Conrad Rachel, Stölting Gabriel, Hendriks Johnny, Ruello Giovanna, Kortzak Daniel, Jordan Nadine, Gensch Thomas, Hidalgo Patricia
Institute of Complex Systems 4, Zelluläre Biophysik, Forschungszentrum Jülich, 52425 Jülich, Germany.
Institute of Complex Systems 4, Zelluläre Biophysik, Forschungszentrum Jülich, 52425 Jülich, Germany; Institute of Biochemistry, Heinrich-Heine University, Düsseldorf, Germany.
iScience. 2018 Sep 28;7:1-15. doi: 10.1016/j.isci.2018.08.012. Epub 2018 Aug 16.
Calcium entry through Ca1.2 L-type calcium channels regulates cardiac contractility. Here, we study the impact of exocytic and post-endocytic trafficking on cell surface channel abundance in cardiomyocytes. Single-molecule localization and confocal microscopy reveal an intracellular Ca1.2 pool tightly associated with microtubules from the perinuclear region to the cell periphery, and with actin filaments at the cell cortex. Channels newly inserted into the plasma membrane become internalized with an average time constant of 7.5 min and are sorted out to the Rab11a-recycling compartment. Ca1.2 recycling suffices for maintaining stable L-type current amplitudes over 20 hr independent of de novo channel transport along microtubules. Disruption of the actin cytoskeleton re-routes Ca1.2 from recycling toward lysosomal degradation. We identify endocytic recycling as essential for the homeostatic regulation of voltage-dependent calcium influx into cardiomyocytes. This mechanism provides the basis for a dynamic adjustment of the channel's surface availability and thus, of heart's contraction.
通过Ca1.2 L型钙通道的钙内流调节心脏收缩力。在此，我们研究了胞吐和胞吞后运输对心肌细胞表面通道丰度的影响。单分子定位和共聚焦显微镜显示，一个细胞内Ca1.2池从核周区域到细胞周边与微管紧密相关，并在细胞皮质与肌动蛋白丝相关。新插入质膜的通道以平均7.5分钟的时间常数内化，并被分选到Rab11a再循环区室。Ca1.2循环足以在20小时内维持稳定的L型电流幅度，而与沿微管的从头通道运输无关。肌动蛋白细胞骨架的破坏将Ca1.2从再循环重新导向溶酶体降解。我们确定内吞再循环对于电压依赖性钙流入心肌细胞的稳态调节至关重要。这种机制为通道表面可用性的动态调节提供了基础，从而也为心脏收缩提供了动态调节的基础。
