关键词： Gene Regulation   Gene Transcription   Histidine   Histone Deacetylase Inhibitors   Nutrition   ATF3   Asparagine Synthetase   Dietary Protein   Histone Demethylase   Nutrient Sensing  

摘要： Following amino acid deprivation, the amino acid response (AAR) induces transcription from specific genes through a collection of signaling mechanisms, including the GCN2-eIF2-ATF4 pathway. The present report documents that the histone demethylase JMJD3 is an activating transcription factor 4 (ATF4)-dependent target gene. The JMJD3 gene contains two AAR-induced promoter activities and chromatin immunoprecipitation (ChIP) analysis showed that the AAR leads to enhanced ATF4 recruitment to the C/EBP-ATF response element (CARE) upstream of Promoter-1. AAR-induced histone modifications across the JMJD3 gene locus occur upon ATF4 binding. Jmjd3 transcription is not induced in Atf4-knock-out cells, but the AAR-dependent activation was rescued by inhibition of histone deacetylation with trichostatin A (TSA). The TSA rescue of AAR activation in the absence of Atf4 also occurred for the Atf3 and C/EBP homology protein (Chop) genes, but not for the asparagine synthetase gene. ChIP analysis of the Jmjd3, Atf3, and Chop genes in Atf4 knock-out cells documented that activation of the AAR in the presence of TSA led to specific changes in acetylation of histone H4. The results suggest that a primary function of ATF4 is to recruit histone acetyltransferase activity to a sub-set of AAR target genes. Thus, absolute binding of ATF4 to these particular genes is not required and no ATF4 interaction with the general transcription machinery is necessary. The data are consistent with the hypothesis that ATF4 functions as a pioneer factor to alter chromatin structure and thus, enhance transcription in a gene-specific manner.

关键词： BIOCHEMICAL markers   ADENYLATE kinase   LUNGS -- Cancer   CANCER invasiveness   METASTASIS   TRANSCRIPTION factors  

摘要： Biomarkers predicting metastatic capacity might assist the development of better therapeutic strategies for aggressive cancers such as lung cancer. In this study, we show that adenylate kinase-4 (AK4) is a progression-associated gene in human lung cancer that promotes metastasis. Analysis of published microarray data showed that AK4 was upregulated in lung adenocarcinoma compared with normal cells. High AK4 expression was associated with advanced stage, disease recurrence and poor prognosis. Loss of AK4 expression suppressed the invasive potential of lung cancer cell lines, whereas AK4 overexpression promoted invasion in vitro and in vivo. Mechanistically, the transcription factor ATF3 was identified as a pivotal regulatory target of AK4. Simultaneous reduction in AK4 and ATF3 expression abolished the inhibitory effects of ATF3 on invasion. ATF3 overexpression in AK4-overexpressing cells limits invasion activity. Furthermore, patients with high AK4 and low ATF3 expression showed unfavorable outcomes compared with patients with low AK4 and high ATF3 expression. Taken together, our findings indicated that AK4 promotes malignant progression and recurrence by promoting metastasis in an ATF3-dependent manner. Cancer Res;72(19);5119-29. (C)2012 AACR.

关键词： TRPV1   Pain   Capsaicin   Vanilloid   Nociception   Resiniferatoxin   ATF3   Dorsal root ganglion   MRS1477   Adelta fiber  

