Mechanisms of Neuronal Calcineurin-NFAT Synapse-to-Nucleus Signaling

神经元钙调神经磷酸酶-NFAT 突触至细胞核信号转导机制

• 批准号: 8666935
• 负责人: MARK L DELL'ACQUA
• 金额: $ 47.85万
• 依托单位: UNIVERSITY OF COLORADO DENVER
• 依托单位国家: 美国
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-12-01 至 2018-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8666935
• 关键词: A kinase anchoring protein; Acute; Adrenergic Receptor; Aging; Alzheimer' s Disease; Attention deficit hyperactivity disorder; Autistic Disorder; Binding; Biochemical; Bipolar Disorder; Brain; Calcineurin; Calcium ion; Calmodulin; Candidate Disease Gene; Cell Communication; Cell Mobility; Cell Nucleus; Code; Communication; Complex; Coupling; Cyclic AMP; Cyclic AMP-Dependent Protein Kinases; Cyclic AMP-Responsive DNA-Binding Protein; Data; Dendrites; Dendritic Spines; Development; Disease; Distal; Docking; Down Syndrome; Electric Stimulation; Feedback; Fluorescence Recovery After Photobleaching; Gene Expression; Gene Expression Regulation; Gene Targeting; Genes; Genetic Transcription; Glutamate Receptor; Glutamates; Goals; Hippocampus (Brain); Image; Impaired cognition; Inherited; Intellectual functioning disability; Knock-in Mouse; Lasers; Lead; Learning; Leucine Zippers; Life; Link; Major Depressive Disorder; Measures; Membrane; Memory; Molecular; Molecular Profiling; Monitor; Mus; Neurodegenerative Disorders; Neuronal Plasticity; Neurons; Pathway interactions; Phosphoric Monoester Hydrolases; Phosphotransferases; Positioning Attribute; Process; Protein Kinase; Proteins; Receptor Activation; Regulation; Reporter Genes; Risk; Scaffolding Protein; Schizophrenia; Shapes; Signal Pathway; Signal Transduction; Single Nucleotide Polymorphism; Slice; Synapses; Synaptic plasticity; T-Cell Activation; Testing; Time; Timothy syndrome; Transcriptional Activation; Transcriptional Regulation; activating transcription factor; autism spectrum disorder; base; cellular imaging; genome wide association study; mRNA Expression; mutant; nervous system disorder; neuronal cell body; neuropsychiatry; novel; novel therapeutics; nuclear factors of activated T-cells; postsynaptic; programs; public health relevance; response; signal processing; transcription factor; voltage

DESCRIPTION (provided by applicant): In hippocampal neurons, somato-dendritic CaV1.2 L-type voltage-gated Ca2+ channels (LTCC) function in excitation-transcription (E-T) coupling. Depolarizations that open LTCCs in postsynaptic neurons activate the transcription factors cAMP-response element binding protein (CREB) and nuclear factor of activated T-cells (NFAT) through Ca2+-regulated kinases and phosphatases. Because LTCC transcriptional regulation is required for long-lasting forms of excitatory synaptic plasticity that underlie learning and memory, it is crucial to understand how LTCC signaling leads to efficient, spatiotemporally specific synapse-to-nucleus communication. A question of fundamental importance in synapse-to-nucleus signaling is: how are early signals in E-T coupling Ca2+ signals in dendritic postsynaptic nanodomains transduced into signals that are reliably relayed over long distances to the nucleus? The postsynaptic scaffold protein A-kinase anchoring protein (AKAP) 79/150 binds to CaV1.2 through a modified leucine zipper (LZ) motif. This AKAP anchors both the cAMP- dependent protein kinase (PKA), via an amphipathic alpha-helical motif, and the Ca2+-calmodulin (CaM)-activated protein phosphatase-2B (calcineurin; CaN), via an atypical PxIxIT docking motif. Anchoring of PKA to AKAP79/150 supports enhancement of neuronal LTCC current amplitude that is potently opposed by Ca2+-dependent feedback through AKAP-anchored CaN. LTCC activation of AKAP-localized CaN is also required for K+ depolarization-triggered NFAT translocation to the nucleus and activation of transcription. However, key synapse-to-nucleus signaling questions remain for the LTCC-AKAP-CaN-NFAT pathway: (1) does the AKAP79/150 signaling complex regulate LTCC Ca2+ influx specifically in dendrites excited by postsynaptic glutamate receptor activation; (2) do these Ca2+ signals in dendrites locally activate CaN-NFAT signaling that ultimately acts in the nucleus; (3) what are the neuronal target genes regulated by this signaling pathway; and (4) is this process engaged during synaptic plasticity? We will explore these crucial questions in three aims that rely upon a combination of Ca2+ imaging (Aim 1), CaN and NFAT imaging (Aim 2), and gene transcription analyses (Aim 3). AKAP79/150 regulation of LTCC Ca2+ influx, CaN-NFAT signaling dynamics, and activity-dependent gene transcription will be investigated in neurons or brain slices expressing AKAP mutants that alter PKA anchoring, CaN anchoring, or LZ domain binding. The overall goal of this project is to test a central hypothesis in synapse-to-nucleus communication that postsynaptic Ca2+ signals are locally re-coded in dendrites as protein-based signals (e.g., NFAT), and relayed to the nucleus to control plasticity-associated gene expression.

