United States Department of Agriculture / Agricultural Research Service Children's Nutrition Research Center, Baylor College of Medicine, Houston, TX, USA.
Department of Pediatrics, Baylor College of Medicine, Houston, TX, USA.
FEBS J. 2011 Jul;278(14):2525-2539. doi: 10.1111/j.1742-4658.2011.08178.x. Epub 2011 Jun 2.
Glutaredoxins (Grxs) have been shown to be critical in maintaining redox homeostasis in living cells. Recently, an emerging subgroup of Grxs with one cysteine residue in the putative active motif (monothiol Grxs) has been identified. However, the biological and physiological functions of this group of proteins have not been well characterized. Here, we characterize a mammalian monothiol Grx (Grx3, also termed TXNL2/PICOT) with high similarity to yeast ScGrx3/ScGrx4. In yeast expression assays, mammalian Grx3s were localized to the nuclei and able to rescue growth defects of grx3grx4 cells. Furthermore, Grx3 inhibited iron accumulation in yeast grx3gxr4 cells and suppressed the sensitivity of mutant cells to exogenous oxidants. In mice, Grx3 mRNA was ubiquitously expressed in developing embryos, adult tissues and organs, and was induced during oxidative stress. Mouse embryos absent of Grx3 grew smaller with morphological defects and eventually died at 12.5 days of gestation. Analysis in mouse embryonic fibroblasts revealed that Grx3(-/-) cells had impaired growth and cell cycle progression at the G(2) /M phase, whereas the DNA replication during the S phase was not affected by Grx3 deletion. Furthermore, Grx3-knockdown HeLa cells displayed a significant delay in mitotic exit and had a higher percentage of binucleated cells. Therefore, our findings suggest that the mammalian Grx3 has conserved functions in protecting cells against oxidative stress and deletion of Grx3 in mice causes early embryonic lethality which could be due to defective cell cycle progression during late mitosis.
谷氧还蛋白 (Grxs) 已被证明在维持活细胞的氧化还原平衡中起着关键作用。最近，人们发现了一个新兴的 Grx 亚组，其假定的活性基序中有一个半胱氨酸残基（单硫醇 Grxs）。然而，这组蛋白质的生物学和生理学功能尚未得到很好的描述。在这里，我们描述了一种与酵母 ScGrx3/ScGrx4 高度相似的哺乳动物单硫醇 Grx（Grx3，也称为 TXNL2/PICOT）。在酵母表达实验中，哺乳动物 Grx3 定位于细胞核，并能够挽救 grx3grx4 细胞的生长缺陷。此外，Grx3 抑制酵母 grx3gxr4 细胞中铁的积累，并抑制突变细胞对外源氧化剂的敏感性。在小鼠中，Grx3 mRNA 在发育中的胚胎、成年组织和器官中广泛表达，并在氧化应激时被诱导。缺乏 Grx3 的小鼠胚胎生长较小，出现形态缺陷，最终在妊娠 12.5 天时死亡。对小鼠胚胎成纤维细胞的分析表明，Grx3(-/-) 细胞在 G2/M 期的生长和细胞周期进程受损，而 S 期的 DNA 复制不受 Grx3 缺失的影响。此外，Grx3 敲低的 HeLa 细胞在有丝分裂后期出现明显的延迟，双核细胞的比例更高。因此，我们的研究结果表明，哺乳动物 Grx3 具有保护细胞免受氧化应激的保守功能，而小鼠中 Grx3 的缺失导致早期胚胎致死，这可能是由于晚期有丝分裂中细胞周期进程的缺陷所致。
