Transcriptional repression of the CTP:phosphocholine cytidylyltransferase gene by sphingosine.
Transcriptional repression of the CTP:phosphocholine cytidylyltransferase gene by sphingosine.
复制标题
鞘氨醇对 CTP：磷酸胆碱胞苷酰转移酶基因的转录抑制。
DOI：
10.1042/bj20040105
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发表时间：
2004
期刊：
影响因子：
--
通讯作者：
Mallampalli,RamaK
中科院分区：
文献类型：
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作者：
Ryan,AlanJ;Fisher,Kurt;Thomas,ChristieP;Mallampalli,RamaK
我们研究了生物活性脂质鞘氨醇对参与表面活性剂磷脂酰胆碱合成的限速酶CCTα（CTP：磷酸胆碱胞苷酰转移酶α）表达的影响。鞘氨醇通过抑制原代肺泡II型上皮细胞CCT活性降低磷脂酰胆碱合成。与对照组相比，鞘氨醇使CCTα蛋白和mRNA水平降低约50%。生物活性脂质不改变CCTα mRNA的稳定性，但显著抑制其转录速率。在小鼠肺上皮细胞中，鞘氨醇选择性降低CCTα启动子-报告基因活性时，转染2 kb CCTα启动子/荧光素酶基因构建体。鞘氨醇还降低了从携带该2 kb近端5′侧翼序列的CCTα启动子-报告基因转基因小鼠中分离的小鼠II型上皮细胞中的转基因表达。缺失分析显示，鞘氨醇的反应被映射到一个负调控元件内的编码区上游814 bp。结果表明，生物活性的鞘脂代谢物抑制表面活性剂脂质合成的抑制基因转录的一个关键的表面活性剂生物合成酶。
We examined the effects of the bioactive lipid, sphingosine, on the expression of the rate-limiting enzyme involved in surfactant phosphatidylcholine synthesis, CCTα (CTP:phosphocholine cytidylyltransferase α). Sphingosine decreased phosphatidylcholine synthesis by inhibiting CCT activity in primary alveolar type II epithelia. Sphingosine decreased CCTα protein and mRNA levels by approx. 50% compared with control. The bioactive lipid did not alter CCTα mRNA stability, but significantly inhibited its transcriptional rate. In murine lung epithelia, sphingosine selectively reduced CCTα promoter-reporter activity when transfected with a 2 kb CCTα promoter/luciferase gene construct. Sphingosine also decreased transgene expression in murine type II epithelia isolated from CCTα promoter-reporter transgenic mice harbouring this 2 kb proximal 5′-flanking sequence. Deletional analysis revealed that sphingosine responsiveness was mapped to a negative regulatory element contained within 814 bp upstream of the coding region. The results indicate that bioactive sphingolipid metabolites suppress surfactant lipid synthesis by inhibiting gene transcription of a key surfactant biosynthetic enzyme.