Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: 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)

Maintenance of genome stability is essential for keeping cellular homeostasis. The DNA damage response is a central component in maintaining genome integrity. Among of the most cytotoxic DNA lesions are double strand breaks (DSBs) caused by ionizing radiation or radiomimetic chemicals. ATM is missing or inactivated in patients with ataxia-telangiectasia. Ataxia-telangiectasia patients display a pleiotropic phenotype and suffer primarily from progressive ataxia caused by degeneration of cerebellar Purkinje and granule neurons. Additional features are immunodeficiency, genomic instability, radiation sensitivity, and cancer predisposition. Disruption of the mouse Atm locus creates a murine model of ataxia-telangiectasia that exhibits most of the clinical features of the human disease but very mild neuronal abnormality. The ATM protein is a multifunctional protein kinase, which serves as a master regulator of cellular responses to DSBs. There is growing evidence that ATM may be involved in addition to the DSB response in other processes that maintain processes in cellular homeostasis. For example, mounting evidence points to increased oxidative stress in the absence of ATM. Here we report that the AP-1 pathway is constantly active in the brains of Atm-deficient mice not treated with DNA damaging agents. A canonical activation (increased phosphorylation of mitogen-activated protein kinase kinase-4, c-Jun N-terminal kinase, and c-Jun) of the AP-1 pathway was found in Atm-deficient cerebra, whereas induction of the AP-1 pathway in Atm-deficient cerebella is likely to mediate elevated expression of c-Fos and c-Jun. Although Atm(+/+) mice are capable of responding to ionizing radiation by activating stress responses such as the AP-1 pathway, Atm-deficient mice display higher basal AP-1 activity but gradually lose their ability to activate AP-1 DNA-binding activity in response to ionizing radiation. Our results further demonstrate that inactivation of the ATM gene results in a state of constant stress.
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PMID:Contribution of the Atm protein to maintaining cellular homeostasis evidenced by continuous activation of the AP-1 pathway in Atm-deficient brains. 1249 86

Phosphorylation at Ser(727) is known to be required for complete activation of STAT3 by diverse stimuli including UV irradiation, but the kinase(s) responsible for phosphorylating STAT3 (Ser(727)) is still not well discerned. In the present study, we observed that activation of ATM is required for a UVA-stimulated increase in Ser(727) phosphorylation of STAT3 as well as in activation and phosphorylation of p90 ribosomal protein S6 kinases (RSKs). Moreover, UVA-stimulated activation of upstream kinases, such as c-Jun N-terminal kinases (JNKs) and ERKs, involved in mediating phosphorylation of RSKs and STAT3 was defective or delayed in ATM-deficient cells. Furthermore, we provide evidence that RSK2-deficient cells were defective for UV-induced Ser(727) phosphorylation of STAT3, and the defect was restored after ectopic expression of transfected full-length RSK2. In vitro experiments showed that active RSK2 and JNK1 induce the phosphorylation of STAT3 precipitates from immunoprecipitation but not from glutathione S-transferase (GST) pull-down. Interestingly, the GST fusion STAT3 proteins mixed together with STAT3 immunoprecipitates can be phosphorylated by JNK. However, the in vitro phosphorylation of STAT3 was reduced by the GST-STAT3 beta protein, a dominant negative form of STAT3. Taken together, our results demonstrate that the STAT3 phosphorylation at Ser(727) is triggered by active RSK2 or JNK1 in the presence of a downstream kinase or a cofactor, and thereby the intracellular phosphorylation process is stimulated through a signaling pathway involving ATM, MAPKs, RSK2, and an as yet unidentified kinase or cofactor. Additionally, RSK2-mediated phosphorylation of STAT3 (Ser(727)) was further determined to be required for basal and UVA-stimulated STAT3 transcriptional activities.
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PMID:Ataxia telangiectasia mutated proteins, MAPKs, and RSK2 are involved in the phosphorylation of STAT3. 1256 65

BRCA1 is a central component of the DNA damage response mechanism and defects in BRCA1 confer sensitivity to a broad range of DNA damaging agents. BRCA1 is required for homologous recombination and DNA damage-induced S and G(2)/M phase arrest. We show here that BRCA1 is required for ATM- and ATR-dependent phosphorylation of p53, c-Jun, Nbs1 and Chk2 following exposure to ionizing or ultraviolet radiation, respectively, and is also required for ATM phosphorylation of CtIP. In contrast, DNA damage-induced phosphorylation of the histone variant H2AX is independent of BRCA1. We also show that the presence of BRCA1 is dispensable for DNA damage-induced phosphorylation of Rad9, Hus1 and Rad17, and for the relocalization of Rad9 and Hus1. We propose that BRCA1 facilitates the ability of ATM and ATR to phosphorylate downstream substrates that directly influence cell cycle checkpoint arrest and apoptosis, but that BRCA1 is dispensable for the phosphorylation of DNA-associated ATM and ATR substrates.
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PMID:A subset of ATM- and ATR-dependent phosphorylation events requires the BRCA1 protein. 1277