摘要： Background: The prevalence of long-term opiate use in treating chronic non-cancer pain is increasing, and prescription opioid abuse and dependence are a major public health concern. To explore alternatives to opioid-based analgesia, the present study investigates a novel allosteric pharmacological approach operating through the cation channel TRPV1. This channel is highly expressed in subpopulations of primary afferent unmyelinated C-and lightly-myelinated Ad-fibers that detect low and high rates of noxious heating, respectively, and it is also activated by vanilloid agonists and low pH. Sufficient doses of exogenous vanilloid agonists, such as capsaicin or resiniferatoxin, can inactivate/deactivate primary afferent endings due to calcium overload, and we hypothesized that positive allosteric modulation of agonist-activated TRPV1 could produce a selective, temporary inactivation of nociceptive nerve terminals in vivo. We previously identified MRS1477, a 1,4-dihydropyridine that potentiates vanilloid and pH activation of TRPV1 in vitro, but displays no detectable intrinsic agonist activity of its own. To study the in vivo effects of MRS1477, we injected the hind paws of rats with a non-deactivating dose of capsaicin, MRS1477, or the combination. An infrared diode laser was used to stimulate TRPV1-expressing nerve terminals and the latency and intensity of paw withdrawal responses were recorded. qRT-PCR and immunohistochemistry were performed on dorsal root ganglia to examine changes in gene expression and the cellular specificity of such changes following treatment. Results: Withdrawal responses of the capsaicin-only or MRS1477-only treated paws were not significantly different from the untreated, contralateral paws. However, rats treated with the combination of capsaicin and MRS1477 exhibited increased withdrawal latency and decreased response intensity consistent with agonist potentiation and inactivation or lesion of TRPV1-containing nerve terminals. The loss of n

关键词： ATF3   cerebral ischemia   inflammation   NF-kappa B   CREB  

摘要： Background and Purpose: Activating transcription factor 3 (ATF3) is a stress-induced transcription factor that has been shown to repress inflammatory gene expression in multiple cell types and diseases. This study was conducted to investigate the role of ATF3 in the pathological processes of cerebral ischemia and its influence on post-ischemic inflammation. Methods: Wild-type (WT) and ATF3 knockout (KO) mice were subjected to middle cerebral artery occlusion (45 min) followed by reperfusion. Infarct volume, brain edema, and neurological deficits were examined. Neural apoptosis, inflammatory gene expression, cellular inflammatory response and Matrix Metallo Proteinases 9 (MMP9) activity were assessed. Activity of the nuclear factor-kappa B (NF-kappa B) signaling pathway and cAMP-responsive element-binding protein (CREB) was studied. Results: Knockout of ATF3 significantly exacerbated the infarct volume and worsened neurological function after brain ischemia. Neural apoptosis, inflammatory gene expression and cellular inflammatory response were upregulated in ATF3 KO mice. The MMP9 mRNA expression and protein activity were increased in ATF3 KO mice. KO of ATF3 led to an elevation in the activity of the NF-kappa B signaling pathway and inhibition of CREB activity. Conclusions: Our study demonstrated that ATF3 was markedly induced by brain ischemia. ATF3 deficiency exacerbated the inflammatory response and brain injury after cerebral ischemia, potentially through further activation of the NF-kappa B signaling pathway. ATF3 is likely an important protective regulator in cerebral ischemic injury. (C) 2012 IBRO. Published by Elsevier Ltd. All rights reserved.

关键词： Small interfering RNA   Cytotoxicity   Transcription factors   Apoptosis   Cancer treatment   Cell cycle and cell division   Cell proliferation   Enzyme-linked immunoassays  

摘要： Although doxorubicin is commonly used in the treatment of many cancer types, its use in chemotherapy has been limited, largely because of its severe side effects, including cardiotoxicity and nephrotoxicity. In this study, we aimed to identify the mechanism of doxorubicin-induced cytotoxicity by using the human kidney proximal tubule cell line HK-2. Furthermore, we investigated the role of activating transcription factor 3 (ATF3) as a mediator of doxorubicin-induced cytotoxicity by using wild-type mouse embryonic fibroblasts (MEF) cells and ATF3 knockout (KO) cells. In HK-2 cells, doxorubicin decreased cell viability in a dose-dependent manner and induced an increase in cells in the sub G1 and G2/M phases at all doses. Doxorubicin treatment showed the following dose-dependent effects: increase in the secretion of tumor necrosis factor alpha;decrease in the expression of phosphorylated protein kinase A and Bcl-2;and increase in the expression of phosphorylated signal transducer and activator of transcription 3, phosphorylated extracellular signal-regulated kinase (ERK), and ATF3. Based on these results, we suggest that doxorubicin induces cytotoxicity through an ERK-dependent pathway, and ATF3 plays a pivotal role as a transcriptional regulator in this process.

