Targeted inhibition of sarcoplasmic reticulum CaMKII activity results in alterations of Ca2+ homeostasis and cardiac contractility
Targeted inhibition of sarcoplasmic reticulum CaMKII activity results in alterations of Ca2+ homeostasis and cardiac contractility
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DOI：
10.1152/ajpheart.00214.2005
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发表时间：
2006-02-01
影响因子：
4.8
通讯作者：
Dedman, JR
中科院分区：
文献类型：
--
作者：
Ji, Y;Zhao, W;Dedman, JR
表达靶向心肌细胞纵向肌浆网（LSR）的Ca 2 +/钙调蛋白依赖性蛋白激酶II（CaMK II）抑制肽的转基因（TG）小鼠在Thr（17）处表现出受磷蛋白磷酸化降低，并且在妊娠和分娩应激时发展为扩张性肌病（Ji Y，Li B，Reed TD，Lorenz JN，Kaetzel MA，and Dedman JR. J Biol Chem 278：25063 - 25071，2003）。在本研究中，这些动物（TG）的肌浆网（SR）CaMKII活性的抑制对心肌细胞的收缩特性和Ca 2+循环的影响进行了评价。对离体做功心脏的分析表明，TG小鼠的最大收缩和舒张速率（+/- dP/dt）中度降低。TG心脏对负荷增加的反应降低。TG心脏对异丙肾上腺素（Iso）的反应呈剂量依赖性;与野生型心脏平行，收缩性能降低。从TG小鼠分离的心肌细胞的评估显示，在基础和Iso刺激条件下，肌细胞缩短和再延长的最大速率降低40 - 47%。虽然抽搐钙离子瞬时振幅没有显着改变，抽搐细胞内钙离子浓度下降的速度减少了类似的47%，在TG肌细胞，表明SR钙摄取功能下降。咖啡因诱导的Ca 2+瞬变表明SR Ca 2+含量和Na+/Ca 2+交换功能不变。磷酸化试验显示兰尼碱受体Ser的磷酸化水平降低了30%（2809）。Iso刺激增加TG小鼠受磷蛋白Ser（16）和ryanodine受体Ser 2809的磷酸化，但不增加受磷蛋白Thr 17的磷酸化。这项研究表明，抑制SR CaMKII活性在LSR的结果在TG心脏的心脏收缩力和Ca 2+处理的改变。
Transgenic ( TG) mice expressing a Ca2+/calmodulin-dependent protein kinase II ( CaMKII) inhibitory peptide targeted to the cardiac myocyte longitudinal sarcoplasmic reticulum ( LSR) display reduced phospholamban phosphorylation at Thr(17) and develop dilated myopathy when stressed by gestation and parturition ( Ji Y, Li B, Reed TD, Lorenz JN, Kaetzel MA, and Dedman JR. J Biol Chem 278: 25063 - 25071, 2003). In the present study, these animals ( TG) are evaluated for the effect of inhibition of sarcoplasmic reticulum ( SR) CaMKII activity on the contractile characteristics and Ca2+ cycling of myocytes. Analysis of isolated work-performing hearts demonstrated moderate decreases in the maximal rates of contraction and relaxation ( +/- dP/dt) in TG mice. The response of the TG hearts to increases in load is reduced. The TG hearts respond to isoproterenol ( Iso) in a dose-dependent manner; the contractile properties were reduced in parallel to wild-type hearts. Assessment of isolated cardiomyocytes from TG mice revealed 40 - 47% decrease in the maximal rates of myocyte shortening and relengthening under both basal and Iso-stimulated conditions. Although twitch Ca2+ transient amplitudes were not significantly altered, the rate of twitch intracellular Ca2+ concentration decline was reduced by similar to 47% in TG myocytes, indicating decreased SR Ca2+ uptake function. Caffeine-induced Ca2+ transients indicated unaltered SR Ca2+ content and Na+/Ca2+ exchange function. Phosphorylation assays revealed an similar to 30% decrease in the phosphorylation of ryanodine receptor Ser(2809). Iso stimulation increased the phosphorylation of both phospholamban Ser(16) and the ryanodine receptor Ser2809 but not phospholamban Thr17 in TG mice. This study demonstrates that inhibition of SR CaMKII activity at the LSR results in alterations in cardiac contractility and Ca2+ handling in TG hearts.