Ardail Dominique, Maalouf Mira, Boivin Anthony, Chapet Olivier, Bodennec Jacques, Rousson Robert, Rodriguez-Lafrasse Claire
Laboratoire de Radiobiologie Cellulaire et Moléculaire, Faculté de Médecine Lyon-Sud, Université Lyon 1, Université de Lyon, Oullins, France.
Int J Radiat Oncol Biol Phys. 2009 Mar 15;73(4):1211-8. doi: 10.1016/j.ijrobp.2008.11.033.
To define which intracellular pools of sphingomyelin and ceramide are involved in the triggering of apoptosis of Jurkat leukemia cells in response to gamma-ray exposure.
We examined the kinetics of ceramide generation at the whole-cell level and in different subcellular compartments (plasma membrane rafts, mitochondria, and endoplasmic reticulum) after irradiation with photons. Ceramide was measured by high-performance liquid chromatography or after pulse labeling experiments, and the presence of sphingomyelinase within mitochondria was assessed by electron microscopy.
Irradiation of Jurkat leukemia cells resulted in the sequential triggering of sphingomyelin hydrolysis, followed by de novo synthesis that led to a late ceramide response (from 24 h) correlated with the triggering of apoptosis. At the subcellular level, pulse-label experiments, using [(3)H]-palmitate as a precursor, strengthened the involvement of the radiation-induced sphingomyelin breakdown and revealed a very early peak (15 min) of ceramide in plasma membrane rafts. A second peak in mitochondria was measured 4 h after irradiation, resulting from an increase of the sphingomyelin content relating to the targeting of acid sphingomyelinase toward this organelle.
These data confirm that ceramide is a major determinant in the triggering of radiation-induced apoptosis and highlight the complexity of the sequential compartment-specific ceramide-mediated response of Jurkat leukemia cells to gamma-rays.
确定鞘磷脂和神经酰胺的哪些细胞内池参与了Jurkat白血病细胞在γ射线照射下凋亡的触发。
我们检测了光子照射后全细胞水平以及不同亚细胞区室（质膜筏、线粒体和内质网）中神经酰胺生成的动力学。通过高效液相色谱法或脉冲标记实验测量神经酰胺，并通过电子显微镜评估线粒体中鞘磷脂酶的存在情况。
照射Jurkat白血病细胞导致鞘磷脂水解的顺序触发，随后是从头合成，导致与凋亡触发相关的晚期神经酰胺反应（从24小时开始）。在亚细胞水平上，使用[（3）H] - 棕榈酸作为前体的脉冲标记实验加强了辐射诱导的鞘磷脂分解的参与，并揭示了质膜筏中神经酰胺的一个非常早期的峰值（15分钟）。照射后4小时测量到线粒体中的第二个峰值，这是由于与酸性鞘磷脂酶靶向该细胞器相关的鞘磷脂含量增加所致。
这些数据证实神经酰胺是辐射诱导凋亡触发的主要决定因素，并突出了Jurkat白血病细胞对γ射线的顺序性区室特异性神经酰胺介导反应的复杂性。
