Aconitase causes iron toxicity in Drosophila pink1 mutants.
Aconitase causes iron toxicity in Drosophila pink1 mutants.
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DOI：
10.1371/journal.pgen.1003478
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发表时间：
2013-04
期刊：
影响因子：
4.5
通讯作者：
Verstreken P
中科院分区：
文献类型：
--
作者：
Esposito G;Vos M;Vilain S;Swerts J;De Sousa Valadas J;Van Meensel S;Schaap O;Verstreken P
pten诱导的激酶1 （PINK1）是一种线粒体激酶，PINK1突变可导致人类早发性帕金森病（PD）。果蝇中pink1的缺失导致线粒体功能缺陷，遗传学数据表明另一种pd相关基因产物Parkin与pink1一起调节功能失调线粒体的清除（线粒体自噬）。因此，pink1突变体表现出形态异常线粒体的积累，但尚不清楚是否有其他因素参与体内pink1的功能，并导致pink1突变体中特定细胞类型的线粒体形态缺陷。为了探索pink1功能的分子机制，我们在果蝇中进行了遗传修饰子筛选，发现乌头酶（aconitase, acon）是pink1的显性抑制因子。Acon定位于线粒体，含有一个不稳定的铁硫[4Fe-4S]簇，可以清除超氧化物，释放过氧化氢和铁，两者结合产生羟基自由基。利用Acon酶突变体和清除游离铁的mitoferritin的表达，我们发现pink1突变体中超氧化物增加导致[4Fe-4S]簇失活，导致氧化应激和线粒体肿胀。我们发现[4Fe-4S]失活作用于pink1下游的一条影响线粒体形态的途径，但独立于parkin。因此，我们的数据表明，在pd相关模型中，超氧化物依赖[4Fe-4S]失活定义了一个潜在的致病级联反应，该反应独立于线粒体自噬，并将铁毒性与线粒体衰竭联系起来。在这项工作中，我们提供了将帕金森病的两个最早观察联系在一起的机制见解：患病黑质神经元中铁的过度积累和线粒体功能障碍，特别是复合物i水平上活性氧的产生增加。我们发现乌头酶突变体在机体和细胞/线粒体水平上都是帕金森相关pink1突变表型的强遗传抑制因子。我们发现pink1突变体的线粒体功能障碍，包括复合物I功能障碍，导致乌头酶铁硫簇的超氧化物依赖失活，导致铁和过氧化物的释放，从而产生羟基自由基和线粒体衰竭。因此，通过表达mitofertiritin或降低aconitase的水平来清除游离铁都可以挽救pink1突变体；而增加的野生型乌头酶，而不是没有铁硫簇的突变体，会导致严重的线粒体缺陷。鉴于电子传递链活性降低、氧化应激增加和黑质天然铁积聚是散发性和家族性帕金森病的共同因素，我们认为乌头酶的氧化失活可能是帕金森病神经元功能障碍的重要致病级联反应。
The PTEN-induced kinase 1 (PINK1) is a mitochondrial kinase, and pink1 mutations cause early onset Parkinson's disease (PD) in humans. Loss of pink1 in Drosophila leads to defects in mitochondrial function, and genetic data suggest that another PD-related gene product, Parkin, acts with pink1 to regulate the clearance of dysfunctional mitochondria (mitophagy). Consequently, pink1 mutants show an accumulation of morphologically abnormal mitochondria, but it is unclear if other factors are involved in pink1 function in vivo and contribute to the mitochondrial morphological defects seen in specific cell types in pink1 mutants. To explore the molecular mechanisms of pink1 function, we performed a genetic modifier screen in Drosophila and identified aconitase (acon) as a dominant suppressor of pink1. Acon localizes to mitochondria and harbors a labile iron-sulfur [4Fe-4S] cluster that can scavenge superoxide to release hydrogen peroxide and iron that combine to produce hydroxyl radicals. Using Acon enzymatic mutants, and expression of mitoferritin that scavenges free iron, we show that [4Fe-4S] cluster inactivation, as a result of increased superoxide in pink1 mutants, results in oxidative stress and mitochondrial swelling. We show that [4Fe-4S] inactivation acts downstream of pink1 in a pathway that affects mitochondrial morphology, but acts independently of parkin. Thus our data indicate that superoxide-dependent [4Fe-4S] inactivation defines a potential pathogenic cascade that acts independent of mitophagy and links iron toxicity to mitochondrial failure in a PD–relevant model. In this work we provide mechanistic insight linking together two of the earliest observations in Parkinson's disease: the excessive build-up of iron in diseased substantia nigra neurons and mitochondrial dysfunction particularly increased reactive oxygen species production at the level of Complex I. We identify aconitase mutants as strong genetic suppressors of Parkinson-related pink1 mutant phenotypes, both at the organismal and at the cellular/mitochondrial level. We show that the mitochondrial dysfunction in pink1 mutants that includes Complex I dysfunction results in superoxide-dependent inactivation of the Aconitase iron-sulfur cluster, leading to the release of iron and peroxide that combine to produce hydroxyl radicals and mitochondrial failure. Consequently, scavenging free iron using expression of mitoferritin or decreasing the levels of aconitase both rescue pink1 mutants; while increased wild-type Aconitase, but not a mutant that does not harbor an iron-sulfur cluster, results in severe mitochondrial defects. Given that reduced electron transport chain activity, increased oxidative stress, and natural iron build-up in the substantia nigra are common factors in sporadic and familial forms of Parkinson's disease, we believe that oxidative inactivation of Aconitase may represent an important pathogenic cascade underlying neuronal dysfunction in Parkinson's disease.
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DOI：
10.1073/pnas.0500346102
发表时间：
2005-07-19
影响因子：
11.1
作者：
Cha, GH;Kim, S;Cho, KS
通讯作者：
Cho, KS
影响因子：
5.7
作者：
Imai Y;Lu B
通讯作者：
Lu B
影响因子：
64.8
作者：
Clark, Ira E.;Dodson, Mark W.;Guo, Ming
通讯作者：
Guo, Ming
影响因子：
2.9
作者：
LAUBLE, H;KENNEDY, MC;STOUT, CD
通讯作者：
STOUT, CD
影响因子：
6.1
作者：
Cannon JR;Tapias V;Na HM;Honick AS;Drolet RE;Greenamyre JT
通讯作者：
Greenamyre JT