关键词： ATF3   Unfolded protein response   Ischemic preconditioning   Infarct size   inflammatory response  

摘要： Ischemic preconditioning (PC) is an adaptive response to transient myocardial ischemia that protects the heart from subsequent ischemia/reperfusion (I/R) injury. However, the mechanisms underlying its cardioprotective effects remain unclear. Myocardium of adult male C57/BL6 mice, preconditioned by 6 cycles of 4 minute coronary occlusion and reperfusion, showed nuclear translocation of ATF3 and ATF6 and PERK phosphorylation 30 min after PC. The abundance of ER proteins, ATF3 and ATF4 was increased 24 h after PC;however, there was no evidence of IRE-1 activation inliVT or ER-stress activated indicator (ERAI) mice expressing XBP-1-Venus fusion protein. PC-induced nuclear translocation of ATF3 was attenuated in transgenic mice with cardiac-restricted overexpression of inducible ATF6. Ischemic PC increased the abundance of inducible nitric oxide synthase, cyclooxygenase-2, heme oxygenase-1 and aldose reductase to levels similar between \NT and ATF3-null hearts;however, the increase in IL-6 and ICAM-1 was exaggerated in ATF3-null hearts. Genetic deletion of ATF3 did not increase infarct size in non-preconditioned hearts but abolished the cardioprotective effects of PC. Larger infarct size in preconditioned ATF3-null hearts was associated with greater neutrophil infiltration in the myocardium, but no ATF3-dependent changes in the total or relative abundance of inflammatory monocytes were observed. Ischemic PC activates the unfolded protein response (UPR) and the activation of ATF3 by ER stress is essential for the cardioprotective effects of late PC. (c) 2014 Elsevier Ltd. All rights reserved.

关键词： NATURAL immunity   TRANSCRIPTION factors   ANTIGENS   HOMEOSTASIS   CELLULAR signal transduction   INFLAMMATION -- Mediators   CYTOKINES  

摘要： Our body is continuously exposed to a diverse array of infectious agents, foreign antigens, and host-derived danger signals. The innate immune system plays a vital role as the first line of defence against these insults by protecting the host from infection and maintaining tissue homeostasis. Families of signalling receptors (e.g. TLRs) recognize invading microbes and co-ordinate an appropriate inflammatory response via the production of pro-inflammatory cytokines and type I interferons (IFNs) to clear infection. However, inappropriate activation of innate immune receptors and unregulated production of inflammatory mediators is thought to be the basis for many acute and chronic inflammatory conditions. Indeed, excessive IFN production is implicated in the pathogenesis of lupus and atherosclerosis. Maintaining a balance between the beneficial and detrimental effects of IFNs is therefore crucial and their production must be tightly regulated. Yet these precise regulatory mechanisms remain poorly understood. We have discovered that macrophages deficient in the transcriptional modulator, ATF3, display significantly greater IFN β production following activation of TLRs and other innate immune receptors, as well as reduced LCMV viral infection. In contrast, overexpression of ATF3 in macrophages reduced the induction of IFN β and increased viral replication. Utilizing a range of molecular biology, biochemical and immunological techniques, integrated with powerful bioinformatics approaches we have investigated the molecular mechanisms responsible for ATF3-mediated regulation of IFN β . Our ATF3 ChIP-seq data has revealed that ATF3 regulates IFN β by binding directly to its promoter. Furthermore, we have found that ATF3 itself is regulated by IFNs and thus forms part of a negative feedback loop during the induction of IFN signalling. Together our findings indicate ATF3 is a critical regulator of the IFN innate immune response. A better understanding of how the innate immune

关键词： LIVER -- Cancer -- Prevention   STAT proteins   GENETIC transcription -- Regulation   CREB protein   CARRIER proteins   SPECTRIN  

