ROLE OF PROLYL ISOMERASE PIN1 IN ALZHEIMER'S DISEASE

描述(摘自申请者的摘要)：神经原纤维缠绕和 阿尔茨海默病(AD)中的老年斑包括 处于过度磷酸化状态的微管相关蛋白tau和A-β， 淀粉样前体蛋白(APP)的一个片段。 Tau和APP的磷酸化和淀粉样变性片段的产生 AD神经元和正常有丝分裂细胞的特征。虽然磷酸化 在丝氨酸或苏氨酸残基上，在脯氨酸之前调节tau功能 对于应用程序的处理，人们对磷酸化的实际作用知之甚少 以及它在AD发病机制中的作用。脯氨酸对人体健康很重要 确定蛋白质结构，因为它以顺式或反式构象存在 并且可以将扭结放入多肽链中。最近，我们已经证明了 丝氨酸/苏氨酸-脯氨酸基序的磷酸化抑制顺式/反式脯氨酸 异构化，并为Pro的WW结构域创建结合位点 异构酶Pin 1。WW结构域与磷蛋白的结合决定了 Pin1在细胞内的定位。Pin1还具有独特的酶活性， 特异性地异构化磷酸化丝氨酸/苏氨酸-脯氨酸键，以及 调节特定于有丝分裂的磷酸蛋白的一个子集的功能， 包括陶。Pin1恢复磷酸化tau的生物学功能 直接或间接地促进去磷酸化，因为磷酸酶， 如PP2A，只对反式磷酸化的 丝氨酸/苏氨酸-脯氨酸异构体。值得注意的是，Pin1被隔离到 在AD的大脑中缠绕和耗尽。由于Pin1的耗尽会影响蛋白质 去磷酸化，并诱导有丝分裂停滞和凋亡，隔离 Pin1可能是tau过度磷酸化、缠结形成的重要因素 和神经细胞的丧失。我们的初步结果表明，Pin1也只与 具有高亲和力的磷酸化APP。因此，我们假设 Pin1可能在阿尔茨海默病的某些病理改变中起重要作用。为了测试 在这个假说中，我们首先计划检验Pin1对生物学的影响。 不同类型的tau激酶或tau蛋白对tau的磷酸化活性 神经原纤维缠结，并阐明Pin1如何恢复生物学 磷酸化tau的活性。接下来，我们将评估两国之间的互动。 Pin1和磷酸化的APP，并确定其在APP处理和 分泌A-β。最后，我们将检查更改PIN1的效果 培养的AD对tau病理及其他神经元表型的作用 细胞，以及使用tau转基因小鼠和Pin1基因敲除小鼠的动物 已经被生成并提供给我们。这些研究最终应该会有所帮助 阐明阿尔茨海默病发病的分子机制，可能 对他们的预防和治疗的新的影响。

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.