Nucleolar Protein Function in Cell Growth and Stress

智力上的优点。这个项目的总体目标是检验以下假设：1)果蝇(果蝇)核仁功能的阻断通过激活P53诱导细胞应激导致细胞程序性死亡(凋亡)；2)某些核仁蛋白在正常生长条件下参与核糖体组装，但当细胞受到应激时，当它们释放到核质中时，调节细胞应激反应。核仁是细胞核内负责核糖体生物合成的亚室，核糖体是一种精细的蛋白质和RNA复合体，一旦输出到细胞质中就会催化蛋白质的合成。Nopp140是一种核仁蛋白，被认为是核糖体组装的伴侣。Nopp140的缺失可能导致核糖体产生不足，或产生结构和功能有缺陷的核糖体。一个特定的目标将检验Nopp140的丧失从而导致核仁功能诱导P53介导的细胞凋亡的假设。这项对果蝇的基础研究对人类Treacher Collins综合征(TCS)有直接影响，TCS的特征是头面部出生缺陷。第二个特定的目的是研究果蝇核干蛋白(NS1)，一种核仁GTP结合蛋白。这一目标将测试NS1是否在非应激细胞中大的核糖体亚单位的成熟和核输出中发挥积极作用。这一目标还将检验核仁作为细胞应激感受器的假设；具体地说，这些研究将确定果蝇NS1是调控已知的核转录因子p53，还是调控TOR信号通路的负调控因子，后者通常会抑制第二种形式的程序性细胞死亡，称为自噬。更广泛的影响。这一奖项将保持过去几年为妇女和少数群体提供的大力支持。例如，一名非裔美国女性研究助理通过该项目得到了支持。路易斯安那州少数民族参与联盟(LAMP)也在这个实验室资助了几名本科生，这是路易斯安那州董事会/NSF项目授予路易斯安那州立大学基础科学学院的一项计划拨款。该实验室中的其他少数族裔学生得到了路易斯安那州立大学罗纳德·E·麦克奈尔学士学位后成就项目的支持，该项目针对的是研究生水平未被充分代表的低收入群体的第一代大学生。目前的奖项还将支持一名少数族裔研究生，他们为该项目的一部分提供了重要的初步数据。目前的奖项还将保持实验室中强大的本科生研究能力。在过去的两年里，九名本科生和两名高中生(作为外展计划的一部分)参与了这个项目的各个方面。作为这一努力影响的一个例子，一名少数族裔本科生研究人员完成了路易斯安那州立大学的荣誉论文，最近以4.00的满分毕业，主修生物科学，并于2009年8月开始在路易斯安那州立大学新奥尔良分校就读医学院。

Intellectual merit. The overall goal of this project is to test the hypotheses that 1) a block in nucleolar function in Drosophila melanogaster (fruit fly) induces cell stress leading to programmed cell death (apoptosis) via p53 activation, and that 2) certain nucleolar proteins participate in ribosome assembly under normal growth conditions, but then regulate cell stress response upon their release to the nucleoplasm when cells are stressed. The nucleolus is the sub-compartment within the cell nucleus that is responsible for the biosynthesis of ribosomes, elaborate protein and RNA complexes that catalyze protein synthesis once they are exported to the cytoplasm. Nopp140 is a nucleolar protein considered to be a chaperone for ribosome assembly. Loss of Nopp140 could result in the under-production of ribosomes, or in the production of ribosomes that are defective in structure and function. One specific aim will test the hypothesis that the loss of Nopp140 and thus nucleolar function induces p53-mediated apoptosis. This basic research in Drosophila has direct implications to the human Treacher Collins Syndrome (TCS) which is characterized by craniofacial birth defects. A second specific aim examines Drosophila nucleostemin (NS1), a nucleolar GTP-binding protein. This aim will test if NS1 plays an active role in the maturation and nuclear export of the large ribosomal subunit in non-stressed cells. This aim will also test the hypothesis that nucleoli act as cell stress sensors; specifically, the studies will determine if Drosophila NS1 regulates either p53, the nuclear transcription factor known to induce apoptosis in both human and Drosophila cells, or negative regulators of the TOR signaling pathway that normally suppresses a second form of programmed cell death called autophagy. Broader impacts. This award will maintain the strong support provided to women and minorities in past years of funding. For example, an African-American female research associate has been supported through this project. Several undergraduate minority students have also been supported in this laboratory by the Louisiana Alliance for Minority Participation (LAMP) which is a Louisiana Board of Regents/NSF Program grant awarded to the LSU College of Basic Sciences. Other minority students in the laboratory have been supported by the Louisiana State University Ronald E. McNair Post-Baccalaureate Achievement Program that targets first-generation college students of low-income groups that are under-represented at the post-graduate level. The current award will also support a minority graduate student, who provided important preliminary data for part of this project. The current award will also maintain strong undergraduate research in the laboratory. In the last two years, nine undergraduates and two high school students (as part of an out-reach program) participated in aspects of this project. As one example of the impact of this effort, one minority undergraduate researcher completed an LSU Honors thesis, recently graduated with a perfect 4.00 GPA with a major in Biological Sciences, and starts medical school at LSU-New Orleans in August, 2009.