Cytosolic peroxidases protect the lysosome of bloodstream African trypanosomes from iron-mediated membrane damage.
Cytosolic peroxidases protect the lysosome of bloodstream African trypanosomes from iron-mediated membrane damage.
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DOI：
10.1371/journal.ppat.1004075
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发表时间：
2014-04
期刊：
影响因子：
6.7
通讯作者：
Krauth-Siegel RL
中科院分区：
文献类型：
--
作者：
Hiller C;Nissen A;Benítez D;Comini MA;Krauth-Siegel RL
非洲锥虫表达三种几乎相同的非硒谷胱甘肽过氧化物酶（Px）型酶，其优选地解毒脂质衍生的氢过氧化物。如前所示，缺乏线粒体Px III的血流布氏锥虫仅显示微弱和短暂的增殖缺陷，而缺乏胞质Px I和Px II的寄生虫经历极快的脂质过氧化和细胞溶解。通过向培养基中补充α-生育酚衍生物Trolox，可以完全挽救表型。然而，细胞快速死亡的机制仍然难以捉摸。在这里，我们表明，溶酶体是细胞损伤的起源。在Trolox存在下，用Alexa Fluor缀合的葡聚糖或LysoTracker喂养px I-II敲除寄生虫，产生离散的溶酶体染色。然而，在撤销抗氧化剂后，信号逐渐扩散到整个细胞体并完全丢失。T.布鲁氏菌通过宿主转铁蛋白的内吞作用获得铁。补充铁或转铁蛋白诱导的培养基，而铁螯合剂去铁胺和脱辅基转铁蛋白衰减裂解的px I-II敲除细胞。免疫荧光显微镜与MitoTracker和抗体对溶酶体标记蛋白p67显示，解体的溶酶体线粒体损伤之前。体内实验证实了线粒体过氧化物酶的作用可以忽略不计：与野生型寄生虫相比，px III敲除细胞感染的小鼠仅显示出轻微延迟的疾病发展。我们的数据表明，在非洲锥虫的血液中，溶酶体，而不是peption，是氧化损伤和胞质锥虫硫酮/tryparedoxin依赖性过氧化物酶的主要网站保护铁诱导的膜过氧化的溶酶体。这一过程似乎与T.布鲁塞。在前环昆虫形式中的细胞溶质px I-II的相应敲除导致在无Trolox培养基中完全存活的细胞。在许多细胞类型中，线粒体是细胞内活性氧的主要来源，但铁诱导的氧化性溶酶体损伤也已被描述。非洲锥虫是人类昏睡病和牛Nagana病的病原体。寄生虫是专性细胞外病原体，在其哺乳动物宿主的血流和体液中繁殖，并在其昆虫载体采采蝇中以原环形式繁殖。细胞质脂质过氧化氢解毒过氧化物酶基因已被敲除的血流布氏锥虫在没有外源抗氧化剂的情况下培养时，在不到两小时内经历极快的膜过氧化和溶解。在这里，我们表明，细胞内损伤的主要网站是单一的终端溶酶体的寄生虫。溶酶体的解体明显先于溶酶体的损伤和寄生虫的死亡。铁，获得的铁负载宿主转铁蛋白的内吞作用，诱导细胞裂解。与胞质酶相反，各自的线粒体过氧化物酶在体外增殖和小鼠感染性方面都是不稳定的。这是第一个报告表明，胞质巯基过氧化物酶是负责保护溶酶体的细胞。
African trypanosomes express three virtually identical non-selenium glutathione peroxidase (Px)-type enzymes which preferably detoxify lipid-derived hydroperoxides. As shown previously, bloodstream Trypanosoma brucei lacking the mitochondrial Px III display only a weak and transient proliferation defect whereas parasites that lack the cytosolic Px I and Px II undergo extremely fast lipid peroxidation and cell lysis. The phenotype can completely be rescued by supplementing the medium with the α-tocopherol derivative Trolox. The mechanism underlying the rapid cell death remained however elusive. Here we show that the lysosome is the origin of the cellular injury. Feeding the px I–II knockout parasites with Alexa Fluor-conjugated dextran or LysoTracker in the presence of Trolox yielded a discrete lysosomal staining. Yet upon withdrawal of the antioxidant, the signal became progressively spread over the whole cell body and was completely lost, respectively. T. brucei acquire iron by endocytosis of host transferrin. Supplementing the medium with iron or transferrin induced, whereas the iron chelator deferoxamine and apo-transferrin attenuated lysis of the px I–II knockout cells. Immunofluorescence microscopy with MitoTracker and antibodies against the lysosomal marker protein p67 revealed that disintegration of the lysosome precedes mitochondrial damage. In vivo experiments confirmed the negligible role of the mitochondrial peroxidase: Mice infected with px III knockout cells displayed only a slightly delayed disease development compared to wild-type parasites. Our data demonstrate that in bloodstream African trypanosomes, the lysosome, not the mitochondrion, is the primary site of oxidative damage and cytosolic trypanothione/tryparedoxin-dependent peroxidases protect the lysosome from iron-induced membrane peroxidation. This process appears to be closely linked to the high endocytic rate and distinct iron acquisition mechanisms of the infective stage of T. brucei. The respective knockout of the cytosolic px I–II in the procyclic insect form resulted in cells that were fully viable in Trolox-free medium. In many cell types, mitochondria are the main source of intracellular reactive oxygen species but iron-induced oxidative lysosomal damage has been described as well. African trypanosomes are the causative agents of human sleeping sickness and the cattle disease Nagana. The parasites are obligate extracellular pathogens that multiply in the bloodstream and body fluids of their mammalian hosts and as procyclic forms in their insect vector, the tsetse fly. Bloodstream Trypanosoma brucei in which the genes for cytosolic lipid hydroperoxide-detoxifying peroxidases have been knocked out undergo an extremely rapid membrane peroxidation and lyse within less than two hours when they are cultured without an exogenous antioxidant. Here we show that the primary site of intracellular damage is the single terminal lysosome of the parasites. Disintegration of the lysosome clearly precedes damage of the mitochondrion and parasite death. Iron, acquired by the endocytosis of iron-loaded host transferrin, induces cell lysis. Contrary to the cytosolic enzymes, the respective mitochondrial peroxidase is dispensable for both in vitro proliferation and mouse infectivity. This is the first report demonstrating that cytosolic thiol peroxidases are responsible for protecting the lysosome of a cell.
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DOI：
10.1186/cc2955
发表时间：
2004-10
期刊：
Critical care (London, England)
影响因子：
--
作者：
Bewick V;Cheek L;Ball J
通讯作者：
Ball J
影响因子：
7.4
作者：
Denamur, Sophie;Tyteca, Donatienne;Mingeot-Leclercq, Marie-Paule
通讯作者：
Mingeot-Leclercq, Marie-Paule
影响因子：
4.8
作者：
Hall, BS;Pal, A;Field, MC
通讯作者：
Field, MC
影响因子：
6.7
作者：
Dellibovi-Ragheb, Teegan A.;Gisselberg, Jolyn E.;Prigge, Sean T.
通讯作者：
Prigge, Sean T.
DOI：
10.1073/pnas.0509035102
发表时间：
2005-12-13
影响因子：
11.1
作者：
Austin, CD;Wen, XH;Scales, SJ
通讯作者：
Scales, SJ