关键词： Adipocyte differentiation   Activating transcription factor 3 (ATF3)   CCAAT/enhancer-binding proteins alpha (C/EBP alpha)   Promoter   Hypoxia  

摘要： ATF3 is a stress-adaptive gene that regulates proliferation or apoptosis under stress conditions. However, the role of ATF3 is unknown in adipocyte cells. Therefore, in this study, we investigated the functional role of ATF3 in adipocytes. Both lentivirus-mediated overexpression of ATF3 and stably-overexpressed ATF3 inhibited adipocyte differentiation in 3T3-L1 cells, as revealed by decreased lipid staining with oil red staining and reduction in adipogenic genes. Thapsigargin treatment and overexpression of ATF3 decreased C/EBP alpha transcript and repressed the activity of the 3.6-kb mouse C/EBP alpha promoter, demonstrating that ATF3 downregulates C/EBP alpha expression. Transfection studies using mutant constructs containing 5'-deletions in the C/EBP alpha promoter revealed that a putative ATF/CRE element, GGATGTCA, is located between -1921 and -1914. Electrophoretic mobility shift assay and chromatin immunoprecipitation assay demonstrated that ATF3 directly binds to mouse C/EBP alpha promoter spanning from -1928 to -1907. Both chemical hypoxia-mimetics or physical hypoxia led to reduce the C/EBP alpha mRNA and repress the promoter activity of the C/EBP alpha gene, whereas increase ATF3 mRNA, suggesting that ATF3 may contribute to the inhibition of adipocyte differentiation in hypoxia through downregulation of C/EBP alpha expression. Collectively, these results demonstrate that ATF3 represses the C/EBP alpha gene, resulting in inhibition of adipocyte differentiation, and thus plays a role in hypoxia-mediated inhibition of adipocyte differentiation. (C) 2012 Elsevier Inc. All rights reserved.

关键词： ATF3   Caspase 3   Schwann cell   Nerve regeneration   Diabetes   BB rat  

摘要： The aim of this study was to evaluate nerve regeneration in relation to the transcription factor, Activating Transcription Factor 3 (ATF 3), and an apoptotic marker, caspase 3, in the Schwann cells of diabetic BB rats (i.e. display type 1 diabetes phenotype). Sciatic nerves in healthy Wistar rats and in diabetic BB rats were transected and immediately repaired. Axonal outgrowth (neurofilament staining) and expression of ATF 3 and caspase 3 were quantified by immunohistochemistry after six days. There was no difference in axonal outgrowth between healthy and diabetic rats. However, the sciatic nerve in the diabetic rats exhibited a larger number of ATF 3 expressing Schwann cells at the site of the lesion and also a higher number of caspase 3 expressing Schwann cells. Similar differences were observed in the distal nerve segment between the healthy and diabetic rats. There were no correlations between the number of Schwann cells expressing ATF 3 and caspase 3. Thus, diabetic BB rats display an increased activation of ATF 3 and also a rise in apoptotic caspase 3 expressing Schwann cells, but with no discrepancy in length of axonal outgrowth after nerve injury and repair at six days. Knowledge about signal transduction mechanisms in diabetes after stress may provide new insights into the development of diabetic neuropathy and neuropathic pain. (C) 2012 Elsevier Ireland Ltd. All rights reserved.

