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)

The viral Jun protein (v-Jun) transforms chicken embryo fibroblasts (CEF) more effectively than its cellular counterpart (c-Jun). In certain cell types v-Jun is also a stronger transcriptional activator than c-Jun. These functional differences between v-Jun and c-Jun result from a deletion in v-Jun (referred to as "delta deletion") that seems to weaken the interaction of Jun with a negative cellular regulator molecule. These observations suggested that the oncogenicity of v-Jun may be due to an enhanced ability to activate transcription of target genes. To test this hypothesis, we constructed several deletions in the delta domain of chicken c-Jun and determined their transforming and transactivating properties. Surprisingly, we found an inverse correlation between the ability of the mutants to transform CEF and to transactivate the collagenase and transin promoters in CEF. In contrast, there was no significant effect of the delta mutations in c-Jun on transactivation in F9 murine embryonal carcinoma cells. The function of the delta region is therefore cell-type specific. The inverse correlation between transformation and transactivation in CEF suggests that the strong growth-promoting effect of v-Jun may be related to a failure to activate the transcription of growth attenuating genes.
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PMID:Mutations in the Jun delta region suggest an inverse correlation between transformation and transcriptional activation. 130 52

Transcription of tissue inhibitor of metalloproteinases-1 (TIMP-1), a secreted protein that regulates the activities of the metalloproteinases, collagenase and stromelysin, is activated by serum growth factors. Transient transfection experiments have revealed several regions of cis-acting regulatory sequences involved in the response of the murine TIMP-1 gene to serum. One area is in the vicinity of the promoter, consisting of a non-consensus binding site (5'-TGAGTAA-3' at -59/-53) for transcription factor AP1 and an adjacent 24 bp region of dyad symmetry that contains a PEA3-binding site. A second is an upstream region (-1020 to -780) that acts as an enhancer when linked to a heterologous promoter, and contains a consensus AP1 binding site (at -803/ -797). Gel retardation assays revealed differences between nuclear factors in mouse C3H10T1/2 cells that bound to the TIMP(-59/ -53)AP1 site and a consensus collagenase TRE (TPA-response element). The TIMP(-59/ -53)AP1 site is a promiscuous motif that binds c-Fos/c-Jun AP1 translated in vitro and is an effective competitor for binding of nuclear AP1 factors to the consensus TRE, but in addition it binds factors that do not associate with the consensus TRE. The TIMP(-59/ -53)AP1 motif and the dyad symmetry region stimulated expression from a thymidine kinase promoter in an additive fashion, and competition experiments showed that excess copies of these factor binding sites reduced expression from a reporter plasmid driven by the TIMP-1 promoter. Our data show that binding sites for AP1 and PEA3 transcription factors are involved in the regulation of TIMP-1 transcription, which suggests that the coordinated induction of TIMP-1, collagenase and stromelysin may be achieved through the actions of a shared set of nuclear transcription factors. However, the properties of the TIMP-1(-59/ -53)AP1 motif likely reflect an additional type of transcriptional regulation restricted to TIMP-1.
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PMID:Involvement of AP1 and PEA3 binding sites in the regulation of murine tissue inhibitor of metalloproteinases-1 (TIMP-1) transcription. 142 Mar 63

The c-ets protooncogenes have recently been shown to code for transcription factors that activate the oncogene responsive unit of the polyoma virus enhancer. We show that transcription of the stromelysin gene, which is highly expressed in transformed cells and tumours, is efficiently activated by c-Ets-1 and -2 through two DNA elements. The distal element is a highly conserved palindrome composed of two strong binding sites for c-Ets-1. The proximal element does not bind c-Ets-1, but may be activated indirectly by increased synthesis of c-Jun and c-Fos. Both ets responsive elements mediate activation by the oncoproteins Ha-Ras, v-Src and v-Mos. These results suggest that c-Ets participates in the mechanisms by which stromelysin gene expression is deregulated in transformed cells and tumours.
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PMID:The c-Ets oncoprotein activates the stromelysin promoter through the same elements as several non-nuclear oncoproteins. 185 Jun 95