摘要： The cytoskeletal protein Spectrin, beta, non-erythrocytic 1(SPTBN1), an adapter protein to SMAD3 in TCF-beta signaling, may prevent hepatocellular carcinoma (HCC) development by downregulating the expression of signal transducer and activator of transcription 3 (STAT3). To elucidate the as yet undefined mechanisms that regulate this process, we demonstrate that higher levels of STAT3 transcription are found in livers of heterozygous SPTBN1(+/-) mice as compared to that of wild type mice. We also found increased levels of ST4T3 mRNA, STAT3 protein, and p-STAT3 in human HCC cell-lines after knockdown of SPTBN1 or SMAD3, which promoted cell colony formation. Inhibition of STAT3 overrode the increase in cell colony formation due to knockdown of SPTBN1 or SMAD3. We also found that inhibition of SPTBN1 or SMAD3 upregulated STAT3 promoter activity in HCC cell-lines, which is dependent upon the cAMP-response element (CRE) and STAT-binding element (SHE) sites of the STAT3 promoter. Mechanistically, suppression of SPTHN1 and SMAD3 augmented the transcription of STAT3 by upregulating the CRE-binding proteins ATF3 and CREB2 and augmented the binding of those proteins to the regions within or upstream of the CRE site of the STAT3 promoter. Finally, in human HCC tissues, SPTBN1 expression correlated negatively with expression levels of STAT3, ATF3, and CREB2;SMAD3 expression correlated negatively with STAT3 expression;and the level of phosphorylated SMAD3 (p-SMAD3) correlated negatively with ATF3 and CREB2 protein levels. SPTBN1 and SMAD3 collaborate with CRE-binding transcription factors to inhibit STAT3, thereby preventing HCC development.

关键词： Cancer Chemoprevention   Chemokine   Early Growth Response Protein 1 (EGR-1)   ER Stress   NF-kB Transcription Factor   ATF3   Apigenin   Intestinal Cancer Cells  

摘要： The cell-protective features of the endoplasmic reticulum (ER) stress response are chronically activated in vigorously growing malignant tumor cells, which provide cellular growth advantages over the adverse microenvironment including chemotherapy. As an intervention with ER stress responses in the intestinal cancer cells, preventive exposure to flavone apigenin potentiated superinduction of a regulatory transcription factor, activating transcription factor 3 (ATF3), which is also known to be an integral player coordinating ER stress response-related gene expression. ATF3 superinduction was due to increased turnover of ATF3 transcript via stabilization with HuR protein in the cancer cells under ER stress. Moreover, enhanced ATF3 caused inhibitory action against ER stress-induced cancer chemokines that are potent mediators determining the survival and metastatic potential of epithelial cancer cells. Although enhanced ATF3 was a negative regulator of the well known proinflammatory transcription factor NF-kappa B, blocking of NF-kappa B signaling did not affect ER stress-induced chemokine expression. Instead, immediately expressed transcription factor early growth response protein 1 (EGR-1) was positively involved in cancer chemokine induction by ER stressors. ER stress-induced EGR-1 and subsequent chemokine production were repressed by ATF3. Mechanistically, ATF3 directly interacted with and recruited HDAC1 protein, which led to epigenetic suppression of EGR-1 expression and subsequent chemokine production. Conclusively, super-induced ATF3 attenuated ER stress-induced cancer chemokine expression by epigenetically interfering with induction of EGR-1, a transcriptional modulator crucial to cancer chemokine production. Thus, these results suggest a potent therapeutic intervention of ER stress response-related cancer-favoring events by ATF3.

关键词： Gene Expression   Gene Therapy   Glucokinase   Metabolic Disease   Pancreatic Islet   Type 2 Diabetes  

摘要： Chronic ethanol consumption induces pancreatic beta-cell dysfunction through glucokinase (Gck) nitration and down-regulation, leading to impaired glucose tolerance and insulin resistance, but the underlying mechanism remains largely unknown. Here, we demonstrate that Gck gene expression and promoter activity in pancreatic beta-cells were suppressed by chronic ethanol exposure in vivo and in vitro, whereas expression of activating transcription factor 3 (Atf3) and its binding to the putative Atf/Creb site (from -287 to -158 bp) on the Gck promoter were up-regulated. Furthermore, in vitro ethanol-induced Atf3 inhibited the positive effect of Pdx-1 on Gck transcriptional regulation, enhanced recruitment of Hdac1/2 and histone H3 deacetylation, and subsequently augmented the interaction of Hdac1/Pdx-1 on the Gck promoter, which were diminished by Atf3 siRNA. In vivo Atf3-silencing reversed ethanol-mediated Gck down-regulation and beta-cell dysfunction, followed by the amelioration of impaired glucose tolerance and insulin resistance. Together, we identified that ethanol-induced Atf3 fosters beta-cell dysfunction via Gck down-regulation and that its loss ameliorates metabolic syndrome and could be a potential therapeutic target in treating type 2 diabetes. The Atf3 gene is associated with the induction of type 2 diabetes and alcohol consumption-induced metabolic impairment and thus may be the major negative regulator for glucose homeostasis.