Exposure of human cells to genotoxic agents induces various signaling pathways involved in the execution of stress- and DNA-damage responses. Inappropriate functioning of the DNA-damage response to ionizing radiation (IR) is associated with the human diseases ataxia-telangiectasia (A-T) and Nijmegen Breakage syndrome (NBS). Here, we show that IR efficiently induces Jun/ATF transcription factor activity in normal human diploid fibroblasts, but not in fibroblasts derived from A-T and NBS patients. IR was found to enhance the expression of c-Jun and, in particular, ATF3, but, in contrast to various other stress stimuli, did not induce the expression of c-Fos. Using specific inhibitors, we found that the ATM- and Nibrin1-dependent activation of ATF3 does neither require p53 nor reactive oxygen species, but is dependent on the p38 and JNK MAPkinases. Via these kinases, IR activates ATF-2, one of the transcription factors acting on the atf3 promoter. The activation of ATF-2 by IR resembles ATF-2 activation by certain growth factors, since IR mainly induced the second step of ATF-2 phosphorylation via the stress-inducible MAPkinases, phosphorylation of Thr69. As IR does not enhance ATF-2 phosphorylation in ATM and Nibrin1-deficient cells, both ATF-2 and ATF3 seem to play an important role in the protective response of human cells to IR.
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PMID:Induction of ATF3 by ionizing radiation is mediated via a signaling pathway that includes ATM, Nibrin1, stress-induced MAPkinases and ATF-2. 1283 46

Angiotensin II (Ang II) exerts a potent growth stimulus on the heart and vascular wall. Activation of the Janus kinase/signal transducer and activator of transcription (JAK/STAT) intracellular signaling pathway by Ang II mediates at least some of the mitogenic responses to this hormone. In other signaling systems that use the JAK/STAT pathway, proteins of the suppressor of cytokine signaling (SOCS) family participate in signal regulation. In the present study it is demonstrated that SOCS3 is constitutively expressed at a low level in rat heart and neonatal rat ventricular myocytes. Ang II at a physiological concentration enhances the expression of SOCS3 mRNA and protein, mainly via AT1 receptors. After induction, SOCS3 associates with JAK2 and impairs further activation of the JAK2/STAT1 pathway. Pretreatment of rats with a specific phosphorthioate antisense oligonucleotide to SOCS3, reverses the desensitization to angiotensin signaling, as detected by a fall in c-Jun expression after repetitive infusions of the hormone. Thus, SOCS3 is induced by Ang II in rat heart and neonatal rat ventricular myocytes and participates in the modulation of the signal generated by this hormone.
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PMID:Suppressor of cytokine signaling 3 is induced by angiotensin II in heart and isolated cardiomyocytes, and participates in desensitization. 1296 61

The MEK1,2 (MAPK/ERK kinase 1 and 2) pathway mediates the up-regulation of plasminogen activator inhibitor-1 (PAI-1) expression in vascular smooth muscle cells by a variety of hormones, including angiotensin II. Transfection of constitutively active MEKK-1, an upstream activator of the mitogen-activated protein (MAP) kinase pathways, was used to isolate an enhancer element located between -89 and -50 bp in PAI-1 promoter that was activated by MEKK-1 and selectively blocked by the MEK1,2 inhibitor PD98059. Mutational analysis revealed that the MEKK-1 response element (MRE) contained 2 cis-acting Sp1- and AP-1-like sequences, located between -75 to -70 and -63 to -52 bp, respectively. Overexpression of Sp1 enhanced MEKK-1-induced MRE promoter activity and a dominant-negative c-Fos blocked this Sp1 response. The combination of Sp1 and c-Jun or c-Fos was required to activate this MRE. Angiotensin II (Ang II) stimulation increased c-Fos, c-Jun, and Sp1 binding to the MRE by 100-, 4.9-, and 1.9-fold, respectively, and these responses were inhibited by PD98059 and AT1 receptor antagonist candesartan. Intravenous Ang II infusion in rats increased aortic c-Fos binding to the MRE. This MRE sequence mediated a 4-fold increase of MEK1,2-dependent PAI-1/luciferase mRNA expression by angiotensin II stimulation. This report identifies the MEK1,2 response element that mediates angiotensin II-stimulated PAI-1 promoter activation and shows that activation of this element requires Sp1 and AP-1 co-activation.
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PMID:MEK1,2 response element mediates angiotensin II-stimulated plasminogen activator inhibitor-1 promoter activation. 1465 94

