A single site (Ser16) phosphorylation in phospholamban is sufficient in mediating its maximal cardiac responses to β-agonists
A single site (Ser16) phosphorylation in phospholamban is sufficient in mediating its maximal cardiac responses to β-agonists
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DOI：
10.1074/jbc.m004079200
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发表时间：
2000-12-08
影响因子：
4.8
通讯作者：
Kranias, EG
中科院分区：
文献类型：
--
作者：
Chu, GX;Lester, JW;Kranias, EG
受磷蛋白（PLB）在β-激动剂刺激期间可通过环AMP依赖性蛋白激酶在Ser（16）处磷酸化，并通过Ca 2 +-钙调蛋白依赖性蛋白激酶在Thr（17）处磷酸化。先前的研究表明，PLB中S16 A的突变导致灌注小鼠心脏中Thr（17）磷酸化的缺乏和β激动剂刺激作用的减弱。为了进一步描述双位点PLB磷酸化之间的功能相互作用，我们产生了在无效背景的心脏隔室中表达T17 A突变PLB的转基因小鼠。在空白背景中表达相似水平的T17 A突变体、S16 A突变体或野生型PLB的株系被平行表征。三组间心肌细胞基础力学和Ca 2+动力学相似。异丙肾上腺素刺激与野生型PLB中Ser（16）和Thr（17）的磷酸化以及T17 A突变型PLB中Ser（16）的磷酸化相关，而S16 A突变型PLB没有可检测的磷酸化。在T17 A突变体PLB中单独的Ser（16）磷酸化导致与野生型肌细胞中类似的机械和Ca 2+动力学参数对异丙肾上腺素的响应，其表现出双位点PLB磷酸化。然而，这些参数在S16 A突变体心肌细胞中显著减弱。因此，PLB中的Ser（16）可以在体内独立于Thr（17）磷酸化，并且Ser（16）的磷酸化足以介导对β-肾上腺素能刺激的最大心脏反应。
Phospholamban (PLB) can be phosphorylated at Ser(16) by cyclic AMP-dependent protein kinase and at Thr(17) by Ca2+-calmodulin-dependent protein kinase during beta -agonist stimulation. A previous study indicated that mutation of S16A in PLB resulted in lack of Thr(17) phosphorylation and attenuation of the beta -agonist stimulatory effects in perfused mouse hearts. To further delineate the functional interplay between dual-site PLB phosphorylation, we generated transgenic mice expressing the T17A mutant PLB in the cardiac compartment of the null background. Lines expressing similar levels of T17A mutant, S16A mutant, or wild-type PLB in the null background mere characterized in parallel. Cardiac myocyte basal mechanics and Ca2+ kinetics were similar among the three groups. Isoproterenol stimulation was associated with phosphorylation of both Ser(16) and Thr(17) in wild-type PLB and Ser(16) phosphorylation in T17A mutant PLB, whereas there was no detectable phosphorylation of S16A mutant PLB. Phosphorylation of Ser(16) alone in T17A mutant PLB resulted in responses of the mechanical and Ca2+ kinetic parameters to isoproterenol similar to those in wild-type myocytes, which exhibited dual-site PLB phosphorylation. However, those parameters were significantly attenuated in the S16A mutant myocytes. Thus, Ser(16) in PLB can be phosphorylated independently of Thr(17) in vivo, and phosphorylation of Ser(16) is sufficient for mediating the maximal cardiac responses to beta -adrenergic stimulation.