PO.MCB09.03 · 分子与细胞生物学
解析铁氧还蛋白还原酶各种异构体在细胞存活和DNA损伤反应中的生物学功能
Dissecting the biological functions of various isoforms of ferredoxin reductase for cell survival and DNA damage response
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摘要 Abstract
中文摘要
铁氧还蛋白还原酶（FDXR）基因表达为七种异构体：异构体1-6由可变剪接产生，异构体7由可变启动子产生。FDXR（主要是参考的线粒体异构体1）是甾醇、血红素和铁硫簇生物合成所必需的，但异构体2-7的功能尚未明确。在此，我们发现异构体1是最丰富的一种，约占FDXR总量的~70%，而异构体4和7分别约占~10%和~7%。我们发现异构体1和4主要定位于线粒体，而缺乏线粒体定位信号的异构体7则在胞质中表达。我们还发现，与异构体1-6的启动子一样，异构体7的P2启动子也可以p53依赖性方式被DNA损伤诱导。为确定异构体特异性活性，我们构建了多株MCF7细胞系，其中敲除了一种或多种异构体。虽然FDXR完全敲除（total FDXR-KO）的MCF7细胞不能存活，但缺失异构体1-6、异构体4或异构体7的细胞仍能存活，但其细胞增殖、DNA损伤反应和修复能力较弱。这些数据表明，每种FDXR异构体都对细胞存活有贡献，且异构体7具有足以维持细胞存活的线粒体外活性。
查看英文原文 English abstract
The ferredoxin reductase (FDXR) gene is expressed as seven isoforms: 1-6 by alternative splicing and 7 by alternative promoter. FDXR, primarily the reference mitochondrial isoform 1, is required for biosynthesis of sterols, heme and iron-sulfur clusters, but isoforms 2-7 are undefined. Here, we found that isoform 1 is the most abundant one, accounting for ~70% of total FDXR whereas isoforms 4 and 7 account for ~10% and ~7%, respectively. We found that isoforms 1 and 4 are mainly localized in the mitochondria whereas isoform 7, which lacks a mitochondria localization signal, is expressed in the cytosol. We also found that like the promoter for isoforms 1-6, the P2 promoter for isoform 7 can be induced by DNA damage in a p53-dependent manner. To determine isoform-specific activity, we generated multiple MCF7 cell lines in that one or more isoforms are knocked out. While total FDXR-KO MCF7 cells are non-viable, cells deficient in isoforms 1-6, isoforms 4 or 7 remain viable but are weak in cell proliferation, DNA damage response and repair. These data suggest that each FDXR isoform contributes to cell survival and that isoform 7 has an extra-mitochondrial activity sufficient for cell survival.
利益披露 Disclosure
K. Nakajima, None..
S. Mohibi, None..
K. K. Hong, None.