H-ras localizes to cell nuclei and varies with the cell cycle.
H-ras localizes to cell nuclei and varies with the cell cycle.
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DOI：
10.1177/1947601911405042
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发表时间：
2011-02-01
期刊：
影响因子：
--
通讯作者：
Friedman, Robert M
中科院分区：
文献类型：
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作者：
Contente, Sara;Yeh, Tze-Jou Annie;Friedman, Robert M
H-Ras在细胞质中的许多信号传导途径中充当信号开关分子，需要H-Ras定位于细胞质膜的内表面，并且H-Ras被认为是细胞质蛋白。通过c-H-ras过表达转化的细胞的免疫印迹研究表明，H-Ras蛋白存在于细胞质和细胞核提取物中，这表明核H-Ras和细胞转化可能相关。出乎意料的是，进一步的研究表明，H-Ras蛋白也存在于非转化和原代小鼠细胞的细胞核中，这些细胞不过度表达H-Ras。小鼠成纤维细胞NIH 3 T3细胞、L细胞和原代成纤维细胞系均在细胞质和细胞核提取物中存在H-Ras。细胞核提取物的同步生长无血清显示的H-Ras和细胞周期蛋白D1的细胞生长后血清添加量的增加。用法尼基转移酶抑制剂处理引起细胞核中H-Ras的丢失。同步培养细胞核的原位免疫荧光研究表明，H-Ras蛋白出现在细胞核中，并从细胞核中消失，细胞通过生长周期。这种循环发生在未转化和ras转化的细胞中。对平行培养物的流式细胞术测量显示，对于每个细胞系，最大百分比的细胞处于S期的时间点对应于H-Ras的明显更强的原位信号的出现。H-Ras除了具有胞质信号传导功能外，还可能参与与复制相关的核信号传导途径。
H-Ras functions as a signal switch molecule in numerous signaling pathways in the cytoplasm, requiring H-Ras localization to the inner surface of the cytoplasmic membrane, and H-Ras is considered to be a cytoplasmic protein. Immunoblot studies of cells transformed by overexpression of c-H-ras indicated that H-Ras protein was present in both cytoplasmic and nuclear extracts, suggesting a possible correlation of nuclear H-Ras and cellular transformation. Unexpectedly, additional studies revealed that H-Ras protein was also present in the nuclei of nontransformed and primary mouse cells, which do not overexpress H-Ras. Mouse fibroblast NIH 3T3 cells, L cells, and a primary fibroblast line all had H-Ras present in both cytoplasmic and nuclear extracts. Nuclear extracts of cells synchronized by growth without serum displayed an increasing amount of H-Ras and cyclin D1 as cells grew after serum addition. Treatment with farnesyltransferase inhibitor caused loss of H-Ras from the nucleus. Immunofluorescence in situ studies of nuclei from synchronized cultures showed that H-Ras protein appeared in and disappeared from the nuclei as the cells moved through the growth cycle. This cycling occurred in both nontransformed and ras-transformed cells. Flow cytometry measurements on parallel cultures revealed that the time point at which the greatest percentage of cells were in S phase, for each line, corresponded to appearance of a noticeably stronger in situ signal for H-Ras. H-Ras may participate in nuclear signaling pathways associated with replication in addition to its cytoplasmic signaling functions.