OVEREXPRESSION OF G(S-ALPHA) PROTEIN IN THE HEARTS OF TRANSGENIC MICE
OVEREXPRESSION OF G(S-ALPHA) PROTEIN IN THE HEARTS OF TRANSGENIC MICE
复制标题
DOI：
10.1172/jci117843
复制
发表时间：
1995-04-01
影响因子：
15.9
通讯作者：
HOMCY, CJ
中科院分区：
文献类型：
--
作者：
GAUDIN, C;ISHIKAWA, Y;HOMCY, CJ
β-肾上腺素能受体-G（s）-腺苷酸环化酶偶联的改变是降低的儿茶酚胺反应性的基础，这是人类和动物心力衰竭模型的标志。为了研究G（s α）表达改变的影响，我们使用大鼠α-肌球蛋白重链启动子在转基因小鼠心脏中过表达G（s α）的短亚型。在转基因小鼠的心脏中，G（s α）mRNA水平选择性地增加，其水平为对照的38倍。尽管mRNA显著增加，但Western印迹法鉴定出G（s α）短同种型的含量仅增加2.8倍，而G（s）活性增加了88%，G（s α）mRNA和G（s α）蛋白水平之间的差异表明，G（s α）的膜含量是转录后调节的。稳态腺苷酸环化酶催化活性在基础或刺激条件（GTP +异丙肾上腺素、GTP γ S、NaF或毛喉素）下均未改变。然而，进展曲线研究确实显示GppNHp刺激腺苷酸环化酶活性所需的滞后期显著减少，此外，具有高亲和力的β-肾上腺素能受体结合激动剂的相对数量显著增加，我们的数据表明，偶联蛋白G（s alpha）的量相对较小的增加可以改变催化剂活化的速率和激动剂高亲和力受体的形成。
Alterations in beta-adrenergic receptor-G(s)-adenylyl cyclase coupling underlie the reduced catecholamine responsiveness that is a hallmark of human and animal models of heart failure, To study the effect of altered expression of G(s alpha), we overexpressed the short isoform of G(s alpha) in the hearts of transgenic mice, using a rat alpha-myosin heavy chain promoter. G(s alpha) mRNA levels were increased selectively in the hearts of transgenic mice, with a level 38 times the control, Despite this marked increase in mRNA, Western blotting identified only a 2.8-fold increase in the content of the G(s alpha) short isoform, whereas G(s) activity was increased by 88%, The discrepancy between G(s alpha) mRNA and G(s alpha) protein levels suggests that the membrane content of G(s alpha) is posttranscriptionally regulated. The steady-state adenylyl cyclase catalytic activity was not altered under either basal or stimulated conditions (GTP + isoproterenol, GTP gamma S, NaF, or forskolin). However, progress curve studies did show a significant decrease in the lag period necessary for GppNHp to stimulate adenylyl cyclase activity, Furthermore, the relative number of beta-adrenergic receptors binding agonist with high affinity was significantly increased, Our data demonstrate that a relatively small increase in the amount of the coupling protein G(s alpha) can modify the rate of catalyst activation and the formation of agonist high affinity receptors.