Various Gq protein-coupled receptor agonists such as the alpha1 adrenoceptor agonist phenylephrine, angiotensin II, and endothelin-1 are potent hypertrophic factors. There is evidence of potential cross talk between these agents, particularly in terms of endothelin-1 as playing a central role in mediating the actions of other hypertrophic factors. Using cultured rat neonatal ventricular myocytes, we assessed the potential cross talk between these factors and sought to examine the potential underlying mechanisms. Twenty-four-hour exposure to either agent produced significant hypertrophy as determined by cell size and molecular markers. Although the hypertrophic effects of phenylephrine and angiotensin II were expectedly prevented by alpha1 and AT1 receptor antagonists, respectively, these effects were also blocked by the ETA receptor antagonist BQ123 [cyclo(D-Asp-Pro-D-Val-Leu-D-Trp)] but not by the ETB antagonist BQ788 (N-cis-2,6-dimethylpiperidinocarbonyl-L-gamma-methylleucyl-D-1-methoxycarbonyltryptophanyl-D-norleucine). Both phenylephrine and angiotensin II significantly increased protein expression of both endothelin receptor subtypes. Both phenylephrine and angiotensin II produced significant activation of p38 as well as extracellular signal-regulated protein kinase and c-Jun NH2-terminal kinase, although this was unaffected by endothelin receptor blockade. Further studies revealed that the effects of phenylephrine and angiotensin II were mediated by stimulated endothelin-1 production occurring via two separate mechanisms: angiotensin II by increasing the levels of the endothelin-1 precursor prepro endothelin-1 and phenylephrine by upregulating endothelin-converting enzyme 1. Our results indicate that the endothelin-1 system plays an obligatory role in the hypertrophic response to both phenylephrine and angiotensin II in cultured myocytes through a mechanism independent of mitogenactivated protein kinase activation.
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PMID:Obligatory role for endogenous endothelin in mediating the hypertrophic effects of phenylephrine and angiotensin II in neonatal rat ventricular myocytes: evidence for two distinct mechanisms for endothelin regulation. 1500 6

The aim of the study was to identify pancreatic stellate cells (PSCs) as a potential target of angiotensin II (ATII) action because recently a local renin-angiotensin system (RAS) has been described in the pancreas. PSCs were isolated from male Wistar rats and investigated for ATII receptor expression and ATII-induced calcium transients, contractions, proliferation, and alpha-smooth muscle actin expression. Quiescent and activated PSCs expressed the ATII receptor subtype AT1 but not AT2. Addition of ATII led to a rapid elevation of intracellular calcium ([Ca]i). The sensitivity toward ATII with respect to calcium transients did not change during the transdifferentiation process. In activated PSCs, ATII dose dependently induced PSC cell contraction. Furthermore, ATII induced an activation of the c-Jun-N-terminal kinase (JNK) and extracellular regulated kinase (Erk), which was inhibited after intracellular calcium chelation by BAPTA-AM. The p38 mitogen-activated protein kinase (p38) was also activated by ATII. BAPTA-AM itself induced p38 activation, which was not further enhanced by ATII. ATII stimulated PSC proliferation, while PSC transdifferentiation, as indicated by alpha-smooth muscle actin expression and collagen type I secretion, was not enhanced. The data suggest that PSCs are targets of ATII action with potential pathophysiological relevance.
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PMID:Effects of angiotensin II on rat pancreatic stellate cells. 1502 44

Mouse embryo fibroblasts deficient for the c-Jun proto-oncogene (c-Jun-/- MEF) undergo p53-dependent premature senescence in conventional culture. This phenotype becomes evident only after several cell divisions, suggesting that senescence may result from exposure to unknown environmental factors. Here, we show that c-Jun-/- MEF can proliferate successfully in low oxygen (3% O2), indicating that premature senescence under conventional culture conditions is a consequence of hyperoxic stress. c-Jun-/- MEF exhibit higher basal levels of DNA damage compared to normal fibroblasts in high but not low oxygen, implying that senescence results from chronic accumulation of spontaneous DNA damage. This accumulation may be attributable, at least in part, to inefficient repair, since DNA damage induced by gamma ionizing radiation and H2O2 persists for longer in c-Jun-/- MEF than in wild-type MEF. Unexpectedly, p53 expression, phosphorylation, and transcriptional activity are largely unaffected by oxygen exposure, indicating that the accumulation of spontaneous DNA damage does not result in chronic activation of p53 as judged by conventional criteria. Finally, we find that c-Jun associates with nuclear foci containing gammaH2AX and ATM following irradiation, suggesting a potential role for c-Jun in DNA repair processes per se.
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PMID:c-Jun-deficient cells undergo premature senescence as a result of spontaneous DNA damage accumulation. 1545 74

N-Methyl-N'-nitro-N'-nitrosoguanidine (MNNG) is a DNA-methylating agent, and deficiency in mismatch repair (MMR) results in lack of sensitivity to this genotoxin (termed alkylation tolerance). A number of DNA damage response pathways are activated in a MMR-dependent manner following MNNG, and several also require ATM kinase activity. Here we show that activation of the transcription factor c-Jun is dependent upon both the MMR component MLH1 and ATM, but not ATR, in response to MNNG. In addition to c-Jun, the upstream MAPKs JNK and MKK4 are also activated in a MLH1- and ATM-dependent manner. We document that c-Jun activation is dependent on the MAPK kinase kinase MEKK1. Additionally, the tyrosine kinase c-Abl is required to activate this signaling cascade and forms a complex with MEKK1 and MLH1. This study indicates that an arm of DNA damage-activated MAPK signaling is activated in an MLH1- and ATM-dependent manner in response to MNNG and perhaps suggests that dysregulation of this signaling is responsible, in part, for alkylation tolerance.
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PMID:MLH1- and ATM-dependent MAPK signaling is activated through c-Abl in response to the alkylator N-methyl-N'-nitro-N'-nitrosoguanidine. 1780 21


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