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

Retinoic acid (RA) and sodium butyrate (NaB) have been implicated in the regulation of growth and differentiation in various cancer cells. To produce an agent with the properties of both RA and NaB, a butyryl aminophenyl ester of RA (4-BPRE) was synthesized. The agent was compared with an aminophenyl ester devoid of the butyryl group (4-APRE) for antitumor potential in vitro. Like RA, 4-hydroxyphenyl retinamide (4-HPR) and 4-APRE, 4-BPRE was an active ligand for all three subtypes of RAR, but not for RXR, as determined by transcription assays in COS-1 cells. In addition, regardless of the butyryl group, 4-BPRE actively suppressed c-Jun transcriptional activity, which may result in reduced expression of matrix metalloproteinases (MMP-1 and MMP-2), and effectively inhibited HCT116 cell invasion into Matrigel. In these respects, 4-BPRE is similar to 4-APRE, and even to RA and 4-HPR. However, our results showed that in HCT116 colon and A549 lung cancer cells, 4-BPRE was much more cytotoxic than RA and 4-APRE, and was also more cytotoxic than 4-HPR, which is the most cytotoxic retinoid derivative under clinical investigation. Subsequent assays using DAPI staining, DNA fragmentation, and FACS analysis suggested that the cytotoxic effect of 4-BPRE is mediated by apoptosis in HCT116 cells. Moreover, 4-BPRE inhibited histone deacetylase (HDAC) activity to some degree, although inhibition was less than that induced by the known HDAC inhibitors TSA and NaB. These results suggest that 4-BPRE could be a promising antitumor retinoid with both NaB activity and RA function.
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PMID:In vitro antitumor potential of 4-BPRE, a butyryl aminophenyl ester of retinoic acid: role of the butyryl group. 1476 28

The beta and gamma subunits of heterotrimeric GTP-binding proteins (Gbetagamma) were found to bi-directionally regulate the UV-induced activation of p38 and c-Jun NH(2)-terminal kinase, and the UV-induced activation of p38 was reported to enhance the resistance of normal keratinocytes to apoptosis. However, the signaling pathway downstream of Gbetagamma for this UV-induced p38 activation is not known. Thus, we examined the role of the Rho GTPase family in the regulation of UV-induced p38 activation by Gbetagamma. We found that overexpression of Gbetagamma increased the UV-induced activation of Cdc42 and that overexpression of constitutively active V12 Cdc42 increased the UV-induced p38 activation. Transfection of dominant negative N17 Cdc42 or small interfering RNA for Cdc42 blocked UV-induced p38 activation mediated by Gbetagamma in COS-1 and HaCaT cells. UV-induced p38 activation by Gbetagamma was blocked by overexpression of dominant negative p21-activated kinase (PAK)-interacting exchange factor beta (betaPix), and wild type betaPix stimulated the UV-induced p38 activation, which was blocked by N17 Cdc42. Gbetagamma increased the UV-induced activation of Ras, and the overexpression of V12 Ras increased UV-induced p38 activation, which was blocked by dominant negative betaPix. UV-induced p38 activation was inhibited by N17 Ras and a farnesyltransferase inhibitor, manumycin A. Gbetagamma also increased the UV-induced phosphorylation of the epidermal growth factor receptor (EGFR), and the UV-induced p38 activation was blocked by an EGFR kinase inhibitor, AG1478. From these results, we conclude that Gbetagamma mediates UV-induced activation of p38 in a Cdc42-dependent way and that EGFR, Ras, and betaPix act sequentially upstream of Cdc42 in COS-1 and HaCaT cells.
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PMID:Cdc42-dependent mediation of UV-induced p38 activation by G protein betagamma subunits. 1497 Feb 10

The gene responsible for multiple endocrine neoplasia type 1, MEN1, encodes the 610-amino acid-protein, menin. Although menin has been reported to bind AP-1 transcription factor JunD and suppress its transcriptional activity, little is known about its molecular mechanisms and physiological role. To better understand the function of menin and its significance in tumorigenesis, we investigated the effect of wild-type and mutant menin proteins on AP-1 transactivation. In COS cells, wild-type menin suppressed JunD-mediated transactivation in a dose-dependent manner, while it augmented c-Jun-mediated transactivation also in a dose-dependent manner. These effects were lost or reduced in all menin mutants examined. Electrophoretic mobility shift assay using AP-1 binding elements as a probe revealed that menin does not affect binding of c-Jun to DNA. Coexpression of menin mutants did not affect the function of wild-type menin. Coexpression of JunD amino-terminal fragment abolished menin-mediated enhancement of c-Jun transactivation, suggesting that Menin-JunD interaction may negatively regulate the enhancing effect of menin on c-Jun-mediated transactivation in COS cells.
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PMID:JunD-menin interaction regulates c-Jun-mediated AP-1 transactivation. 1525 79

