Cholesterol depletion impairs contractile machinery in neonatal rat cardiomyocytes.
Cholesterol depletion impairs contractile machinery in neonatal rat cardiomyocytes.
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DOI：
10.1038/srep43764
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发表时间：
2017-03-03
影响因子：
4.6
通讯作者：
Gardel ML
中科院分区：
文献类型：
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作者：
Hissa B;Oakes PW;Pontes B;Ramírez-San Juan G;Gardel ML
胆固醇调节许多细胞过程。耗尽其在骨骼肌纤维中的合成会导致空泡化和收缩损伤。然而，人们对胆固醇降低如何影响心肌细胞行为知之甚少。在这里，我们通过用甲基-β-环糊精孵育新生儿心肌细胞来消耗胆固醇。牵引力显微镜显示，降低胆固醇会增加细胞收缩速率并产生细胞松弛缺陷。胆固醇消耗也会增加膜张力、Ca2+ 峰值频率和细胞内 Ca2+ 浓度。这些变化可能与跨肌膜的 Caveolin-3 和 L 型 Ca2+ 通道分布的变化相关。由于 cAMP 依赖性 PKA 活性增强，通道调节也受到影响，增加了 L 型 Ca2+ 通道开放事件的可能性。免疫荧光显示，胆固醇消耗消除了肌节组织，由于钙蛋白酶的蛋白水解活性增加而改变了 α-辅肌动蛋白带的间距和排列。我们提出了一种机制，其中胆固醇消耗触发信号级联，最终导致心肌细胞的收缩障碍和肌原纤维破坏。
Cholesterol regulates numerous cellular processes. Depleting its synthesis in skeletal myofibers induces vacuolization and contraction impairment. However, little is known about how cholesterol reduction affects cardiomyocyte behavior. Here, we deplete cholesterol by incubating neonatal cardiomyocytes with methyl-beta-cyclodextrin. Traction force microscopy shows that lowering cholesterol increases the rate of cell contraction and generates defects in cell relaxation. Cholesterol depletion also increases membrane tension, Ca2+ spikes frequency and intracellular Ca2+ concentration. These changes can be correlated with modifications in caveolin-3 and L-Type Ca2+ channel distributions across the sarcolemma. Channel regulation is also compromised since cAMP-dependent PKA activity is enhanced, increasing the probability of L-Type Ca2+ channel opening events. Immunofluorescence reveals that cholesterol depletion abrogates sarcomeric organization, changing spacing and alignment of α-actinin bands due to increase in proteolytic activity of calpain. We propose a mechanism in which cholesterol depletion triggers a signaling cascade, culminating with contraction impairment and myofibril disruption in cardiomyocytes.