Two-pore Channels (TPC2s) and Nicotinic Acid Adenine Dinucleotide Phosphate (NAADP) at Lysosomal-Sarcoplasmic Reticular Junctions Contribute to Acute and Chronic β-Adrenoceptor Signaling in the Heart.
Two-pore Channels (TPC2s) and Nicotinic Acid Adenine Dinucleotide Phosphate (NAADP) at Lysosomal-Sarcoplasmic Reticular Junctions Contribute to Acute and Chronic β-Adrenoceptor Signaling in the Heart.
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DOI：
10.1074/jbc.m115.684076
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发表时间：
2015-12-11
期刊：
影响因子：
--
通讯作者：
Terrar DA
中科院分区：
文献类型：
--
作者：
Capel RA;Bolton EL;Lin WK;Aston D;Wang Y;Liu W;Wang X;Burton RA;Bloor-Young D;Shade KT;Ruas M;Parrington J;Churchill GC;Lei M;Galione A;Terrar DA
背景：释放钙离子的信使烟酸腺嘌呤二核苷酸磷酸（NAADP）通过溶酶体双孔通道（TPC 2）发挥作用。结果如下：Tpcn 2 −/−心肌细胞对β-肾上腺素受体刺激的急性反应降低，慢性心肌肥大和肥大发生减少。结论：心肌β-肾上腺素能受体激动的急、慢性效应依赖于NAADP通过溶酶体中的TPC 2发挥作用。意义：NAADP/TPC 2信号通路为心脏治疗提供了新的策略。Ca 2+渗透性2型双孔通道（TPC 2）是许多不同类型细胞中烟酸腺嘌呤二核苷酸磷酸（NAADP）诱导的Ca 2+释放所需的溶酶体蛋白。在这里，我们研究TPC 2蛋白的心脏的生理和病理生理的重要性。NAADP-AM未能增强Tpcn 2 −/−小鼠心肌细胞中的Ca 2+反应，与野生型（WT）小鼠的心肌细胞不同。Ca 2 +/钙调素依赖性蛋白激酶II抑制剂抑制NAADP在心肌细胞中的作用。异丙肾上腺素可增加WT小鼠肌细胞中的Ca 2+瞬变和伴随动作电位的收缩，但Tpcn 2 −/−小鼠肌细胞中β-肾上腺素受体刺激的这些效应降低。在Tpcn 2 −/−小鼠的心肌细胞中，异丙肾上腺素诱发的L型Ca 2+电流幅度增加保持不变，表明β肾上腺素受体或偶联机制没有丢失。Tpcn 2 −/−小鼠的整个心脏也显示出异丙肾上腺素的变力作用降低，急性β肾上腺素受体刺激后心律失常的趋势降低。与WT对照组相比，长期暴露于异丙肾上腺素的Tpcn 2 −/−小鼠的心脏显示出较低的心脏肥大和较高的心肌发生阈值。电子显微镜显示溶酶体与肌浆网形成紧密接触（间距约25 nm）。我们认为，溶酶体和肌浆网之间依赖于NAADP和TPC 2的Ca 2+信号传导纳米结构域是心肌细胞β-肾上腺素受体信号转导的重要元件。总之，我们的观察结果将溶酶体/肌浆网连接处的NAADP和TPC 2的作用定义为心脏中β-肾上腺素能信号传导的急性作用以及将β-肾上腺素受体的慢性刺激与肥大和相关心律失常联系起来的应激途径中的意外但主要的贡献者。
Background: The Ca2+-releasing messenger nicotinic acid adenine dinucleotide phosphate (NAADP) acts via lysosomal two-pore channels (TPC2). Results: Tpcn2−/− cardiac myocytes showed reduced acute responses to β-adrenoreceptor stimulation and chronically reduced cardiac hypertrophy and arrhythmogenesis. Conclusion: Acute and chronic effects of cardiac β-adrenoreceptor stimulation depend on NAADP acting via TPC2 in lysosomes. Significance: NAADP/TPC2 signaling pathways offer new strategies for cardiac therapeutics. Ca2+-permeable type 2 two-pore channels (TPC2) are lysosomal proteins required for nicotinic acid adenine dinucleotide phosphate (NAADP)-evoked Ca2+ release in many diverse cell types. Here, we investigate the importance of TPC2 proteins for the physiology and pathophysiology of the heart. NAADP-AM failed to enhance Ca2+ responses in cardiac myocytes from Tpcn2−/− mice, unlike myocytes from wild-type (WT) mice. Ca2+/calmodulin-dependent protein kinase II inhibitors suppressed actions of NAADP in myocytes. Ca2+ transients and contractions accompanying action potentials were increased by isoproterenol in myocytes from WT mice, but these effects of β-adrenoreceptor stimulation were reduced in myocytes from Tpcn2−/− mice. Increases in amplitude of L-type Ca2+ currents evoked by isoproterenol remained unchanged in myocytes from Tpcn2−/− mice showing no loss of β-adrenoceptors or coupling mechanisms. Whole hearts from Tpcn2−/− mice also showed reduced inotropic effects of isoproterenol and a reduced tendency for arrhythmias following acute β-adrenoreceptor stimulation. Hearts from Tpcn2−/− mice chronically exposed to isoproterenol showed less cardiac hypertrophy and increased threshold for arrhythmogenesis compared with WT controls. Electron microscopy showed that lysosomes form close contacts with the sarcoplasmic reticulum (separation ∼25 nm). We propose that Ca2+-signaling nanodomains between lysosomes and sarcoplasmic reticulum dependent on NAADP and TPC2 comprise an important element in β-adrenoreceptor signal transduction in cardiac myocytes. In summary, our observations define a role for NAADP and TPC2 at lysosomal/sarcoplasmic reticulum junctions as unexpected but major contributors in the acute actions of β-adrenergic signaling in the heart and also in stress pathways linking chronic stimulation of β-adrenoceptors to hypertrophy and associated arrhythmias.
影响因子：
3.2
作者：
Parkesh R;Vasudevan SR;Berry A;Galione A;Dowden J;Churchill GC
通讯作者：
Churchill GC