We have studied the activity of the AP-1 site, a target for the Fos and Jun family of transcription factors, in the context of the human stromelysin promoter (-1303 to +4). In transiently transfected human HepG2, HeLa and fibroblast cell cultures, point-mutations in any position of the stromelysin AP-1 sequence TGAGTCA (-70 to -64) reduced both the basal level and TPA-induced expression from the stromelysin promoter. TPA-induction fold of the mutant promoters, however, was comparable to that of the wild-type promoter. Similarly, antisense c-Fos mRNA expression reduced basal activity but had no significant effect on the relative TPA-response of the stromelysin promoter. Further, in mouse F9 cells cotransfected with c-Fos and c-Jun expression plasmids, the transfected wild-type stromelysin promoter activity was increased 57-fold whereas no transactivation was detected for an AP-1 mutant stromelysin promoter. In gelshift assays, stromelysin promoter fragments (-101 to -11), containing the mutated AP-1 site, all failed to bind or compete for the in vitro synthesized Fos and Jun proteins. We interpret these data to suggest that the Fos and Jun proteins, or similar activity, and the AP-1 site are required for the basal level expression of the human stromelysin gene. Strikingly, these data also suggest that the stromelysin AP-1 site is not necessary for the TPA-response.
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PMID:The AP-1 site is required for basal expression but is not necessary for TPA-response of the human stromelysin gene. 190 6

The promoter regions of several phorbol diester-(TPA-) inducible genes (collagenase, stromelysin, hMT IIA, and SV40) share a conserved 9 bp motif. Synthetic copies of these closely related sequences conferred TPA inducibility upon heterologous promoters. Footprinting analysis indicated that these TPA-responsive elements (TREs) are recognized by a common cellular protein: the previously described transcription factor AP-1. A point mutation that eliminated the basal and induced activity of the TRE also interfered with its ability to bind AP-1. Treatment of cultured cells with TPA led to a rapid 3- to 4-fold increase in TRE binding activity, by a posttranslational mechanism. These results strongly suggest that AP-1 is at the receiving end of a complex pathway responsible for transmitting the effects of phorbol ester tumor promoters from the plasma membrane to the transcriptional machinery.
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PMID:Phorbol ester-inducible genes contain a common cis element recognized by a TPA-modulated trans-acting factor. 303 32

Some growth factor-induced genes, such as the c-fos gene, are activated rapidly and transiently without intervening protein synthesis. Others, like the rat transin gene, are activated more slowly but more durably and their activation requires prior protein synthesis. It is tempting to speculate that certain rapidly-activated genes code for transcription factors which interact directly with promoter regions of genes like the transin gene to trigger their expression. Unfortunately, little is known about the majority of primary response genes to support this hypothesis. The proto-oncogene c-jun codes for the transcription factor AP-1 or a closely related protein. We show that epidermal growth factor stimulates transcription of the c-jun gene in fibroblasts as a primary response. This supports the notion that increased expression of genes encoding transcription factors is an important element of the signal transduction mechanism, assuring the long-term transcriptional response of cells to growth factors.
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PMID:Epidermal growth factor stimulates transcription of the c-jun proto-oncogene in rat fibroblasts. 313 98

Mouse 3T3 fibroblasts lacking c-fos were employed to demonstrate an essential function of the UV-inducible transcription factor AP-1 (Fos/Jun) in the response to the cytotoxic effects of short-wavelength ultraviolet (UVC) radiation. Clonogenic survival and proliferation of cells lacking c-fos were drastically reduced following UV irradiation. This UV hypersensitivity manifests itself primarily in increased cell death, partly by apoptosis, and prolonged recovery time from UV-induced cell cycle arrest. Co-culture with wild-type cells did not ameliorate the hypersensitivity of mutant cells. Transcriptional induction of the c-Fos target genes collagenase I, stromelysin-1 and stromelysin-2 by UV is almost absent in cells lacking c-fos which correlates with a reduced UV induction of AP-1 DNA-binding and transactivation activity. The repair of UV-induced DNA lesions was not affected, as shown by unscheduled DNA synthesis and host cell reactivation assays. These data demonstrate that c-Fos is involved in a novel protective function other than DNA repair against the harmful consequences of UVC.
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PMID:Fos is an essential component of the mammalian UV response. 748 23

