摘要： Detailed histological and ultrastructural studies were conducted on transgenic (TG) mice over-expressing the human activating transcription factor 3 (ATF3) gene, targeted to the heart by using an a-myosin heavy chain promoter. The transgenic mice showed biatrial enlargement when compared with nontransgenic (nTG) control of the same strain, with no apparent gross anatomical or ultrastructural changes in the ventricles. Visible atrial calcification occurred in 56% of the TG mice but none of the nTG mice. Gross anatomical changes were observed after 2–4 weeks of age and continued throughout the 67 weeks of the experiment. The hearts of TG mice were approximately 4 times heavier, and the myocytes about 2.3 times larger, than those of nTG mice. Chondroid metaplasia associated with mural thrombosis was observed in Muridae here for the first time to my knowledge. These processes accelerated changes in the atria of TG mice during a 12-week period and were responsible for mineralization of thrombi in the atrial chamber. Proliferation of connective tissue, circular collagen bundles with fibroblasts around mineralized areas, and dilated vascular spaces in the myocardial layer were followed eventually, by ossification. In this advanced stage, most myocytes had degenerated, as was proven by myofibril preparation and SDS-PAGE. Destruction of atrial myocytes was attributed to mineralization of mitochondria and vacuolization. Very few myocytes in the right atrium also underwent apoptosis, detected by the TUNEL assay, in a 36-week-old TG mouse. Electron microscopic examination showed that atria from the TG mice had papillar-pleated nuclear membranes and blebbing nuclei. Digestion of cytoplasmic components led to pseudohypertrophy of the TG mouse atrium. Hypertrophic myocytes showed degeneration and destruction of such cytoplasmic components as myofibrils, mitochondria, and Z-lines. However, comparison of TG and nTG mice showed that aging was not a factor in the structural alteration

摘要： Endothelial cell injury underlies an increased occurrence of thromboembolic vascular disease in hereditary hyperhomocysteinemia. We have previously shown that homocysteine causes activation of c-Jun NH2-terminal kinase (JNK) and activating transcription factor 3/liver regenerating factor 1 (ATF3/LRF1) and induces apoptosis in human umbilical vein endothelial cells (HUVECs). In this study, the activation of JNK and ATF3 in HUVECs was mediated by the endoplasmic reticulum. (ER) resident transmembrane kinase IRE1 alpha and beta, which sense and transduce signal of the accumulationj of unfolded proteins in the ER. Moreover, dominant negative mutants of tumor necrosis factor receptor-associated factor 2 and mitogen-activated kinase kinase 4 and 7, as well as antisense ATF3 cDNA, inhibited cell death by homocysteine. These results indicate that the activation of JNK and ATF3 through the ER stress of homocysteine plays a role in the homocysteine-induced cell death. The JNK-ATF3 pathway may be implicated in endothelial cell injury associated with hereditary hyperhomocysteinemia. (C) 2001 Elsevier Science.

摘要： DNA topoisomerase inhibitors are effective chemotherapeutic agents on several solid tumor cells. They induce a specific signaling cascade that executes ani active cell death process (apoptosis), including caspase activation, and the blockage of the signaling is associated with drug-resistance of tumor cells. However;little is known about the initial signal transduction induced by the agents. In the present study, we screened genes that are initially upregulated in caspase-independent manner. We found that the activating transcription factor 3 (ATF3) protein, a repressor of cyclic-AMP responsive element (CRE)-dependent transcription, was strongly induced among CRE-BP/ATF members and subsequently accumulated in nuclei following camptothecin or etoposide treatment. During induction of apoptosis, the accumulation and the nuclear translocation of ATF3 coincided with the activation of caspase protease and were not inhibited by the broad caspase inhibitor Z-VAD-fmk, indicating that ATF3 induction is not a downstream event of caspase activation. When stably or transiently overexpressed, ATF3 markedly accelerated the drug-induced apoptosis and enhanced caspase protease activation. ATF3 strongly downregulated CRE-dependent transcription, while ATF3 did not affect the expression levels of Bcl-2, Bcl-x, or Bax. Our present results indicate that ATF3 plays a critical role in accelerating caspase protease activation and apoptosis. Since CRE-dependent transcription functions as cell survival signaling, ATF3 could control the upstream signaling of apoptosis by repressing CRE-dependent gene expression of cell survival factors.

关键词： Biochemistry  

摘要： Activating transcription factor 3 (ATF3) is a member of the ATF/cAMP-response element-binding protein family of transcription factors. It is a transcriptional repressor, and the expression of its corresponding gene is induced by stress signals in a variety of tissues, including the liver. In this report, we demonstrate that ATF3 is induced in the pancreas by partial pancreatectomy, streptozotocin treatment, and ischemia coupled with reperfusion. Furthermore, ATF3 is induced in cultured islet cells by oxidative stress. Interestingly, transgenic mice expressing ATF3 in the liver and pancreas under the control of the transthyretin promoter have defects in glucose homeostasis and perinatal lethality. We present evidence that expression of ATF3 in the liver represses the expression of genes encoding gluconeogenic enzymes. Furthermore, expression of ATF3 in the pancreas leads to abnormal endocrine pancreas and reduced numbers of hormone-producing cells. Analyses of embryos indicated that the ATF3 transgene is expressed in the ductal epithelium in the developing pancreas, and the transgenic pancreas has fewer mitotic cells than the non-transgenic counterpart, providing a potential explanation for the reduction of endocrine cells. Because ATF3 is a stress-inducible gene, these mice may represent a model to investigate the molecular mechanisms for some stress-associated diseases.

