The Function of rpL5 and rpL11 in induction of p53

rpL5和rpL11在p53诱导中的作用

• 批准号: 8236578
• 负责人: GEORGE THOMAS
• 金额: $ 32.58万
• 依托单位: UNIVERSITY OF CINCINNATI
• 依托单位国家: 美国
• 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/8236578
• 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' 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

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。核糖体生物发生的损害改变了核糖体与mRNA的比例，最终改变了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经在两种造血疾病，5q-综合征和Diamond Blackfan贫血（DBA）中得到证实，这两种疾病的特征是核糖体蛋白（rp）基因的亚型突变或缺失。这些疾病的患者首先发展为骨髓增生异常，但在以后的生活中有发展为各种癌症的倾向，特别是急性髓性白血病（AML）。rp基因作为单倍不足肿瘤抑制因子的概念最初来自模型系统的研究，包括果蝇和斑马鱼。该实验室最近的研究提供了一个模型来解释骨髓发育不良和发展为癌症的可能性。我们发现，在40S或60S核糖体生物发生中断时，p53的上调是由60S rps、rpL5和rpL11与人类双分钟2 （MDM2或Hdm2）的结合介导的，导致G1细胞周期阻滞。然而，在40S而非60S核糖体生物发生受损的情况下，这种影响需要rpL5和rpL11的翻译上调，以产生足够的蛋白质与Hdm2结合，以面对持续的60S核糖体生物发生和整体蛋白质合成的减少。rpL5和rpL11的翻译上调依赖于5' TOP序列，该序列作为翻译抑制因子，位于rp mrna的转录起始位点。这个检查点的缺失很可能是5q-综合征和DBA患者发展为AML的倾向的原因。两个发现强调了这个检查点在p53阳性肿瘤中的重要性：(i)肿瘤进展的程度与核核大小和RNA聚合酶1 （Pol 1）活性直接相似；（ii）放线菌素D，在低浓度下，选择性地抑制RNA Pol 1，在G1期抑制p53/MDM2野生型（WT）肿瘤细胞。总之，这些观察结果使我们假设rpL5/rpL11复合物在核糖体生物发生受损的反应中上调，从而诱导p53细胞周期阻滞并阻止肿瘤进展。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，鉴定除rp5/rpL11外介导该反应的组分，以及一般翻译与p53检查点在控制肿瘤进展中超越5q-综合征和DBA的作用，这将有助于开发新的癌症治疗方法。