关键词： activating transcription factor 3 (ATF3)   mitogen activated protein kinase (MAPK)   MAPK kinase (MKK)   p38   stress kinase   stress response  

摘要： ATF3 (activating transcription factor 3) gene encodes a member of the ATF/CREB (cAMP-response-element-binding protein) family of transcription factors. Its expression is induced by a wide range of signals, including stress signals and signals that promote cell proliferation and motility. Thus the ATF3 gene can be characterized as an 'adaptive response' gene for the cells to cope with extra- and/or intra-cellular changes. In the present study, we demonstrate that the p38 signalling pathway is involved in the induction of ATF3 by stress signals. Ectopic expression of CA (constitutively active) MKK6 [MAPK (mitogen-activated protein kinase) kinase 6], a kinase upstream of p38, indicated that activation of the p38 pathway is sufficient to induce the expression of the ATF3 gene. Inhibition of the pathway indicated that the p38 pathway is necessary for various signals to induce ATF3, including anisomycin, IL-1 beta (interleukin 1 beta), TNF alpha (tumour necrosis factor alpha) and H2O2. Analysis of the endogenous ATF3 gene indicates that the regulation is at least in part at the transcription level. Specifically, CREB, a transcription factor known to be phosphorylated by p38, plays a role in this induction. Interestingly, the ERK (extracellular-signal-regulated kinase) and JNK (c-Jun N-terminal kinase)/SAPK (stress-activated protein kinase) signalling pathways are neither necessary nor sufficient to induce ATF3 in the anisomycin stress paradigm. Furthermore, analysis of caspase 3 activation indicated that knocking down ATF3 reduced the ability of MKK6(CA) to exert its pro-apoptotic effect. Taken together, our results indicate that a major signalling pathway, the p38 pathway, plays a critical role in the induction of ATF3 by stress signals, and that ATF3 is functionally important to mediate the pro-apoptotic effects of p38.

关键词： amino acid response element (AARE)   amino acid-sensing   activating transcription factor 3 (ATF3)   CCAAT/enhancer-binding protein (C/EBP)   histone acetylation   transcription regulation  

摘要： Expression of ATF3 (activating transcription factor 3) is induced by a variety of environmental stress conditions, including nutrient limitation. In the present study, we demonstrate that the increase in ATF3 mRNA content following amino acid limitation of human HepG2 hepatoma cells is dependent on transcriptional activation of the ATF3 gene, through a highly coordinated amino acid-responsive programme of transcription factor synthesis and action. Studies using transient overexpression and knockout fibroblasts showed that several ATF and C/EBP (CCAAT/enhancer-binding protein) family members contribute to ATF3 regulation. Promoter analysis showed that a C/EBP-ATF composite site at -23 to -15 bp relative to the transcription start site of the ATF3 gene functions as an AARE (amino acid response element). Chromatin immunoprecipitation demonstrated that amino acid limitation increased ATF4, ATF3, and C/EBP beta binding to the ATF3 promoter, but the kinetics of each was markedly different. Immediately following histidine removal, there was a rapid increase in histone H3 acetylation prior to an enhancement in ATF4 binding and in histone H4 acetylation. These latter changes closely paralleled the initial increase in RNA pol II (RNA polymerase II) binding to the promoter and in the transcription rate from the ATF3 gene. The increase in ATF3 and C/EBP beta binding was considerably slower and more closely correlated with a decline in transcription rate. A comparison of the recruitment patterns between ATF and C/EBP transcription factors and RNA polymerase II at the AARE of several amino acid-responsive genes revealed that a highly co-ordinated response programme controls the transcriptional activation of these genes following amino acid limitation.

