RNA silencing of the mitochondrial ABCB7 transporter in HeLa cells causes an iron-deficient phenotype with mitochondrial iron overload
RNA silencing of the mitochondrial ABCB7 transporter in HeLa cells causes an iron-deficient phenotype with mitochondrial iron overload
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DOI：
10.1182/blood-2006-08-041632
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发表时间：
2007-04-15
期刊：
影响因子：
20.3
通讯作者：
Arosio, Paolo
中科院分区：
文献类型：
--
作者：
Cavadini, Patrizia;Biasiotto, Giorgio;Arosio, Paolo
X连锁铁粒幼细胞性贫血伴共济失调（XLSA/A）是由转运蛋白ABCB 7缺陷引起的，其特征是红系细胞中线粒体铁沉积和原卟啉过量。我们描述了ABCB 7沉默在HeLa细胞中进行连续转染siRNA。ABCB 7缺陷细胞的表型的特征在于增殖速率的强烈降低，其不能通过铁补充来挽救，铁缺乏的明显迹象，以及线粒体中的铁积累的大的约6倍的增加，其对于线粒体铁蛋白是很难获得的。细胞表现出增加的原卟啉IX，更高的敏感性H2 O2毒性，和线粒体超氧化物歧化酶2（SOD 2）的活性降低，而线粒体酶的活性，如柠檬酸合酶或琥珀酸脱氢酶，和ATIP含量没有降低。相反，乌头酸酶活性，特别是胞质，IRP 1形式，减少。结果支持了ABCB 7参与铁从线粒体转移到细胞质以及细胞质Fe/S酶成熟的假设。此外，研究结果表明，XLSA/A的贫血是由铁的积累引起的，铁的积累形式不容易用于血红素合成。
X-linked sideroblastic anemia with ataxia (XLSA/A) is caused by defects of the transporter ABCB7 and is characterized by mitochondrial iron deposition and excess of protoporphyrin in erythroid cells. We describe ABCB7 silencing in HeLa cells by performing sequential transfections with siRNAs. The phenotype of the ABCB7-deficient cells was characterized by a strong reduction in proliferation rate that was not rescued by iron supplementation, by evident signs of iron deficiency, and by a large approximately 6-fold increase of iron accumulation in the mitochondria that was poorly available to mitochondrial ferritin. The cells showed an increase of protoporphyrin IX, a higher sensitivity to H2O2 toxicity, and a reduced activity of mitochondrial superoxide dismutase 2 (SOD2), while the activity of mitochondrial enzymes, such as citrate synthase or succinate dehydrogenase, and ATIP content were not decreased. In contrast, aconitase activity, particularly that of the cytosolic, IRP1 form, was reduced. The results support the hypothesis that ABCB7 is involved in the transfer of iron from mitochondria to cytosol, and in the maturation of cytosolic Fe/S enzymes. In addition, the results indicate that anemia in XLSA/A is caused by the accumulation of iron in a form that is not readily usable for heme synthesis.