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Query: UNIPROT:P05412 (c-Jun)
 11,453 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The functional induction of c-fos in the sodium butyrate-induced differentiation of F-98 glioma cells was studied. Fos protein level was increased by butyrate. In contrast, c-Jun protein was constitutively expressed and was not affected by butyrate. Gel-retardation assay indicates Fos as a component of the complex formed between the consensus oligonucleotide of the TPA (PMA, phorbol 12-myristate 13-acetate) response element (TRE) and nuclear extract prepared from butyrate-treated cells. Transfection studies showed that butyrate increased transcription from a multimeric TRE-driven reporter construct, and the effect was mimicked by transfecting cells with fos-expression plasmid. Furthermore, under conditions of c-fos over-expression, transactivation by butyrate was essentially abolished. These data suggest that Fos induction had a functional role in gene activation. Characterization of stable c-fos transfectants demonstrated that these cells displayed alterations in morphology, showed serum-dependent growth, had slower growth rates and grew to lower saturation densities than did untransfected F-98 cells or transfected cells that did not express c-fos. Immunofluorescent staining indicated that fos transfectants also had elevated glial fibrillary acidic protein ('GFAP') expression. Transfection of the c-fos promoter-chloramphenicol acetyltransferase fusion gene into F-98 cells revealed that activation of c-fos by butyrate was exerted at the promoter level, and sequences located within nucleotides -757 to -402 of the c-fos promoter were responsible for butyrate induction. Our data indicate that transcriptional activation of c-fos through its promoter by butyrate resulted in increased Fos protein expression. Transfection studies show that both c-fos and butyrate activate TRE-containing genes, and fos may be a downstream mediator of butyrate. Furthermore, expression of c-fos plays a major role in modulating the growth properties of F-98 cells.
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PMID:Analysis of c-fos expression in the butyrate-induced F-98 glioma cell differentiation. 786 28

Glucocorticoids (GC) are potent repressors of both basal and corticotropin releasing factor (CRF) stimulated transcription of the proopiomelanocortin (POMC) gene in corticotrope cells of the anterior pituitary. Despite the finding of a novel, high affinity glucocorticoid receptor (GR) binding site within the proximal region of the POMC promoter, the mechanism by which GC inhibit POMC transcription is still uncertain. Recent studies have described mechanisms whereby GC inhibit transcription of other genes via a direct interaction with components of the transcription factor AP-1. Since it has been shown that CRF stimulates c-fos in AtT-20 corticotrope cells, and that c-fos over-expression elevates POMC transcription, the current study has investigated whether GC can repress c-fos and c-jun gene expression and AP-1 DNA binding activity in AtT-20 corticotrope cells. Acute treatment with doses of dexamethasone (DEX) that markedly inhibited nuclear POMC hnRNA had no effect on basal c-fos mRNA expression, but resulted in a transient down regulation of c-jun. In addition, acute DEX pretreatment significantly lowered CRF stimulation of POMC gene expression and attenuated the CRF stimulation of c-fos mRNA by 25%. Although DEX treatment of AtT-20 cells did not affect AP-1 DNA binding capacity of nuclear extracts, DEX pretreatment blunted the stimulation of AP-1 binding in response to CRF. In further studies, nuclear extracts from CRF-treated cells were coincubated with nuclear extracts from control or DEX treated cells. High levels of DEX treated extracts led to a relative repression of CRF-induced AP-1 binding, suggesting that ligand-activated GR may lower available AP-1 levels by direct protein: protein interaction. Finally, the composition of AP-1 in AtT-20 nuclear extracts was found to be heterogeneous, with the variation dependent upon hormonal treatment. These data suggest that in the corticotrope cell relatively high levels of activated GR may influence CRF-induced AP-1 DNA binding via transient genomic actions on basal c-jun and stimulated c-fos and/or via direct protein:protein interactions.
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PMID:Glucocorticoid regulation of c-fos, c-jun and transcription factor AP-1 in the AtT-20 corticotrope cell. 789 65

Clinical and animal data suggest that exposure of developing brain to cocaine has adverse consequences. One candidate mechanism for such effects is drug regulation of gene expression. In adult rats, cocaine induces expression of nuclear immediate early genes with specific spatial and temporal patterns. The products of such genes (e.g., c-Fos, c-Jun, and Zif/268) subserve the coupling of cell surface receptor stimulation to transcriptional regulation. Thus, activation of immediate early gene expression in developing brain by cocaine could alter programs of neural gene expression and, thereby, neuronal phenotype and function. We report that, during rat brain development, cocaine produced brain region-specific and developmental age-specific induction of c-fos, c-jun, and zif/268 mRNAs. At each age studied (P8, P15, P28, and adults), we found that acute cocaine administration resulted in a unique cell-specific pattern of c-fos mRNA induction and c-Fos protein expression in striatum. We also observed cocaine-induced activation of AP-1 DNA binding activity in striatal extracts prepared at these different ages, suggesting that the observed induction of c-fos and c-jun may have biological consequences for the developing brain. These findings suggest a mechanism by which cocaine could alter patterns of gene expression during critical developmental periods with differential regional, temporal, and cellular vulnerabilities and, therefore, consequences for developing brain.
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PMID:Postnatal age defines specificity of immediate early gene induction by cocaine in developing rat brain. 789 38