关键词： 5-HT1B/1D receptor activation   ATF3   c-Fos immunoreactive labeling   CGRP receptor blockade   IL-6   Neuropathic pain   Nociceptive tests  

摘要： Previous studies showed that 5-hydroxytryptamine (5-HT)(1B/1D) receptor stimulation by triptans alleviates neuropathic pain caused by chronic constriction injury to the infraorbital nerve (CCI-ION) but not the sciatic nerve (CCI-SN) in rats. To assess whether such differential effects in the cephalic vs extracephalic territories is a property shared by other antimigraine drugs, we used the same models to investigate the effects of olcegepant, which has an antimigraine action mediated through calcitonin gene-related peptide (CGRP) receptor blockade. Adult male rats underwent unilateral CCI to the ION or the SN, and subsequent allodynia and/or hyperalgesia were assessed in ipsilateral vibrissal territory or hindpaw, respectively, using von Frey filaments and validated nociceptive tests. c-Fos expression was quantified by immunohistochemistry and interleukin 6 and activating transcription factor 3 (ATF3) mRNAs by real-time quantitative reverse transcriptase-polymerase chain reaction. Like naratriptan (0.1 to 0.3 mg/kg, subcutaneously), olcegepant (0.3 to 0.9 mg/kg, intravenously) markedly reduced mechanical allodynia in CCI-ION rats. In contrast, in CCI-SN rats, mechanical allodynia was completely unaffected and hyperalgesia was only marginally reduced by these drugs. A supra-additive antiallodynic effect was observed in CCI-ION rats treated with olcegepant (0.3 mg/kg intravenously) plus naratriptan (0.1 mg/kg subcutaneously), whereas this drug combination remained inactive in CCI-SN rats. Olcegepant (0.6 mg/kg, intravenously) significantly reduced the number of c-Fos immunolabeled cells in spinal nucleus of the trigeminal nerve and upregulation of ATF3 transcript (a marker of neuron injury) but not that of interleukin-6 in trigeminal ganglion of CCI-ION rats. These findings suggest that CGRP receptor blockade might be of potential interest to alleviate trigeminal neuropathic pain. (C) 2012 International Association for the Study of Pain. Published by Elsevier B.V. All

关键词： Trigeminal ganglion neurons   Electrophysiology   ATF3   Na(v)1.3   Culture  

摘要： To clarify whether changes to the cellular properties of sensory neurons occur after a brief culture, we compared the electrophysiological and immunohistochemical properties of rat trigeminal ganglion neurons. We compared these neurons after acute dissociation and after a 1-day culture under serum-free and neurotrophin-free conditions. In whole-cell patch-clamp recordings. the 1-day cultured neurons required a lower current threshold to induce an action potential in both small- and medium-sized neurons. Furthermore, the input resistance was higher in the medium-sized neurons after a 1-day culture compared to the acutely dissociated medium-sized neurons. Immunofluorescent studies demonstrated that both the translocation of the activating transcription factor 3 (ATF3) into the nucleus and the expression of a low threshold Na+ channel (Na(v)1.3) were upregulated after 1-day of culture. However, in the acutely dissociated neurons, ATF3 translocation occurred at low levels, and Na(v)1.3 was not expressed. These electrophysiological and immunohistochemical changes after 1-day of culture were very similar to the reported changes that occur after nerve injury. Our study demonstrated that injury-like characteristics appear to be manifested in the 1-day cultured sensory neurons, which do not occur in acutely dissociated neurons. Overall, our results are relevant and will help when interpreting the results of studies examining dissociated sensory neurons in pain research. Crown Copyright (C) 2012 Published by Elsevier Ireland Ltd. All rights reserved.

