关键词： RNA-protein interaction   Non-stop decay (NSD)   RNA exosome   SKIV2L   RNA quality control  

摘要： Hepatitis B virus (HBV) -x protein is a transcriptional regulator required for the HBV life cycle. HBx also induces complications in the host such as hepatocellular carcinoma. We previously showed that HBx mRNA is degraded by the Ski2/RNA exosome complex. In the present study, we report the regulation of this system through the control of Ski2 expression. We identified interleukin (IL) -1 beta as an inducer of expression from the Ski2 promoter. IL-1 beta induced the expression of ATF3 transcription factor, which in turn binds to cyclic AMP-responsive element sequence in the Ski2 promoter and is responsible for Ski2 promoter induction by IL-1 beta. We previously reported that Ski2 expression increases HBx mRNA degradation;consistent with those data, we showed here that HBx mRNA is degraded in response to IL-1 beta treatment. Interestingly, HBx also significantly induced Ski2 expression. To our knowledge, this is the first report to show activation of the Ski2/RNA exosome complex by both the host and HBV. Understanding the regulation of the Ski2/RNA exosome system is expected to facilitate prevention of HBx-mediated complications through targeting the posttranscriptional degradation of HBx mRNA;and will also help shedding a light on the role of RNA decay systems in inflammation. (C) 2018 Elsevier Inc. All rights reserved.

摘要： Activating transcription factor 3 (ATF3) is a stress-induced transcription factor that plays important roles in regulating immune and metabolic homeostasis. Activation of the mechanistic target of rapamycin (mTOR) and hypoxia-inducible factor (HIF) transcription factors are crucial for the regulation of immune cell function. Here, we investigated the mechanism by which the ATF3/mTOR/HIF-1 axis regulates immune responses in a liver ischemia/reperfusion injury (IRI) model. Deletion of ATF3 exacerbated liver damage, as evidenced by increased levels of serum ALT, intrahepatic macrophage/neutrophil trafficking, hepatocellular apoptosis, and the upregulation of pro-inflammatory mediators. ATF3 deficiency promoted mTOR and p70S6K phosphorylation, activated high mobility group box 1 (HMGB1) and TLR4, inhibited prolyl-hydroxylase 1 (PHD1), and increased HIF-1 alpha activity, leading to Foxp3 downregulation and ROR gamma t and IL-17A upregulation in IRI livers. Blocking mTOR or p70S6K in ATF3 knockout (KO) mice or bone marrow-derived macrophages (BMMs) downregulated HMGB1, TLR4, and HIF-1 alpha and upregulated PHD1, increasing Foxp3 and decreasing IL-17A levels in vitro. Silencing of HIF-1 alpha in ATF3 KO mice ameliorated IRI-induced liver damage in parallel with the downregulation of IL-17A in ATF3-deficient mice. These findings demonstrated that ATF3 deficiency activated mTOR/p70S6K/HIF-1 alpha signaling, which was crucial for the modulation of TLR4-driven inflammatory responses and T cell development. The present study provides potential therapeutic targets for the treatment of liver IRI followed by liver transplantation.

关键词： 肾上腺皮质腺癌   激活转录因子3   信号通路   细胞凋亡   作用机制  

摘要： 目的 研究下调激活转录因子3（ATF3）的表达对肾上腺皮质腺癌细胞增殖的影响及其作用机制.方法 利用免疫组化和Western印迹分别检测ATF3在人肾上腺皮质肿瘤组织和细胞中的表达;运用脂质体2000转染法将siATF3转染肾上腺皮质腺癌细胞Sw-13和NCI-H259R细胞,运用逆转录PCR检测ATF3 mRNA表达;Western印迹法检测ATF3、cleaved caspase 3、caspase 3、cleaved PARP、PARP蛋白表达;四甲基偶氮唑盐（MTT）和异硫氰酸胍标记磷脂结蛋白（AnnexinV-FITC）/碘化丙啶（ PI）分别测定细胞增殖率和细胞凋亡率;NCI-H259R细胞分别经 NVP-BEZ235、Perifosine、BKM120、IWP-2、PP2、KN93、Everolimus作用后,运用实时荧光定量PCR（ realtime PCR）测定ATF3 mRNA的表达;MTT比色法检测ATF3对抑制相关信号通路后细胞增殖的影响.结果 ATF3 在人肾上腺皮质腺肿瘤组织和细胞中呈高表达;而转染siATF3的Sw-13和NCI-F259R细胞ATF3 mRNA和蛋白表达显著降低;与阴性对照组（ NC siRNA）比较, siATF3转染显著抑制Sw-13和NCI-F259R细胞增殖（P＜0.05）,细胞凋亡率显著增加（P＜0.05）;Western印迹结果显示siATF3转染的细胞cleaved caspase 3和cleaved PARP蛋白水平显著增加;realtime PCR结果显示,与二甲基亚砜（DMSO）溶剂对照组相比,PP2、KN93、IWP-2信号通路抑制剂均显著抑制ATF3 mRNA的表达（P＜0.05）,而ATF3能够显著促进PP2、KN93、IWP-2信号抑制剂作用NCI-F259R细胞后的增殖活性.结论 ATF3在肾上腺皮质腺癌组织和细胞中高表达,下调ATF3的表达能抑制Sw-13和NCI-H259R细胞增殖,激活细胞凋亡通路诱导细胞凋亡;其机制与Wnt/β-catenin通路、CaMKI通路及SRC通路的激活相关.