描述（申请人提供）：在海马神经元中，体细胞树突CaV1.2 L型电压门控Ca2+通道（LTCC）在兴奋转录（E-T）耦合中发挥作用。打开突触后神经元中 LTCC 的去极化通过 Ca2+ 调节的激酶和磷酸酶激活转录因子 cAMP 反应元件结合蛋白 (CREB) 和活化 T 细胞核因子 (NFAT)。由于 LTCC 转录调控是学习和记忆基础的长期兴奋性突触可塑性所必需的，因此了解 LTCC 信号如何导致有效的、时空特异性的突触与细胞核通讯至关重要。突触到细胞核信号传导的一个根本性问题是：E-T 中的早期信号如何与树突状突触后纳米域中的 Ca2+ 信号耦合，转变成能够长距离可靠地传递到细胞核的信号？ 突触后支架蛋白 A 激酶锚定蛋白 (AKAP) 79/150 通过修饰的亮氨酸拉链 (LZ) 基序与 CaV1.2 结合。该 AKAP 通过两亲性 α 螺旋基序锚定 cAMP 依赖性蛋白激酶 (PKA)，并通过非典型 PxIxIT 对接基序锚定 Ca2+-钙调蛋白 (CaM) 激活的蛋白磷酸酶-2B（钙调神经磷酸酶；CaN）。 PKA 锚定到 AKAP79/150 支持神经元 LTCC 电流振幅的增强，而这与通过 AKAP 锚定的 CaN 的 Ca2+ 依赖性反馈强烈相反。 K+ 去极化触发的 NFAT 易位至细胞核和转录激活也需要 LTCC 激活 AKAP 定位的 CaN。然而，LTCC-AKAP-CaN-NFAT 通路的关键突触到细胞核信号转导问题仍然存在：(1) AKAP79/150 信号复合物是否调节突触后谷氨酸受体激活所激发的树突中的 LTCC Ca2+ 流入？ （2）树突中的这些Ca2+信号是否局部激活最终作用于细胞核的CaN-NFAT信号？ （3）该信号通路调控的神经元靶基因有哪些； (4) 这个过程在突触可塑性期间参与吗？我们将通过结合 Ca2+ 成像（目标 1）、CaN 和 NFAT 成像（目标 2）以及基因转录分析（目标 3）的三个目标来探索这些关键问题。将在表达改变 PKA 锚定、CaN 锚定或 LZ 结构域结合的 AKAP 突变体的神经元或脑切片中研究 AKAP79/150 对 LTCC Ca2+ 流入、CaN-NFAT 信号动力学和活动依赖性基因转录的调节。该项目的总体目标是测试突触到细胞核通讯的一个中心假设，即突触后 Ca2+ 信号在树突中局部重新编码为基于蛋白质的信号（例如 NFAT），并传递到细胞核以控制可塑性 -相关基因表达。