Single molecule kinetics in the familial hypertrophic cardiomyopathy D166V mutant mouse heart
Single molecule kinetics in the familial hypertrophic cardiomyopathy D166V mutant mouse heart
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DOI：
10.1016/j.yjmcc.2009.11.004
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发表时间：
2010-05-01
影响因子：
5
通讯作者：
Borejdo, J.
中科院分区：
文献类型：
--
作者：
Muthu, Priya;Mettikolla, Prasad;Borejdo, J.
与家族性肥厚型心肌病（FHC）恶性表型相关的肌节突变之一是MYL2基因编码的心室肌球蛋白调节轻链（RLC）中的D166V点突变。在这份报告中，我们表明，肌球蛋白跨桥连接和解离率显着不同，等距收缩心脏肌原纤维从右心室转基因（Tg）-D166V和Tg-WT小鼠。我们已经推导出肌球蛋白跨桥动力学速率通过跟踪荧光标记的单个肌动蛋白分子的方向。取向（通过偏振荧光测量）在两种状态之间振荡，对应于肌动蛋白结合和肌动蛋白游离状态的肌球蛋白跨桥。在等长收缩过程中，跨桥附着率从Tg-WT肌原纤维的3 s（-1）降低到Tg-D166 V肌原纤维的1.4 s（-1）。脱离率从1.3 s（-1）（Tg-WT）降至1.2 s（-1）（Tg-D166 V）。我们还表明，与Tg-WT相比，Tg-D166V肌原纤维中的RLC磷酸化水平大大降低。我们的研究结果表明，RLC中D166V突变所带来的肌球蛋白跨桥动力学的改变可能是突变心脏功能受损的原因，并导致其无法有效泵血。(C)2009爱思唯尔有限公司版权所有。
One of the sarcomeric mutations associated with a malignant phenotype of familial hypertrophic cardiomyopathy (FHC) is the D166V point mutation in the ventricular myosin regulatory light chain (RLC) encoded by the MYL2 gene. In this report we show that the rates of myosin cross-bridge attachment and dissociation are significantly different in isometrically contracting cardiac myofibrils from right ventricles of transgenic (Tg)-D166V and Tg-WT mice. We have derived the myosin cross-bridge kinetic rates by tracking the orientation of a fluorescently labeled single actin molecule. Orientation (measured by polarized fluorescence) oscillated between two states, corresponding to the actin-bound and actin-free states of the myosin cross-bridge. The rate of cross-bridge attachment during isometric contraction decreased from 3 s(-1) in myofibrils from Tg-WT to 1.4 s(-1) in myofibrils from Tg-D166V. The rate of detachment decreased from 1.3 s(-1) (Tg-WT) to 1.2 s(-1) (Tg-D166V). We also showed that the level of RLC phosphorylation was largely decreased in Tg-D166V myofibrils compared to Tg-WT. Our findings suggest that alterations in the myosin cross-bridge kinetics brought about by the D166V mutation in RLC might be responsible for the compromised function of the mutated hearts and lead to their inability to efficiently pump blood. (C) 2009 Elsevier Ltd. All rights reserved.