关键词： 转录激活因子3(ATF3)   RT-PCR   Realtime-PCR   免疫组化   小鼠  

摘要： ATF3(activating transcription factor 3)作为压力诱导因子,在接受外界信号后能够迅速升高表达,调节靶基因,维持细胞稳态,因而被认为和多种疾病相关,关于ATF3在正常组织的功能目前并不清楚.为了确认ATF3在正常小鼠脑中是否表达,利用RT-PCR、Realtime-PCR、Western blot和免疫组化方法检测了ATF3的表达.实验结果显示:ATF3 m RNA和蛋白在所有正常小鼠的额叶、顶叶、枕叶、颞叶、丘脑、小脑和海马等部位均有表达,且不同部位的ATF3 m RNA和蛋白表达量没有统计学差异.证明了ATF3在小鼠脑正常生理状态下能够稳定表达,提示该基因在正常小鼠脑中具有生理功能.

关键词： ATF2   ATF3   neuropathic pain   tactile allodynia   thermal hyperalgesia  

摘要： Transcription factors are proteins that modulate the transcriptional rate of target genes in the nucleus in response to extracellular or cytoplasmic signals. Activating transcription factors 2 (ATF2) and 3 (ATF3) respond to environmental signals and maintain cellular homeostasis. There is evidence that inflammation and nerve injury modulate ATF2 and ATF3 expression. However, the function of these transcription factors in pain is unknown. The purpose of this study was to investigate the contribution of ATF2 and ATF3 to nerve injury-induced neuropathic pain. L5/6 spinal nerve ligation induced tactile allodynia and thermal hyperalgesia. Moreover, nerve damage enhanced ATF2 and ATF3 protein expression in injured L5/6 dorsal root ganglia and spinal cord but not in uninjured L4 dorsal root ganglia. Nerve damage also enhanced ATF2 immunoreactivity in dorsal root ganglia and spinal cord 7 to 21 days post-injury. Repeated intrathecal post-treatment with a small-interfering RNA targeted against ATF2 (ATF2 siRNA) or anti-ATF2 antibody partially reversed tactile allodynia and thermal hyperalgesia. In contrast, ATF3 siRNA or anti-ATF3 antibody did not modify nociceptive behaviors. ATF2 immunoreactivity was found in dorsal root ganglia and spinal cord co-labeling with NeuN mainly in non-peptidergic (IB4(+)) but also in peptidergic (CGRP ) neurons. ATF2 was found mainly in small- and medium-sized neurons. These results suggest that ATF2, but not ATF3, is found in strategic sites related to spinal nociceptive processing and participates in the maintenance of neuropathic pain in rats.

关键词： Bioinformatics   Biology and life sciences   Cancer cell migration   Cancers and neoplasms   Carcinogenesis   Cell biology   Cell migration   Cell motility   Cell signaling   Colorectal cancer   Database and informatics methods   Developmental biology   DNA transcription   Gene expression   Gene regulation   Genetics   Medicine and health sciences   Oncology   Research and analysis methods   Research Article   Sequence analysis   Sequence motif analysis   Signal transduction   Signaling cascades   Wnt signaling cascade  

摘要： Aberrant Wnt/beta-catenin signaling is implicated in tumorigenesis and the progression of human colorectal cancers, and mutations in the components of the Wnt/beta-catenin signaling pathway are observed in the majority of patients. Therefore, extensive studies on the Wnt signaling pathway and its target genes are crucial to understand the molecular events of tumorigenesis and develop an efficacious therapy. In this study, we showed that the stress response gene ATF3 is transcriptionally activated by the binding of beta-catenin and TCF4 to the redundant TCF4 site at the proximal promoter region of the ATF3 gene, indicating that ATF3 is a direct target of the Wnt/beta-catenin pathway. The loss of function or overexpression studies showed that ATF3 inhibited the migration or invasion of HCT116 cells. The expression of some MMP and TIMP genes and the ratio of MMP2/9 to TIMP3/4 mRNAs was differentially regulated by ATF3. Therefore, though ATF3 is activated downstream of the Wnt/beta-catenin pathway, it acts as a negative regulator of the migration and invasion of HCT116 human colon cancer cells exhibiting aberrant Wnt/beta-catenin activity. ATF3 is a candidate biomarker and target for human colorectal cancer treatment and prevention.

