Promotion of Proapoptotic Signals by Lysosomal Photodamage
Promotion of Proapoptotic Signals by Lysosomal Photodamage
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DOI：
10.1111/php.12456
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发表时间：
2015-07-01
影响因子：
3.3
通讯作者：
Reiners, John J., Jr.
中科院分区：
文献类型：
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作者：
Kessel, David;Reiners, John J., Jr.
我们之前报道过，低水平的溶酶体光损伤增强了随后线粒体光损伤的疗效，导致凋亡细胞死亡的显著促进。我们现在扩展我们的顺序PDT方案的分析，包括两个额外的溶酶体靶向光敏剂。由于渗透性增强，这些药剂比最初研究中使用的药剂（n -天冬氨酸氯E6， NPe6）更有效。添加细胞渗透性半胱氨酸蛋白酶抑制剂E-64d和钙螯合剂BAPTA-AM几乎完全抑制了pdt诱导的线粒体膜电位丢失和原aspase3和-7的激活。然而，这些抑制剂并没有抑制BH3模拟或线粒体光损伤的促凋亡作用。通常与自噬相关的蛋白ATG7或ATG5的敲低抑制了顺序PDT方案引起的光损伤。这些作用似乎与自噬过程无关，因为自噬的药理抑制没有提供这种保护。ATG7和ATG5敲低的作用可能反映了ATG7在调节溶酶体通透性中的作用，以及ATG5蛋白水解片段放大线粒体促凋亡过程的可能性。我们的研究结果表明，顺序靶向溶酶体和线粒体的低剂量光损伤可能比使用单一光敏剂具有显著的优势。
We previously reported that low-level lysosomal photodamage enhanced the efficacy of subsequent mitochondrial photodamage, resulting in a substantial promotion of apoptotic cell death. We now extend our analysis of the sequential PDT protocol to include two additional lysosomal-targeting photosensitizers. These agents, because of enhanced permeability, are more potent than the agent (N-aspartyl chlorin E6, NPe6) used in the initial study. Addition of the cell-permeable cysteine protease inhibitor E-64d and calcium chelator BAPTA-AM almost completely suppressed sequential PDT-induced loss of mitochondrial membrane potential and activation of procaspases-3 and -7. These inhibitors did not, however, suppress the proapoptotic effect of a BH3 mimetic or mitochondrial photodamage. Knockdowns of ATG7 or ATG5, proteins normally associated with autophagy, suppressed photodamage induced by the sequential PDT protocol. These effects appear to be independent of the autophagic process as pharmacological inhibition of autophagy offered no such protection. Effects of ATG7 and ATG5 knockdowns may reflect the role that ATG7 plays in regulating lysosome permeability, and the likelihood that a proteolytic fragment of ATG5 amplifies mitochondrial proapoptotic processes. Our results suggest that low-dose photodamage that sequentially targets lysosomes and mitochondria may offer significant advantages over the use of single photosensitizers.