关键词： Biochemistry   Biology and life sciences   Cell biology   Molecular biology   Neuroscience   Physiology   Research Article  

摘要： Joint inflammatory diseases are debilitating and very painful conditions that still lack effective treatments. Recently, glial cells were shown to be crucial for the development and maintenance of chronic pain, constituting novel targets for therapeutic approaches. At the periphery, the satellite glial cells (SGCs) that surround the cell bodies of primary afferents neurons in the dorsal root ganglia (DRG) display hypertrophy, proliferation, and activation following injury and/or inflammation. It has been suggested that the expression of neuronal injury factors might initially trigger these SGCs-related events. We then aimed at evaluating if SGCs are involved in the establishment/maintenance of articular inflammatory pain, by using the monoarthritis (MA) model, and if the neuronal injury marker activating transcriptional factor 3 (ATF3) is associated with these SGCs' reactive changes. Western Blot (WB) analysis of the glial fibrillary acidic protein (GFAP) expression was performed in L4-L5 DRGs from control non-inflamed rats and MA animals at different time-points of disease (4, 7, and 14d, induced by complete Freund's adjuvant injection into the left hind paw ankle joint). Data indicate that SGCs activation is occurring in MA animals, particularly after day 7 of disease evolution. Additionally, double-immunostaining for ATF3 and GFAP in L5 DRG sections shows that SGCs's activation significantly increases around stressed neurons at 7d of disease, when compared with control animals. The specific labelling of GFAP in SGCs rather than in other cell types was also confirmed by immunohistochemical labeling. Finally, BrdU incorporation indicates that proliferation of SGCs is also significantly increased after 7 days of MA. Data indicate that SGCs play an important role in the mechanisms of articular inflammation, with 7 days of disease being a critical time-point in the MA model, and suggest that ATF3 might be involved in SGCs' reactive changes such as activation.

关键词： glycyl-tRNA synthetase   motor impairment   ATF3   microglia   recombinant adenovirus  

摘要： Distal spinal muscular atrophy type V (dSMA-V) is a hereditary neurodegenerative axonal neuropathy and a glycyl-tRNA synthetase (GARS)-associated neuropathy that is caused by a mutation in GARS. Herein, we report a new GARS-associated neuropathy mouse model using an adenovirus vector system equipped with a neuron-specific promoter. In this model, we showed an increased number of activated microglia around the L129P mutant-expressing motor neuron cell bodies and the increased nerve injury signal in L129P mutant-expressing motor neuron cell bodies. In addition, we found that the mouse model exhibited impaired motor function caused by the L129P mutant. We propose that the neuroinflammation may be associated with motor neuron impairment in GARS-associated neuropathies.

关键词： INFLAMMATION   GENETIC transcription   REPERFUSION (Physiology)   KIDNEYS -- Wounds & injuries   CELL adhesion molecules   MONOCYTE chemotactic factor  

