Distinct structural domains within C19ORF5 support association with stabilized microtubules and mitochondrial aggregation and genome destruction
Distinct structural domains within C19ORF5 support association with stabilized microtubules and mitochondrial aggregation and genome destruction
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DOI：
10.1158/0008-5472.can-04-3865
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发表时间：
2005-05-15
期刊：
影响因子：
11.2
通讯作者：
McKeehan, WL
中科院分区：
文献类型：
--
作者：
Liu, LY;Vo, A;McKeehan, WL
C19 ORF 5是微管相关蛋白MAP 1A/MAP 1B的序列同源物，除了它与微管相关蛋白和紫杉醇样微管稳定剂和候选肿瘤抑制剂RASSF 1A的关联之外，其功能未知。在这里，我们表明，当在哺乳动物细胞中过表达的重组C19 ORF 5（C19 ORF 5C）的393-氨基酸残基COOH末端表现出四种类型的分布模式成比例的表达水平。尽管C19 ORF 5C通常分布在整个胞质溶胶中而没有微管缔合，但C19 ORF 5C特异性地在紫杉醇处理的细胞中的稳定微管上积累，并在体外与紫杉醇稳定微管直接相互作用。天然的113-kDa全长C19 ORF 5和较短的56-kDa形式类似地与肝细胞中的稳定化微管和来自其裂解物的稳定化微管相关。随着C19 ORF 5的积累，它出现在线粒体上并逐渐诱导线粒体的不同核周聚集体。C19 ORF 5与细胞色素c缺乏的线粒体重叠，膜电位降低。线粒体聚集导致DNA的总降解，这是一种与细胞死亡相关的过程，我们称之为线粒体聚集和基因组破坏（MAGD）。缺失突变显示，C19 ORF 5超稳定微管结合结构域位于< 100个残基的高度碱性序列中，而MAGD活性位于更下游的独特的25个残基序列中（F967-A991）。我们的研究结果表明，C19 ORF 5介导的微管细胞骨架和线粒体之间的通信控制细胞死亡和缺陷的基因组破坏通过不同的双功能结构域。C19 ORF 5的积累和由此产生的MAGD信号的超稳定的微管可能参与肿瘤抑制活性的RASSF 1A，一种天然的微管稳定剂和相互作用的伴侣与C19 ORF 5，和紫杉烷类药物家族。
C19ORF5 is a sequence homologue of microtubule-associated proteins MAP1A/MAP1B of unknown function, except for its association with mitochondria-associated proteins and the paclitaxel-like microtubule stabilizer and candidate tumor suppressor RASSF1A. Here, we show that when overexpressed in mammalian cells the recombinant 393-amino acid residue COOH terminus of C19ORF5 (C19ORF5C) exhibited four types of distribution patterns proportional to expression level. Although normally distributed throughout the cytosol without microtubular association, C19ORF5C specifically accumulated on stabilized microtubules in paclitaxel-treated cells and interacted directly with paclitaxel-stabilized microtubules in vitro. The native 113-kDa full-length C19ORF5 and a shorter 56-kDa form similarly associated with stabilized microtubules in liver cells and stabilized microtubules from their lysates. As C19ORF5 accumulated, it appeared on mitochondria and progressively induced distinct perinuclear aggregates of mitochondria. C19ORF5 overlapped with cytochrome c-deficient mitochondria with reduced membrane potential. Mitochondrial aggregation resulted in gross degradation of DNA, a cell death-related process we refer to as mitochondrial aggregation and genome destruction (MAGD). Deletion mutagenesis revealed that the C19ORF5 hyperstabilized microtubule-binding domain resides in a highly basic sequence of < 100 residues, whereas the MAGD activity resides further downstream in a distinct 25-residue sequence (F967-A991). Our results suggest that C19ORF5 mediates communication between the microtubular cytoskeleton and mitochondria in control of cell death and defective genome destruction through distinct bifunctional structural domains. The accumulation of C19ORF5 and resultant MAGD signaled by hyperstabilized microtubules may be involved in the tumor suppression activity of RASSF1A, a natural microtubule stabilizer and interaction partner with C19ORF5, and the taxoid drug family.