Peroxisomal-proliferator-activated receptor α activates transcription of the rat hepatic malonyl-CoA decarboxylase gene:: a key regulation of malonyl-CoA level
Peroxisomal-proliferator-activated receptor α activates transcription of the rat hepatic malonyl-CoA decarboxylase gene:: a key regulation of malonyl-CoA level
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DOI：
10.1042/bj20031565
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发表时间：
2004-03-15
影响因子：
4.1
通讯作者：
Kim, YS
中科院分区：
文献类型：
--
作者：
Lee, GY;Kim, NH;Kim, YS
MCD （malonyl-CoA decarboxylase）是一种催化丙二酰辅酶a脱羧的酶，在调节丙二酰辅酶a浓度中起重要作用。最近，人们观察到PPARa（过氧化物酶体增殖激活受体a）（-/-）小鼠心脏中MCD的表达显著降低，其中脂肪酸氧化率随着丙二酰辅酶a水平的增加而降低[Campbell， Kozak, Wagner, Altarejos, Dyck, Belke, Severson, Kelly and Lopaschuk (2002) J. Biol]。化学通报，2004,22(4):387 - 387。这表明MCD可能受ppar - α的转录调节。为了研究PPARalpha是否真正负责大鼠MCD基因的转录调控，我们在CV-1细胞中进行了瞬时报告实验。在共转染ppar /类视黄醇X受体a表达质粒的CV-1细胞中，启动子活性提高了17倍。在启动子区域的序列分析中，鉴定出三个假定的PPREs （PPAR响应元件），启动子缺失分析显示PPRE2和PPRE3具有功能。电泳迁移位移分析显示，pparα /类维生素a X受体异二聚体确实与两种PPRE结合，并且pparα与PPRE的结合特异性也通过突变寡核苷酸实验得到证实。这些结果表明，这些元素表现为ppar α激活的响应位点。在wy14643处理的大鼠肝癌细胞和非诺贝特喂养的大鼠肝脏中，MCD mRNA水平也被发现增加，这表明ppar α可以通过与启动子中的PPREs结合来激活大鼠肝脏MCD转录。我们认为MCD通过改变丙二酰辅酶a的浓度，在了解活化的PPARa和脂肪酸氧化之间的调节机制方面发挥了重要作用。
MCD (malonyl-CoA decarboxylase), which catalyses decarboxylation of malonyl-CoA, is known to play an important role in the regulation of malonyl-CoA concentration. Recently, it has been observed that the expression of MCD is significantly decreased in the hearts of the PPARa (peroxisome-proliferator-activated receptor a) (-/-) mice, where the rate of fatty-acid oxidation is decreased by the increased malonyl-CoA level [Campbell, Kozak, Wagner, Altarejos, Dyck, Belke, Severson, Kelly and Lopaschuk (2002) J. Biol. Chem. 277, 4098-4103]. This suggests that MCD may be transcriptionally regulated by PPARalpha. To investigate whether PPARalpha is truly responsible for transcriptional regulation of the rat MCD gene, transient reporter assay was performed in CV-1 cells. The promoter activity was increased by 17-fold in CV-1 cells co-transfected with PPARalpha/ retinoid X receptor a expression plasmid. In sequence analysis of the promoter region, three putative PPREs (PPAR response elements) were identified, and promoter deletion analysis showed that PPRE2 and PPRE3 were functional. Electrophoretic mobility-shift assays revealed that PPARalpha/retinoid X receptor a heterodimer indeed bound to the two PPREs, and the binding specificity of PPARalpha on PPRE was also confirmed by experiments with mutated oligonucleotides. These results indicate that the elements behaved as a responsive site to PPARalpha activation. MCD mRNA levels in WY14643-treated rat hepatoma cells as well as in the liver of fenofibrate-fed Otsuka Long-Evans Tokushima fatty rats were also found to be increased, suggesting that PPARalpha can activate the rat hepatic MCD transcription by binding to the PPREs in the promoter. We propose that MCD performs an important role in understanding the regulatory mechanism between activated PPARa and fatty-acid oxidation by altering the malonyl-CoA concentration.