Transcriptional regulation of N-acetylglutamate synthase.
Transcriptional regulation of N-acetylglutamate synthase.
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DOI：
10.1371/journal.pone.0029527
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发表时间：
2012
期刊：
影响因子：
3.7
通讯作者：
Caldovic L
中科院分区：
文献类型：
--
作者：
Heibel SK;Lopez GY;Panglao M;Sodha S;Mariño-Ramírez L;Tuchman M;Caldovic L
尿素循环在哺乳动物的肝脏内将有毒的氨转化为尿素。尿素生成至少需要6种酶，这与膳食蛋白质摄入量有关。尿素循环基因的转录至少部分地受糖皮质激素和胰高血糖素激素信号通路调节。N-乙酰谷氨酸合酶（NAGS）产生一种独特的辅因子，N-乙酰谷氨酸（NAG），其对于尿素生成的第一和限速酶氨甲酰磷酸合成酶1（CPS 1）的催化功能是必需的。然而，尽管NAGS在氨去除中起着重要作用，但对其调节机制知之甚少。我们确定了NAGS基因翻译起始上游的两个高度保守区域。报告基因测定证实，这些区域代表启动子和增强子，并且增强子是组织特异性的。在启动子内，我们确定了肝脏和小肠之间不同的多个转录起始位点。几个转录因子结合基序保守的启动子和增强子区域内，而TATA盒基序是不存在的。DNA-蛋白质下拉分析和染色质免疫沉淀证实了Sp1和CREB的结合，而不是C/EBP在启动子和HNF-1和NF-Y的结合，而不是SMAD 3或AP-2在增强子中。这些基序的功能的重要性，证明了报告构建体的每个基序的诱变后的转录减少。所呈现的数据强烈地表明，已知响应于激素和饮食的Sp1、CREB、HNF-1和NF-Y调节NAGS转录。这提供了响应激素和饮食变化的尿素生成调节的分子机制。
The urea cycle converts toxic ammonia to urea within the liver of mammals. At least 6 enzymes are required for ureagenesis, which correlates with dietary protein intake. The transcription of urea cycle genes is, at least in part, regulated by glucocorticoid and glucagon hormone signaling pathways. N-acetylglutamate synthase (NAGS) produces a unique cofactor, N-acetylglutamate (NAG), that is essential for the catalytic function of the first and rate-limiting enzyme of ureagenesis, carbamyl phosphate synthetase 1 (CPS1). However, despite the important role of NAGS in ammonia removal, little is known about the mechanisms of its regulation. We identified two regions of high conservation upstream of the translation start of the NAGS gene. Reporter assays confirmed that these regions represent promoter and enhancer and that the enhancer is tissue specific. Within the promoter, we identified multiple transcription start sites that differed between liver and small intestine. Several transcription factor binding motifs were conserved within the promoter and enhancer regions while a TATA-box motif was absent. DNA-protein pull-down assays and chromatin immunoprecipitation confirmed binding of Sp1 and CREB, but not C/EBP in the promoter and HNF-1 and NF-Y, but not SMAD3 or AP-2 in the enhancer. The functional importance of these motifs was demonstrated by decreased transcription of reporter constructs following mutagenesis of each motif. The presented data strongly suggest that Sp1, CREB, HNF-1, and NF-Y, that are known to be responsive to hormones and diet, regulate NAGS transcription. This provides molecular mechanism of regulation of ureagenesis in response to hormonal and dietary changes.
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DOI：
10.1016/s0006-291x(02)02696-7
发表时间：
2002-12-13
影响因子：
3.1
作者：
Caldovic, L;Morizono, H;Tuchman, M
通讯作者：
Tuchman, M
影响因子：
64.5
作者：
DORN, A;BOLLEKENS, J;MATHIS, D
通讯作者：
MATHIS, D
影响因子：
5.3
作者：
Christoffels, VM;Grange, T;Lamers, WH
通讯作者：
Lamers, WH
DOI：
10.1016/0167-4781(88)90128-5
发表时间：
1988-09-07
期刊：
BIOCHIMICA ET BIOPHYSICA ACTA
影响因子：
--
作者：
DUBOIS, N;CAVARD, C;BRIAND, P
通讯作者：
BRIAND, P
影响因子：
2.9
作者：
Deng, WG;Zhu, Y;Wu, KK
通讯作者：
Wu, KK