KV1.5 potassium channel gene regulation by Sp1 transcription factor and oxidative stress
KV1.5 potassium channel gene regulation by Sp1 transcription factor and oxidative stress
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DOI：
10.1152/ajpheart.00637.2007
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发表时间：
2007-11-01
影响因子：
4.8
通讯作者：
Beech, David J.
中科院分区：
文献类型：
--
作者：
Fountain, Samuel J.;Cheong, Alex;Beech, David J.
K（V）1.5是一种电压门控钾通道，在调节血管张力和心脏动作电位方面具有重要的功能，并且是许多治疗药物开发计划的目标。尽管K（V）1.5很重要，但人们对其基础基因Kcna 5的表达控制机制知之甚少。我们鉴定了鼠Kcna 5基因的5'侧翼区，其驱动原代平滑肌细胞和平滑肌细胞系中荧光素酶报告基因的表达。该启动子含有CACCC核苷酸基序，我们已经证明，在体内生理条件下结合主动脉中的Sp1转录因子。抑制Sp1-Kcna 5启动子的相互作用，使用光辉霉素A，显性负Sp1突变体，或破坏的CACCC盒通过诱变抑制启动子活性。相反，外源Sp1的表达增强启动子活性。Sp1对氧化应激具有已知的敏感性，并且与此属性一致，Kcna 5启动子活性被过氧化氢诱导的氧化应激抑制。我们的研究结果表明，Kcna 5启动子在血管平滑肌的活性是严重依赖于Sp1的调节通过CACCC盒基序和识别机制，可能会影响K（V）1.5通道的表达在生理或病理条件下的表达。
K(V)1.5, a voltage-gated potassium channel, has functional importance in regulating blood vessel tone and cardiac action potentials and is a target for numerous therapeutic drug development programs. Despite the importance of K(V)1.5, there is little knowledge of the mechanisms controlling expression of its underlying gene, Kcna5. We identified a 5' flanking region of the murine Kcna5 gene that drives expression of a luciferase reporter gene in primary smooth muscle cells and a smooth muscle cell line. The promoter contained CACCC nucleotide motifs, which we have shown to bind the Sp1 transcription factor in the aorta under physiological conditions in vivo. Inhibition of Sp1-Kcna5 promoter interactions using mithramycin A, a dominant-negative Sp1 mutant, or disruption of the CACCC boxes by mutagenesis inhibited promoter activity. Conversely, expression of exogenous Sp1 augmented promoter activity. Sp1 has known sensitivity to oxidative stress and, consistent with this property, Kcna5 promoter activity was suppressed by hydrogen peroxide-induced oxidative stress. Our results show that Kcna5 promoter activity in vascular smooth muscle is critically dependent on Sp1 regulation via CACCC box motifs and identify mechanisms that potentially influence the expression of K(V)1.5 channel expression in physiological or pathological conditions.