关键词： Diabetic liver injury   ATF3   STAT1   Streptozotocin (STZ)   Apoptosis  

摘要： It is well-established that the administration of streptozotocin accelerates diabetic liver injury as well as type-1 diabetes, however the underlying mechanisms are poorly understood. Here we investigated the molecular mechanisms of diabetic liver injury in a model of streptozotocin (STZ)-induced type-1 diabetes. STZ administration induced type-1 diabetes and chronic liver injury was associated with increased STAT1, which is implicated in diabetic liver injury by virtue of its ability to promote hepatocyte apoptosis, in the liver and pancreas, which were all strongly inhibited in STAT1(-/-) mice. Similarly, STZ-induced ATF3, a stress-inducible gene, was completely abolished in the liver of IFN-gamma(-/-) mice, but not in STAT1(-/-) mice. Inhibition of STAT1 by siRNA or dominant-negative DNA did not affect ATF3 protein expression but blocked IFN-gamma-induced ATF3 translocation from the cytosol into the nucleus. In contrast, inhibition of ATF3 by using siRNA diminished STAT1 protein expression and IFN-gamma/STZ-induced hepatocyte apoptosis. Furthermore, GST pull-down and co-IP assay showed that STAT1 bound to C-terminal domain of ATF3. Such direct interaction increased the stability of STAT1 by inhibiting its ubiquitination as well as proteasome activity. Our results suggest that STAT1 is a common signaling pathway contributing to STZ-induced diabetes and diabetic liver injury. ATF3 functions as a potent regulator of STAT1 stability, accelerating STZ-induced diabetes and diabetic liver injury. (C) 2009 Elsevier Inc. All rights reserved.

关键词： experimental glaucoma   IOP elevation   neurotrophin   Trk receptor   p75(NTR)   Atf3  

摘要： Reduced retrograde transport of neurotrophins (NT) and their receptors has been hypothesized to contribute directly to retinal ganglion cell (RGC) loss in glaucoma. However, strategies of supplementing NT and NT receptors have failed to avert ultimate RGC death in experimental glaucoma. This study examines the response of major components of the NT system and their interacting proteins in a rat glaucoma model. Unilateral chronic intraocular pressure (IOP) elevation was produced by episcleral vein injection of hypertonic saline (N = 99). Retinas were collected and grouped by extent of optic nerve injury. Quantitative reverse transcription PCR, western blot analysis and immunohistochemistry were used to determine mRNA and protein levels and protein localization. Out of three RGC-specific Brn3 proteins (Brn3a, b, and c), only Brn3a was significantly downregulated at the message level to 35 +/- 4% of fellow values with the severest nerve injury. With IOP elevation, no significant alterations were found in retinal mRNA levels for BDNF, NGF, NT-4/5 or NT-3. The abundance of mature retinal BDNF protein was not significantly affected by elevated IOP, while proBDNF protein decreased linearly with increasing injury grade (r(2) = 0.50). In retinas with the severest nerve injury, TrkB and TrkC receptor mRNA levels significantly declined to 67 +/- 9% and 44 +/- 5% of fellow values, respectively. However, the levels of TRKB protein and its phosphorylated form were unchanged. Message level for p75(NTR) was linearly upregulated up to 219 +/- 26% with increasing injury (r(2) = 0.46), but no alteration was detected at protein level. The mRNA expression of p75(NTR) apoptosis adaptor proteins NADE, NRIF, and Lingo1 were significantly downregulated in retinas with the greatest nerve injury. A positive correlation was found between injury extent and message levels for Jun (r(2) = 0.23) as well as Junb (r(2) = 0.27), and RGC labeling of activated JUN protein increased. Atf3 mRNA levels de

关键词： ATF3   Transcriptional regulation   Immunity   TLRs   Oncogenesis   Gene expression  

摘要： Activating transcription factor 3 (ATF3) is a member of the ATF/cyclic AMP response element-binding (ATF/CREB) family of transcription factors. It is an adaptive-response gene that participates in cellular processes to adapt to extra- and/or intracellular changes, where it transduces signals from various receptors to activate or repress gene expression. Advances made in understanding the immunobiology of Toll-like receptors have recently generated new momentum for the study of ATF3 in immunity. Moreover, the role of ATF3 in the regulation of the cell cycle and apoptosis has important implications for understanding susceptibility to and progression of several cancers.

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.)