关键词： 3D reconstruction   ATF3   BBB   NeuN   neuronal survival   p-c-Jun  

摘要： Studies of spinal cord injury using contusion (impact) injury paradigms have shown that neuronal death is an acute event that is largely over within 24 h. However, much less is known about cell death following compression injury, despite compression being a key component of natural spinal injuries. We have therefore used neuronal nuclei (NeuN) immunostaining to examine the spatiotemporal pattern of neuronal loss after static compression injury in adult rats. 3D reconstruction was used to reveal the full effect of the injury. Neuronal loss at the injury epicentre, assessed by NeuN immunostaining, amounted to 44% at 1 day but increased to 73% at 3 days and 81% at 1 month. Neuronal loss was also seen 5 mm rostral and caudal to the epicentre, but was not significant until 3 days. NeuN loss was greatest in the ventral horns and in the intermediate grey matter, with the lateral dorsal horns relatively spared. Cystic cavities formed after injury, but were not evident until 4 weeks and were small in size. In contrast to the slow profile of neuronal loss, the compression injury also evoked a transient expression of activating transcription factor-3 (ATF3) and activated c-Jun in neurons. ATF3 expression peaked at 3 days and declined at 7 days. Our spatiotemporal analysis of compression injury shows that neuronal loss is much more protracted than in contusion injury, and highlights the potential for neuroprotective strategies. This study is also the first indication of ATF3 involvement in spinal cord injury.

关键词： ATF3   hypoxia   anoxia   HIF   p53   MKK7/JNK  

摘要： Solid tumors often have an inadequate blood supply, which results in large regions that are subjected to hypoxic or anoxic stress. Hypoxia-inducible factor-1 (HIF-1) is a transcription factor that regulates much of the transcriptional response of cells to hypoxia. Activating transcription factor 3 (ATF3) is another transcription factor that responds to a variety of stresses and is often upregulated in cancer. We investigated the regulation of ATF3 by oxygen deprivation. ATF3 induction occurred most robustly under anoxia, is common, and it is not dependent on presence of HIF-1 or p53, but is sensitive to the inhibition of c-Jun NH2-terminal kinase activation and the antioxidant N-acetylcystein. ATF3 could also be induced by desferrioxamine but not by the mitochondrial poison cyanide or the nonspecific 2-oxoglutarate dioxygenase inhibitor dimethyloxalylglycine. We also show that anoxic ATF3 mRNA is more stable than normoxic mRNA providing a mechanism for this induction. Thus, this study demonstrates that the regulation of ATF3 under anoxia is independent of 2-oxoglutarate dioxygenase, HIF-1 and p53, presumably involving multiple regulatory pathways.

关键词： 前列腺癌   激活转录因子3   免疫组织化学   Western Blot  

摘要： 目的：检测激活转录因子3(ATF3)在正常前列腺、前列腺增生和前列腺癌组织中的表达情况，初步探讨ATF3在前列腺癌的发生、发展、转移中的作用，并分析ATF3表达与前列腺癌临床病理特征的关系。 方法：采用免疫组织化学S-P法和Western Blot检测正常前列腺、良性前列腺增生及前列腺癌组织中ATF3的表达，对比其表达的差异，并分析其表达水平与前列腺癌临床病理参数的关系。 结果：免疫组化显示：ATF3在正常前列腺组织中无阳性表达，良性前列腺增生组织中阳性表达率为13.04％，在前列腺癌组织中阳性表达率为58.70％，ATF3在前列腺癌组织中的表达明显高于正常前列腺组织和良性前列腺增生组织(P＜0.01)。在不同病理分级前列腺癌组织中，高分化组ATF3的表达明显低于于中分化组和低分化组(P＜0.05)，中分化组ATF3的表达明显低于低分化组(P＜0.05)。ATF3在Whitmore-Jewett分期C+D期组的表达明显高于A+B组(P＜0.05)。ATF3在转移性前列腺癌组织中的表达明显高于无转移组(P＜0.05)。ATF3在前列腺癌组织中的表达与术前PSA水平无相关性。Western Blot结果显示：ATF3在前列腺癌组织中的表达较正常前列腺组织和前列腺增生组织高(P＜0.05)。 结论：ATF3在前列腺癌组织的表达高于正常前列腺组织和良性前列腺增生组织。ATF3的表达与临床分期、病理分级、是否伴有转移有关。ATF3表达与术前血清PSA水平无相关性。ATF3可能与前列腺癌的发生、发展、侵袭和转移有关。ATF3可以作为预测前列腺癌的恶性程度和预后的指标。进一步研究前列腺癌中ATF3产生的分子机制和ATF3相关的信号传导通路，有可能揭示前列腺癌的发生机制。