摘要： Transcriptional repressor activating transcription factor 3 (ATF3) is induced by various stress stimuli, including inflammation-induced renal injury. In addition, ATF3 also down-regulates adhesion molecules like intercellular adhesion molecule (ICAM), vascular cell adhesion molecule (VCAM), and monocyte chemotactic protein-1 (MCP-1). However, the relation between up-regulated ATF3 after renal ischemia/reperfusion (I/R) injury and MCP-1 is not completely understood. In this study, we demonstrated that, in renal I/R induced inflammation, induction of adhesion molecules (interleukin-6, P-selectin, E-selectin, ICAM, VCAM, and MCP-1) was higher in ATF3-knockout mice than in wild-type animals. Molecular and biochemical analyses revealed that ATF3 binds to the ATF/CRE sites in the MCP-1 promoter and inhibits the secretion of MCP-1 from renal epithelial cells after I/R injury. Urinary exosome containing ATF3 RNA was 60-fold higher in patients with acute kidney injury than in normal controls, but no difference in total urinary ATF3 RNA levels was found. In addition, in vitro study showed that exosome containing ATF3 RNA derived from epithelial cells also inhibits MCP-1 expression in the epithelial cells and macrophage migration. Furthermore, direct administration of the epithelium-derived exosomal ATF3 RNA attenuates I/R induced kidney injury. Together, our studies reveal a novel regulatory mechanism of MCP-1 expression mediated by the exosomal ATF3 RNA under renal I/R insult and suggest a potential targeted therapy for I/R induced acute kidney injury. J. Cell. Physiol. 229: 1202-1211, 2014. (c) 2014 Wiley Periodicals, Inc.

关键词： Apoptosis   Cancer Therapy   Colon Cancer   ER Stress   Gene Regulation   Reactive Oxygen Species (ROS)   ATF3   DR5   p53-independent  

摘要： Death receptor 5 (DR5) is a death domain-containing transmembrane receptor that triggers cell death upon binding to its ligand, TNF-related apoptosis-inducing ligand (TRAIL), and a combination of TRAIL and agents that increase the expression of DR5 is expected to be a novel anticancer therapy. In this report, we demonstrate that the stress response gene ATF3 is required for endoplasmic reticulum stress-mediated DR5 induction upon zerumbone (ZER) and celecoxib (CCB) in human p53-deficient colorectal cancer cells. Both agents activated PERK-eIF2 alpha kinases and induced the expression of activating transcription factor 4 (ATF4)-CCAAT enhancer-binding protein (C/EBP) homologous protein, which were remarkably suppressed by reactive oxygen species scavengers. In the absence of ATF3, the induction of DR5 mRNA and protein was abrogated significantly, and this was associated with reduced cell death by cotreatment of TRAIL with ZER or CCB. By contrast, exogenous expression of ATF3 caused a more rapid and elevated expression of DR5, resulting in enhanced sensitivity to apoptotic cell death by TRAIL/ZER or TRAIL/CCB. A reporter assay demonstrated that at least two ATF/cAMP response element motifs as well as C/EBP homologous protein motif at the proximal region of the human DR5 gene promoter were required for ZER-induced DR5 gene transcription. Taken together, our results provide novel insights into the role of ATF3 as an essential transcription factor for p53-independent DR5 induction upon both ZER and CCB treatment, and this may be a useful biomarker for TRAIL-based anticancer therapy.

关键词： epilepsy   activating transcription factor 3   p53   axon growth   MFS  

摘要： Epilepsy is a common and often deleterious neurological condition. Emerging evidence has demonstrated the roles of innate immunity and the associated inflammatory processes in epilepsy. In a previous study, we found that Toll-like receptors (TLRs) are upregulated and promote mossy fiber sprouting (MFS) in an epileptic model. As downstream effectors of TLRs, the activating transcription factor 3 (ATF3) and p53 proteins were shown to be involved in neurite outgrowth. In the present study, we hypothesized that ATF3 and p53 participate in the process of epilepsy and can affect MFS. To investigate this hypothesis, we examined the expression of ATF3 and p53 in hippocampal tissues of rats kindled by pentylenetetrazole (PTZ) using immunofluorescence, immunohistochemistry and western blotting. MFS was evaluated by Timm staining in the hippocampus. Results from these experiments revealed that expression of ATF3 and p53 is significantly higher (p<0.05) in the CA3 area of the hippocampus in the PTZ-treated group compared to the control group. ATF3 expression gradually increased from 3 days to 4 weeks, peaked at 4 weeks and decreased slightly at 6 weeks in the PTZ group, while the expression of p53 was maintained at similar levels at different time-points following PTZ treatment. No obvious difference in the expression of these proteins was observed between the PTZ and the control group in the dentate gyrus (DG) area (p>0.05). The degree of MFS in the PTZ group peaked at 4 weeks and was maintained at a high level until 6 weeks post-PTZ treatment. In conclusion, ATF3 and p53 may be involved in the occurrence of seizure and play critical roles in MFS in the PTZ kindling model.