AKAP-dependent regulation of Cardiac SR Ca handling

心脏 SR Ca 处理的 AKAP 依赖性调节

• 批准号: 9910438
• 负责人: Donald M Bers
• 金额: $ 49.6万
• 依托单位: UNIVERSITY OF CALIFORNIA AT DAVIS
• 依托单位国家: 美国
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-04-01 至 2022-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9910438
• 关键词: A kinase anchoring protein; ATP phosphohydrolase; Address; Adrenergic Agents; Affect; Affinity; Area; Arrhythmia; Binding; Calcium; Cardiac; Cardiac Myocytes; Cells; Coupling; Cyclic AMP; Cyclic AMP-Dependent Protein Kinases; Data; Dependence; Dimerization; Failure; Fluorescence Recovery After Photobleaching; Functional disorder; Heart; Heart Diseases; Heart failure; Kinetics; Knock-out; Measures; Mediating; Muscle Cells; Pathologic; Phosphorylation; Physiological; Process; Proteins; Regulation; RyR2; Ryanodine Receptor Calcium Release Channel; Sarcoplasmic Reticulum; Signal Transduction; Site; Speed; Testing; Therapeutic Intervention; Work; beta-adrenergic receptor; calmodulin-dependent protein kinase II; dimer; fighting; heart function; insight; novel; novel therapeutics; phospholamban; receptor function; response; spatiotemporal; therapeutic target; uptake

Project Summary/ Abstract Beta-adrenergic receptor (β-AR) activation affects cardiac excitation-contraction coupling (ECC) through coordinated increases in sarcoplasmic reticulum (SR) Ca uptake by SERCA and release via ryanodine receptor (RyR) channels. Reduced SR Ca uptake and sensitized SR Ca release contribute to reduced SR Ca content in heart failure (HF), and are key therapeutic targets in HF. However, there are key gaps in our fundamental understanding of ß-AR regulation of these SR Ca handling processes in cardiac myocytes, which our team is well- poised to address. SR Ca uptake is basally inhibited by phospholamban (PLB), an effect that is relieved by PLB phosphorylation by PKA. A quantitative mechanistic question is how a small number of PKA molecules in the cell can rapidly phosphorylate the far more numerous (>200- fold) and widely distributed PLB, to uniformly accelerate [Ca]i decline and SR Ca load upon ß-AR activation. It is unlikely that dedicated anchoring of PKA near each small cluster of PLB molecules would suffice from a quantitative standpoint. New data suggest that PLB phosphorylation can decrease PLB affinity of A-kinase anchoring protein, AKAP7. We will test the hypothesis that upon ß-AR activation, the AKAP7 that is bound to un-phosphorylated PLB phosphorylates nearby PLB molecules, but then detaches, only to bind again quickly to a neighboring area of unphosphorylated PLBs (i.e. “hovering” along the SR, phosphorylating sequential PLB clusters). This new paradigm, which differs from the standard, accepted 1:1 relationship between other AKAPs and their targets, may be critical to rapid adrenergic fight-or- flight response. Aim 1 will test how AKAP7 mobility is influenced by PLB binding and phosphorylation to expedite adrenergic cardiac lusitropy. Aim 2 will test consequences of disrupting the AKAP7-PLB interaction with respect to spatiotemporal spread of SERCA activation in single myocytes. Aim 3 will test for AKAP7-CaMKII interaction and its potential effects on PLB & RyR. This work will provide novel and clear mechanistic data regarding the fundamental mechanism of rapid synchronous adrenergic activation throughout the myocyte and heart. This may present a novel type of AKAP function, where targeted translocation of the AKAP amplifies signaling to very large numbers of target sites.

项目摘要/摘要 β-肾上腺素能受体（β-AR）激活会影响心脏兴奋 - 收缩耦合（ECC） 通过协调的增加，Serca和Serca和 通过Ryanodine受体（RYR）通道释放。 SR CA的吸收和敏感的SR CA降低 释放有助于减少心力衰竭（HF）的SR CA含量，并且是关键疗法 HF目标。但是，我们对ß-ar的基本理解存在关键差距 对心肌细胞中这些SR CA处理过程的调节，我们的团队非常好 中毒要解决。 Sr Ca的吸收基本上受到磷团（PLB）的抑制，这种作用是 通过PKA释放PLB磷酸化。定量的机械性问题是一个小的 细胞中的PKA分子数量可以迅速磷酸化众多（> 200-- 折叠）和广泛分布的PLB，以均匀加速[Ca] I下降和SR CA负载 ß-ar激活后。在每个PLB群附近，PKA的专用锚定不太可能 从定量的角度来看，分子足够了。新数据表明PLB 磷酸化可以降低A-激酶锚定蛋白AKAP7的PLB亲和力。我们将测试 β-AR激活后的假设是未磷酸化PLB的AKAP7 磷酸化附近的PLB分子，但随后分离，只是迅速结合到A 未磷酸化PLB的相邻区域（即沿SR的“悬停”，磷酸化 顺序PLB簇）。这个与标准不同的新范式接受了1：1 其他AKAP与其目标之间的关系对于快速的肾上腺素战斗可能至关重要 飞行响应。 AIM 1将测试AKAP7移动性如何受PLB结合和 AIM 2将测试磷酸化的后果，以加快肾上腺心脏的lusitropy。 相对于SERCA的时空传播，破坏AKAP7-PLB相互作用 单个肌细胞激活。 AIM 3将测试AKAP7-CAMKII相互作用及其潜力 对PLB＆RYR的影响。这项工作将提供有关有关的新颖和清晰的机械数据 整个肌细胞中快速同步肾上腺素激活的基本机制 和心。这可能会呈现一种新型的AKAP函数，其中有针对性的易位 AKAP放大器向大量目标位点发出信号。