Ptdins Transfer Protein Function and Neurodegeneration

描述（由申请人提供）： 本研究的目的是进行详细分析的一类研究不足的蛋白质：哺乳动物磷脂酰肌醇/磷脂酰胆碱转移蛋白（PITP）。PITP在哺乳动物细胞中的功能和作用机制仍有待阐明。该研究计划旨在确定特定哺乳动物PITP亚型（PITPalpha）的功能机制。该提议基于我们对PITPalpha敲除小鼠的创建和表征。PITP-/-小鼠患有脊髓小脑变性、低血糖症和不能通过小肠吸收膳食脂肪和脂溶性维生素（即乳糜微粒滞留病）。这些表型在出生时表现出来，并且PITPalpha-/-小鼠迅速死于这些疾病。PITPalpha-/-小鼠是一种理想的疾病模型，因为它出生时是活的，但表现出强大的表型。 表型发生的速度很快。利用这种独特的模式，我们将进行三方面的调查。 首先，我们将恢复PITPalpha-/-小鼠小肠的PITPalpha表达，以检验我们的假设，即膳食脂肪吸收不良综合征是低血糖和脊髓小脑变性的主要因素。在这项工作中，我们建议开发一个培养的肠上皮细胞模型，其中乳糜微粒的组装和运输可以详细研究。第二，我们的数据表明PITAlpha缺陷神经元表现出内在缺陷;最有可能是通过所谓的“生存途径”进行信号传导。使用遗传，生物化学和信号转导的方法，我们将测试这一假设在PITPalpha-/-模型。这些研究将通过利用一种新的果蝇系统研究PITPct信号功能来补充。第三，我们将使用基因组工程的方法，功能解剖的生理功能，个别PITPalpha磷脂转移活动。特别是，我们将测试是否PITPalpha的关键生理功能是促进磷酸肌醇合成，如果是这样，什么特定的磷酸肌醇调节PITPalpha依赖性的方式和参与的信号通路。PITP在调节与不同细胞过程相互作用的信号转导途径中发挥核心作用。我们现在确定这些功能界面与人类乳糜微粒潴留疾病、葡萄糖稳态紊乱和脊髓小脑变性有关。Bankaitis实验室独特地准备解决PITPalpha功能机制的问题，因为它已经开发了独特的实验系统进行分析。

DESCRIPTION (provided by applicant): The objective of this research is to undertake a detailed analysis of an under-investigated class of proteins: the mammalian phosphatidylinositol/phosphatidylcholine transfer proteins (PITPs). The functions and mechanisms of function of PITPs in mammalian cells remain to be elucidated. The research plan is designed to identify mechanisms of function of a specific mammalian PITP isoform (PITPalpha). This proposal is founded on our creation and characterization of a PITPalpha knockout mouse. PITP-/- mice suffer from spinocerebellar degeneration, hypoglycemia, and failure to absorb dietary fat and fat-soluble vitamins across the small intestine (i.e. a chylomicron retention disease). These phenotypes manifest themselves upon birth and PITPalpha-/- mice rapidly succumb to these disorders. The PITPalpha-/- mouse is an ideal disease model in that it is born alive, but manifests powerful phenotypes. The rates of phenotype onset are rapid. Using this unique model, we will undertake three lines of investigation. First, we will restore PITPalpha expression to the small intestine of the PITPalpha-/- mouse to test our hypothesis that the dietary fat malabsorption syndrome is a primary factor in hypoglycemia and spinocerebellar degeneration. In this effort, we propose to develop a cultured enterocyte model in which chylomicron assembly and transport can be studied in detail. Second, our data indicate the PITPalpha-deficient neurons exhibit intrinsic defects; most likely in signaling through the so-called 'survival pathways'. Using genetic, biochemical and signaling approaches we will test this hypothesis in the PITPalpha-/- model. These studies will be complemented by exploitation of a novel Drosophila system for study of PITPct signaling functions. Third, we will use genome engineering approaches to functionally dissect the physiological functions of individual PITPalpha phospholipid transfer activities. In particular, we will test whether the key physiological function of PITPalpha is to facilitate phosphoinositide synthesis and, if so, what specific phosphoinositides are regulated in a PITPalpha-dependent manner and what signaling pathways are involved. PITPs play central roles in regulating signal transduction pathways that interface with diverse cellular processes. We now establish that these functional interfaces are relevant to human chylomicron retention disease, disorders of glucose homeostasis, and spinocerebellar degeneration. The Bankaitis laboratory is uniquely poised to address questions of mechanism of PITPalpha function as it has developed unique experimental systems for analysis.