CA2+ SIGNALING-- ROLE IN ABETA-INDUCED MEMORY DEFICITS

描述(改编自申请人的摘要)：尽管通常 一致认为大脑中淀粉样蛋白13(A，B)多肽的积累有助于 对于阿尔茨海默病(AD)的发病机制， A13与阿尔茨海默病的联系仍未解决。我们的研究表明，短暂的 亚神经毒性时A、B或其活性片段A、B_2S_(35)灌流 浓度强烈抑制了长时相的早期和晚期 大鼠海马片齿状回的增强(LTP)，以及 钙调神经磷酸酶可挽救A、13对晚期LTP的损害 抑制剂。此外，A132s 35的急性应用导致快速BUT 培养细胞内一过性钙离子升高和钙振荡增强 海马神经元。我们已经在这里提议进一步调查这一联系 关于诱导钙信号转导和抑制钙信号转导的关系 海马区LTP。推测A，约诱导细胞内钙离子 钙调蛋白依赖的钙调神经磷酸酶升高和随后的激活 蛋白磷酸酶在LTP损伤中起关键作用。钙离子瞬变 可能促进依赖钙离子的NMDA受体失活或脱敏 通道，抑制LTP的诱导。钙调神经磷酸酶的激活也可能 改变磷酸酶级联反应和几种蛋白激酶之间的平衡 系统，导致LTP门控机制的改变和/或 CAMP反应元件结合蛋白(CREB)的磷酸化状态。这些 信令更改反过来会抑制LTP的后续组件。因此，VIA Ca~(2+)信号A、13的改变干扰心肌细胞早期和晚期成分 LTP，这可能是阿尔茨海默氏症记忆缺陷的细胞基础 疾病。电生理、免疫细胞化学和神经化学方法 将被用来检验这一假设。建议的具体目标是：1) 进一步刻画A、B对早、晚期的抑制作用 齿状LTP的成分；2)检测A，13是否抑制NMDA受体 突触后神经元抑制LTP诱导的通道；3)确定 钙调神经磷酸酶激活是否与钙诱导的钙升高有关 用于抑制NMDA通道；4)阻止约9个AP是否激活 钙调神经磷酸酶/PP1级联反应损害LTP的中间相； 确定A，13是否通过一种途径改变CREB的磷酸化 钙调神经磷酸酶依赖机制，从而抑制晚期LTP。

DESCRIPTION (adapted from applicant's abstract): Although it is generally agreed that accumulation of amyloid 13 (A,B) peptides in the brain contributes to the pathogenesis of Alzheimer's disease (AD), the cellular mechanisms that link A13 to AD dementia remain unresolved. Our studies showed that brief perfusion with A,B or its active fragment A,B2s 35 at subneurotoxic concentrations strongly inhibited the early and late phase of long-term potentiation (LTP) in the dentate gyrus of rat hippocampal slices, and impairment of late-phase LTP by A,13 could be rescued by calcineurin inhibitors. Furthermore, acute application of A132s 35 resulted in rapid but transient intracellular Ca2+ rises and enhanced Ca2+ oscillations in cultured hippocampal neurons. We have proposed here to further investigate the link between A, about induced alterations in Ca2+ signaling and inhibition of hippocampal LTP. It is hypothesized that A, about induced intracellular Ca2+ rises and subsequent activation of calcineurin, a Ca2+/calmodulin-dependent protein phosphatase, play the key role in LTP impairment. The Ca2+ transient may facilitate Ca2+-dependent inactivation or desensitization of NMDA receptor channels, suppressing induction of LTP. Activation of calcineurin may also shift the balance between a phosphatase cascade and several protein kinase systems, leading to changes in a LTP gating mechanism and/or alterations in the phosphorylation state of cAMP-response element binding protein (CREB). These signaling changes can in turn suppress the later components of LTP. Thus, via altered Ca2+ signaling A,13 interferes with both early and late components of LTP, which forms a possible cellular basis for memory deficits in Alzheimer's disease. Electrophysiological, immunocytochemical and neurochemical approaches will be used to test this hypothesis. The proposed Specific Aims are: 1) To further characterize the inhibitory action of A,B on both early and late components of dentate LTP; 2) To examine whether A,13 inhibits NMDA receptor channels of postsynaptic neurons to suppress LTP induction; 3) To determine whether A, about induced Ca2+ rises and calcineurin activation are responsible for inhibition of NMDA channels; 4) To deter aboutnine whether Ap activates the calcineurin/PP1 cascade to impair the inter aboutnediate phase of LTP; and 5) To determine whether A,13 alters CREB phosphorylation via a calcineurin-dependent mechanism, thus suppressing the late-phase LTP.