关键词： bZip proteins   ATF3   ATF4   ATF6   stress response  

摘要： The mammalian ATF/CREB family of transcription factors represents a large group of basic region-leucine zipper (bZip) proteins which was originally defined in the late 1980s by their ability to bind to the consensus ATF/CRE site 'TGACGTCA'. Over the past decade, cDNA clones encoding identical or homologous proteins have been isolated by different laboratories and given different names. These proteins can be grouped into subgroups according to their amino acid similarity. In this review, we will briefly describe the classification of these proteins with a historical perspective of their nomenclature. We will then review three members of the ATF/CREB family of proteins: ATF3, ATF4 and ATF6. We will address four issues for each protein: (a) homologous proteins and alternative names, (b) dimer formation with other bZip proteins. (c) transcriptional activity, and (d) potential physiological functions. Although the name Activating Transcription Factor (ATF) implies that they are transcriptional activators, some of these proteins are transcriptional repressors. ATF3 homodimer is a transcriptional repressor and ATF4 has been reported to be either an activator or a repressor. We will review the reports on the transcriptional activities of ATF4. and propose potential explanations for the discrepancy, Although the physiological functions of these proteins are not well understood. some clues can be gained from studies with different approaches. When the data are available, we will address the following questions. (a) How is the expression (at the mRNA level or protein level) regulated? (b) How are the transcriptional activities regulated'? (c) What are the interacting proteins (other than bZip partners)? (d) What are the consequences of ectopically expressing the gene (gain-of-function) or deleting the gene (loss-of-function)? Although answers to these questions are far from being complete, together they provide clues to the functions of these ATF proteins. Despite the diversit

关键词： ATF3   Jun   AP1   chicken embryo fibroblasts   cell transformation  

摘要： Activating Transcription Factor 3 (ATF3) is a member of the bZip family of transcription factors. Previous studies in mammalian cells suggested that like other bZip family members e.g. Jun and Fos, ATF3 might play a role in the control of cell proliferation and participate in oncogenic transformation, To investigate this putative ATF3 function directly, the rat ATF3 protein was compared with v-Jun for its ability to transform primary cultures of chick embryo fibroblasts (CEFs). Like CEFs accumulating v-Jun, CEFs accumulating the ATF3 protein displayed a typical, fusiform morphology, associated with an enhanced capacity to grow in medium with reduced amount of serum. However, in contrast to v-Jun-transformed CEFs, the ATF3 overexpressing cells could not promote colony formation from single cells in agar. Partial transformation induced by ATF3 was found to be associated with repression of multiple cellular genes that are also down-regulated by v-Jun, including those coding for the extracellular components fibronectin, decorin, thrombospondin 2, and the pro-apoptotic protein Par-4. These data demonstrate that, at least in primary avian cells, rat ATF3 possesses an intrinsic oncogenic potential. Moreover, the results suggest that ATF3 might induce growth factor independence by down-regulating a subset of the genes repressed by v-Jun.

关键词： esophageal squamous cell carcinoma (ESC)   comparative genomic hybridization (CGH)   amplicon map   human activating transcription factor 3 (ATF3)   centromere protein F (CENPF)  

摘要： Using comparative genomic hybridization (CGH), we investigated copy number aberrations in 29 esophageal squamous cell carcinoma (ESC) cell lines. All lines displayed numerous chromosome imbalances. The most frequent losses were observed on chromosome 18q (65.5%), Xp (48.3%), 3p (44.8%), 49 (44.8%), 8p (41.4%), 11923-25 (34.5%) and 4p (27.6%), whereas the most common copy number gains were noted at 8q (86.2%), 3q (82.8%), 5p (69%), 7p (69%), 20q (65.5%), 9q (55.2%), 11q (55.2%), 1q (48.3%), Xq (44.8%) and 18p (37.9%). High-level gains (HLGs) were detected at 39q26 (9 cases), 8q23 (6 cases), 5p14-15 (6 cases), 18p11.2-11.3 (6 cases), 3q27-28 (5 cases), 5p13 (3 cases), 7p14-15 (3 cases), 20q12-13 (3 cases), 11q13 (3 cases), 14q21 (2 cases), 20p11.2 (2 cases), 13q32 (2 case), and 1q32 (1 case). Among them, HLGs of 1q32 have been reported in other types of cancer, including glioblastoma and breast cancers. We successfully narrowed down the smallest common amplicon involving 1q-gain to the genomic segment between D1S414 and D1S2860 by fluorescence in situ hybridization (FISH). Southern and northern blot analysis clearly demonstrated that ATF3, human activating transcription factor-3 and CENPF, centromere protein F,mapped within this region, were significantly amplified and over-expressed in 1q32 amplicon.

