关键词： PBO   ROS   ATF3   liver   oxidative stress  

摘要： To clarify the mechanism of piperonyl butoxide (PBO)-induced hepatocarcinogenesis in mice, male mice were subjected to a two-thirds partial hepatectomy, N-diethylnitrosamine (DEN) initiation, and a diet containing 0.6% PBO for eight weeks. The incidence of gamma-glutamyl transpeptidase (GGT)-positive foci and PCNA-positive cells was significantly increased in the DEN + PBO group compared with the DEN-alone group. Real-time reverse transcription-polymerase chain reaction (RT-PCR) analysis showed up-regulation of genes related to metabolism, such as cytochrome P450 1A1 and 2B10, and metabolic stress, such as Por, Nqo1, Nrf2, abcc3, and abcc4. Early responsive genes downstream of mitogen-activated protein kinase (MAPK), such as c-fos, c-jun, c-myc, and activating transcription factor 3 (ATF3), were also up-regulated in this group. Positive immunohistochemical staining for ATF3 was diffusely observed in nonproliferating hepatocytes of the DEN + PBO group, but altered foci were negative or weakly positive for ATF3. The nuclei of hepatocytes within ATF3-negative foci were positive for cyclin D. Thus PBO can induce oxidative stress, activate the MAPK pathway, and increase ATF3 transcript levels in hepatocytes outside the altered foci during the early stage of PBO-induced hepatocarcinogenesis in mice.

关键词： Activating transcription factor 3   Mutant huntingtin   Polyglutamine   Huntington's disease   Cell death  

摘要： Huntington's disease is a progressive neurodegenerative disorder caused by a polyglutamine expansion near the N-terminus of huntingtin. The mechanisms of polyglutamine neurotoxicity, and cellular responses are not fully understood. We have studied gene expression profiles by short oligo array using an inducible PC12 cell model expressing an N-terminal huntingtin fragment with expanded polyglutamine (Htt-N63-148Q) Mutant huntingtin Htt-N63 induced cell death and increased the mRNA and protein levels of activating transcription factor 3 (ATF3). Mutant Htt-N63 also significantly enhanced ATF3 transcriptional activity by a promoter-based reporter assay. Overexpression of ATF3 protects against mutant Htt-N63 toxicity and knocking down ATF3 expression reduced Htt-N63 toxicity in a stable PC12 cell line. These results indicated that ATF3 plays a critical role in toxicity induced by mutant Htt-N63 and may lead to a useful therapeutic target. (C) 2009 Elsevier B.V. All rights reserved.

关键词： 食管癌   激活转录因子3   细胞生长  

摘要： 背景与目的:激活转录因子3(activating transcription factor 3,ATF3)在食管癌中表达异常下调,但其功能仍不清楚。本研究拟探讨ATF3在食管癌细胞过表达对癌细胞生长及裸鼠成瘤的影响。材料与方法:利用分子克隆技术将ATF3基因完整编码区克隆至真核细胞表达载体pcDNA3中,获得重组表达质粒;将该表达质粒转染食管癌EC109细胞并用G418筛选稳定表达的细胞克隆;用Western blot检测ATF3的过表达效果;对ATF3过表达的细胞与相应对照细胞进行细胞克隆形成实验和裸鼠体内成瘤实验,以分析ATF3过表达对食管癌细胞生长的影响。结果:ATF3的过表达在体外可以降低食管癌细胞的克隆形成能力;在体内可以抑制食管癌细胞在雌鼠中的成瘤能力,但对雄鼠中的成瘤能力没有明显影响。结论:ATF3的过表达可以抑制食管癌细胞的生长,ATF3可能在食管癌的发生发展中发挥重要作用。

关键词： Fibroid   myometrium   jun   fos   ATF3   racial disparity   stress  

摘要： Objective: To determine whether expression of the stress response gene ATF3 and related members of activator protein complex-1, cJun and cFos, were altered in leiomyoma compared with myometrium, and whether this difference might correlate with leiomyoma size or race. Design: Laboratory study. Setting: University hospital. Patient(s): Fifteen women undergoing hysterectomy for symptomatic leiomyoma. Intervention(s): Tissue procurement, RNA isolation, reverse-transcriptase polymerase chain reaction, real-time reverse-transcriptase polymerase (RT-PCR) chain reaction, immunohistochemistry, Western blot. Main Outcome Measure(s): Expression of mRNA and protein in leiomyoma and patient-matched myometrium. Result(s): mRNA transcripts of ATF3 were decreased in leiomyoma compared with matched myometrium by both RT-PCR and real-time RT-PCR. The decrease was greater than fivefold in a majority of samples. The reduction seen in ATF3 mRNA expression did not show a correlation with race and leiomyoma size. Surprisingly, immunohistochemistry and Western blot analysis demonstrated an elevation of ATF3 protein expression by a mean of 2.9-fold. Transcripts of related AP-1 genes, cJun and cFos, were significantly decreased by a mean of -29.57 for cJun and -23.78 for cFos, but there was no significant change in protein expression of the two transcription factors. Conclusions: Alterations in ATF3 gene expression resemble the response to mechanical and ischemic stress reported in other tissues. Results suggested that ATF3 protein expression was increased in leiomyoma, and may reflect increased tissue stress. (Fertil Steril (R) 2009;92:748-55. (C)2009 by American Society for Reproductive Medicine.)

关键词： adipocytes   ATF3   fatty acids   inflammation   macrophages   TLR4  

摘要： Obese adipose tissue is markedly infiltrated by macrophages, suggesting that they may participate in the inflammatory pathways that are activated in obese adipose tissue. Evidence has suggested that saturated fatty acids released via adipocyte lipolysis serve as a naturally occurring ligand that stimulates Toll-like receptor (TLR)4 signaling, thereby inducing the inflammatory responses in macrophages in obese adipose tissue. Through a combination of cDNA microarray analyses of saturated fatty acid-stimulated macrophages in vitro and obese adipose tissue in vivo, here we identified activating transcription factor (ATF)3, a member of the ATF/cAMP response element-binding protein family of basic leucine zipper-type transcription factors, as a target gene of saturated fatty acids/TLR4 signaling in macrophages in obese adipose tissue. Importantly, ATF3, when induced by saturated fatty acids, can transcriptionally repress tumor necrosis factor-alpha production in macrophages in vitro. Chromatin immunoprecipitation assay revealed that ATF3 is recruited to the region containing the activator protein-1 site of the endogenous tumor necrosis factor-alpha promoter. Furthermore, transgenic overexpression of ATF3 specifically in macrophages results in the marked attenuation of proinflammatory M1 macrophage activation in the adipose tissue from genetically obese KKA(y) mice fed high-fat diet. This study provides evidence that ATF3, which is induced in obese adipose tissue, acts as a transcriptional repressor of saturated fatty acids/TLR4 signaling, thereby revealing the negative feedback mechanism that attenuates obesity-induced macrophage activation. Our data also suggest that activation of ATF3 in macrophages offers a novel therapeutic strategy to prevent or treat obesity-induced adipose tissue inflammation. (Circ Res. 2009;105: 25-32.)