Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P05412 (c-Jun)
 11,453 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

NGFI-A is an immediate-early gene that encodes a transcription factor whose DNA-binding domain is composed of three zinc fingers. To define the domains responsible for its transcriptional activity, a mutational analysis was conducted with an NGFI-A molecule in which the zinc fingers were replaced by the GAL4 DNA-binding domain. In a cotransfection assay, four activation domains were found within NGFI-A. Three of the activation domains are similar to those characterized previously: one contains a large number of acidic residues, another is enriched in proline and glutamine residues, and another has some sequence homology to a domain found in Krox-20. The fourth bears no resemblance to previously described activation domains. NGFI-A also contains an inhibitory domain whose removal resulted in a 15-fold increase in NGFI-A activity. This increase in activity occurred in all mammalian cell types tested but not in Drosophila S2 cells. Competition experiments in which increasing amounts of the inhibitory domain were cotransfected along with NGFI-A demonstrated a dose-dependent increase in NGFI-A activity. A point mutation within the inhibitory domain of the competitor (I293F) abolished this property. When the analogous mutation was introduced into native NGFI-A, a 17-fold increase in activity was observed. The inhibitory effect therefore appears to be the result of an interaction between this domain and a titratable cellular factor which is weakened by this mutation. Downmodulation of transcription factor activity through interaction with a cellular factor has been observed in several other systems, including the regulation of transcription factor E2F by retinoblastoma protein, and in studies of c-Jun.
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PMID:Transcriptional activity of the zinc finger protein NGFI-A is influenced by its interaction with a cellular factor. 841 79

Among multiple CRE (cyclic AMP response element)-binding proteins, CRE-BP1 (also designated ATF-2) has two unique characteristics: it mediates the adenovirus E1A-induced trans-activation and forms a heterodimer with c-Jun. Two structures, a putative metal finger and a leucine zipper, in CRE-BP1 are responsible for these capacities. As a new member of a CRE-BP1 family that has similar metal finger and leucine zipper structures, we have isolated cDNA clones of CRE-BPa by cross-hybridization with CRE-BP1 cDNA. CRE-BPa protein consists of 508 amino acids and has a molecular weight of 56,840. CRE-BPa protein is highly homologous with CRE-BP1 in four regions: two of them are the regions containing the putative metal finger or the DNA-binding domain consisting of the basic amino acid cluster and the leucine zipper. Like CRE-BP1, CRE-BPa binds to CRE with higher affinity than to the 12-O-tetradecanoylphorbol-13-acetate response element as a homodimer or a CRE-BPa/c-Jun or CRE-BPa/CRE-BP1 heterodimer. However, using the c-Myb-CRE-BPa fusion protein, it was show that CRE-BPa could not mediate the E1A-induced trans-activation. Expression of CRE-BPa mRNA was found in a limited number of cell lines, and multiple sizes of CRE-BPa mRNA species were detected in some cell lines and tissues. CRE-BPa will be useful to clarify the mechanism of CRE-mediated transcriptional activation by E1A or c-Jun.
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PMID:Isolation and characterization of a novel member of the gene family encoding the cAMP response element-binding protein CRE-BP1. 844 Jul 10

Glucocorticoid receptors (GRs) are ligand-inducible transcription factors that contain several functional domains. We tested whether GR activity can be reconstituted using domains expressed in separate molecules. Hence, we developed a general approach in which proteins can be individually expressed but interact specifically through the leucine zippers of c-Jun and c-Fos fused to each protein. The GR was divided into two different fragments, one encoding the N-terminal trans-activation and DNA-binding domains and conferring constitutive activity to a glucocorticoid-responsive reporter gene, and one containing the C-terminal, ligand-binding domain. Coexpression of the trans-activation-DNA-binding domain and the ligand-binding domain fragments leads to reconstituted ligand-regulated GR activity that is completely dependent on the presence of compatible zippers. These results suggest that, in GRs and perhaps other members of the steroid/thyroid hormone receptor superfamily, ligand-mediated function does not require that these domains be present in cis, but that they can also function in trans. This, together with the absence of interdomain dimerization signals, also suggests that these domains possibly evolved from separate genes.
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PMID:Reconstitution of ligand-mediated glucocorticoid receptor activity by trans-acting functional domains. 844 2

The ability of the nuclear oncoprotein Jun to activate transcription is controlled both by level of DNA binding and by the activity of its transactivation domain. Control of DNA binding is achieved by two mechanisms: phosphorylation and redox regulation. Mutation of Ser-226 inhibits phosphorylation of the DNA binding, resulting in enhanced DNA-binding and transactivation activity of Jun. In contrast, mutation of Cys-252, which is the target for repression of DNA-binding activity under oxidative conditions, results in a strong decrease of Jun-specific activation of transcription. However, transactivation by c-Jun-Cys-252 is fully restored upon mutation of Ser-226. Both mutations are also found in the oncogenic counterpart of c-Jun, v-Jun, and are the only differences between these proteins in the DNA-binding domain, suggesting that v-Jun escapes down-modulation of DNA binding by both mechanisms. However, inhibition of phosphorylation of Ser-226 is absolutely required for the ability of v-Jun to activate transcription of AP-1-dependent genes in a redox-independent manner.
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PMID:Mutation of a phosphorylation site in the DNA-binding domain is required for redox-independent transactivation of AP1-dependent genes by v-Jun. 847 39

