Reciprocal regulation of β1-adrenergic receptor gene transcription by Sp1 and early growth response gene 1:: Induction of EGR-1 inhibits the expression of the β1-adrenergic receptor gene
Reciprocal regulation of β1-adrenergic receptor gene transcription by Sp1 and early growth response gene 1:: Induction of EGR-1 inhibits the expression of the β1-adrenergic receptor gene
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DOI：
10.1124/mol.61.2.379
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发表时间：
2002-02-01
影响因子：
3.6
通讯作者：
Vu, KN
中科院分区：
文献类型：
--
作者：
Bahouth, SW;Beauchamp, MJ;Vu, KN
β（1）-肾上腺素能受体（β（1）-AR）在调节心率和响应于儿茶酚胺的收缩性中起关键作用。我们的研究集中在确定调节β（1）-AR基因表达的因素。我们确定β（1）-AR启动子中bp-394和bp-330之间的65个碱基对（bp）区域指导基础转录。位于-377和-365之间的元素可以结合Sp1和Sp3。在果蝇SL 2细胞中，Sp1刺激β 1-AR启动子的表达，而Sp3不能激活转录。定点突变表明，一个完整的Sp1结合位点是必不可少的基础启动子的活性保持。除了结合Sp家族成员外，-381和-367之间的核苷酸可以结合锌指转录因子Egr-1。Egr-1和Sp1结合位点部分重叠，其结合序列在哺乳动物β（1）-AR基因中是保守的。用佛波醇-12-肉豆蔻酸酯-13-乙酸酯诱导新生大鼠心室肌细胞中的Egr-1，或在HeLa S3细胞中通过调节四环素应答启动子中Egr-1的表达，抑制β（1）-AR启动子的表达。SK-N-MC细胞中Sp1的过表达使β（1）-AR mRNA增加了2.4倍，而Egr-1的过表达使β（1）-AR mRNA减少了40%。Egr-1与Sp1的共表达使Sp1介导的β（1）-AR mRNA上调降低60%。突变显示，完整的Sp1结合位点对于观察Egr-1的转录抑制是必不可少的，并且Egr-1通过与Sp1竞争结合到其重叠位点来抑制β（1）-AR基因的转录。这些结果揭示了一种新的生理相关的转录机制，相互调节β（1）-AR基因的表达。
The beta(1) -adrenergic receptor (beta(1)-AR) plays a key role in regulating heart rate and contractility in response to catecholamines. Our studies have focused on defining the factors that regulate the expression of the beta(1)-AR gene. We determined that a 65-base-pair (bp) region in the beta(1)-AR promoter between bp-394 and bp -330 directs basal transcription. An element located between -377 and -365 can bind Sp1 and Sp3. In Drosophila melanogaster SL2 cells, Sp1 stimulated the expression of the beta(1)-AR promoter, whereas Sp3 was unable to activate transcription. Site-directed mutagenesis indicated that an intact Sp1-binding site is essential for maintaining the activity of the basal promoter. In addition to binding Sp family members, the nucleotides between -381 and -367 can bind the zinc-finger transcription factor Egr-1. The Egr-1 and Sp1 binding sites are partially overlapping and their binding sequence is conserved among mammalian beta(1)-AR genes. The induction of Egr-1 in rat neonatal ventricular myocytes with phorbol-12-myristate-13-acetate or in HeLa S3 cells by regulated expression of Egr-1 in a tetracycline-responsive promoter, suppressed expression from the beta(1)-AR promoter. Overexpression of Sp1 in SK-N-MC cells increased beta(1)-AR mRNA by 2.4-fold, whereas overexpression of Egr-1 reduced beta(1)-AR mRNA by 40%. Coexpression of Egr-1 with Sp1 reduced Sp1-mediated up-regulation of beta(1)-AR mRNA by 60%. Mutagenesis revealed that an intact Sp1-binding site is essential for observing transcriptional repression by Egr-1 and that Egr-1 suppressed the transcription of the beta(1)-AR gene by competing with Sp1 for binding to their overlapping sites. These results reveal a novel physiologically relevant transcriptional mechanism for reciprocal regulation of beta(1)-AR gene expression.