Hepatopoietin (HPO)/augmenter of liver regeneration (ALR) is a specific hepatotrophic growth factor, which plays a key role in liver regeneration. Our previous study indicated that HPO executes its function by an inter-reactive network of the autocrine, paracrine and endocrine pathways. Recently, we have demonstrated that intracellular HPO interacts with Jun activation domain-binding protein 1 (JAB1) and leads to potentiation of activating protein-1 (AP-1) activity in a MAPK independent fashion. JAB1 is the fifth subunit of the COP9 signalosome (CSN), which is first identified as a suppressor of plant morphogenesis. A protein complex kinase activity associated with the CSN has been reported but not identified yet. In this report, we investigated further the association of HPO with the whole CSN. HPO exists in a complex with the eight-component CSN, both when purified from glycerol gradient centrifugation and when reciprocal immunoprecipitated from the lysates of transfected COS-7 cells. Intracellular HPO colocalizes with endogenous CSN in nucleus of hepatic cells. In addition, intracellular function of HPO that increases the phosphorylation of c-Jun leading to potentiate the AP-1 activity is inhibited by curcumin, a potent inhibitor of CSN-associated kinase. Taken together, these results elucidate a novel relationship of intracellular growth factor, HPO with large protein complex, CSN, which suggests a possible linkage between CSN and liver regeneration.
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PMID:Hepatopoietin interacts directly with COP9 signalosome and regulates AP-1 activity. 1530 29

Abnormal phosphorylation of amyloid-beta precursor protein (APP) is a pathologic feature of Alzheimer's disease. To begin to understand the mechanism of APP phosphorylation, we studied this process in differentiating neurons under normal physiological conditions. We found that c-Jun NH2-terminal kinase (JNK), not cyclin-dependent kinase 5, is required for APP phosphorylation, leading to localized accumulation of phosphorylated APP (pAPP) in neurites. We show that JNK-interacting protein-3 (JIP-3), a JNK scaffolding protein that does not bind APP, selectively increases APP phosphorylation, accumulation of pAPP into processes, and stimulates process extension in both neurons and COS-1 cells. Downregulation of JIP-3 by small interfering RNA impairs neurite extension and reduces the amount of localized pAPP. Finally, whereas stress-activated JNK generates pAPP only in the cell body, concomitant expression of JIP-3 restores pAPP accumulation into neurites. Thus, APP phosphorylation, transport of the generated pAPP into neurites, and neurite extension are interdependent processes regulated by JIP-3/JNK, in a pathway distinct from stress-activated JNK signaling.
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PMID:c-Jun NH2-terminal kinase-interacting protein-3 facilitates phosphorylation and controls localization of amyloid-beta precursor protein. 1582 26

Tumour angiogenesis is mediated by increased levels of vascular endothelial growth factor (VEGF). We have studied the mechanism by which endogenous activation of Rho oncoproteins regulates VEGF expression in COS-7 and NIH3T3 cells. We carried out transient and stable transfection with constitutively activated rhoA, rac1, and cdc42 mutants in COS-7 and NIH3T3 cells, respectively in the absence of external stimuli. Western blot and inmunohistochemistry assays of those cells revealed increased VEGF protein expression. Cotransfection with constitutively activated rhoA, rac1, and cdc42 mutants and a VEGF promoter-reporter construct showed an increase in VEGF promoter transcriptional activity induced by Rho oncoproteins in COS-7 and NIH3T3. c-Jun kinase had been described as a MAPK involved in Rho oncoproteins pathways. Interestingly, we found that c-Jun kinase chemical inhibition as well as transient transactivation assays using dominant negative c-Jun kinase mutant abolished the VEGF promoter transcriptional induction by Rac1 and Cdc42 but not by RhoA. These findings indicate that Rho oncoprotein endogenously activated regulates VEGF expression through a transcriptional mechanism, and that the c-Jun kinase activity is a mediator in the expression of VEGF induced by Rac1 and Cdc42 oncoproteins, but not of that induced by RhoA.
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PMID:c-Jun kinase mediates expression of VEGF induced at transcriptional level by Rac1 and Cdc42Hs but not by RhoA. 1644 Mar 8

Dual leucine zipper-bearing kinase (DLK) is a mixed-lineage kinase family member that acts as an upstream activator of the c-Jun N-terminal kinases. As opposed to other components of this pathway, very little is currently known regarding the mechanisms by which DLK is regulated in mammalian cells. Here we identify the stress-inducible heat shock protein 70 (Hsp70) as a negative regulator of DLK expression and activity. Support for this notion derives from data showing that Hsp70 induces the proteasomal degradation of DLK when both proteins are co-expressed in COS-7 cells. Hsp70-mediated degradation occurs with expression of wild-type DLK, which functions as a constitutively activated protein in these cells but not kinase-defective DLK. Interestingly, the Hsp70 co-chaperone CHIP, an E3 ubiquitin ligase, seems to be indispensable for this process since Hsp70 failed to induce DLK degradation in COS-7 cells expressing a CHIP mutant unable to catalyze ubiquitination or in immortalized fibroblasts derived from CHIP knock-out mice. Consistent with these data, we have found that endogenous DLK becomes sensitive to CHIP-dependent proteasomal degradation when it is activated by okadaic acid and that down-regulation of Hsp70 levels with an Hsp70 antisense attenuates this sensitivity. Therefore, our studies suggest that Hsp70 contributes to the regulation of activated DLK by promoting its CHIP-dependent proteasomal degradation.
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PMID:Down-regulation of the mixed-lineage dual leucine zipper-bearing kinase by heat shock protein 70 and its co-chaperone CHIP. 1693 12

