GNL3L Is a Nucleo-Cytoplasmic Shuttling Protein: Role in Cell Cycle Regulation
GNL3L Is a Nucleo-Cytoplasmic Shuttling Protein: Role in Cell Cycle Regulation
复制标题
GNL3L 是一种核细胞质穿梭蛋白：在细胞周期调节中的作用
作者：
Indu Jose Thoompumkal;M. S. Subba Rao;A. Kumaraswamy;R. Krishnan;S. Mahalingam
GNL 3L是一种进化上保守的高分子量GTP结合核仁蛋白，属于GTPases的HSR 1-MMR 1亚家族。GNL 3 L是一种核质穿梭蛋白，其从细胞核输出对Leptomycin B敏感。缺失诱变揭示C-末端结构域（氨基酸501-582）对于GNL 3L从细胞核的输出是必需的和足够的，并且C-末端结构域内的疏水残基（M567、L570和572）的交换损害了该过程。蛋白质-蛋白质相互作用分析的结果表明，GNL 3L与CRM 1的相互作用是其从细胞核输出的关键。GNL 3L的异位表达导致细胞在细胞周期的“G2/M”期的较少积累，而内源性GNL 3L的消耗导致“G2/M”停滞。有趣的是，细胞周期分析后的BrdU标记测定表明，与野生型或核输入缺陷型GNL 3 L相比，在表达核输出缺陷型突变体（GNL 3 L NES内斯）的细胞中发生显著增加的DNA合成。此外，Rb在丝氨酸780处的过度磷酸化增加以及GNL 3 L β内斯异位表达后E2 F1、细胞周期蛋白A2和E1的上调导致更快的“S”期进展。总的来说，本研究提供的证据表明，GNL 3L从细胞核输出的CRM 1依赖的方式和GNL 3L的核定位是重要的，以促进细胞增殖过程中的'S'期进程。
GNL3L is an evolutionarily conserved high molecular weight GTP binding nucleolar protein belonging to HSR1-MMR1 subfamily of GTPases. The present investigation reveals that GNL3L is a nucleo-cytoplasmic shuttling protein and its export from the nucleus is sensitive to Leptomycin B. Deletion mutagenesis reveals that the C-terminal domain (amino acids 501–582) is necessary and sufficient for the export of GNL3L from the nucleus and the exchange of hydrophobic residues (M567, L570 and 572) within the C-terminal domain impairs this process. Results from the protein-protein interaction analysis indicate that GNL3L interaction with CRM1 is critical for its export from the nucleus. Ectopic expression of GNL3L leads to lesser accumulation of cells in the ‘G2/M’ phase of cell cycle whereas depletion of endogenous GNL3L results in ‘G2/M’ arrest. Interestingly, cell cycle analysis followed by BrdU labeling assay indicates that significantly increased DNA synthesis occurs in cells expressing nuclear export defective mutant (GNL3L∆NES) compared to the wild type or nuclear import defective GNL3L. Furthermore, increased hyperphosphorylation of Rb at Serine 780 and the upregulation of E2F1, cyclins A2 and E1 upon ectopic expression of GNL3L∆NES results in faster ‘S’ phase progression. Collectively, the present study provides evidence that GNL3L is exported from the nucleus in CRM1 dependent manner and the nuclear localization of GNL3L is important to promote ‘S’ phase progression during cell proliferation.
影响因子：
11.2
作者：
C. Sherr
通讯作者：
C. Sherr
影响因子：
10.5
作者：
Alt, JR;Cleveland, JL;Diehl, JA
通讯作者：
Diehl, JA
DOI：
10.1073/pnas.90.15.6914
发表时间：
1993-08-01
影响因子：
11.1
作者：
FLEMINGTON, EK;SPECK, SH;KAELIN, WG
通讯作者：
KAELIN, WG