Cell growth‐dependent subcellular localization of p8
Cell growth‐dependent subcellular localization of p8
复制标题
DOI：
10.1002/jcb.20682
复制
发表时间：
2006-04
影响因子：
4
通讯作者：
M. P. Valacco;C. Varone;C. Malicet;E. Cánepa;J. Iovanna;S. Moreno
中科院分区：
文献类型：
--
作者：
M. P. Valacco;C. Varone;C. Malicet;E. Cánepa;J. Iovanna;S. Moreno
p8是一种应激诱导蛋白，生物化学上与结构因子HMG - I/Y相关，在许多癌症中过表达，是肿瘤扩张所必需的。p8在生长方面发挥作用的分子机制尚不清楚。利用免疫细胞化学，我们发现p8在亚融合细胞中呈现核定位，但在高密度生长的细胞中，它定位于整个细胞。在Go/G1中阻滞的细胞，无论是通过血清剥夺还是羟基脲处理，都显示p8的核-细胞质定位，无论在活跃分裂细胞的其余细胞周期阶段定位是核。人类与果蝇p8序列的比较预测了一个保守的二部核定位序列（NLS）。假设的NLS已被证明是功能性的，因为核输入依赖于能量（被叠氮化钠加2 -脱氧葡萄糖抑制），融合蛋白GFP-p8和GFP-NLSp8定位于细胞核，而GFP-p8NLSmut中含有Lys 65、69、76和77突变为Ala，定位于整个细胞。p8的定位不涉及CRM1转运体，因为它对leptomycin b不敏感。MAPK途径的抑制剂不影响p8的亚细胞定位。曲古抑素A抑制去乙酰化可促进p8的细胞质积累。结果表明，p8生长阶段依赖的定位受乙酰化调节，p8在细胞内不是自由的，而是形成复合物的一部分，它可能在两种亚细胞定位中发挥作用。j .细胞。生物化学学报，26(3):366 - 379,2006。©2005 Wiley‐Liss, Inc。
p8 is a stress‐induced protein, biochemically related to the architectural factor HMG‐I/Y, overexpressed in many cancers and required for tumor expansion. The molecular mechanisms by which p8 may exert its effect in aspects of growth is unknown. Using immunocytochemistry, we found that p8 presents nuclear localization in sub‐confluent cells, but it localizes throughout the whole cell in high density grown cells. Cells arrested in Go/G1, either by serum deprivation or by hydroxyurea treatment, show a nucleo‐cytoplasmic localization of p8, whether in the rest of the cell cycle stages of actively dividing cells the localization is nuclear. A comparison of p8 sequences from human to fly predicts a conserved bipartite nuclear localization sequence (NLS). The putative NLS has been demonstrated to be functional, since nuclear import is energy dependent (inhibited by sodium azide plus 2‐deoxyglucose), and fusion proteins GFP–p8 and GFP–NLSp8 localize to the nucleus, whereas GFP–p8NLSmut in which with Lys 65, 69, 76, and 77 mutated to Ala localized to the whole cell. p8 localization does not involve the CRM1 transporter, since it is insensitive to leptomycin B. Inhibitors of MAPK pathways did not affect p8 subcellular localization. The inhibition of deacetylation with Trichostatin A promotes cytoplasmic accumulation of p8. The results suggest that p8 growth stage‐dependent localization is regulated by acetylation, that p8 is not free within the cell but forming part of a complex and that it may exert a role in both subcellular localizations. J. Cell. Biochem. 97: 1066–1079, 2006. © 2005 Wiley‐Liss, Inc.