Laboratory of Biochemistry, School of Pharmacy, Kitasato University, 5-9-1 Shirokane, Minato-ku, Tokyo, 108-8642, Japan.
Department of Infection Biology, Graduate School of Comprehensive Human Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, 305-8575, Japan.
Biochem Biophys Res Commun. 2021 Jun 25;559:99-105. doi: 10.1016/j.bbrc.2021.04.026. Epub 2021 Apr 30.
Ribosome formation occurs in the nucleolus through interaction with various trans-acting factors. Therefore, hundreds of nucleolar proteins have a function in ribosome formation, although the precise function of each nucleolar protein in ribosome formation is largely unclear. We have previously identified an uncharacterized protein, G-patch domain-containing protein 4 (GPATCH4 or G4), as a component of the pre-ribosomes purified with either nucleolin (NCL) or NPM1. In this present study, we sought to clarify the localization and function of G4. We identified that G4 localizes to both the nucleolus and the Cajal body. Although knockdown of G4 did not have a significant effect on pre-ribosomal RNA processing, cell growth did decrease. Interestingly, G4 knockdown also decreased the number of fibrillar center and dense fibrillar component regions inside the nucleolus. This data has identified G4 as a novel nucleolar protein involved in the regulation of cell growth and nucleolar structure.
核糖体的形成是通过与各种反式作用因子相互作用发生在核仁中的。因此，尽管每个核仁蛋白在核糖体形成中的精确功能在很大程度上尚不清楚，但数百种核仁蛋白都具有核糖体形成的功能。我们之前已经鉴定出一种未被表征的蛋白，G- 斑结构域包含蛋白 4（GPATCH4 或 G4），作为用核仁蛋白（NCL）或 NPM1 纯化的前核糖体的组成部分。在本研究中，我们试图阐明 G4 的定位和功能。我们确定 G4 定位于核仁和 Cajal 体。虽然 G4 的敲低对前核糖体 RNA 处理没有显著影响，但细胞生长确实减少了。有趣的是，G4 的敲低也减少了核仁内纤维中心和致密纤维成分区域的数量。这些数据表明 G4 是一种参与调节细胞生长和核仁结构的新型核仁蛋白。