关键词： ATF3   电离辐射   细胞凋亡   DNA损伤修复  

摘要： 目的阐明辐射损伤中ATF3蛋白诱导表达的生物学功能及其调控机制,为探讨辐射损伤防护的新方法提供依据。方法 HCT116(Tet-off)细胞分为4组,即对照组(细胞未进行任何处理)、诱导组(加入诺考达唑诱导ATF3蛋白表达)、照射组(单纯接受射线照射)、照射+诱导组(细胞加入诺考达唑诱导ATF3蛋白表达后接受射线照射)。流式细胞术分析细胞周期变化。Caspase decay分析细胞凋亡。克隆形成率测定细胞增殖。结果与对照组相比较,诱导组细胞周期出现G1期阻滞。表达ATF3蛋白的细胞内出现Caspase 3和多聚ADP-核糖聚合酶(PARP)裂解,对照组则未出现2种蛋白的裂解。诱导组的细胞克隆形成率(15.09%)低于对照组(21.13%),但高于照射组(2.25%)和照射+诱导组(5.24%)。结论 ATF3表达可诱导细胞周期G1阻滞、细胞凋亡和增殖能力下降,且对于受照射的细胞可能有一定的辐射保护作用。

关键词： DR5   ATF3   p53   CPT   TRAIL  

摘要： Stress response gene ATF3 is one of the p53 target genes and has a tumor suppressor role in cancer. However, the biological role of p53-ATF3 pathway is not well understood. Death receptor 5 (DR5) is a death domain-containing transmembrane receptor that triggers cell death upon binding to its ligand TRAIL (tumor necrosis factor-related apoptosis-inducing ligand), and a combination of TRAIL and agents that increase the expression of DR5 is expected as a novel anticancer therapy. In this report, we demonstrate that ATF3 is required for efficient DR5 induction upon DNA damage by camptothecin (CPT) in colorectal cancer cells. In the absence of ATF3, induction of DR5 messenger RNA and protein is remarkably abrogated, and this is associated with reduced cell death by TRAIL and CPT. By contrast, exogenous expression of ATF3 causes more rapid and elevated expression of DR5, resulting in enhanced sensitivity to apoptotic cell death by TRAIL/CPT. Reporter assay and DNA affinity precipitation assay demonstrate that at least three ATF/CRE motifs at the proximal promoter of the human DR5 gene are involved in the activation of DNA damage-induced DR5 gene transcription. Furthermore, ATF3 is shown to interact with p53 to form a complex on the DR5 gene by Re-chromatin immunoprecipitation assay. Taken together, our results provide a novel insight into the role of ATF3 as an essential co-transcription factor for p53 upon DNA damage, and this may represent a useful biomarker for TRAIL-based anticancer therapy. Oncogene (2012) 31, 2210-2221;doi:10.1038/onc.2011.397;published online 19 September 2011

关键词： ATF3   EGR-1   ROS   Patulin  

摘要： Patulin is a fungal mycotoxin of Aspergilus and Penicillium that is commonly found in rotting fruits and exerts its potential toxic effect mainly by reactive oxygen species (ROS) generation. However, the effect of patulin on cancer cells as well as its intracellular mechanism has been controversial and not clearly defined yet In this study, patulin was found to induce G1/S accumulation and cell growth arrest accompanied by caspase-3 activation, PARP cleavage and ATF3 expression in human colon cancer cell line HCT116. Ser/Thr phosphorylation of a transcription factor. EGR-1, was increased while its expression did not change upon patulin treatment to the cells. Knockdown of ATF3 and EGR-1 using their respective siRNAs showed EGR-1 dependent ATF3 expression. Moreover, treatment of the cells with antioxidants N-acetylcysteine (NAC) and glutathione (GSH) revealed that patulin induced ATF3 expression and apoptosis were dependent on ROS generation. ATF3 expression was also increased by patulin in other colorectal cancer cell types, Caco2 and SW620. Collectively, our data present a new anti-cancer molecular mechanism of patulin, suggesting EGR-1 and ATF3 as critical targets for the development of anti-cancer chemotherapeutics. In this regard, patulin could be a candidate for the treatment of colorectal cancers. (C) 2011 Elsevier Inc. All rights reserved.

