Reduced force production during low blood flow to the heart correlates with altered troponin I phosphorylation
Reduced force production during low blood flow to the heart correlates with altered troponin I phosphorylation
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DOI：
10.1007/s10974-009-9180-2
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发表时间：
2009-06-01
影响因子：
2.7
通讯作者：
Ogut, Ozgur
中科院分区：
文献类型：
--
作者：
Christopher, Bridgette;Pizarro, Gresin O.;Ogut, Ozgur
建立低心肌血流量的大鼠模型来检验细肌丝和粗肌丝蛋白质的翻译后变化与心肌收缩力下降相关的假设。左前降支动脉收缩导致低血流量3天后，大鼠心脏在休息时表现出缩短分数减少，并且与低剂量多巴酚丁胺相比，在接受高剂量多巴酚丁胺刺激时，缩短分数相对下降，反映出能量储备减少。与假手术的对应物相比，来自低血流量心脏的透化纤维表现出每个横截面的最大力和 Ca2+ 敏感性的下降。通过二维凝胶电泳、质谱和磷酸化特异性抗体对肌节蛋白进行检查，为肌钙蛋白 I (TnI) 的 Ser23/24 和 Ser43/45 磷酸化提供了证据。总 TnI 磷酸化在各组之间没有差异，但 Ser23/24 磷酸化随着低血流量而下降，这意味着 TnI 其他位点的磷酸化随之增加。亲和层析表明，与来自假手术心脏的 TnI 相比，来自低血流心肌的 TnI 对 Ca2+ 结合肌钙蛋白 C 的相对亲和力降低，从而提供了降低低血流纤维中产生力的 Ca2+ 敏感性的机制。这些发现表明，由于磷酸化位点分布的变化而导致的 TnI 功能改变是导致心脏收缩力降低的早期因素。
A rat model of low myocardial blood flow was established to test the hypothesis that post-translational changes to proteins of the thin and thick muscle filaments correlate with decreased cardiac contractility. Following 3 days of low blood flow by constriction of the left anterior descending artery, rat hearts demonstrated a reduction in fractional shortening at rest and a relative decline in fractional shortening when challenged with high dose versus low dose dobutamine, reflecting reduced energy reserves. Permeabilized fibers from low blood flow hearts demonstrated a decline in maximum force per cross-section and Ca2+ sensitivity as compared to their sham operated counterparts. An examination of sarcomeric proteins by twodimensional gel electrophoresis, mass spectrometry, and phospho-specific antibodies provided evidence for Ser23/24 and Ser43/45 phosphorylation of troponin I (TnI). Total TnI phosphorylation was not different between the groups, but Ser23/24 phosphorylation declined with low blood flow, implying an accompanying increase in phosphorylation at other sites of TnI. Affinity chromatography demonstrated that TnI from low blood flow myocardium had reduced relative affinity to Ca2+ bound troponin C compared to TnI from sham operated hearts, providing a mechanism for reduced Ca2+ sensitivity of force production in low blood flow fibers. These findings suggest that altered TnI function, due to changes in the distribution of phosphorylated sites, is an early contributor to reduced contractility of the heart.