MECHANISMS OF P27KIPL-ASSOCIATED NEOPLASIA

这项建议的总体目标是表征p27kip1蛋白的正常调控，以及该调控的缺失如何促进多步骤肿瘤的发生。P27kip1是细胞周期蛋白依赖性蛋白激酶(CDK)抑制因子CIP/KIP家族的一员，可与抑制CDK反应的抗增殖信号结合。P27的表达受有丝分裂原等生理刺激的调节。相反，p27表达的缺失与细胞分裂和肿瘤形成的增加有关。P27的低表达与细胞分裂增加和肿瘤的发生有关。在许多人类癌症中，p27的低表达与不良的预后相关，而p27在小鼠中作为肿瘤抑制因子发挥作用。P27在肿瘤中丢失的机制以及它如何参与肿瘤转化在很大程度上是未知的。本提案中描述的实验解决了这两个问题。P27的丰度在许多水平上受到控制，包括蛋白分解、翻译、磷酸化和亚细胞定位。在这个提案中，我们将定义p27的核运输机制，以及它们如何与其他p27调控模式相结合，以全面调控p27的丰度和功能。我们已经确定了一种新的核孔蛋白，称为PASSTA，它与p27相互作用，并在小鼠中创建了PASSTA的靶向缺失，从而导致胚胎死亡、神经管缺陷和侏儒症。我们现在将验证PASSTA介导p27和核孔之间的相互作用的假设，并确定这些相互作用在正常细胞和肿瘤细胞中的机制和生理后果。P27抑制肿瘤的机制尚不清楚。我们已经建立了一个小鼠模型，通过插入突变诱导p27缺失和野生型小鼠的淋巴瘤，从而在多步转化中识别与p27丢失协同的基因。P27缺失的动物表现出极大的淋巴生成加速。我们现在将确定这些淋巴瘤中的激活基因，确定它们如何与p27丢失协同作用，并检查它们是否与与低p27表达相关的人类癌症类似。最终，了解正常和肿瘤细胞中p27调控的潜在机制可能会导致识别治疗癌症和其他疾病的新的治疗靶点。

The overall goal of this proposal is to characterize the normal regulation of the p27 kip1 protein, and how loss of this regulation contributes to multi-step tumorigenesis. p27kip1 is a member of the Cip/Kip family of cyclin-dependent kinase (CDK) inhibitors, which bind to an inhibit CDKs in response to anti-proliferative signals. P27 expression is regulated by physiologic stimuli such as mitogen. Conversely, loss of p27 expression is associated with increased cell division and tumorigenesis. Low p27 expression is associated with increased cell division and tumorigenesis. Low p27 expression correlates with poor outcome in many human cancers, and p27 function as a tumor suppressor in mice. The mechanism of p27 loss in tumors and how this participates in neoplastic transformation is largely unknown. The experiments described in this proposal address both of these issues. P27 abundance is controlled at many levels, including proteolysis, translation, phosphorylation, and subcellular localization. In this proposal, we will define the nuclear transport mechanisms of p27, and how they are integrated with other modes of p27 control to globally regulate p27 abundance and function. We have identified a novel nuclear pore protein, termed PASSTA, that interacts with p27 and created a targeted deletion of PASSTA in mice that causes embryonic lethality, neural tube defects, and dwarfism. We will now test the hypothesis that PASSTA mediates interactions between p27 and the nuclear pore, and determine the mechanisms and physiologic consequences of these interactions in normal and tumor cells. The mechanism of tumor suppression by p27 is not clearly understood. We have established a mouse model to identify genes that cooperate with p27 loss in multi-step transformations by using insertional mutagenesis to induce lymphomas in p27 null and wild type mice. P27 null animals exhibit greatly accelerated lymphogenesis. We will now identify the activated genes in these lymphomas, determine how they synergize with p27 loss, and examine if they are similarly involved with human cancer associated with low p27 expression. Ultimately, understanding the mechanisms underlying p27 regulation in normal and neoplastic cells may lead to the identification of novel therapeutic targets for the treatment of cancer and other diseases.