关键词： type 1 diabetes   pancreatic beta cells   JunB   ATF3   apoptosis  

摘要： Destruction of insulin-producing pancreatic beta-cells by local autoimmune inflammation is a hallmark of type 1 diabetes. Histochemical analysis of pancreases from non-obese diabetic mice indicated activation of the transcription factor JunB/AP-1 (activator protein-1) after autoimmune infiltration of the islets. In vitro studies demonstrated that the cytokines tumor necrosis factor (TNF)-alpha and interferon (IFN)-gamma induce JunB expression as a protective mechanism against apoptosis in both human and rodent beta-cells. The gene network affected was studied by microarray analysis showing that JunB regulates nearly 20% of the cytokine-modified beta-cell genes, including the transcription factor ATF3. Direct transcriptional induction of ATF3 by JunB is a key event for beta-cell survival after TNF-alpha + IFN-gamma treatment. Moreover, pharmacological upregulation of JunB/ATF3 via increased cAMP protected rodent primary beta-cells and human islet cells against pro-inflammatory mediators. These results were confirmed in genetically modified islets derived from Ubi-JunB transgenic mice. Our findings identify ATF3 as a novel downstream target of JunB in the survival mechanism of beta-cells under inflammatory stress. Oncogene (2012) 31, 1723-1732;doi:10.1038/onc.2011.353;published online 15 August 2011

关键词： ATF3   肿瘤   作用机制  

摘要： ATF3转录激活因子3是转录因子ATF/CREB家族中成员之一,为一适应性反应基因参与细胞内外复杂进程。大量研究表明,其通过精细调控增殖及凋亡间平衡在肿瘤的形成和侵袭转移方面发挥重要作用,然而这种作用依赖靶基因和细胞内外环境的不同表现为双重作用,或抑制肿瘤形成或促进肿瘤发生。现就ATF3在肿瘤方面的研究进展予以综述。

关键词： 尿道下裂   氟他胺   雌二醇   生殖结节   器官培养   发病机制   调控机理   动物模型  

摘要： 尿道下裂是泌尿系统做常见的先天性发育异常。目前发病率逐年增高，具体机制尤其是分子生物学机制仍不明确。目前学者们一致认为，尿道下裂是有多因素共同作用引发的。在前期工作中，我们发现了ATF3基因在尿道下裂的发病中起到关键基因的作用。本研究主要探讨尿道下裂的关键基因—ATF3的调控机理。\n 1.尿道下裂动物模型构建:我们用不同剂量的氟他胺和雌激素给孕12.5～17.5d C57小鼠灌胃，结果显示随着雌激素剂量的增加，雄性后代出现尿道下裂的比例增加，肛门与生殖器间距离(ADG)在缩短，同时也产生死胎。氟他胺浓度50mg/kg/d灌胃时，雌激素浓度100ug/kg/d灌胃时，小鼠存活率较高，尿道下裂发生率理想，可作为理想的尿道下裂模型浓度。尿道下裂模型中，死亡胎鼠的性别都是以雄性为主。两者对雄性小鼠尿道发育有重要干扰。\n 2.生殖结节(GT)器官培养体外尿道下裂模型的构建:GT是阴茎的前体，E14.5d是小鼠胚胎前尿道管化发育的开始，该时期的雄性胚胎GT大小＜1mm3，适于体外培养，我们将之切下放于Millicell插入式器官型组织培养板微孔膜上，37℃培养72小时后发现GT在离体培养下出现了明显的生长，其形态结构出现了类似于同期体内阴茎发育的变化，在10nM DHT存在下，GT长度增加了42％，面积增加了45.6％，我们首次建立了体外尿道发育模型，在模型培养液中加入雌激100nM，尿道发育受到抑制，产生尿道下裂。可作为研究尿道下裂或阴茎发育异常等发生机制的新工具。\n 3.免疫组化检测不同时期尿道发育重要信号通路发现:TGF-β1、TGF-β RⅢ、ATF3、AR在E14、E19、尿道下裂标本中，有明显差别。从具体结果看，发生较大较明显变化的是间质。间质的病理性改变是引起尿道发育异常如尿道下裂的主要原因。因此，我们培养成功生殖结节间质细胞进一步实验。\n 4.雌激素刺激间质细胞之后，免疫荧光检测、Western Blot、RT-PCR、Realtime-PCR结果都显示:ATF3蛋白的表达、定量、ATF3mRNA都有了不同程度的表达升高，且荧光素酶分析结果显示:ATF3启动子活性明显升高。这些结果都印证了我们的假说。ATF3作用迅速，在雌激素干预后的45min即开始作用，2h后逐渐消失。定位上看位于细胞质和细胞核，以细胞质为主。从实验结果看，雌激素是通过ATF3进行调控，并引起尿道下裂的。

