Biological Roles of the Prolyl Isomerase, PIN1

脯氨酰异构酶 PIN1 的生物学作用

• 批准号: 6985074
• 负责人: ANTHONY R MEANS
• 金额: $ 32.73万
• 依托单位: DUKE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-08-06 至 2010-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6985074
• 关键词: antisense nucleic acid; cell growth regulation; developmental genetics; enzyme activity; enzyme mechanism; gene deletion mutation; gene targeting; human tissue; laboratory mouse; leukocyte activation /transformation; lymphocyte; peptidylprolyl isomerase; phenotype; protein binding

DESCRIPTION (provided by applicant): The overarching hypothesis of the proposed research is that loss of function of the Pin1 prolyl isomerase can result in differential susceptibility to tumorigenesis. Pin1 was originally identified as a regulator of a fungal protein kinase required for mitosis and so was suggested to play important roles in cell cycle progression. It is now known that Pin1 functions in both G1 and G2 of the cell cycle and several Pin1 binding proteins that also play important roles in the cell cycle have been identified. Pin1 binds to proteins phosphorylated on pSer/pThr-Pro motifs and isomerization of the prolyl amide bond can cause a conformational change that regulates the abundance of the target protein in the cell either in a positive or negative manner. Pin1 has been implicated to be important in human cancers not only because it is involved in cell cycle regulation but also as several studies have reported either increased levels of Pin1 in human tumor specimens or Loss of Heterozygosity of the portion of chromosome 19p13.3 that contains Pin1. Thus, the question of whether the loss of Pin1 could, depending on the genetic background, either sensitize or protect cells from transformation remains enigmatic. Evaluation of fibroblasts from Pin1 null mice in a pure C57BL6/J genetic background revealed two novel target proteins for Pin1 to be c-Myc, and cyclin E1. Pin1 regulates the degradation of c- Myc. The absence of Pin1 from immortalized mouse fibroblasts increases c-Myc and cyclin E1 levels, results in genomic instability and renders these cells sensitive to Ras-mediated transformation. To extend these remarkably provocative results and address this fascinating conundrum, it is proposed to: 1) evaluate the mechanism of action of Pin1 by using NMR to determine how Pin1 binds to c-Myc and biochemistry/cell biology to evaluate whether Pin1 regulates accumulation of cyclin E1 as it does c-Myc; 2) examine how the loss of function of Pin1 contributes to genomic instability in immortalized mouse fibroblasts; and 3) test the hypothesis that loss of function of Pint can alter the timing of tumorigenesis in a genetically engineered mouse model of cancer wherein spontaneous recombination in whole animals is necessary to activate an oncogenic allele of K-Ras, which in turn leads to tumorigenesis in 100% of the mice by 300 days. We hope that completion of these proposed studies will help to clarify the potential role of Pin1 and/or its target proteins in carcinogenesis.

描述（由申请人提供）：拟议研究的总体假设是Pin 1脯氨酰异构酶功能丧失可导致对肿瘤发生的不同易感性。Pin 1最初被鉴定为有丝分裂所需的真菌蛋白激酶的调节剂，因此被认为在细胞周期进程中发挥重要作用。现在已知Pin 1在细胞周期的G1和G2中起作用，并且已经鉴定了几种在细胞周期中也起重要作用的Pin 1结合蛋白。Pin 1与pSer/pThr-Pro基序上磷酸化的蛋白质结合，脯氨酰酰胺键的异构化可引起构象变化，从而以正或负方式调节细胞中靶蛋白的丰度。Pin 1被认为在人类癌症中很重要，不仅因为它参与细胞周期调控，而且因为一些研究报告了人类肿瘤标本中Pin 1水平的增加或含有Pin 1的染色体19p13.3部分的杂合性丢失。因此，根据遗传背景，Pin 1的缺失是否可以使细胞敏感或保护细胞免于转化的问题仍然是个谜。在纯C57 BL 6/J遗传背景中对Pin 1缺失小鼠的成纤维细胞进行评估，发现Pin 1的两种新型靶蛋白是c-Myc和细胞周期蛋白E1。Pin 1调节c-Myc的降解。永生化小鼠成纤维细胞中Pin 1的缺失增加了c-Myc和细胞周期蛋白E1的水平，导致基因组不稳定，并使这些细胞对Ras介导的转化敏感。为了扩展这些显著的挑衅性结果并解决这个迷人的难题，建议：1）通过使用NMR来确定Pin 1如何与c-Myc结合以及生物化学/细胞生物学来评估Pin 1的作用机制，以评估Pin 1是否像调节c-Myc那样调节细胞周期蛋白E1的积累; 2）检查Pin 1的功能丧失如何导致永生化小鼠成纤维细胞中的基因组不稳定性;和3）检验Pint功能的丧失可以改变癌症的基因工程小鼠模型中肿瘤发生的时间的假设，其中在整个动物中的自发重组对于激活K-Ras的致癌等位基因是必需的，这反过来导致到300天时在100%的小鼠中肿瘤发生。我们希望这些研究的完成将有助于阐明Pin 1和/或其靶蛋白在致癌作用中的潜在作用。