Zhu Chun-Hong, Kim Jinyong, Shay Jerry W, Wright Woodring E
Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX, USA.
PLoS One. 2008;3(11):e3716. doi: 10.1371/journal.pone.0003716. Epub 2008 Nov 13.
Stress Granules (SG) are sites of accumulation of stalled initiation complexes that are induced following a variety of cellular insults. In a genetic screen for factors involved in protecting human myoblasts from acute oxidative stress, we identified a gene encoding a protein we designate SGNP (Stress Granule and Nucleolar Protein).
METHODOLOGY/PRINCIPAL FINDINGS: A gene-trap insertional mutagenesis screen produced one insertion that conferred resistance to sodium arsenite. RT-PCR/3' RACE was used to identify the endogenous gene expressed as a GFP-fusion transcript. SGNP is localized in both the cytoplasm and nucleolus and defines a non-nucleolar compartment containing 5.8S rRNA, a component of the 60S ribosomal subunit. Under oxidative stress, SGNP nucleolar localization decreases and it rapidly co-localizes with stress granules. The decrease in nucleolar SGNP following oxidative stress was accompanied by a large increase in nucleolar 5.8S rRNA. Knockdown of SGNP with shRNA increased global mRNA translation but induced growth arrest and cell death.
These results suggest that SGNP is an essential gene that may be involved in ribosomal biogenesis and translational control in response to oxidative stress.
应激颗粒（SG）是在多种细胞损伤后诱导产生的停滞起始复合物的聚集位点。在一项针对保护人类成肌细胞免受急性氧化应激影响的相关因子的基因筛选中，我们鉴定出一个编码蛋白的基因，我们将其命名为SGNP（应激颗粒和核仁蛋白）。
方法/主要发现：基因捕获插入诱变筛选产生了一个赋予对亚砷酸钠抗性的插入突变。利用逆转录聚合酶链反应/3' 端快速扩增cDNA末端（RT-PCR/3' RACE）来鉴定作为绿色荧光蛋白（GFP）融合转录本表达的内源基因。SGNP定位于细胞质和核仁中，并定义了一个包含5.8S核糖体RNA（60S核糖体亚基的一个组成部分）的非核仁区室。在氧化应激下，SGNP的核仁定位减少，并且它迅速与应激颗粒共定位。氧化应激后核仁中SGNP的减少伴随着核仁中5.8S rRNA的大量增加。用短发夹RNA（shRNA）敲低SGNP增加了整体mRNA翻译，但诱导了生长停滞和细胞死亡。
这些结果表明SGNP是一个必需基因，可能参与核糖体生物合成和对氧化应激的翻译控制。