We have examined the hypothesis that neuronal programmed cell death requires a genetic program; we used a model wherein rat sympathetic neurons maintained in vitro are deprived of NGF and subsequently undergo apoptosis. To evaluate gene expression potentially necessary for this process, we used a PCR-based technique and in situ hybridization; patterns of general gene repression and selective gene induction were identified in NGF-deprived neurons. A temporal cascade of induced genes included "immediate early genes," which were remarkable in that their induction occurred hours after the initial stimulus of NGF removal and the synthesis of some required ongoing protein synthesis. The cascade also included the cell cycle gene c-myb and the genes encoding the extracellular matrix proteases transin and collagenase. Concurrent in situ hybridization and nuclear staining revealed that while c-jun was induced in most neurons, c-fos induction was restricted to neurons undergoing chromatin condensation, a hallmark of apoptosis. To evaluate the functional role of the proteins encoded by these genes, neutralizing antibodies were injected into neurons. Antibodies specific for either c-Jun or the Fos family (c-Fos, Fos B, Fra-1, and Fra-2) protected NGF-deprived neurons from apoptosis, whereas antibodies specific for Jun B, Jun D, or three nonimmune antibody preparations had no protective effect. Because these induced genes encode proteins ranging from a transcription factor necessary for death to proteases likely involved in tissue remodeling concurrent with death, these data may outline a genetic program responsible for neuronal programmed cell death.
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PMID:Altered gene expression in neurons during programmed cell death: identification of c-jun as necessary for neuronal apoptosis. 779 22

Retinoic acid receptors (RARs) regulate gene expression either by directly binding to the RAR-responsive elements or by antagonizing the action of c-Jun/c-Fos (AP1). AP1 is involved in the expression of metalloproteases, cytokines and other factors which play critical roles in the turnover of extracellular matrix, inflammation and hyperproliferation in diseases such as psoriasis, rheumatoid arthritis and in tumor metastases. We demonstrate here that synthetic retinoids inhibit 12-O-tetradecanoylphorbol-14-acetate-induced transcription from the stromelysin AP1 motif through RAR alpha, -beta, and -gamma. Interestingly, these diaryl acetylenic retinoids, which are potent agonists only for RAR beta and RAR gamma, but not for RAR alpha, in transactivation assays, are able to inhibit AP1-dependent gene expression through RAR alpha. Thus these analogs can differentially affect the transactivation and AP1 antagonistic functions of RAR alpha. These results demonstrate that the transactivation and AP1 antagonistic functions are separable, and it should be possible to develop retinoids that are completely specific for AP1 antagonism through all RARs. Furthermore, using an RAR-selective ligand, we also demonstrate the separation of ligand binding and AP1 antagonism functions of RARs.
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PMID:Separation of transactivation and AP1 antagonism functions of retinoic acid receptor alpha. 782 31

Okadaic acid (OA) is a novel, non-phorbol ester-type tumor promoter, which is a specific inhibitor of protein phosphatases 1 and 2A. Treatment of human fibrosarcoma HT-1080 cells with OA resulted in induction of collagenase and stromelysin-1 mRNA levels, while mRNA levels for tissue inhibitor of metalloproteinases-1 were enhanced to a lesser extent. Induction of collagenase and stromelysin-1 mRNA levels was dependent on protein synthesis. Exposure of HT-1080 cells to OA resulted in marked and persistent induction of junB, junD, and c-fos mRNA levels up to 24 h, while c-jun mRNA levels were only slightly elevated. In transiently transfected HT-1080 cells, OA-elicited activation of a 3.8-kilobase collagenase promoter/reporter gene construct was entirely dependent on junB expression, as determined by cotransfection with a junB antisense expression construct. Overexpression of JunB in HT-1080 cells enhanced collagenase promoter activity by 10-fold, and OA augmented trans-activation of collagenase promoter by c-Jun and JunB. The results indicate that induction of collagenase gene expression by OA is mediated by enhanced JunB expression, as well as enhanced trans-activating capacity of AP-1 complexes containing c-Jun and JunB. These results also suggest that selective overexpression of junB may enhance invasive and metastatic potential of neoplastic cells.
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PMID:Okadaic acid-elicited transcriptional activation of collagenase gene expression in HT-1080 fibrosarcoma cells is mediated by JunB. 784 22


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