A Kruppel-like factor KLF15 contributes fasting-induced transcriptional activation of mitochondrial acetyl-CoA synthetase gene AceCS2
A Kruppel-like factor KLF15 contributes fasting-induced transcriptional activation of mitochondrial acetyl-CoA synthetase gene AceCS2
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DOI：
10.1074/jbc.m312079200
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发表时间：
2004-04-23
影响因子：
4.8
通讯作者：
Sakai, J
中科院分区：
文献类型：
--
作者：
Yamamoto, J;Ikeda, Y;Sakai, J
乙酰辅酶A合成酶2(AceCS2)通过线粒体基质中的柠檬酸循环产生乙酰辅酶A供氧化。AceCS2在骨骼肌中高表达，并在禁食后强烈诱导。对C2C12和人肌管中AceCS2转录本的定量检测表明，禁食诱导的AceCS2基因的表达似乎不依赖于胰岛素的作用。对小鼠AceCS2基因5‘侧翼区的分析表明，Kruppel-like factor15(KLF15)在AceCS2基因的反式激活中起关键作用。AceCS2启动子区域的缺失和突变分析表明，最近端的KLF位点是KLF15反式激活AceCS2基因的缩短区。利用Sp缺失的果蝇SL2细胞，我们证明了KLF15和Sp1的结合导致了AceCS2启动子的协同激活。对AceCS2启动子3个GC盒的突变分析表明，位于KLF15最近端8个碱基下游的GC盒是KLF15和Sp1协同反式激活AceCS2基因的最重要的GC盒。GST下拉实验表明KLF15在体外与Sp1相互作用。对各种KLF转录本的定量分析表明，禁食48h强烈地诱导了骨骼肌中KLF15的转录本。与AceCS2启动子的反式激活一起，KLF15在很大程度上促进了禁食诱导的AceCS2的表达。此外，KLF15过表达诱导了成肌细胞和肌管中AceCS2的转录水平，表明体内AceCS2基因的表达确实是由KLF15诱导的。
Acetyl-CoA synthetase 2 (AceCS2) produces acetylCoA for oxidation through the citric acid cycle in the mitochondrial matrix. AceCS2 is highly expressed in the skeletal muscle and is robustly induced by fasting. Quantification of AceCS2 transcripts both in C2C12 and human myotubes indicated that fasting-induced AceCS2 gene expression appears to be independent on insulin action. Characterization of 5'-flanking region of the mouse AceCS2 gene demonstrates that Kruppel-like factor 15 (KLF15) plays a key role in the trans-activation of the AceCS2 gene. Deletion and mutation analyses of AceCS2 promoter region revealed that the most proximal KLF site is a curtail site for the trans-activation of the AceCS2 gene by KLF15. Using Sp-null Drosophila SL2 cells, we showed that the combination of KLF15 and Sp1 resulted in a synergistic activation of the AceCS2 promoter. Mutation analyses of three GC-boxes in the AceCS2 promoter indicated that the GC-box, located 8 bases downstream of the most proximal KLF15 site, is the most important GC-box in the synergistic trans-activation of the AceCS2 gene by KLF15 and Sp1. GST pull-down assays showed that KLF15 interacts with Sp1 in vitro. Quantification of various KLF transcripts revealed that 48 h fasting robustly induced the KLF15 transcripts in the skeletal muscle. Together with the trans-activation of the AceCS2 promoter, it is suggested that fasting-induced AceCS2 expression is largely contributed by KLF15. Furthermore, KLF15 overexpression induced the levels of AceCS2 transcripts both in myoblasts and in myotubes, indicating that AceCS2 gene expression in vivo is indeed induced by KLF15.