关键词： end-to-side repair   transcription factor   ATF3   cell activation   nerve injury  

摘要： We wanted to find out if any of three different types of manipulations: a piece of muscle or nerve put parallel to a nerve;an epineurial window made, or sutures inserted into a nerve, or both;or pieces of nerve sutured to an epineurial window end-to-side to the musculocutaneous or sciatic nerve, resulted in activation of activating transcription factor 3 ( ATF3) in neurons and in non-neuronal cells. ATF3, a marker of cell activation, was investigated by immunocytochemistry one week after manipulation. A piece of nerve or muscle parallel to a nerve did not induce ATF3 locally in the nerve and induced ATF3 only rarely in neurons. In contrast, an epineurial window or insertion of sutures, or both, with or without attachment of a piece of nerve placed end-to-side, induced robust ATF3 expression. We conclude that an injury to a peripheral nerve trunk associated with end-to-side nerve repair, activates neurons and non-neuronal cells and may contribute to sprouting of axons into the nerve attached end-to-side.

关键词： .cytochalasin   Transcription factors   response element   endochondral   Activating   represses   cyclin  

摘要： Background: Coordinated chondrocyte proliferation and differentiation are required for normal endochondral bone growth. Transcription factors binding to the cyclicAMP response element (CRE) are known to regulate these processes. One member of this family, Activating Tanscription Factor 3 (ATF3), is expressed during skeletogenesis and acts as a transcriptional repressor, but the function of this protein in chondrogenesis is unknown. Results: Here we demonstrate that Atf3 mRNA levels increase during mouse chondrocyte differentiation in vitro and in vivo. In addition, Atf3 mRNA levels are increased in response to cytochalasin D treatment, an inducer of chondrocyte maturation. This is accompanied by increased Atf3 promoter activity in cytochalasin D-treated chondrocytes. We had shown earlier that transcription of the cell cycle genes cyclin D1 and cyclin A in chondrocytes is dependent on CREs. Here we demonstrate that overexpression of ATF3 in primary mouse chondrocytes results in reduced transcription of both genes, as well as decreased activity of a CRE reporter plasmid. Repression of cyclin A transcription by ATF3 required the CRE in the cyclin A promoter. In parallel, ATF3 overexpression reduces the activity of a SOX9-dependent promoter and increases the activity of a RUNX2-dependent promoter. Conclusion: Our data suggest that transcriptional induction of the Atf3 gene in maturing chondrocytes results in down-regulation of cyclin D1 and cyclin A expression as well as activation of RUNX2-dependent transcription. Therefore, ATF3 induction appears to facilitate cell cycle exit and terminal differentiation of chondrocytes.

关键词： shockwave   analgesic effect   nerve fiber   injury   regeneration  

摘要： Although extracorporeal shockwave has been applied in the treatment of various diseases, the biological basis for its analgesic effect remains unclear. Therefore, we investigated the dorsal root ganglion neurons of rats following shockwave exposure to the footpad to elucidate its effect on the peripheral nervous system. We used activating transcription factor 3 (ATF3) and growth-associated phosphoprotein (GAP-43) as markers for nerve injury and axonal regeneration, respectively. The average number of neurons inummoreactive for ATF3 increased significantly in the treated rats at all experimental time points, with 78.3% of those neurons also exhibiting immunoreactivity for GAP-43. Shockwave exposure induced injury of the sensory nerve fibers within the exposed area. This phenomenon may be linked to the desensitization of the exposure area, not the cause of pain, considering clinical research with a particular absence of painful adverse effect. Subsequent active axonal regeneration may account for the reinnervation of exposed area and the amelioration of the desensitization. (c) 2006 Elsevier B.V. All rights reserved.

