The transcriptional basis of tumor promotion

肿瘤促进的转录基础

• 批准号: 8246301
• 负责人: JOSEPH D LOCKER
• 金额: $ 35.49万
• 依托单位: ALBERT EINSTEIN COLLEGE OF MEDICINE
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-09-30 至 2012-09-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8246301
• 关键词: Address; Adenoviruses; Apoptosis; Binding; Binding Sites; Biological; Biological Process; Cell Cycle; Cell Proliferation; Complex; Cyclin D1; Funding; Gene Expression; Genes; Genetic Transcription; Goals; Growth; Hepatocyte; Hormones; Hyperplasia; Individual; Injury; Investigation; Knockout Mice; Lead; Ligands; Liver; Liver Regeneration; Malignant Neoplasms; Mediating; Mediator of activation protein; Messenger RNA; Mitogens; Modeling; Molecular; Molecular Profiling; Mus; Mutate; Natural regeneration; Nuclear Receptors; Nucleic Acid Regulatory Sequences; Partial Hepatectomy; Pathway interactions; Pharmaceutical Preparations; Phase; Process; Proteins; RXR; Rattus; Regulation; Regulatory Pathway; Research; Research Personnel; Response Elements; Role; Stimulus; System; Tertiary Protein Structure; Testing; Thyroid Hormones; Transcription Coactivator; Transcription Factor AP-1; Transcriptional Activation; Transcriptional Regulation; Tumor Promoters; Tumor Promotion; Work; activating transcription factor; base; cell growth; cell type; chromatin remodeling; novel; null mutation; rapid growth; reconstitution; research study; response; transcription factor

PROJECT SUMMARY We compared four processes that activate cell proliferation in the liver: (1) hyperplasia induced by the tumor promoter, TCPOBOP; (2) antipromotional hyperplasia induced by thyroid hormone; (3) rapid liver regeneration after partial hepatectomy (PH) in the rat; and (4) more protracted regeneration after PH in the mouse. The first phase of the project generated a comprehensive system of microarray expression profiles of all four processes. TCPOBOP is a direct ligand for the nuclear receptor transcription factor, CAR, and rapidly induces liver growth and cell proliferation. The expression profiles showed rapid induction of Gadd45¿, Jun, and Fosl2 mRNA after TCPOBOP treatment; we focused on transcriptional regulation of these three genes, and on Cyclin D1 as their downstream target. A Gadd45¿-null mouse had active proliferation after TCPOBOP treatment, but impaired transcription and liver growth. Molecular studies showed that Gadd45¿ directly binds CAR and acts as a transcriptional coactivator. Thus, rapid induction of Gadd45¿ is anabolic and enables the high rate of transcription needed for rapid growth. However, other investigators have found that Gadd45¿ regulates apoptosis and proliferation. The research proposed in Aim 1 will investigate how Gadd45¿, only 18 kD, can function as a coactivator, by determining its binding partners in the transcription complex, and its effects on progressive chromatin remodeling during transcriptional activation. Other experiments will determine how Gadd45¿ can have so many critical functions, by mutating individual protein domains and testing each for effects on CAR-binding, coactivation, activation, apoptosis, and proliferation. Additional studies will use adenovirus to reconstitute mutated Gadd45¿ in the livers of nul mice and test the importance of each separate function in hyperplasia. Aim 2 will address the diverse mechanisms by which CAR, a cis acting transcription factor, activates CAR- responsive regulatory regions of Fosl2. Experiments will also test whether Jun and Fosl2 are responsible for inducing hyperplasia, by studying TCPOBOP treatment in conditional Fosl2- and Jun-null mice, and by using adenovirus to induce liver expression vivo. Preliminary studies showed that Fosl2 and Jun combine to stimulate transcription of Cyclin D1 through a novel upstream regulatory region. Aim 3 will investigate the mechanisms that activate Cyclin D1 transcription and explain context-specific stimulation by Fosl2. Experiments will also determine the alternative pathways by which liver regeneration and T3-induced hyperplasia activate Cyclin D1 transcription.

项目总结 我们比较了激活肝脏细胞增殖的四个过程：(1)增殖 肿瘤促进剂TCPOBOP诱导；(2)抗促进性增殖 甲状腺激素；(3)大鼠肝部分切除后快速肝再生； (4)小鼠PH后再生时间延长。项目的第一阶段 项目生成了所有四个基因芯片表达谱的综合系统 流程。TCPOBOP是核受体转录因子CAR的直接配体， 并迅速诱导肝脏生长和细胞增殖。表达谱显示 TCPOBOP治疗后快速诱导GADD45？、Jun和Fosl2基因的表达 重点是这三个基因的转录调控，以及Cyclin D1作为它们的 下游目标。TCPOBOP后GADD45基因缺失小鼠增殖活跃 治疗，但损害转录和肝脏生长。分子研究表明 GADD45？直接与CAR结合并作为转录共激活因子发挥作用。因此，快速 GADD45？的诱导是合成代谢的，并且能够实现所需的高转录速率 快速增长。然而，其他研究人员发现，GADD45？调节细胞凋亡 和扩散。目标1中提出的研究将调查GADD45？，只有18 Kd，可以通过确定其在 转录复合体及其在进行性染色质重塑中的作用 转录激活。其他实验将确定GADD45是如何做到这一点的 许多关键功能，通过突变单个蛋白质结构域并测试每个结构域 对CAR结合、共激活、激活、凋亡和增殖的影响。其他内容 研究将使用腺病毒在NUL小鼠的肝脏中重建突变的GADD45？ 并测试每个单独的功能在增生症中的重要性。目标2将解决 作为顺式作用的转录因子，CAR激活CAR-1的不同机制。 Fosl2的响应性调控区域。实验还将测试Jun和Fosl2 负责诱导增生，通过研究TCPOBOP治疗条件 Fosl2和Jun缺失型小鼠，并使用腺病毒在体内诱导肝脏表达。 初步研究表明，Fosl2和Jun结合起来可以刺激转录 细胞周期蛋白D1通过一个新的上游调控区域。目标3将调查 激活Cyclin D1转录的机制和解释特定上下文 Fosl2的刺激。实验还将确定可供选择的途径 肝再生和T3诱导的增殖激活了Cyclin D1的转录。