A novel cellular gene, SFA-2, was isolated by differential hybridization of a cDNA library, using probes obtained from an adult T-cell leukemia cell line in comparison with normal CD4+ T cells and MOLT-4 cell line. The mRNA of the SFA-2 gene is approximately 0.9-kb in size and encodes a protein of 125 amino acids, containing a basic region-leucine zipper DNA-binding domain. The N-terminal region of SFA-2 is rich in serine and contains a consensus sequence for casein kinase II phosphorylation. The SFA-2 gene was strongly expressed in mature T and B lymphocytes, and was up-regulated after transformation by human T-cell leukemia virus type I. The SFA-2 did not homodimerize efficiently but formed heterodimer preferentially with c-Jun. The SFA-2/c-Jun heterodimer bound preferentially to the AP-1 and CRE sites.
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PMID:SFA-2, a novel bZIP transcription factor induced by human T-cell leukemia virus type I, is highly expressed in mature lymphocytes. 863 63

The adenovirus 12S E1A protein can stimulate the activity of the c-jun promoter through a conserved region 1 (CR1)-dependent mechanism. The effect is mediated by two AP-1/ATF-like elements, jun1 and jun2, that preferentially bind c-Jun-ATF-2 heterodimers. In this study, we show that the ATF-2 component of the c-Jun-ATF-2 heterodimer is the primary target for 12S E1A: 12S E1A can enhance the transactivating activity of the N terminus of ATF-2 when fused to a heterologous DNA-binding domain, whereas the transactivating activity of the c-Jun N terminus is not significantly affected. Activation of the ATF-2 N terminus by 12S E1A is dependent on CR1. In the context of the 13S E1A protein, CR1 and CR3 can both contribute to activation of ATF-2, and their relative contributions are dependent on the cell type. In contrast to activation of ATF-2 by stress-inducing agents, CR1-dependent activation of ATF-2 was found not to depend strictly on the presence of threonines 69 and 71 in the N terminus of ATF-2, which are targets for phosphorylation by stress-activated protein kinases (SAPKs). In agreement with this observation, we did not observe phosphorylation of threonines 69 and 71 or constitutively enhanced SAPK activity in E1A- plus E1B-transformed cell lines. These data suggest that CR1-dependent activation of ATF-2 by 12S E1A does not require phosphorylation of threonines 69 and 71 by SAPK.
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PMID:The CR1 and CR3 domains of the adenovirus type 5 E1A proteins can independently mediate activation of ATF-2. 870 4

Transcription factors of the NFAT family regulate the production of effector proteins that coordinate the immune response. The immunosuppressive drugs FK506 and cyclosporin A (CsA) act by blocking a Ca2+-mediated signalling pathway leading to NFAT. Although FK506 and CsA have enabled human organs to be transplanted routinely, the toxic side-effects of these drugs limit their usage. This toxicity might be absent in antagonists that target NFAT directly. As a first step in the structure-based search for NFAT antagonists, we now report the identification and solution structure of a 20K domain of NFATc (NFATc-DBD) that is both necessary and sufficient to bind DNA and activate transcription cooperatively. Although the overall fold of the NFATc DNA-binding domain is related to that of NF-kappaB p50 (refs 2, 3), the two proteins use significantly different strategies for DNA recognition. On the basis of these results, we present a model for the cooperative complex formed between NFAT and the mitogenic transcription factor AP-1 on the interleukin-2 enhancer.
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PMID:Unusual Rel-like architecture in the DNA-binding domain of the transcription factor NFATc. 899 Jan 22

Marek's disease virus (MDV) is one of the most oncogenic herpesviruses and induces T lymphomas in chickens within weeks after infection. Only a limited number of viral transcripts are detected in MDV tumor samples and cell lines. One of the major transcripts encodes MEQ, a 339-amino-acid bZIP protein which is homologous to the Jun/Fos family of transcription factors. The C-terminal half of MEQ contains proline-rich repeats and, when fused to the DNA-binding domain of a yeast transcription factor, Gal4 (residues 1 to 147), exhibits transactivation function. MEQ can dimerize with itself and with c-Jun. The MEQ-c-Jun heterodimers bind to an AP-1-like enhancer within the MEQ promoter region with greater affinity than do homodimers of either protein, and they transactivate MEQ expression. Here we show that MEQ is expressed in the nucleus but, interestingly, with a predominant fraction in the nucleoli and coiled bodies. This makes MEQ the first bZIP protein to be identified in the nucleoli. MEQ contains two stretches of basic residues, designated basic region 1 (BR1) and basic region 2 (BR2). Using a series of deletion mutants, we have mapped the primary nuclear localization signal (NLS) and the sole nucleolar localization signal (NoLS) to the BR2 region. BR1 was shown to provide an auxiliary signal in nuclear translocation. To demonstrate that BR2 is an authentic NoLS, BR2 was fused to cytoplasmic v-Raf (delta gag) kinase. The BR2-Raf fusion protein was observed to migrate into the nucleoplasm and the nucleolus. The BR2 region can be further divided into two long arginine-lysine stretches, BR2N and BR2C, which are separated by the five amino acids Asn-Arg-Asp-Ala-Ala (NRDAA). We provide evidence that the requirement for nuclear translocation is less stringent than that for nucleolar translocation, as either BR2N or BR2C alone is sufficient to translocate the cytoplasmic v-Raf (delta gag) into the nucleus, but only in combination can they translocate v-Raf (delta gag) into the nucleolus. Our studies demonstrate that MEQ is both a nuclear and nucleolar protein, adding MEQ to the growing list of transactivators which localize to the nucleolus.
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PMID:Nucleolar and nuclear localization properties of a herpesvirus bZIP oncoprotein, MEQ. 906 Jun 82

