关键词： Colon cancer   Activating transcription factor 3   ATF3   HT-29   CaCO2   Metastasis  

摘要： Colorectal cancer is one of the commonest of solid malignancy in the world. Activating transcription factor 3 (ATF3), a homolog of the mouse TI-241 and rat LFR-1, is a stress responsive gene that has been widely indicated in different malignancies. However, the role of ATF3 in colon cancer is paradoxical with both a suggested pro- and anti-tumorigenic role. The objective of the current study was to investigate the role of ATF3 in colon cancer metastasis using HT29 and CaCO2 colon cancer cell lines. Expression of ATF3 was initially evaluated in five pairs of colon cancer and matched noncancerous colon tissues. The role of ATF3 in promoting in vitro migration and invasion were evaluated by siRNA-mediated knockdown and adenovirus-mediated overexpression of ATF3. In addition, the role of ATF3 in promoting in vivo tumor growth and hepatic metastasis was investigated by shRNA-mediated knockdown of ATF3. Expression of ATF3 was more in the colon cancer tissues as compared with the pooled noncancerous control colon tissue. Our results showed that in both HT29 and CaCO2 cells, ATF3 promoted in vitro motility and invasion. Furthermore, knockdown of ATF3 attenuated subcutaneous tumor growth and CD31(+) neovasculature in xenograft assays with HT29 and CaCO2 cells and inhibited hepatic metastasis. Cumulatively, our results unequivocally show that ATF3 promotes colon cancer metastasis.

关键词： Activating transcription factor 3   Cardiac hypertrophy   Fibrosis   Inflammation  

关键词： ONCOGENES   RESEARCH   CYCLOSPORINE   ULTRAVIOLET radiation -- Physiological effect   SQUAMOUS cell carcinoma   TRANSPLANTATION of organs, tissues, etc. -- Complications   TRANSCRIPTION factors   NF-kappa B (DNA-binding protein)   TREATMENT  

摘要： Cutaneous squamous cell carcinoma (SCC) represents the most important cutaneous complication following organ transplantation. It develops mostly on sun-exposed areas. A recent study showed the role of activating transcription factor 3 (ATF3) in SCC development following treatment with calcineurin inhibitors. It has been reported that ATF3, which may act as an oncogene, is under negative calcineurin/nuclear factor of activated T cells (NFAT) control and is upregulated by calcineurin inhibitors. Still, these findings do not fully explain the preferential appearance of SCC on chronically sun-damaged skin. We analyzed the influence of UV radiation on ATF3 expression and its potential role in SCC development. We found that ATF3 is a specifically induced AP1 member in SCC of transplanted patients. Its expression was strongly potentiated by combination of cyclosporine A and UVA treatment. UVA induced ATF3 expression through reactive oxygen species-mediated nuclear factor erythroid 2-related factor 2 (NRF2) activation independently of calcineurin/NFAT inhibition. Activated NRF2 directly binds to ATF3 promoter, thus inducing its expression. These results demonstrate two mechanisms that independently induce and, when combined together, potentiate the expression of ATF3, which may then force SCC development. Taking into account the previously defined role of ATF3 in the SCC development, these findings may provide an explanation and a mechanism for the frequently observed burden on SCCs on sunexposed areas of the skin in organ transplant recipients treated by calcineurin inhibitors.

关键词： Autophagy   Lung injury   Endotoxemia   Sepsis   Inflammatory response   ATF3 sequestration  

摘要： Autophagy has emerged as a key regulator of the inflammatory response. To examine the role of autophagy in the development of organ dysfunction during endotoxemia, wild-type and autophagy-deficient (Atg4b-null) mice were challenged with lipopolysaccharide. Animals lacking Atg4b showed increased mortality after endotoxemia. Among the different organs studied, only the lungs showed significant differences between genotypes, with increased damage in mutant animals. Autophagy was activated in lungs from wild-type, LPS-treated mice. Similarly, human bronchial cells show an increased autophagy when exposed to serum from septic patients. We found an increased inflammatory response (increased neutrophilic infiltration, higher levels of Il6, Il12p40, and Cxcl2) in the lungs from knockout mice and identified perinuclear sequestration of the anti-inflammatory transcription factor ATF3 as the putative mechanism responsible for the differences between genotypes. Finally, induction of autophagy by starvation before LPS exposure resulted in a dampened pulmonary response to LPS in wild-type, but not knockout, mice. Similar results were found in human bronchial cells exposed to LPS. Our results demonstrate the central role of autophagy in the regulation of the lung response to endotoxemia and sepsis and its potential modulation by nutrition.

