Long-chain acylcarnitines activate cell stress and myokine release in C2C12 myotubes: calcium-dependent and -independent effects
Long-chain acylcarnitines activate cell stress and myokine release in C2C12 myotubes: calcium-dependent and -independent effects
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DOI：
10.1152/ajpendo.00602.2014
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发表时间：
2015-06-01
影响因子：
5.1
通讯作者：
Adams, Sean H.
中科院分区：
文献类型：
--
作者：
McCoin, Colin S.;Knotts, Trina A.;Adams, Sean H.
酰卡尼汀是反映酰辅酶A状态的重要脂质生物标志物，是具有生物活性和炎症性质的代谢物。这项研究在骨骼肌模型中检测了长链酰基肉碱激活细胞炎症、应激和死亡途径的可能性。分化的C2C12肌管经L-C14、C16、C18和C18：1肉碱处理后，IL-6的产生呈剂量依赖性增加，细胞通透性和细胞死亡的标志物也随之增加，这在较短的链长度下观察不到。以L-C16肉碱为代表的长链酰基肉碱在胞外初始浓度为25 mM时，IL-6的产量在25、50和100mU时分别比载体高4.1、14.9和31.4倍。此外，L-C16肉碱还能激活c-jun氨基末端激酶、细胞外信号调节激酶和p38丝裂原激活的蛋白激酶，在6 h内诱导细胞损伤和死亡，并适度激活凋亡的caspase-3蛋白。L-C16肉碱使细胞内钙迅速升高，最明显的是增加了10µM，这表明钙可能是长链酰基肉碱某些活性的潜在机制。细胞内钙离子螯合剂BAPTA-AM使L-C16肉碱介导的IL-6产生钝化65%。然而，BAPTA-AM不能减弱细胞通透性和死亡反应，这表明这些结果不依赖于钙。16碳两性化合物氨基磺基甜菜碱-16定性地模拟了L-C16肉碱相关的细胞应激结果，表明高实验浓度的长链酰基肉碱的作用是通过膜破坏实现的。在这里，提出了一个模型，在该模型中，酰卡尼汀细胞膜相互作用沿生理-病理生理条件下遇到的一系列细胞浓度发生，从而调节基于膜的系统的功能并影响细胞生物学。
Acylcarnitines, important lipid biomarkers reflective of acyl-CoA status, are metabolites that possess bioactive and inflammatory properties. This study examined the potential for long-chain acylcarnitines to activate cellular inflammatory, stress, and death pathways in a skeletal muscle model. Differentiated C2C12 myotubes treated with L-C14, C16, C18, and C18:1 carnitine displayed dose-dependent increases in IL-6 production with a concomitant rise in markers of cell permeability and death, which was not observed for shorter chain lengths. L-C16 carnitine, used as a representative long-chain acylcarnitine at initial extracellular concentrations >= 25 mu M, increased IL-6 production 4.1-, 14.9-, and 31.4-fold over vehicle at 25, 50, and 100 mu M. Additionally, L-C16 carnitine activated c-Jun NH2-terminal kinase, extracellular signal-regulated kinase, and p38 mitogen-activated protein kinase between 2.5- and 11-fold and induced cell injury and death within 6 h with modest activation of the apoptotic caspase-3 protein. L-C16 carnitine rapidly increased intracellular calcium, most clearly by 10 mu M, implicating calcium as a potential mechanism for some activities of long-chain acylcarnitines. The intracellular calcium chelator BAPTA-AM blunted L-C16 carnitine-mediated IL-6 production by >65%. However, BAPTA-AM did not attenuate cell permeability and death responses, indicating that these outcomes are calcium independent. The 16-carbon zwitterionic compound amidosulfobetaine-16 qualitatively mimicked the L-C16 carnitine-associated cell stress outcomes, suggesting that the effects of high experimental concentrations of long-chain acylcarnitines are through membrane disruption. Herein, a model is proposed in which acylcarnitine cell membrane interactions take place along a spectrum of cellular concentrations encountered in physiological-to-pathophysiological conditions, thus regulating function of membrane-based systems and impacting cell biology.