摘要： 29

摘要： It has been reported that the expression of activating transcription factor 3 (ATF3) is closely associated with both microRNA (miRNA) processing and the progress of many cancers. Our study aimed to explore the interaction between ATF3 and miR-488 in tongue squamous cell carcinoma (TSCC). Quantitative real-time PCR was performed to detect the levels of ATF3 and miR-488 in TSCC tissues and cell lines. Cell invasion and epithelial–mesenchymal transition (EMT) were assessed to determine the biological functions of miR-488 and ATF3 in TSCC cells. The mRNA and protein levels of ATF3 were measured using quantitative RT-PCR and western blotting. Luciferase assays were performed to validate ATF3 as an miR-488 target in TSCC cells. We found that the level of miR-488 significantly decreased and the expression of ATF3 significantly increased in TSCC tissues and cell lines. A low level of miR-488 was closely associated with increased expression of ATF3 in TSCC tissues. Introducing miR-488 significantly inhibited the invasion and EMT of TSCC cells, and knockdown of miR-488 promoted both processes. The bioinformatics analysis predicted that ATF3 is a potential target gene of miR-488. The luciferase reporter assay showed that miR-488 could directly target ATF3. ATF3 silencing had similar effects to miR-488 overexpression on TSCC cells. Overexpression of ATF3 in TSCC cells partially reversed the inhibitory effects of the miR-488 mimic. miR-488 inhibited cell invasion and EMT of TSCC cells by directly downregulating ATF3 expression.

关键词： apoptosis   ATF   cisplatin   ERK1   Noxa  

摘要： The platinum-based DNA damaging agent cisplatin is used as a standard therapy for locally advanced head and neck squamous cell carcinoma (HNSCC). However, the mechanisms underpinning the cytotoxic effects of this compound are not entirely elucidated. Cisplatin produces anticancer effects primarily via activation of the DNA damage response, followed by inducing BCL-2 family dependent mitochondrial apoptosis. We have previously demonstrated that cisplatin induces the expression of proapoptotic BCL-2 family protein, Noxa, that can bind to the prosurvival BCL-2 family protein, MCL-1, to inactivate its function and induce cell death. Here, we show that the upregulation of Noxa is critical for cisplatin-induced apoptosis in p53-null HNSCC cells. This induction is regulated at the transcriptional level. With a series of Noxa promoter-luciferase reporter assays, we find that the CRE (cAMP response element) in the promoter is critical for the Noxa induction by cisplatin treatment. Among the CREB/ATF transcription factors, ATF3 and ATF4 are induced by cisplatin, and downregulation of ATF3 or ATF4 reduced cisplatin-induced Noxa. ATF3 and ATF4 bind to and cooperatively activate the Noxa promoter. Furthermore, ERK1 is involved in cisplatin-induced ATF4 and Noxa induction. In conclusion, ATF3 and ATF4 are important regulators that induce Noxa by cisplatin treatment in a p53-independent manner.

摘要： Leptin acts via its receptor (LepRb) to modulate gene expression in hypothalamic LepRb-expressing neurons, thereby controlling energy balance and glucose homeostasis. Despite the importance of the control of gene expression in hypothalamic LepRb neurons for leptin action, the transcriptional targets of LepRb signaling have remained undefined because LepRb cells contribute a small fraction to the aggregate transcriptome of the brain regions in which they reside. We thus employed translating ribosome affinity purification followed by RNA sequencing to isolate and analyze mRNA from the hypothalamic LepRb neurons of wild-type or leptin-deficient (Lep(ob/ob)) mice treated with vehicle or exogenous leptin. Although the expression of most of the genes encoding the neuropeptides commonly considered to represent the main targets of leptin action were altered only following chronic leptin deprivation, our analysis revealed other transcripts that were coordinately regulated by leptin under multiple treatment conditions. Among these, acute leptin treatment increased expression of the transcription factor Atf3 in LepRb neurons. Furthermore, ablation of Atf3 from LepRb neurons (Atf3(LepRb)KO mice) decreased leptin efficacy and promoted positive energy balance in mice. Thus, this analysis revealed the gene targets of leptin action, including Atf3, which represents a cellular mediator of leptin action.