Morphological Dynamics of Mitochondria in Bovine Aortic Endothelial Cell under Cyclic Stretch
Morphological Dynamics of Mitochondria in Bovine Aortic Endothelial Cell under Cyclic Stretch
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DOI：
10.14326/abe.4.60
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发表时间：
2015
影响因子：
1
通讯作者：
Ayano Shinmura;A. Tsukamoto;T. Hamada;K. Takemura;T. Ushida;S. Tada
中科院分区：
文献类型：
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作者：
Ayano Shinmura;A. Tsukamoto;T. Hamada;K. Takemura;T. Ushida;S. Tada
线粒体是合成ATP、产生活性氧（ROS）并控制细胞命运如凋亡和衰老的亚细胞器。线粒体产生与其形态相关的不同量的ROS。周期性牵张是由于动脉搏动而对细胞施加的机械刺激，并诱导细胞产生线粒体ROS。因此，可以推测线粒体的形态变化可能在周期性拉伸下细胞中线粒体ROS产生中起作用。然而，线粒体的形态是否真的在周期性拉伸下发生了改变仍不清楚。本研究试图回答这个问题，通过延时成像牛主动脉内皮细胞（BAECs）的线粒体形态动力学的两个水平的单轴循环拉伸：（1）生理水平（5%，1 Hz）1小时，（2）超生理水平（20%，1 Hz）1小时。线粒体用Mito-tracker橙子染色，MicroP软件和FibrilTool用于线粒体比对和长度分析。与无拉伸（0%）相比，在拉伸的生理水平（5%）下没有观察到线粒体的平均长度的明显变化，而平均长度通过拉伸的超生理水平（20%）降低。此外，细胞排列在0%和5%拉伸之间没有差异，但是当施加20%拉伸时，细胞在拉伸方向上垂直排列。三个水平的周期性拉伸对细胞的圆形度无显著影响。因此，BAEC在20%拉伸下表现出线粒体动力学和细胞重塑动力学的变化，但在5%拉伸下两者均未显示出变化。结果表明，线粒体形态动力学的变化与细胞动力学的变化，特别是细胞排列的变化相关。
Mitochondria are subcellular organelles that synthesize ATP, generate reactive oxygen species (ROS), and control cellular fates such as apoptosis and aging. Mitochondria generate different amounts of ROS in association with their morphologies. Cyclic stretch is a mechanical stimulation exerted on cells due to arterial pulsation, and induces cells to generate mitochondrial ROS. Therefore, one can speculate that morphological changes of mitochondria may play a role in mitochondrial ROS generation in cells under cyclic stretch. However, whether the morphologies of mitochondria are actually altered under cyclic stretch remains unclear. This study attempted to answer this question by time-lapse imaging the morphological dynamics of mitochondria in bovine aortic endothelial cells (BAECs) subjected to two levels of uniaxial cyclic stretch: (1) a physiologic level (5% at 1 Hz) for 1 hour, and (2) a supra-physiologic level (20% at 1 Hz) for 1 hour. Mitochondria were stained with Mito-tracker Orange, and MicroP software and FibrilTool were used for mitochondrial alignment and length analyses. No clear changes in the average length of mitochondria were observed at the physiological level of stretch (5%) compared to no stretch (0%), while the average length was decreased by the supra-physiological level of stretch (20%). In addition, cellular alignment was not different between 0% and 5% stretches, but the cells became perpendicularly aligned in the direction of stretch when 20% stretch was applied. Cellular circularity was not signi cantly different among the three levels of cyclic stretch. Thus, BAECs exhibited changes in both mitochondrial dynamics and cellular remodeling dynamics under 20% stretch, but showed no changes in both under 5% stretch. The results indicate that changes in morphological dynamics of mitochondria correlate with changes in cellular dynamics, particularly change in cellular alignment.