关键词： Activating transcription factor 3   C/EBP homologous protein   Cyclosporin A   HK-2 cell   Nephrotoxicity  

摘要： Calcineurin inhibitors such as cyclosporin A (CsA) are widely used to treat organ transplantation-associated complications. However, CsA use is limited due to renal dysfunction. This study attempts to characterize the mechanism of CsA-induced nephrotoxicity using a human embryonic kidney cell line (HK-2). We performed microarray-based whole-genome expression analysis in HK-2 cells. CsA treatment induced the expression of endoplasmic reticulum (ER) stress-related and apoptosis-inducing genes at 6 and 24 h, respectively, indicating that ER-stress predisposed the cells to apoptosis. G1 phase cell-cycle arrest was also observed via ER stress in CsA-treated cells. Furthermore, we found an inverse relationship between activating transcription factor 3 (ATF3), a stress-inducible protein, and C/EBP homologous protein (CHOP), an apoptosis-inducing protein. Moreover, when ATF3 knockdown cells were exposed to CsA, a prompt induction of CHOP was observed, which stimulated ROS production and induced cell death-related genes as compared to wild type. Taken together, our data demonstrate that ATF3 plays a pivotal role in the attenuation of CsA-induced nephrotoxicity by downregulating CHOP and ROS production mediated by ER stress. (C) 2014 Elsevier Inc. All rights reserved.

关键词： LIPIDS   BIOMOLECULES   CYTOLOGY   CELLS   LUPUS erythematosus  

摘要： Type I IFN plays a key role in anti-viral responses. It also has been shown that deregulation of Type I IFN expression following abnormal activation of TLRs contributes to pathogenesis of systemic lupus erythematosus. In this study we find PIKfyve, a class III lipid kinase, is required for endolysosomal TLR-induced expression of type I IFN in mouse and human cells. PIKfyve binds to phosphatidylinositol 3P and synthesizes phosphatidylinositol (3,5)P2, and plays a critical role in endolysosomal trafficking. However, PIKfyve modulates type I IFN production via mechanisms independent of receptor and ligand trafficking in endolysosomes. Instead, pharmacological or genetic inactivation of PIKfyve rapidly induces expression of transcription repressor ATF3, which is necessary and sufficient for suppression of type I IFN expression by binding to its promoter and blocking its transcription. Thus, we have uncovered a novel phosphoinositide-mediated regulatory mechanism that controls TLR-mediated induction of type I IFN, which may provide new therapeutic indication for PIKfyve inhibitor.

关键词： ATF3   activating transcription factor   AU   arbitrary units   bHLH   basic helix-loop-helix   bZIP   Basic Leucine Zipper   CC   central canal   CREB   cAMP responsive element-binding   CSF   cerebrospinal fluid   DAPI   4,6-diamidino-2-phenylindole   DCX   doublecourtin   EdU   5-ethynyl-20-deoxyuridine   FMS   funicular migratory stream   GFAP   glial fibrillary acidic protein   MAPK   mitogen-activated protein kinases   PM   pathological medium   RMS   rostral migratory stream   SPCs   stem and progenitor cells   TBP   TATA binding protein  

摘要： The present study identified ATF3 as a novel dynamic marker for ependymal stem/progenitor cells (nestin, vimentin and SOX2 positive) around the central canal of the neonatal or adult rat spinal cord. While quiescent ependymal cells showed cytoplasmic ATF3 expression, during 6-24 h in vitro these cells mobilized and acquired intense nuclear ATF3 staining. Their migratory pattern followed a centrifugal pathway toward the dorsal and ventral funiculi, reminiscent of the rostral migratory stream of the brain subventricular stem cells. Thus, the chain cell formation was, by analogy, termed funicular migratory stream (FMS). The FMS process preceded the strong proliferation of ependymal cells occurring only after 24 h in vitro. Pharmacological inhibition of MAPK-p38 and JNK/c-Jun (upstream effectors of ATF3 activation) prevented the FMS mobilization of ATF3 nuclear-positive cells. Excitotoxicity or ischemia-like conditions, reported to evoke neuronal and glial injury, did not further enhance migration of ependymal cells at 24 h, suggesting that, at this early stage of damage, the FMS phenomenon had peaked and that more extensive repair processes are delayed beyond this time point. ATF3 is, therefore, useful to identify activation and migration of endogenous stem cells of the rat spinal cord in vitro. (C) 2014 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://***/licenses/by-nc-nd/3.0/).

