ROLE OF PROLYL ISOMERASE PIN1 IN ALZHEIMER'S DISEASE

描述（来自申请人的摘要）：神经元缠结和神经纤维缠结。 阿尔茨海默病（AD）中的老年斑由以下组成： 处于过度磷酸化状态的微管相关蛋白tau，以及A-β， 淀粉样前体蛋白（APP）的片段。 tau蛋白和APP的磷酸化以及淀粉样蛋白生成片段的产生， AD神经元和正常有丝分裂细胞的特征。虽然磷酸化 脯氨酸之前的丝氨酸或苏氨酸残基调节tau功能 和APP加工，很少有人知道磷酸化实际上做什么 以及它如何参与AD的发病机制。脯氨酸对于 决定蛋白质的结构，因为它以顺式或反式构象存在 并能在多肽链中形成扭结。最近，我们已经证明， 丝氨酸/苏氨酸-脯氨酸基序上的磷酸化抑制顺式/反式脯氨酰 异构化，并且还为脯氨酰的WW结构域产生结合位点。 异构酶Pin 1。WW结构域与磷蛋白的结合决定了 Pin 1在细胞中的定位。Pin 1还具有独特的酶活性， 特异性异构化磷酸化丝氨酸/苏氨酸-脯氨酸键，和 调节有丝分裂特异性磷蛋白的确定子集的功能， 包括tau。Pin 1恢复磷酸化tau蛋白的生物学功能 直接或间接地通过促进去磷酸化， 例如PP 2A，仅使反式磷酸化的 丝氨酸/苏氨酸-脯氨酸异构体。值得注意的是，Pin 1被隔离到 缠结并耗尽AD大脑。由于Pin 1的缺失会影响蛋白质 去磷酸化，并诱导有丝分裂停滞和凋亡， Pin 1可能是tau蛋白过度磷酸化、缠结形成的重要因素 和神经元损失。我们的初步结果表明，Pin 1也只结合 具有高亲和力的磷酸化APP。因此，我们假设 Pin 1可能在AD的某些病理变化中起重要作用。测试 这个假设，我们首先计划检查Pin 1对生物学的影响， 通过各种tau激酶或存在于细胞中的tau的磷酸化tau的活性 神经元缠结，并阐明Pin 1如何恢复生物 磷酸化tau的活性。接下来，我们将评估 Pin 1和磷酸化APP，并确定其在APP加工中的作用， A-β分泌最后，我们将研究改变Pin 1 在AD的tau病理学和其他神经元表型中的功能 细胞，以及在使用tau转基因小鼠和Pin 1敲除小鼠的动物中， 已经生成并提供给我们。这些研究最终会帮助 阐明AD发病机制的分子机制，并可能具有 其预防和治疗的新含义。

DESCRIPTION (From the Applicant's Abstract): The neurofibrillary tangles and senile plaques in Alzheimer's disease (AD) consist of the microtubule-associated protein tau in a hyperphosphorylated state, and A-beta, a fragment of the amyloid precursor protein (APP), respectively. Phosphorylation of tau and APP and production of amyloidogenic fragments are features of both AD neurons and normal mitotic cells. Although phosphorylation on serine or threonine residues preceding proline regulates the tau function and APP processing, little is known about what phosphorylation actually does and how it is involved in the pathogenesis of AD. Proline is important for determining protein structure because it exists in cis or trans conformation and can put kinks into a polypeptide chain. Recently, we have shown that phosphorylation on serine/threonine-proline motifs restrains cis/trans prolyl isomerization, and also creates binding sites for the WW domain of the prolyl isomerase Pin 1. The binding of the WW domain with phosphoproteins determines the localization of Pin1 in cells. Pin1 also has unique enzymatic activity that specifically isomerizes phosphorylated serine/threonine-proline bonds, and regulates the function of a defined subset fo mitosis-specific phosphoproteins, including tau. Pin1 restores the biological function of phosphorylated tau directly or indirectly by promoting dephosphorylation because the phosphatases, such as PP2A, dephosphorylate only the trans phosphorylated serine/threonine-proline isomer. Significantly, Pin1 is sequestered into the tangles and depleted in AD brains. Since depletion of Pin1 affects protein dephosphorylation, and induces mitotic arrest and apoptosis, sequestration of Pin1 may be an important factor for tau hyperphosphorylation, tangle formation and neuronal loss. Our preliminary results showed that Pin1 also binds only the phosphorylated APP with a high affinity. Therefore, we have hypothesized that Pin1 may play an important role in some pathological changes of AD. To test this hypothesis, we first plan to examine the effect of Pin1 on the biological activity of phosphorylated tau by various tau kinases or tau present in the neurofibrillary tangles, and to elucidate how Pin1 restores the biological activity of phosphorylated tau. Next, we will evaluate the interaction between Pin1 and phosphorylated APP, and determine its role in APP processing and A-beta secretion. Finally, we will examine the effects of altering the Pin1 function on the tau pathology and other neuronal phenotype of AD in cultured cells, and in animals using tau transgenic mice and Pin1 knockout mice that have been generated and provided to us. These studies should eventually help elucidate the molecular mechanisms of the pathogenesis of AD, and may have novel implications for their prevention and therapies.