p67 Transcription Regulates Translation in Serum-starved and Mitogen-activated KRC-7 Cells*
p67 Transcription Regulates Translation in Serum-starved and Mitogen-activated KRC-7 Cells*
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DOI：
10.1074/jbc.272.19.12699
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发表时间：
1997-05
期刊：
影响因子：
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通讯作者：
Swati Gupta;A. Bose;N. Chatterjee;D. Saha;Shiyong Wu;N. Gupta
中科院分区：
文献类型：
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作者：
Swati Gupta;A. Bose;N. Chatterjee;D. Saha;Shiyong Wu;N. Gupta
研究了在完全培养基中生长的KRC-7细胞（大鼠肝癌）在血清饥饿和有丝分裂原激活期间蛋白质合成的调节。在血清饥饿时，细胞几乎完全丧失p67 mRNA、p67蛋白和蛋白质合成活性。佛波醇12-肉豆蔻酸酯13-乙酸酯添加后，相同的血清饥饿的细胞恢复p67 mRNA，p67蛋白，和蛋白质合成活性。此外，从血清饥饿的细胞提取物磷酸化的真核起始因子-2（eIF-2）α-亚基。当使用来自在完全培养基中生长的细胞或丝裂原活化的细胞的提取物时，没有观察到这种eIF-2 α-亚基磷酸化（Gupta，S.，吴，S.，查特吉，N.，Ilan，J.，Ilan，J.，奥斯特曼，J.C.，和Gupta，N. K. 05 The Dog of the Dog（1995）5，113-122）。现报告如下。1)eIF-2激酶活性在完全培养基中生长的细胞中，在血清饥饿和随后的有丝分裂原刺激后是相同的。然而，在完全培养基中生长的细胞中的eIF-2激酶以及在血清饥饿细胞的有丝分裂原活化后不能磷酸化eIF-2 α-亚基，因为这些细胞含有p67。在通过p67抗体去除内源性p67后，来自所有这些细胞的提取物类似地磷酸化外源性添加eIF-2。2)没有一种细胞提取物显示出p67去糖基化酶活性。3)通过表达p67 cDNA，在血清饥饿的细胞中合成p67 mRNA。在血清饥饿的细胞中，p67 mRNA的出现伴随着p67蛋白的出现。此外，在血清饥饿的细胞中的蛋白质合成率恢复到接近在汇合细胞中观察到的水平。p67 cDNA的表达也显着增加在完全培养基中生长的细胞和有丝分裂原激活的细胞中的蛋白质合成速率。这些结果表明，血清饥饿细胞中蛋白质合成活性的丧失是由于p67 mRNA的丧失。p67 mRNA在血清饥饿细胞中表达稳定。因此，这些结果表明，在血清饥饿的细胞中p67 mRNA的损失是由于p67转录的损失。p67转录调节翻译。
The regulation of protein synthesis was studied in KRC-7 cells (rat hepatoma) grown in complete medium, during serum starvation, and mitogen activation. Upon serum starvation, the cells lost almost completely p67 mRNA, p67 protein, and protein synthesis activity. After phorbol 12-myristate 13-acetate addition, the same serum-starved cells regained p67 mRNA, p67 protein, and protein synthesis activity. Also, the extracts from the serum-starved cells phosphorylated the eukaryotic initiation factor-2 (eIF-2) α-subunit. This eIF-2 α-subunit phosphorylation was not observed when the extracts from either the cells grown in complete medium or mitogen-activated cells were used (Gupta, S., Wu, S., Chatterjee, N., Ilan, J., Ilan, J., Osterman, J. C., and Gupta, N. K. (1995) Gene Expr. 5, 113–122). We now report the following. 1) The eIF-2 kinase activity was the same in the cells grown in complete medium, after serum starvation, and subsequent mitogen stimulation. However, the eIF-2 kinase in the cells grown in complete medium and also after mitogen activation of the serum-starved cells cannot phosphorylate eIF-2 α-subunit as these cells contain p67. After removal of endogenous p67 by p67 antibodies, the extracts from all these cells similarly phosphorylated exogenously added eIF-2. 2) None of the cell extracts showed p67 deglycosylase activity. 3) The p67 mRNA was synthesized in serum-starved cells by expression of a p67 cDNA. The appearance of p67 mRNA in the serum-starved cells was accompanied by the appearance of p67 protein. Also, the rates of protein synthesis in the serum-starved cells were restored nearly to the level observed in the confluent cells. The expression of p67 cDNA also significantly increased protein synthesis rates in the cells grown in complete medium and in mitogen-activated cells. These results show that the loss of protein synthesis activity in serum-starved cells was due to loss of p67 mRNA. The expressed p67 mRNA was stable in serum-starved cells. These results, therefore, suggest that the loss of p67 mRNA in serum-starved cells is due to loss of p67 transcription. The p67 transcription regulates translation.