delta-9-Tetrahydrocannabinol (THC) is a major psychoactive component of cannabis. We have recently localized a receptor for THC in the forebrain and found in the caudate-putamen that its gene expression is modulated by glucocorticoids, dopamine and glutamate. Here, we report for the first time, using quantitative in situ hybridization, that acute THC (5 mg kg-1, i.p.) regulates the mRNA levels of multiple immediate early genes in the adult rat forebrain. Twenty minutes after a single THC injection, significant increases in concentration of the mRNAs for C-FOS, C-JUN and ZIF-268 were observed in the cingulate cortex (75, 45 and 37%) and for C-FOS and ZIF-268 in the fronto-parietal cortex (60 and 64%) and caudate-putamen (81 and 32%) while JUN-D mRNA levels were not changed. These transcription factor genes might mediate putative THC modulation of neurotransmitter gene expression.
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PMID:Activation of multiple transcription factor genes by tetrahydrocannabinol in rat forebrain. 791 80

The present studies have characterized the regulation of interleukin-6 (IL-6) gene expression during pokeweed mitogen (PWM)-driven human B-cell differentiation. PWM induced an early and transient increase in the expression of immediate-early response genes of the jun/fos leucine zipper family (c-jun, jun B, c-fos, and fos-B). The induction of c-jun mRNA by PWM was concentration dependent. Nuclear run-on assays showed that PWM treatment is associated with an increased rate of c-jun gene transcription. The induction of c-jun mRNA precedes the induction of IL-6 gene expression and IL-6 secretion by the B cells. c-Jun antisense, but not sense, oligodeoxynucleotide (ODN) significantly decreases PWM-related B-cell (1) proliferation; (2) IL-6 mRNA induction; (3) IL-6 secretion; and (4) nuclear extract binding to AP-1 in electrophoretic mobility shift assay. In contrast, c-Fos anti-sense ODN did not effect either IL-6 mRNA induction or IL-6 secretion triggered in B cells by PWM. The results further show activation of c-Raf-1 kinase in PWM-treated B cells. Raf-1 acts upstream to mitogen-activated protein (MAP) kinase; therefore, studies were performed to assay for MAP kinase activation in these cells. The results show an increase in phosphorylation of myelin basic protein (MBP) and c-Jun "Y" peptide in PWM-treated B cells. Taken together, these findings suggest that PWM is able to initiate an intracytoplasmic signaling cascade in normal human splenic B cells, which, at least in part, involves serine/threonine protein kinases. These results show transient induction of immediate-early response genes in B cells and support a potential role for the c-jun gene product in regulation of IL-6 transcription and secretion.
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PMID:Identification of upstream signals regulating interleukin-6 gene expression during in vitro treatment of human B cells with pokeweed mitogen. 791 42

Irradiation of HeLa cells with short-wavelength ultraviolet light (UVC) induces the modification and activation of the preexisting transcription factors c-Fos-c-Jun (AP-1) and TCF/Elk-1, as well as the protein synthesis independent transcriptional activation of the c-fos and c-jun genes. This response to UVC is mediated via obligatory cytoplasmic signal transduction, involving Ras and Raf, Src, and MAP kinases. The UVC response is inhibited by prior down-modulation of growth factor receptor signaling upon growth factor prestimulation, by suramin (an inhibitor of receptor activation) or by expression of a dominant negative epidermal growth factor (EGF) receptor mutant. These data suggest the involvement of several growth factor receptors in the UVC response. Indeed, UVC induces the suramin-inhibitable immediate tyrosine phosphorylation of the EGF receptor.
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PMID:Involvement of growth factor receptors in the mammalian UVC response. 792 65

Evi-1 is a gene, encoding a zinc finger protein, associated with a common viral integration site in murine leukemias. It is suggested that Evi-1 plays important roles in embryogenesis and transformation of myeloid cells. To elucidate mechanisms by which Evi-1 induces such biological effects, we analyzed the relationship between Evi-1 and AP-1 which could regulate cellular proliferation and differentiation. When Evi-1 was expressed, transactivation through a 12-O-tetradecanoylphorbol 13-acetate-responsive element was observed in NIH3T3 and P19 cells. Evi-1-transfected P19 cells showed some differentiated phenotypes and increased expression of endogenous c-Jun and c-Fos. These results indicate that Evi-1 raises AP-1 activity. Evi-1 caused stimulation of the c-fos promoter transactivation, which seems to be a main mechanism of AP-1 activation, through at least two portions of the promoter. Evi-1 has the first zinc finger domain at the N terminus and the second zinc finger domain near the C-terminus. We constructed deletion mutants of Evi-1 and investigated the functions of these domains. It was shown that the second zinc finger domain is essential for the activation of AP-1 and transactivation of the c-fos promoter.
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PMID:Evi-1 raises AP-1 activity and stimulates c-fos promoter transactivation with dependence on the second zinc finger domain. 792 53