关键词： Activating Transcription Factor 3   cis acting element   ATF3 gene   prostate epithelium   Androgen Receptor   Leucine Zippers   Stress Response Signaling   Androgens   Argon   Prostatic Hyperplasia  

摘要： Activating transcription factor 3 (ATF3) is a common mediator of cellular stress response signaling and is often aberrantly expressed in prostate cancer. We report here that ATF3 can directly bind the androgen receptor (AR) and consequently repress AR-mediated gene expression. The ATF3-AR interaction requires the leucine zipper domain of ATF3 that independently binds the DNA-binding and ligand-binding domains of AR, and the interaction prevents AR from binding to cis-acting elements required for expression of androgen-dependent genes while inhibiting the AR N- and C-terminal interaction. The functional consequences of the loss of ATF3 expression include increased transcription of androgen-dependent genes in prostate cancer cells that correlates with increased ability to grow in low-androgen-containing medium and increased proliferative activity of the prostate epithelium in ATF3 knockout mice that is associated with prostatic hyperplasia. Our results thus demonstrate that ATF3 is a novel repressor of androgen signaling that can inhibit AR functions, allowing prostate cells to restore homeostasis and maintain integrity in the face of a broad spectrum of intrinsic and environmental insults.

关键词： actinic keratosis   ATF3   squamous cell carcinoma  

摘要： The histopathologic distinction between benign and malignant cutaneous keratinocytic proliferations can pose a difficult diagnostic challenge often with important clinical implications. Activating transcription factor 3 (ATF3) has emerged as a potential biomarker which may aid in the segregation of these lesions, and we hypothesize that ATF3 expression may be a specific marker of cutaneous squamous cell carcinoma (SCC). Using immunohistochemistry, we characterized ATF3 expression in a series of 126 cutaneous epithelial proliferations, including SCC (n?=?27), basal cell carcinomas (BCC, n?=?59), seborrheic keratoses with atypia (SK, n?=?16), hyperplastic actinic keratoses (AK, n?=?12) and prurigo nodularis cases (PN, n?=?12). We showed strong, nuclear and/or nucleolar expression of ATF3 in a statistically significant number of cases of SCC compared to BCC, SK and PN. We conclude that ATF3 expression is a surrogate of malignancy (or pre-malignancy) in keratinocytic epithelial proliferations and thus helps distinguish SCC from other cutaneous epithelial neoplasms.

关键词： NSCLC   ATF3   mutation   methylation   risk  

摘要： Background: Non-small cell lung cancer (NSCLC) accounts for 85% of all cases of lung cancer and has a poor prognosis. Activating transcription factor 3 (ATF3), a member of the ATF/cyclic adenosine monophosphate response element binding (ATF/cyclic response element binding) family of transcription factors, has been implicated in the pathogenesis of several types of cancer. However, whether the expression of ATF3 is aberrant in NSCLC and genetic variants, or DNA methylation of the gene contributes to the tumorigenesis of NSCLC, are largely unknown. Methods: The expression of ATF3 in four NSCLC cell lines and normal human bronchial epithelial cell (HBEpiC) line was detected by Western blot analysis. The mutation of the 5'-flanking 1500-bp and coding sequence regions of the ATF3 gene were screened using DNA direct sequencing, and bisulfite-sodium modification sequencing was used to detect the promoter methylation status of the gene. Results: up-regulated expression of ATF3 was observed in NSCLC cell lines, and there was no difference in the sequence regions of the ATF3 gene between NSCLC cells and HBEpiC cells, which were validated in lung cancer tissues and their corresponding paracarcinoma tissues. Conclusion: Our findings suggest that the tumorigenesis of NSCLC may particularly attribute to increased expression of ATF3 but not the genetic variants of the gene.