关键词： IMMUNE system   PROTEINS   TRANSCRIPTION factors   CYTOKINES   DNA microarrays   MACROPHAGES  

摘要： The innate immune system is absolutely required for host defence, but, uncontrolled, it leads to inflammatory disease. This control is mediated, in part, by cytokines that are secreted by macrophages. Immune regulation is extraordinarily complex, and can be best investigated with systems approaches ( that is, using computational tools to predict regulatory networks arising from global, high-throughput data sets). Here we use cluster analysis of a comprehensive set of transcriptomic data derived from Toll-like receptor (TLR)-activated macrophages to identify a prominent group of genes that appear to be regulated by activating transcription factor 3 (ATF3), a member of the CREB/ATF family of transcription factors. Network analysis predicted that ATF3 is part of a transcriptional complex that also contains members of the nuclear factor (NF)-kappa B family of transcription factors. Promoter analysis of the putative ATF3-regulated gene cluster demonstrated an over-representation of closely apposed ATF3 and NF-kappa B binding sites, which was verified by chromatin immunoprecipitation and hybridization to a DNA microarray. This cluster included important cytokines such as interleukin (IL)-6 and IL-12b. ATF3 and Rel ( a component of NF-kappa B) were shown to bind to the regulatory regions of these genes upon macrophage activation. A kinetic model of Il6 and Il12b messenger RNA expression as a function of ATF3 and NF-kappa B promoter binding predicted that ATF3 is a negative regulator of Il6 and Il12b transcription, and this hypothesis was validated using Atf3-null mice. ATF3 seems to inhibit Il6 and Il12b transcription by altering chromatin structure, thereby restricting access to transcription factors. Because ATF3 is itself induced by lipopolysaccharide, it seems to regulate TLR-stimulated inflammatory responses as part of a negative-feedback loop.

关键词： 3T3 Cells   3T3 Cells   Activating Transcription Factor 3/metabolism   Adipocytes/physiology   Adiponectin/genetics   Animals   Base Sequence   Binding Sites   Gene Expression Regulation   Luciferases/genetics   Luciferases/metabolism   Mice   NFATC Transcription Factors/metabolism   Promoter Regions, Genetic   RNA, Messenger/genetics   Transfection  

摘要： Expression of adiponectin decreases with obesity and insulin resistance. At present, the mechanisms responsible for negatively regulating adiponectin expression in adipocytes are poorly understood. In this investigation, we analyzed the effects of 5' serial deletion constructs on the murine adiponectin promoter. Here, we identified the repressor region located between -472 and -313 bp of the promoter. Removal of the putative nuclear factor of activated T-cells (NFATs) binding site increased the promoter activity, and overexpression of NFATc4 reduced the promoter activity. Treatment with the calcium ionophore A23187, an activator of NFAT, reduced mRNA as well as promoter activity. The binding of NFATc4 to the promoter was associated with increased recruitment of histone deacetylase 1 and reduced acetylation of histone H3 at the promoter site. In addition, binding of activating transcription factor 3 (ATF3) to the putative activator protein-1 site located adjacent to the NFAT binding site also repressed the promoter activity. Treatment with thapsigargin, an inducer of ATF3, reduced both mRNA and promoter activity. Importantly, the binding activities of NFATc4 and ATF3, increased significantly in white adipose tissues of ob/ob and db/db mice compared with controls. Taken together, this study demonstrates for the first time that NFATc4 and ATF3 function as negative regulators of adiponectin gene expression, which may play critical roles in downregulating adiponectin expression in obesity and type 2 diabetes.