The Function of rpL5 and rpL11 in induction of p53

rpL5和rpL11在p53诱导中的作用

基本信息

批准号：
8616731
负责人：
GEORGE THOMAS
金额：
$ 31.6万
依托单位：
UNIVERSITY OF CINCINNATI
依托单位国家：
美国
项目类别：
财政年份：
2012
资助国家：
美国
起止时间：
2012-03-01 至 2017-02-28
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8616731
关键词：
Abnormal Cell Acute Myelocytic Leukemia Antigens Binding Biochemical Biogenesis Biological Models Cell Cycle Arrest Cell Cycle Progression Cell Line Cell Proliferation Cell division Cells Cellular Structures Complement Complex DNA Polymerase III Dactinomycin Data Defect Development Diamond-Blackfan anemia Disease Double Minutes Drosophila genus Dysmyelopoietic Syndromes Genes Genetic Programming Genetic Translation Growth Human Human Pathology Impairment Laboratory Study Lesion Life Lymphoma MDM2 gene Malignant Neoplasms Mediating Messenger RNA Mitotic Cell Cycle Modeling Molecular Monitor Mutation Normal Cell Patients Pattern Polymerase Process Production Proliferating Protein Biosynthesis Proteins RNA, Ribosomal, 5S Ribosomal Proteins Ribosomal RNA Ribosomes Role Site Sjogren&apos s Syndrome Syndrome Testing Transcription Factor TFIIIA Translations Tumor Biology Tumor Suppressor Proteins Up-Regulation Work Zebrafish cancer cell cancer therapy cell growth chromosome 5q loss daughter cell design human FRAP1 protein neoplastic cell novel prevent response tool tumor tumor progression tumorigenesis

项目摘要

DESCRIPTION (provided by applicant): A proliferating cell expends most of its energy in the biogenesis of nascent ribosomes. The increased number of ribosomes provides the translational capacity required for the cell to synthesize the full complement of proteins necessary to enter the mitotic cell cycle and divide. The importance of ribosome biogenesis to cell proliferation is underscored by the fact that a lesion in ribosome biogenesis alters the ratio of ribosomes to mRNA, which eventually modifies the pattern of translation and the genetic program, resulting in aberrant growth. Given these observations, we initially predicted that cells would have evolved a checkpoint to monitor nascent ribosome biogenesis. The importance of this concept to human pathology has been demonstrated in two haemopoietic disorders, 5q- syndrome and Diamond Blackfan Anemia (DBA), which are characterized by hypomorphic mutations or deletions in ribosomal protein (rp) genes. Patients with these diseases first develop myelodysplasias, but have the propensity to progress to a wide range of cancers later in life, particularly acute myeloid leukemia (AML). The concept that rp genes act as haploinsufficient tumor suppressors initially came from studies in model systems, including Drosophila and zebrafish. Recent studies from this laboratory have provided a model to explain both the myelodysplasia and the potential to develop cancer. We showed that upon disruption of either 40S or 60S ribosome biogenesis there is an upregulation of p53 mediated by the binding of the 60S rps, rpL5 and rpL11, to human double minute 2 (MDM2 or Hdm2), leads to G1 cell-cycle arrest. However, in circumstances where 40S, but not 60S, ribosome biogenesis is impaired, this effect requires the translational upregulation of rpL5 and rpL11 to generate sufficient protein to bind to Hdm2 in the face of continued 60S ribosome biogenesis and a decrease in global protein synthesis. The translational upregulation of rpL5 and rpL11 is dependent on the 5' TOP sequence, which acts as translational repressor, and resides at the transcriptional start site of rp mRNAs. Loss of this checkpoint is most likely responsible for the propensity of 5q- syndrome and DBA patients to develop AML. The importance of this checkpoint in p53 positive tumors is underscored by two findings: (i) the extent of tumor progression directly parallels nucleolar size and RNA polymerase 1 (Pol 1) activity and (ii) actinomycin D, which at low concentrations, selectively inhibits RNA Pol 1, arrests p53/MDM2 wild type (WT) tumor cells in G1. Together, these observations have led us to hypothesize that the rpL5/rpL11 complex is upregulated in response to impaired ribosome biogenesis to induce p53 cell-cycle arrest and to prevent tumor progression. These studies are relevant to tumor biology as they are designed to elucidate the mechanism by which impaired ribosome biogenesis mediates cell cycle progression, the identification of components in addition to rp5/rpL11 which mediate this response, and the role of general translation versus the p53 checkpoint in controlling tumor progression beyond 5q- syndrome and DBA, which will aid in the development of novel cancer treatments.

描述（由申请人提供）：增殖细胞在新生核糖体的生物发生中消耗其大部分能量。核糖体数量的增加提供了细胞合成进入有丝分裂细胞周期和分裂所需的全部蛋白质所需的翻译能力。核糖体生物发生中的损伤会改变核糖体与 mRNA 的比例，最终改变翻译模式和遗传程序，导致异常生长，这一事实强调了核糖体生物发生对细胞增殖的重要性。鉴于这些观察结果，我们最初预测细胞会进化出一个检查点来监测新生核糖体的生物发生。这一概念对人类病理学的重要性已在两种造血系统疾病（5q 综合征和 Diamond Blackfan 贫血 (DBA)）中得到证明，其特征是核糖体蛋白 (rp) 基因的低等位性突变或缺失。患有这些疾病的患者首先会出现骨髓增生异常，但在以后的生活中可能会发展为多种癌症，特别是急性髓系白血病 (AML)。 rp 基因作为单倍体不足肿瘤抑制因子的概念最初来自对模型系统（包括果蝇和斑马鱼）的研究。该实验室最近的研究提供了一个模型来解释骨髓增生异常和发展为癌症的可能性。我们发现，在 40S 或 60S 核糖体生物合成遭到破坏后，60S rps、rpL5 和 rpL11 与人双分钟 2（MDM2 或 Hdm2）结合介导的 p53 上调，导致 G1 细胞周期停滞。然而，在 40S 而不是 60S 核糖体生物发生受损的情况下，面对持续的 60S 核糖体生物发生和整体蛋白质合成减少，这种效应需要 rpL5 和 rpL11 的翻译上调，以产生足够的蛋白质与 Hdm2 结合。 rpL5 和 rpL11 的翻译上调取决于 5' TOP 序列，该序列充当翻译抑制子，位于 rp mRNA 的转录起始位点。该检查点的缺失很可能导致 5q 综合征和 DBA 患者发生 AML 的倾向。两项发现强调了该检查点在 p53 阳性肿瘤中的重要性：(i) 肿瘤进展的程度与核仁大小和 RNA 聚合酶 1 (Pol 1) 活性直接平行；(ii) 放线菌素 D 在低浓度下选择性抑制RNA Pol 1 将 p53/MDM2 野生型 (WT) 肿瘤细胞阻滞在 G1 期。总之，这些观察结果使我们推测 rpL5/rpL11 复合物响应核糖体生物发生受损而上调，从而诱导 p53 细胞周期停滞并防止肿瘤进展。这些研究与肿瘤生物学相关，因为它们旨在阐明受损核糖体生物发生介导细胞周期进展的机制、除 rp5/rpL11 之外介导这种反应的成分的鉴定，以及一般翻译相对于 p53 检查点的作用控制肿瘤进展超出 5q 综合征和 DBA，这将有助于开发新型癌症治疗方法。