关键词： Nod2   ATF3   chemokines   ribotoxic stress   intestinal epithelial cells  

摘要： Chronic exposure to gut bacteria and bacterial products including Nod2 ligands triggers homeostatic regulation in response to various mucosal insults. Activating transcription factor 3 (ATF3) is a negative regulator of proinflammatory cytokines via bacterial pattern recognition. On the assumption that ATF3 can be a critical modulator of epithelial inflammation, chronic stimulation of Nod2 was assessed for its effects on ATF3 and proinflammatory signals in response to mucosal ribotoxic insult, which is a critical etiological factor of human intestinal inflammatory disease. Muramyl dipeptide, the minimal moiety of bacterial peptidoglycan, is the Nod2 ligand, and pre-exposure to it enhanced ATF3 expression in ribotoxic stress-exposed human enterocytes. In terms of gene regulation, Nod2 preactivation potentiated ATF3 induction by enhancing stability of the ATF3 transcript, which was particularly linked to the regulation of the 3'-untranslated region of the human ATF3 gene. Moreover, chronic stimulation of Nod2 enhanced both the basal and the ribotoxic stress-stimulated cytoplasmic translocation of the HuR protein, which bound to and stabilized ATF3 messenger RNA (mRNA). Functionally, chronic stimulation of Nod2 also led to superinduction of proinflammatory chemokine genes by the mucoactive ribotoxic stress. However, the chemokine superinduction was not affected by ATF3 gene regulation although Nod2-triggered ATF3 had suppressive effects on the proinflammatory nuclear factor kappa B (NF-kappa B) signal. This paradoxical superinduction of chemokines was also mediated by enhanced mRNA stabilization by HuR protein in spite of ATF3-mediated suppression of NF-kB signal in human intestinal epithelial cells.

关键词： JNK knockout   CIP2A   ATF3   c-Myc   Ras transformation  

摘要： Ras is one of the most frequently activated oncogenes in cancer. Two mitogen-activated protein kinases (MAPKs) are important for ras transformation: extracellular signal-regulated kinase (ERK) and c-Jun N-terminal kinase 2 (JNK2). Here we present a downstream signal amplification cascade that is critical for ras transformation in murine embryonic fibroblasts. This cascade is coordinated by ERK and JNK2 MAPKs, whose Ras-mediated activation leads to the enhanced levels of three oncogenic transcription factors, namely, c-Myc, activating transcription factor 2 (ATF2) and ATF3, all of which are essential for ras transformation. Previous studies show that ERK-mediated serine 62 phosphorylation protects c-Myc from proteasomal degradation. ERK is, however, not alone sufficient to stabilize c-Myc but requires the cooperation of cancerous inhibitor of protein phosphatase 2A (CIP2A), an oncogene that counteracts protein phosphatase 2A-mediated dephosphorylation of c-Myc. Here we show that JNK2 regulates Cip2a transcription via ATF2. ATF2 and c-Myc cooperate to activate the transcription of ATF3. Remarkably, not only ectopic JNK2, but also ectopic ATF2, CIP2A, c-Myc and ATF3 are sufficient to rescue the defective ras transformation of JNK2-deficient cells. Thus, these data identify the key signal converging point of JNK2 and ERK pathways and underline the central role of CIP2A in ras transformation. Oncogene (2012) 31, 390-401;doi:10.1038/onc.2011.230;published online 27 June 2011