c-Jun transcriptional activity is stimulated by phosphorylation at two N-terminal sites: Ser-63 and -73. Phosphorylation of these sites is enhanced in response to a variety of extracellular stimuli, including growth factors, cytokines, and UV irradiation. New members of the mitogen-activated protein (MAP) kinase group of signal-transducing enzymes, termed JNKs, bind to the activation domain of c-Jun and specifically phosphorylate these sites. However, the N-terminal sites of c-Jun were also suggested to be phosphorylated by two other MAP kinases, ERK1 and ERK2. Despite these reports, we find that unlike the JNKs, ERK1 and ERK2 do not phosphorylate the N-terminal sites of c-Jun in vitro; instead they phosphorylate an inhibitory C-terminal site. Furthermore, the phosphorylation of c-Jun in vivo at the N-terminal sites correlates with activation of the JNKs but not the ERKs. The ERKs are probably involved in the induction of c-fos expression and thereby contribute to the stimulation of AP-1 activity. Our study suggests that two different branches of the MAP kinase group are involved in the stimulation of AP-1 activity through two different mechanisms.
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PMID:c-Jun N-terminal phosphorylation correlates with activation of the JNK subgroup but not the ERK subgroup of mitogen-activated protein kinases. 793 87

Independent of its ability to block translation, anisomycin intrinsically initiates intracellular signals and immediate-early gene induction [L. C. Mahadevan and D. R. Edwards, Nature (London) 349:747-749, 1991]. Here, we characterize further its action as a potent, selective signalling agonist. In-gel kinase assays show that epidermal growth factor (EGF) transiently activates five kinases: the mitogen-activated protein (MAP) kinases ERK-1 and -2, and three others, p45, p55, and p80. Anisomycin, at inhibitory and subinhibitory concentrations, does not activate ERK-1 and -2 but elicits strong sustained activation of p45 and p55, which are unique in being serine kinases whose detection is enhanced with poly-Glu/Tyr or poly-Glu/Phe copolymerized in these gels. Translational arrest using emetine or puromycin does not activate p45 and p55 but does prolong EGF-stimulated ERK-1 and -2 activation. Rapamycin, which blocks anisomycin-stimulated p70/85S6k activation without affecting nuclear responses, has no effect on p45 or p55 kinase. p45 and p55 are activable by okadaic acid or UV irradiation, and both kinases phosphorylate the c-Jun NH2-terminal peptide 1-79, putatively placing them within c-Jun NH2-terminal kinase/stress-activated protein kinase (JNK/SAPK) subfamily of MAP kinases. Thus, the EGF- and anisomycin-activated kinases p45 and p55 are strongly implicated in signalling to c-fos and c-jun, whereas the MAP kinases ERK-1 and -2 are not essential for this process.
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PMID:Anisomycin-activated protein kinases p45 and p55 but not mitogen-activated protein kinases ERK-1 and -2 are implicated in the induction of c-fos and c-jun. 793 49

Single ultraviolet (u.v.) irradiation of mammalian cells in culture evokes the transcriptional activation of various proto-oncogenes, among them members of the fos/jun family which are known to play an important role in cell proliferation and differentiation. u.v. exposure of mammalian skin results in growth arrest and cell death followed by hyperproliferation of epidermal cells. To obtain information in vivo about a possible relationship between u.v.-induced proto-oncogene expression and cellular alterations, we have analysed the expression of c-fos, fosB, c-jun, junB, bcl-2 and bax in rat epidermis after single and chronic u.v. irradiation. We present data demonstrating that the transcripts of these genes are constitutively expressed in the epidermis and that expression is differentially modulated by u.v. exposure. Single u.v. irradiation causes a rapid and sustained increase in c-jun, junB and c-fos mRNA and a decline in bcl-2 transcripts, whereas expression of bax remained unchanged. c-Fos and c-Jun immunoreactivity was localized throughout the epidermal cell layers 1.5 h after single irradiation, but restricted to basal cells at 48 h suggesting an involvement in both u.v.-induced apoptosis and hyperproliferation. 48 h after chronic exposure a significantly higher induction and a totally different pattern of epidermal proto-oncogene expression was detectable which may be associated with malignancy. Superfusion of rat skin with c-fos antisense oligodeoxynucleotides inhibited the increase in c-Fos immunolabeled epidermal cells 1.5 h after single u.v. irradiation demonstrating that antisense oligodeoxynucleotides are capable of penetrating mammalian skin and modulating the u.v. response in vivo. However, suppression of the early c-Fos activation did not significantly affect the formation of sunburn cells in the u.v.-exposed epidermis. Thus, c-Fos does not seem to play a major role in u.v.-induced apoptosis or other members of the fos/jun family may compensate for a loss in c-Fos.
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PMID:Differential regulation of c-fos, fosB, c-jun, junB, bcl-2 and bax expression in rat skin following single or chronic ultraviolet irradiation and in vivo modulation by antisense oligodeoxynucleotide superfusion. 793 45


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