Cancer cell signaling through lipids complexed to proteins

描述（由申请人提供）：美国癌症协会2012年的报告显示，自1999年以来，美国大多数癌症的发病率正在下降或稳定。一些值得注意的例外是非裔美国人和西班牙裔美国人的肝癌，非裔美国妇女的子宫内膜癌，50岁以下患者的结直肠癌，以及所有人口统计学中的胰腺癌。在所有这些组织中，NR 5A核受体（NR 5A 1和NR 5A 2）介导的遗传程序是发育，分化和成人功能的重要决定因素。在分子水平上，这两种转录因子结合磷酸肌醇（PIP），这是PTEN依赖性癌症中PI-3激酶信号传导所必需的磷脂。然而，关于这些脂质如何调节NR 5A转录功能，或者这些机制的失调如何导致上述癌症，几乎一无所知。基于《科学》杂志目前正在修订的一份手稿，我们假设与NR 5A（和其他核蛋白）结合的PIP脂质直接被癌细胞中的PI 3-激酶肌醇多磷酸多激酶（IPMK）和PTEN脂质磷酸酶重塑。这一假设与PI 3激酶和PTEN仅作用于膜中的磷酸肌醇的标准教条明显不同。在目标1中，我们将确定目前可用的小分子如何使用酶学和晶体学抑制IPMK，加速这些抑制剂的改进，并利用相对低风险的项目，在晶体学，X射线衍射方法和分子结构测定方面培训PI。在目标2中，我们将使用突变分析来映射NR 5A 1和IPMK之间的界面，并尝试结晶NR 5A/PIP/IPMK以确定该复合物的界面结构。这种高风险高回报的结构是由目标1对冲的。在目标3中，我们将使用假设驱动的生物化学鉴定作为PTEN和IPMK底物的新型蛋白质/PIP复合物。候选人在蛋白质化学，酶学，生物化学和细胞生物学方面接受过广泛的培训，但没有接受过结构生物学方面的培训。导师冬青英格拉哈姆和顾问团队在结构生物学方面有着丰富的经验，特别是罗伯特·弗莱彻在NR 5A结构及其与胰腺癌的联系方面，以及娜塔莉亚·朱拉在激酶结构和膜癌生物学方面。候选人将扩大他的研究计划，作为一个独立的调查员与此K 01奖提供的培训，开辟新的途径，癌症研究。

DESCRIPTION (provided by applicant): The American Cancer Society's 2012 report revealed that incidence rates are decreasing or stable for most cancers in the United States since 1999. Some notable exceptions are liver cancer in African Americans and Hispanics, endometrial cancer in African American women, colorectal cancer in patients under 50, and pancreatic cancer in every demographic. In all these tissues, NR5A nuclear receptors (NR5A1 and NR5A2) mediate genetic programs that are essential determinants of development, differentiation and adult function. At the molecular level, these two transcription factors bind phosphoinositides (PIPs), phospholipids that are essential to PI-3 kinase signaling in PTEN-dependent cancers. However almost nothing is known about how these lipids regulate NR5A transcriptional functions, or how dysregulation of those mechanisms contributes to the cancers mentioned above. Based on a manuscript currently in revision at Science, we hypothesize that PIP lipids bound to NR5As (and other nuclear proteins) are directly remodeled by the PI3- kinase inositol polyphosphate multikinase (IPMK) and the PTEN lipid phosphatase in cancer cells. This hypothesis is a clear departure from the standard dogma that PI3- kinases & PTEN only act on phosphoinositides in membranes. In Aim 1, we will determine how currently available small molecules inhibit IPMK using enzymology and crystallography, accelerating improvements of these inhibitors and training the PI in crystallography, X-ray diffraction methods and molecular structure determination, taking advantage of a relatively low-risk project. In Aim 2, we will use mutational analyses to map the interface between NR5A1 and IPMK, and attempt to crystallize NR5A/PIP/IPMK to determine the interfacial structure of this complex. This high-risk high-reward structure is hedged by Aim 1. In Aim 3, we will identify novel protein/PIP complexes that are substrates of PTEN and IPMK, using hypothesis-driven biochemistry. The candidate has had extensive training in protein chemistry, enzymology, biochemistry and cell biology, but has not had any training in structural biology. The mentor Holly Ingraham and advisory team have extensive experience in structural biology, particularly Robert Fletterick in NR5A structure and its links to pancreatic cancer, and Natalia Jura in kinase structure and membrane cancer biology. The candidate will expand his research program as an independent investigator with the training afforded by this K01 award, opening new avenues to cancer research.