The Bric-a-brac, Tramtrack, Broad-complex (BTB) domain is a protein-protein interaction domain that is found in many zinc finger transcription factors. BTB containing proteins play important roles in a variety of cellular functions including regulation of transcription, regulation of the cytoskeleton, protein ubiquitination, angiogenesis, and apoptosis. Here, we report the cloning and characterization of a novel human gene, KLHL31, from a human embryonic heart cDNA library. The cDNA of KLHL31 is 5743 bp long, encoding a protein product of 634 amino acids containing a BTB domain. The protein is highly conserved across different species. Western blot analysis indicates that the KLHL31 protein is abundantly expressed in both embryonic skeletal and heart tissue. In COS-7 cells, KLHL31 proteins are localized to both the nucleus and the cytoplasm. In primary cultures of nascent mouse cardiomyocytes, the majority of endogenous KLHL31 proteins are localized to the cytoplasm. KLHL31 acts as a transcription repressor when fused to GAL4 DNA-binding domain and deletion analysis indicates that the BTB domain is the main region responsible for this repression. Overexpression of KLHL31 in COS-7 cells inhibits the transcriptional activities of both the TPA-response element (TRE) and serum response element (SRE). KLHL31 also significantly reduces JNK activation leading to decreased phosphorylation and protein levels of the JNK target c-Jun in both COS-7 and Hela cells. These results suggest that KLHL31 protein may act as a new transcriptional repressor in MAPK/JNK signaling pathway to regulate cellular functions.
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PMID:A novel human BTB-kelch protein KLHL31, strongly expressed in muscle and heart, inhibits transcriptional activities of TRE and SRE. 1871 55

Copper is an essential metal that is able to produce reactive oxygen species and to induce intracellular oxidative stress. Several studies have examined the effects of excessive copper and oxidative stress on various organisms and tissues, but few have addressed the molecular mechanisms by which copper affects transcription. Our results demonstrated that, in COS-7 cells, copper treatment caused an increase in the binding of nuclear proteins to activating protein-1 and antioxidant response elements. The level of copper-inducible nuclear protein binding was modulated by increasing or decreasing the level of intracellular oxidative stress. Copper exposure also led to an increase in the steady-state levels of c-fos, c-jun, and c-myc mRNAs. Exposure to copper resulted in an increase in the levels of phosphorylation and activation of the c-Jun N-terminal kinase/stress-activated protein kinase and p38 pathways. The activation of these pathways resulted in a concomitant increase in c-Jun phosphorylation. We investigated the hypothesis that copper-induced oxidative stress leads to the formation of stable lipid peroxidation by-products that activate mitogen-activated protein kinase (MAPK) pathways, ultimately affecting transcription. While exposure did result in the production of 4-hydroxynonenal, the timing of the increased levels of proto-oncogene mRNA, phosphorylation of c-jun, and phosphorylation and activation of MAPKs, as well as the inability of the lipophilic antioxidant vitamin E to abrogate MAPK phosphorylation, suggest that the formation of stable lipid peroxidation by-products may not be the primary mechanism by which copper activates MAPKs. These results further elucidate the effects of copper on signal transduction pathways to alter gene expression.
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PMID:Mechanism of copper-activated transcription: activation of AP-1, and the JNK/SAPK and p38 signal transduction pathways. 1879 45

Prostate tumor overexpressed-1 (PTOV1), a modulator of the Mediator transcriptional regulatory complex, is expressed at high levels in prostate cancer and other neoplasias in association with a more aggressive disease. Here we show that PTOV1 interacts directly with receptor of activated protein C kinase 1 (RACK1), a regulator of protein kinase C and Jun signaling and also a component of the 40S ribosome. Consistent with this interaction, PTOV1 was associated with ribosomes and its overexpression promoted global protein synthesis in prostate cancer cells and COS-7 fibroblasts in a mTORC1-dependent manner. Transfection of ectopic PTOV1 enhanced the expression of c-Jun protein without affecting the levels of c-Jun or RACK1 mRNA. Conversely, knockdown of PTOV1 caused significant declines in global protein synthesis and c-Jun protein levels. High levels of PTOV1 stimulated the motility and invasiveness of prostate cancer cells, which required c-Jun, whereas knockdown of PTOV1 strongly inhibited the tumorigenic and metastatic potentials of PC-3 prostate cancer cells. In human prostate cancer samples, the expression of high levels of PTOV1 in primary and metastatic tumors was significantly associated with increased nuclear localization of active c-Jun. These results unveil new functions of PTOV1 in the regulation of protein translation and in the progression of prostate cancer to an invasive and metastatic disease.
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PMID:Regulation of protein translation and c-Jun expression by prostate tumor overexpressed 1. 2345 24


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