence of c-Fos is able to suppress the expression of c-Jun/ATF2-mediated target genes and, therefore, apoptosis. Taken together, our findings provide evidence that potassium deprivation-induced neuronal apoptosis is mediated by concurrent upregulation of c-Jun/ATF2 heterodimerization and downregulation of c-Fos expression. This paradigm demonstrates opposing roles for ATF2 and c-Fos in c-Jun-mediated neuronal apoptosis.

scholarly journals Regulation of the gene promoter for extracellular signal-regulated protein kinase 2 by transcription factors NF-Y and Sp3

2000 ◽  
Vol 347 (1) ◽  
pp. 155-161 ◽  
Author(s):  
Naoaki SUGIURA ◽  
Kunio TAKISHIMA
Keyword(s):  
Transcription Factors ◽  
Protein Kinase ◽  
Promoter Activity ◽  
Dominant Negative ◽  
Mitogen Activated Protein Kinase ◽  
Flanking Sequence ◽  
Mobility Shift ◽  
Extracellular Signal ◽  
Promoter Deletion Analysis ◽  
Ccaat Box

We have previously shown that the maximal promoter activity of the gene for extracellular signal-regulated protein kinase 2 (ERK2; also known as p42 mitogen-activated protein kinase) resides in the 371 bp 5ʹ-flanking sequence. In the present study we defined roles for a CCAAT box and two adjacent GC boxes in the activity of this promoter. Deletion analysis and DNase I footprinting of this 371 bp region indicated that the CCAAT box at -64 and GC boxes at -86 and -39 are crucial for promoter activity. Electrophoretic mobility-shift assays showed that transcription factor NF-Y/CBF binds to the CCAAT box. Sp1 and Sp3, members of the Sp family of transcription factors, bind to the GC boxes of the ERK2 promoter. The binding of Sp3 was predominant over that of Sp1. Disruption by mutation of any of the CCAAT box and GC boxes similarly decreased promoter activity. These three cis elements exhibited a moderate synergy in promoter function. The transactivating role of NF-Y was corroborated by the finding that a dominant-negative form of NF-YA diminished the promoter activity. These results provide clues for refining our understanding of not only the regulation of expression of the gene for ERK2 but also mechanisms by which NF-Y and Sp1/Sp3 regulate transcription.

Functional Toll-like receptor 4 mutations modulate the response to fibrinogen

2008 ◽  
Vol 100 (08) ◽  
pp. 301-307 ◽  
Author(s):  
Kunal Patel ◽  
Shu Ye ◽  
Conrad P. Hodgkinson
Keyword(s):  
Transcription Factors ◽  
Promoter Activity ◽  
Activator Protein 1 ◽  
Toll Like Receptor ◽  
Toll Like Receptor 4 ◽  
Human Macrophages ◽  
Inflammatory Protein ◽  
Extracellular Signal ◽  
Cytokine Synthesis ◽  
Kinase Phosphorylation

SummaryFibrinogen has been implicated in atherosclerosis; in part by activating the lipopolysaccharide (LPS) receptor Toll-like receptor 4 (TLR4). The fibrinogen-TLR4 signalling pathway remains un-characterised. In human macrophages fibrinogen stimulated interleukin (IL)6 expression and ERK (extracellular signal-related kinase) phosphorylation. In HEK293-CD14-MD2 cells expressing TLR4, fibrinogen induced robust phosphorylation of ERK1, p38α and JNK and activated transcription factors NFκB, Elk-1 and AP-1 (activator protein-1).The net effect of this signaling pathway was a pro-inflammatory response characterised by IL6 and TNFα synthesis and increased IL8,matrix metalloproteinase (MMP)1, MMP9, and MCP-1 promoter activity. Two common TLR4 mutations, D299G and T399I, render the receptor LPS hyporesponsive. The effect of fibrinogen on polymorphic variant TLR4s was markedly different; enhancing activation of kinases, transcription factors, cytokine synthesis and promoter activity. This study indicates that fibrinogen activates TLR4, explaining how fibrinogen promotes inflammatory protein expression.

scholarly journals Activator Protein-1 and Smad Proteins Synergistically Regulate Human Follicle-Stimulating Hormone β-Promoter Activity

Endocrinology ◽  
2008 ◽  
Vol 149 (11) ◽  
pp. 5577-5591 ◽  
Author(s):  
Ying Wang ◽  
Jérôme Fortin ◽  
Pankaj Lamba ◽  
Marco Bonomi ◽  
Luca Persani ◽  
...  
Keyword(s):  
Signaling Pathways ◽  
Promoter Activity ◽  
Molecular Mechanisms ◽  
Activin A ◽  
Dominant Negative ◽  
Activator Protein 1 ◽  
Reporter Activity ◽  
Activator Protein ◽  
Mapk Cascades ◽  
Smad Proteins

GnRH1 stimulates the synthesis and secretion of FSH and LH from the anterior pituitary gland. The molecular mechanisms through which GnRH1 produces these effects in humans have not been determined. Here, we examined transcriptional regulation of the human FSHβ (FSHB) subunit using reporter assays in immortalized murine gonadotrope cells. GnRH1 dose and time dependently stimulated FSHB promoter activity, with peak stimulation occurring at 8 h. GnRH1 rapidly stimulated various MAPK cascades, though the ERK1/2 and p38 pathways appeared to be most critical for FSHB induction. Indeed, constitutively active forms of both Raf1 kinase and MAP2K6 (MKK6) were sufficient to stimulate reporter activity. GnRH1 stimulated activator protein-1 (AP-1) (FosB, c-fos, JunB, and cJun) synthesis and complex formation, the latter of which bound to a conserved cis-element within −120 bp of the transcription start site. A second, lower affinity, site was mapped more proximally. Mutations of both cis-elements diminished GnRH1-stimulated promoter activity, though disruption of the higher affinity site had a more dramatic effect. A dominant-negative Fos protein dose dependently inhibited GnRH1-stimulated FSHB transcription, confirming a role for endogenous AP-1 proteins. MAPK kinase 1 (MEK1) and p38 inhibitors significantly attenuated GnRH1-stimulated c-fos, FosB, and JunB synthesis, suggesting a mechanism whereby the ERK1/2 and p38 signaling pathways regulate FSHB transcription. Activins and inhibins potently regulate FSH synthesis in rodents, but their roles in FSH regulation in humans are less clear. Activin A, though weak on its own, synergized with GnRH1 to stimulate human FSHB promoter activity. In contrast, activin A partially inhibited GnRH1-stimulated LHβ subunit (LHB) transcription. The GnRH1 and activin A signaling pathways appear to converge at the level of the high-affinity AP-1 site. Fos and Jun proteins synergistically regulate reporter activity through this element, and their effects are potentiated by coexpression of either Smad2 or Smad3, effectors in the activin signaling cascade. In summary, GnRH1 and activin A synergistically regulate human FSHB subunit transcription. The combined actions of AP-1 and Smad proteins acting through a conserved AP-1 element provide a candidate mechanism for this effect. The ability of activins to potentiate selectively the effects of GnRH1 on FSHB expression suggests a model for preferential increases in FSH secretion at the luteal-follicular transition of the menstrual cycle.

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