Transcriptional regulation of L-type calcium channel expression in cardiac myocytes
Transcriptional regulation of L-type calcium channel expression in cardiac myocytes
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DOI：
10.1006/jmcc.2000.1217
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发表时间：
2000-10-01
影响因子：
5
通讯作者：
Marsh, JD
中科院分区：
文献类型：
--
作者：
Fan, QI;Chen, B;Marsh, JD
L型钙通道是一种异源多聚体蛋白复合物，在心肌肌膜中表达。尽管蛋白激酶A（PKA）对其亚基的翻译后调节已被广泛报道，但对调节钙通道亚基（α（1C）、α（2）-δ和β（2A）亚基）表达的分子过程知之甚少。我们小组以前的研究表明，用β-肾上腺素能激动剂处理肌细胞可增加α（1C）单位的稳态mRNA水平。本研究旨在确定L型钙通道所有亚基的mRNA水平是否受β-肾上腺素能激动剂协调控制，以及这是否主要通过控制转录速率而发生。核运行分析被用来确定这些基因在培养的新生大鼠心肌细胞的转录起始率。在异丙肾上腺素（10（-7）M）处理的心肌细胞中，编码α（1C）、α（2）-δ和β（2A）亚基的基因转录增强。α（1C）、α（2）-δ和β（2A）亚基基因的转录起始速率的增加分别为对照的404%、367%和240%。用β-肾上腺素能拮抗剂普萘洛尔（10（-5）M）或PKA抑制剂H-89（10（-6）M）预处理可阻断异丙肾上腺素的作用，而单独使用这两种药物对基因转录率没有显著影响。异丙肾上腺素治疗后，亚基的稳态mRNA水平增加。这些结果表明β-肾上腺素能刺激和PKA信号通路在心肌细胞L-型钙通道的转录调控中起重要作用。该离子通道的所有亚基的表达都在协同转录控制下。(C)北京大学出版社.
The L-type calcium channel is a heteromultimeric protein complex, which is expressed in the cardiac sarcolemma. Although post-translational regulation of its subunits by protein kinase A (PKA) has been widely reported, little is known about molecular processes that regulate expression of calcium channel subunits (alpha (1C), alpha (2)-delta, and beta (2A) subunits). Previous studies from our group demonstrate that the steady-state mRNA level of the alpha (1C) unit is increased by treatment of myocytes with beta -adrenergic agonists. The current study is designed to determine whether the mRNA levels for all subunits of the L-type calcium channel are coordinately controlled by a beta -adrenergic agonist, and whether this occurs predominantly through control of rate of transcription. Nuclear run-on assays were used to determine the transcription initiation rate of these genes in cultured neonatal rat cardiac myocytes. In isoproterenol (10(-7) M)-treated myocytes, transcription of genes encoding the alpha (1C), alpha (2)-delta, and beta (2A) subunits was enhanced. The increases in transcription initiation rate for alpha (1C), alpha (2)-delta, and beta (2A) subunits genes were 404%, 367%, and 240% of control, respectively. Pretreatment with the beta -adrenergic antagonist propranolol (10(-5) M or PKA inhibitor H-89 (10(-6) M) blocked the effects of isoproterenol, while either drug alone did not affect the gene transcription rate significantly. Steady state mRNA levels of the subunits increased following isoproterenol treatment. These results suggest that beta -adrenergic stimulation and the PKA signaling pathway play an important role in transcriptional regulation of the L-type calcium channel in myocyte. The expression of all the subunits of this ion channel is under coordinate transcriptional control. (C) 2000 Academic Press.