Apoptosis induced by exposure to a low steady-state concentration of H2O2 is a consequence of lysosomal rupture
Apoptosis induced by exposure to a low steady-state concentration of H2O2 is a consequence of lysosomal rupture
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DOI：
10.1042/0264-6021:3560549
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发表时间：
2001-06-01
影响因子：
4.1
通讯作者：
Brunk, UT
中科院分区：
文献类型：
--
作者：
Antunes, F;Cadenas, E;Brunk, UT
我们用一种新技术重新检验了溶酶体氧化应激诱导细胞凋亡的假说，这种新技术使培养中的细胞暴露在低稳态浓度的过氧化氢中。这种稳态技术比团注给药方法更好地模拟体内的情况。过氧化氢诱导的细胞凋亡的一个关键方面是，尽管细胞可能在暴露于这种特定的活性氧物种后几分钟内变得活跃，但只有在几个小时后才能明显地观察到细胞凋亡。在目前的工作中，我们首次证明了过氧化氢的触发作用和较晚的细胞凋亡发生之间的几个相关联系：(I)短时间(15分钟)暴露在过氧化氢中几乎立即导致溶酶体破裂，尽管有限；(Ii)早期溶酶体损伤和后来的细胞凋亡对过氧化氢表现出类似的剂量相关反应；(Iii)这两种事件都被铁络合剂，包括去铁胺预先抑制。已知这种化合物只被内吞作用摄取，因此定位于溶酶体隔室。在氧化应激后，当细胞再次处于标准培养条件下时，观察到溶酶体破裂的时间依赖地持续增加，导致凋亡细胞中完整的溶酶体数量显著减少，而同一批氧化应激暴露的非凋亡细胞主要显示完整的溶酶体。综上所述，我们的结果强化了先前的发现，并强烈表明溶酶体破裂是一个早期的上游起始事件，是溶酶体内铁催化的氧化过程的结果，当细胞凋亡由氧化应激诱导时。
We have re-examined the lysosomal hypothesis of oxidative-stress-induced apoptosis using a new technique for exposing cells in culture to a low steady-state concentration of H2O2. This steady-state technique mimics the situation in vivo better than the bolus-administration method. A key aspect of H2O2-induced apoptosis is that the apoptosis is evident only after several hours, although cells may become committed within a few minutes of exposure to this particular reactive oxygen species. In the present work, we were able to show, for the first time, several correlative links between the triggering effect of H2O2 and the later onset of apoptosis: (i) a short (15 min) exposure to H2O2 caused almost immediate, albeit limited, lysosomal rupture; (ii) early lysosomal damage, and later apoptosis, showed a similar dose-related response to H2O2; (iii) both events were inhibited by pretreatment with iron chelators, including desferrioxamine. This compound is known to be taken up by endocytosis only and thus to become localized in the lysosomal compartment. After exposure to oxidative stress, when cells were again in standard culture conditions, a time-dependent continuous increase in lysosomal rupture was observed, resulting in a considerably lowered number of intact lysosomes in apoptotic cells, whereas non-apoptotic cells from the same batch of oxidative-stress-exposed cells showed mainly intact lysosomes. Taken together, our results reinforce earlier findings and strongly suggest that lysosomal rupture is an early upstream initiating event, and a consequence of intralysosomal iron-catalysed oxidative processes, when apoptosis is induced by oxidative stress.