Regulation of S-adenosylmethionine decarboxylase activity by alterations in the intracellular polyamine content.
Regulation of S-adenosylmethionine decarboxylase activity by alterations in the intracellular polyamine content.
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通过改变细胞内多胺含量来调节 S-腺苷甲硫氨酸脱羧酶活性。
DOI：
10.1042/bj2880511
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发表时间：
1992
期刊：
影响因子：
--
通讯作者：
Pegg,AE
中科院分区：
文献类型：
--
作者：
Shantz,LM;Holm,I;Jänne,OA;Pegg,AE
在哺乳动物细胞系（HT 29、CHO和COS-7）中研究了添加外源性亚精胺和精胺以及两种多胺生物合成抑制剂α-二氟甲基鸟氨酸（DFMO）（其降低亚精胺浓度）和正丁基-1，3-二氨基丙烷（其消耗精胺）对S-腺苷甲硫氨酸脱羧酶（ADMetDC）活性表达的影响。多胺含量与β-MetDC水平呈负相关，精胺是β-MetDC活性的更有效的阻遏物，但只有亚精胺影响β-MetDC mRNA的量。转染COS-7细胞或CHO细胞与质粒构建体含有氯霉素乙酰转移酶（CAT）报告基因驱动的部分的CRAMMEDC启动子区域表明，CAT的表达被改变亚精胺，但不是精胺，这表明有一个亚精胺响应元件在这个启动子。用pSAMh 1瞬时转染COS-7细胞，pSAMh 1是一种在具有SV 40启动子和复制起点的载体中含有pSAMhDC cDNA的质粒，导致pSAMhDC表达的大幅增加。虽然用正丁基-1，3-二氨基丙烷处理COS-7细胞大大增加了内源性pSAMh 1 MetDC活性，但该抑制剂引起的精胺耗竭并不刺激pSAMh 1 MetDC表达。pSAMh 1 cDNA从pSAMh 1 MetDC mRNA的5′端缺失72个核苷酸，精胺的翻译调控可能涉及该区域。DFMO处理可显著抑制COS-7细胞中pSAMh 1的cDNAMetDC表达，但增加了内源性cDNAMetDC活性。在COS-7细胞中，DFMO也抑制了其他含有SV 40复制起点的质粒的表达，但在CHO细胞中不抑制。DFMO处理不干扰由RSV启动子驱动的质粒的表达。这些结果表明，低亚精胺水平干扰含有SV 40复制起点的质粒的复制。
The effects of addition of exogenous spermidine and spermine and of two inhibitors of polyamine biosynthesis, alpha-difluoromethylornithine (DFMO), which decreases spermidine concentrations, and n-butyl-1,3-diaminopropane, which depletes spermine, on the expression of S-adenosylmethionine decarboxylase (AdoMetDC) activity were studied in mammalian cell lines (HT29, CHO and COS-7). AdoMetDC levels were inversely related to the polyamine content, and spermine was the more potent repressor of AdoMetDC activity, but only spermidine affected the amount of AdoMetDC mRNA. Transfection of COS-7 cells or CHO cells with plasmid constructs containing a chloramphenicol acetyltransferase (CAT) reporter gene driven by portions of the AdoMetDC promoter region indicated that CAT expression was altered by spermidine, but not by spermine, suggesting that there is a spermidine-responsive element in this promoter. Transient transfection of COS-7 cells with pSAMh1, a plasmid containing the AdoMetDC cDNA in a vector with the SV40 promoter and origin of replication, led to a large increase in AdoMetDC expression. Although treatment of COS-7 cells with n-butyl-1,3-diaminopropane greatly increased endogenous AdoMetDC activity, the spermine depletion brought about by this inhibitor did not stimulate AdoMetDC expression from pSAMh1. The pSAMh1 cDNA is missing 72 nucleotides from the 5′ end of the AdoMetDC mRNA, and it is possible that translational regulation by spermine involves this region. The expression of AdoMetDC from pSAMh1 in COS-7 cells was greatly inhibited by DFMO treatment, although endogenous AdoMetDC activity was increased. The expression of other plasmids containing the SV40 origin of replication was also inhibited by DFMO in COS-7 cells, but not in CHO cells. DFMO treatment did not interfere with the expression of plasmids driven by the RSV promoter. These results suggest that low spermidine levels interfere with the replication of plasmids containing the SV40 origin of replication.