关键词： Calcium Signaling   Cell Signaling   Gene Expression   Glutamate Receptors Ionotropic (AMPA   NMDA)   Neurobiology   Neurodegeneration   Neuroprotection   Neurotransmitters   Signal Transduction  

摘要： Background: Injured neurons display dendritic beadings, which represent focal swellings of dendrites. Results: Increased synaptic activity and overexpression of ATF3 reduce dendritic beading after an excitotoxic insult. Conclusion: ATF3 overexpression facilitates recovery of neuronal network function after an excitotoxic insult. Significance: ATF3-based dendroprotection promotes functional recovery after neuronal injury. The focal swellings of dendrites (dendritic beading) are an early morphological hallmark of neuronal injury and dendrotoxicity. They are associated with a variety of pathological conditions, including brain ischemia, and cause an acute disruption of synaptic transmission and neuronal network function, which contribute to subsequent neuronal death. Here, we show that increased synaptic activity prior to excitotoxic injury protects, in a transcription-dependent manner, against dendritic beading. Expression of activating transcription factor 3 (ATF3), a nuclear calcium-regulated gene and member of the core gene program for acquired neuroprotection, can protect against dendritic beading. Conversely, knockdown of ATF3 exacerbates dendritic beading. Assessment of neuronal network functions using microelectrode array recordings revealed that hippocampal neurons expressing ATF3 were able to regain their ability for functional synaptic transmission and to participate in coherent neuronal network activity within 48 h after exposure to toxic concentrations of NMDA. Thus, in addition to attenuating cell death, synaptic activity and expression of ATF3 render hippocampal neurons more resistant to acute dendrotoxicity and loss of synapses. Dendroprotection can enhance recovery of neuronal network functions after excitotoxic insults.

关键词： activating transcription factor3 (ATF3)   apoptosis   cell death   heat shock protein90 (HSP90)   necrosis  

摘要： Necrosis and apoptosis are the two major forms of cell death. We have studied the mechanisms that regulate the cell death observed during treatment of mouse cancer cell line FM3A with the anticancer drug 5-fluoro-2-deoxyuridine (FUdR). To detect causal differences between necrosis and apoptosis, we exploited the necrosis in original clone F28-7 and the apoptosis in its variant F28-7-A that occur on treatment with FUdR. Activating transcription factor3 (ATF3) was strongly induced during necrosis but not apoptosis. In addition, we found that ATF3 expression is regulated by heat shock protein90 (HSP90) at the mRNA stage. Knockdown of Atf3 by siRNA in the F28-7 cells resulted in apoptotic morphology rather than necrotic morphology. These results suggest that ATF3 is a cell-death regulator in necrosis and apoptosis.

关键词： Drug Resistance   Invasion   Lung Cancer   Migration   p53   ATF3   Mutant p53  

摘要： Background: Mutant p53 often acquires tumor-promoting activities, including the promotion of cancer cell survival, invasion, and metastasis. Results: Activating transcription factor 3 (ATF3) bound mutant p53 proteins, sensitized cancer cells to chemotherapy, and suppressed mutant p53-mediated cell migration. Conclusion: ATF3 suppressed the tumor-promoting function of mutant p53. Significance: Targeting ATF3 could be a novel strategy for treating p53-mutated cancer. Mutant p53 proteins (mutp53) often acquire oncogenic activities, conferring drug resistance and/or promoting cancer cell migration and invasion. Although it has been well established that such a gain of function is mainly achieved through interaction with transcriptional regulators, thereby modulating cancer-associated gene expression, how the mutp53 function is regulated remains elusive. Here we report that activating transcription factor 3 (ATF3) bound common mutp53 (e.g. R175H and R273H) and, subsequently, suppressed their oncogenic activities. ATF3 repressed mutp53-induced NFKB2 expression and sensitized R175H-expressing cancer cells to cisplatin and etoposide treatments. Moreover, ATF3 appeared to suppress R175H- and R273H-mediated cancer cell migration and invasion as a consequence of preventing the transcription factor p63 from inactivation by mutp53. Accordingly, ATF3 promoted the expression of the metastasis suppressor SHARP1 in mutp53-expressing cells. An ATF3 mutant devoid of the mutp53-binding domain failed to disrupt the mutp53-p63 binding and, thus, lost the activity to suppress mutp53-mediated migration, suggesting that ATF3 binds to mutp53 to suppress its oncogenic function. In line with these results, we found that down-regulation of ATF3 expression correlated with lymph node metastasis in TP53-mutated human lung cancer. We conclude that ATF3 can suppress mutp53 oncogenic function, thereby contributing to tumor suppression in TP53-mutated cancer.