关键词： Activating Transcription Factor 3   Cells, Cultured   Endothelium, Vascular/physiology   Gene Expression Regulation/drug effects   Gene Expression Regulation/physiology   Homocysteine/pharmacology   Humans   JNK Mitogen-Activated Protein Kinases   Mitogen-Activated Protein Kinases/physiology   Promoter Regions, Genetic   Signal Transduction/drug effects   Signal Transduction/physiology   Transcription Factors/physiology  

摘要： Activating transcription factor (ATF)3 is a member of ATF/cyclic adenosine monophosphate (cAMP)-responsive element binding protein (ATF/CREB) family of transcription factors and functions as a stress-inducible transcriptional repressor. To understand the stress-induced gene regulation by homocysteine, we investigated activation of the ATF3 gene in human endothelial cells. Homocysteine caused a rapid induction of ATFB3 at the transcriptional level. This induction was preceded by a rapid and sustained activation of c-Jun NH2-terminal kinase/stress-activated protein kinase (JNK/SAPK), and dominant negative mitogen-activated protein kinase kinase 4 and 7 abolished these effects. The effect of homocysteine appeared to be specific, because cysteine or homocystine had no appreciable effect, but it was mimicked by dithiothreitol and P-mercaptoethanol as well as tunicamycin, The homocysteine effect was not inhibited by an active oxygen scavenger. Deletion analysis of the 5' flanking sequence of the ATF3 gene promoter revealed that one of the major elements responsible for the induction by homocysteine is an ATF/cAMP responsive element (CRE) located at -92 to -85 relative to the transcriptional start site. Gel shift, immunoprecipitation, and cotransfection assays demonstrated that a complex (or complexes) containing ATF2, c-Jun, and ATF3 increased binding to the ATF/CRE site in the homocysteine-treated cells and activated the ATF3 gene expression, while ATF3 appeared to repress its own promoter. These data together suggested a novel pathway by which homocysteine causes the activation of JNK/SAPK and subsequent ATF3 expression through its reductive stress. Activation of JNK/SAPK and ATF3 expression in response to homocysteine may have a functional role in homocysteinemia-associated endothelial dysfunction. (Blood, 2000;96: 2140-2148) (C) 2000 by The American Society of Hematology.

关键词： 转录激活因子3   细胞   培养的   DNA结合蛋白质类/生理学   E选择素/遗传学   基因表达调控/药物作用   启动区(遗传学)   RNA   信使/遗传学   受体   胞质和核/激动剂   受体   胞质和核/生理学   重组蛋白质类/拮抗剂和抑制剂   重组蛋白质类/药理学   阻遏蛋白质类/生理学   转录因子/激动剂   转录因子/生理学   肿瘤坏死因子α/拮抗剂和抑制剂   肿瘤坏死因子α/药理学   人类  

摘要： Peroxisome proliferator-activated receptor (PPAR) activators were shown to inhibit the expression of E-selectin of human vascular endothelial cells in response to tumor necrosis factor-alpha (TNF-alpha). Troglitazone, pioglitazone, alpha-clofibrate, and 15-deoxy-Delta 12,14-prostaglandin J2 all inhibited the TNF-alpha-stimulated E-selectin gene transcription in reporter assay. To further clarify the underlying transcriptional regulation, nuclear factor(s) that binds to the nuclear factor-endothelial leukocyte adhesion molecule 1 (NF-ELAM1) site of the E-selectin gene promoter was investigated. The activators caused a significant induction of liver regenerating factor 1 (LRF1)/activating transcription factor 3 (ATF3), which bound to the NF-ELAM1 site and repressed the TNF-alpha-induced E-selectin gene expression. From these data, the effect of PPAR activators was mediated, in part, through the induction of LRF1/ATF3. This might provide a novel molecular mechanism of antiinflammatory effect of PPAR activators. (C) 2000 Academic Press.

关键词： ATF3   phosphorothioate oligonucleotide   inhibitory effect  

摘要： ATF3 is a transcription factor belonging to the Jun/Fos family whose mouse homologue (TI-241) was isolated, using the differential screening method, from B16 mouse melanoma cells as a blood-borne metastasis-associated gene. Here we show the tumorigenicity-inhibiting effect of an antisense oligonucleotide designed to reduce the expression of ATF3 in HT29 colon cancer cells. HT29 cells were reported to metastasize to the skin after intravenous inoculation. The antisense oligonucleotide inhibited cell attachment to the collagen-coated floor of the plates and invasion of HT29 cells in vitro, which are thought to be two important factors in the process of cancer metastasis and ectopic tumor growth. While the antisense oligonucleotide had no effect on cell growth of HT29 cells in vitro, mice that were inoculated subcutaneously with HT29 cells and treated with the antisense oligonucleotide survived longer than the control mice due to the inhibition of tumor growth in vivo. These show that ATF3 plays an important role in the ectopic growth/metastasis of HT29 colon cancer cells.