The transcription factors Fos, Jun, and Ets regulate the expression of human stromelysin-1 and collagenase-1 genes. Recently, we found that ERG, an Ets family member, activates collagenase-1 gene but not stromelysin-1 by physically interacting with c-Fos/c-Jun. Interestingly, ERG binds to stromelysin-1 promoter and represses its activation by ETS2. Here, to investigate the molecular mechanism of this regulation, we have used an in vitro protein-protein interaction assay and studied the transcription factor interactions of ETS2. We found that ETS2 could weakly associate with in vitro synthesized ETS1, c-Fos, and c-Jun and strongly with c-Fos/c-Jun complex and ERG via several distinct ETS2 domains including the C-terminal region that contains the DNA-binding domain. Strikingly, these interactions were stabilized in vitro by DNA as they were inhibited by ethidium bromide. Both the N-terminal region, comprising the transactivation domain, and the C-terminal region of ETS2 associated with ERG and, interestingly, the interaction of ERG through the transactivation domain of ETS2 was DNA-independent. The DNA-dependent interaction of ETS2 with c-Fos/c-Jun was enhanced by specific DNA fragments requiring two Ets-binding sites of the stromelysin-1 promoter. Using the two hybrid system, we also demonstrated that ETS2 interacts with c-Jun or ERG in vivo.
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PMID:The Ets transcription factors interact with each other and with the c-Fos/c-Jun complex via distinct protein domains in a DNA-dependent and -independent manner. 933 86

The urokinase-type plasminogen activator receptor (u-PAR) has been implicated in tumor progression, and previous studies have shown that the expression of this gene is strongly up-regulated by PMA. Although the signaling mechanism by which PMA modulates u-PAR expression is not known, the effect of this phorbol ester on the expression of other genes has been ascribed to activation of the c-Raf-1-ERK signaling pathway. However, in the current study we examined an alternate possibility that the inductive effect of PMA on u-PAR expression also required a JNK1-dependent signaling cascade usually associated with stress-inducing stimuli. PMA treatment of the u-PAR-deficient OVCAR-3 ovarian cancer cells, which contain low JNK activities, resulted in a rapid (5 min) increase in JNK activity. Maximal JNK activity (12-fold induction) occurred after 30 min; this preceding the earliest detected rise in u-PAR protein (2 h). Dose-response studies with PMA also indicated that the increased JNK activity was tightly correlated with elevated u-PAR protein levels. The stimulation of u-PAR promoter activity by PMA required an intact upstream AP-1 motif (-184) and in PMA-treated cells this motif was bound with c-Jun as indicated from mobility shift assays. PMA up-regulated the c-Jun trans acting activity as indicated by the higher activity of a GAL4-regulated luciferase reporter in phorbol-ester-treated cells co-transfected with an expression vector encoding the c-Jun transactivation domain fused to the GAL4 DNA-binding domain. The ability of PMA to stimulate u-PAR promoter activity was effectively titrated out by the co-expression of either a kinase-defective JNK1 or a dominant negative MEKK1 the latter being an upstream activator of JNK1. Conversely, u-PAR promoter activity was stimulated by the co-expression of a constitutively active MEKK1 and this induction was antagonized by the inclusion of the kinase-defective JNK1 plasmid. We also determined the biological significance of the JNK1-dependent signaling cascade in regulating u-PAR promoter activity by c-Ha-ras since this oncogene is activated and/or overexpressed in a variety of tumors including ovarian cancer. Transfection of an activated c-Ha-ras into OVCAR-3 cells stimulated u-PAR promoter activity over 20-fold and this could be countered by the individual expression of dominant negative expression constructs to Rac-1, MEKK1 or JNK1. Taken together, these data suggest that the PMA- or c-Ha-Ras-dependent stimulation of u-PAR gene expression requires a JNK1-dependent signaling module and that, at least for PMA, the concurrent stimulation of a JNK1-independent signaling module is also required. Thus, caution should be exercised in invoking linear signaling modules to account for the regulation of inducible gene expression.
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PMID:Stimulation of urokinase-type plasminogen activator receptor expression by PMA requires JNK1-dependent and -independent signaling modules. 967 6


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