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.

关键词： Activating Transcription Factor 3/biosynthesis   Adipose Tissue/metabolism   Animals   Cell Line, Tumor   Cell Proliferation   Cholesterol/blood   Gene Expression Profiling   Humans   Male   Mice   Mice, SCID   Oligonucleotide Array Sequence Analysis/methods   Prostate/metabolism   Signal Transduction/physiology  

摘要： Elevated circulating cholesterol is a systemic risk factor for cardiovascular disease and metabolic syndrome, however the manner in which the normal prostate responds to variations in cholesterol levels is poorly understood. In this study we addressed the molecular and cellular effects of elevated and suppressed levels of circulating cholesterol on the normal prostate. Integrated bioinformatic analysis was performed using DNA microarray data from two experimental formats: (1) ventral prostate from male mice with chronically elevated circulating cholesterol and (2) human prostate cells exposed acutely to cholesterol depletion. A cholesterol-sensitive gene expression network was constructed from these data and the transcription factor ATF3 was identified as a prominent node in the network. Validation experiments confirmed that elevated cholesterol reduced ATF3 expression and enhanced proliferation of prostate cells, while cholesterol depletion increased ATF3 levels and inhibited proliferation. Cholesterol reduction in vivo alleviated dense lymphomononuclear infiltrates in the periprostatic adipose tissue, which were closely associated with nerve tracts and blood vessels. These findings open new perspectives on the role of cholesterol in prostate health, and provide a novel role for ATF3, and associated proteins within a large signaling network, as a cholesterol-sensing mechanism.

关键词： salermide   death receptor 5 (DR5)   ATF3   ATF4   CHOP   endoplasmic reticulum (ER) stress   Sirt1   2  

摘要： Sirtuins (a class III histone deacetylase) have emerged as novel targets for cancer therapy. Salermide, a reverse amide compound that inhibits Sirtuin 1 (Sirt1) and Sirtuin 2 (Sirt2), has been shown to induce apoptosis in human cancer cells. The mechanism underlying cellular apoptotic signalling by salermide remains unclear. In this study, we show that salermide up-regulates the expression of death receptor 5 (DR5) in human non-small cell lung cancer (NSCLC) cells. Blocking DR5 expression by gene silencing technology results in a decrease in activated forms of several pro-apoptotic proteins (caspase-8, caspase-9, caspase-3, PARP). Increasing DR5 protein expression correlates with salermide-induced apoptosis in human NSCLC cells. We discovered that IRE-1a, Bip, activating transcription factor 3 (ATF4), activating transcription factor 3 (ATF3) and C/EBP homologous protein (CHOP) are induced by salermide, which suggests that DR5-dependent apoptosis is induced by endoplasmic reticulum stress. Moreover, knockdown of Sirt1 and Sirt2 expression resulted in up-regulation of ATF4, CHOP and DR5. Transfected NSCLC cells with ATF4, ATF3 or CHOP siRNA results in a decline in pro-apoptotic proteins (such as caspase-8, caspase-9, caspase-3 and PARP) despite salermide treatment. We demonstrate that salermide induces expression of ATF4, and ATF4 up-regulates ATF3 and subsequently modulates CHOP. This suggests that DR5 is modulated by the ATF4-ATF3-CHOP axis in NSCLC after Sirt1/2 inhibition or salermide treatment. This study highlights the importance of DR5 up-regulation in apoptosis induced by Sirt1/2 inhibition and elucidates the underlying mechanism in human NSCLC cells.

关键词： activating transcription factor 3 (Atf3)   early growth response 1 (Egr1)   hypertrophy   immediate early gene   microarray   negative feedback  

摘要： Endothelin-1 promotes cardiomyocyte hypertrophy by inducing changes in gene expression. Immediate early genes including Atf3 (activating transcription factor 3), Egr1 (early growth response 1) and Ptgs2 (prostaglandin-endoperoxide synthase 2) are rapidly and transiently up-regulated by endothelin-1 in cardiomyocytes. Atf3 regulates the expression of downstream genes and is implicated in negative feedback regulation of other immediate early genes. To identify Atf3-regulated genes, we knocked down Atf3 expression in cardiomyocytes exposed to endothelin-1 and used microarrays to interrogate the transcriptomic effects. The expression of 23 mRNAs (including Egr1 and Ptgs2) was enhanced and the expression of 25 mRNAs was inhibited by Atf3 knockdown. Using quantitative PCR, we determined that: knockdown of Atf3 had little effect on up-regulation of Egr1 mRNA over 30 min, but abolished the subsequent decline, causing sustained Egr1 mRNA expression and enhanced protein expression. This resulted from direct binding of Atf3 to the Egr1 promoter. Mathematical modelling established that Atf3 can suffice to suppress Egr1 expression. Given the widespread co-regulation of Atf3 with Egr1, we suggest that the Atf3-Egr1 negative feedback loop is of general significance. Loss of Atf3 caused abnormal cardiomyocyte growth, presumably resulting from the dysregulation of target genes. The results of the present study therefore identify Atf3 as a nexus in cardiomyocyte hypertrophy required to facilitate the full and proper growth response.