Myosin Regulatory Light Chain (RLC) Phosphorylation Change as a Modulator of Cardiac Muscle Contraction in Disease
Myosin Regulatory Light Chain (RLC) Phosphorylation Change as a Modulator of Cardiac Muscle Contraction in Disease
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肌球蛋白调节轻链 (RLC) 磷酸化变化作为疾病中心肌收缩的调节剂
DOI：
10.1016/j.bpj.2012.11.1720
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发表时间：
2013
影响因子：
3.4
通讯作者：
Toepfer C
中科院分区：
文献类型：
--
作者：
Toepfer C
方法和结果：SDS-PAGE电泳测定心力衰竭对人心力衰竭（HF）样品和大鼠慢性MI模型上cRLC磷酸化的影响。我们报告了在心衰进展中RLC磷酸化的增加。克隆并表达重组cRLC。重组RLC差异磷酸化在体外使用心肌肌球蛋白轻链激酶（cMLCK）和ZIP激酶。将重组RLC物质交换到透化的心脏小梁中，以在缩短期间进行机械测量（松弛测试和力-速度实验方案）。我们观察到降低RLC磷酸化时，峰值功率，峰值功率速度（VPP）和峰值等长收缩力下降。相反，与对照相比，富集RLC磷酸化增加峰值功率、VPP和峰值最大无负荷缩短速度（VMAX）。结论：改变cRLC磷酸化对心肌的机械功能具有显著影响，并且在HF进展期间显著改变。这些结果强调了理解粗丝调节的重要性，特别是cRLC磷酸化调节心肌功能的能力。1583-Pos Board B475比目鱼肌中Titin近端IG结构域的去除导致Titin mRNA的差异剪接Danielle E.查尔斯·巴克Chung，John E.史密斯，亨克L.格朗齐耶美国亚利桑那州图森市亚利桑那大学。肌联蛋白是已知的最大的蛋白质，在横纹肌中起分子弹簧的作用。其弹性特性是通过肌联蛋白的弹簧样结构域（包括免疫球蛋白样（IG）和PEVK）的差异剪接获得的。我们的实验室最近创建了一种新的小鼠模型，其中9个近端IG结构域（肌联蛋白外显子30-38，蛋白质大小减少90 kDa）被删除（IG KO）。令人惊讶的是，在来自IG KO小鼠的骨骼肌中，发现肌联蛋白经历额外的差异剪接以产生较小的肌联蛋白同种型。这些剪接的变化被发现是发育调节的，并在不同的肌肉中发生不同程度的变化。最显著的是，在成年比目鱼肌中，与野生型小鼠中发现的一种较大的同种型（3.61 MDa 5 0.057）相比，IG KO中存在两种较小的肌联蛋白同种型（分别为3.42 MDa 5 0.008和3.24 MDa 5 0.027）。Titin微阵列分析显示，与野生型相比，IG KO小鼠除了缺少外显子30-38之外，还具有PEVK区域中外显子的显著下调。与肌联蛋白大小的减少一致，IG KO比目鱼肌在肌肉松弛长度以上20%处产生增加的被动张力（19%，p= 0.02），如通过完整力学探测的。然而，与IG KO相比，野生型中比目鱼肌和其他肌肉的最大主动张力没有显著差异。通过Affytek Array发现两种肌联蛋白结合蛋白差异表达，CARP（在IG KO中增加7.23倍，p< 0.001）和肌桥蛋白（在IG KO中减少2.13倍，p< 0.001）。肌联蛋白结合蛋白差异表达的原因及选择性剪接的肌肉特异性变化有待进一步研究。
Methods and Results: SDS-PAGE electrophoresis determined the effects of heart failure on cRLC phosphorylation on human heart failure (HF) samples and a rat chronic-MI model. We report an increase in RLC phosphorylation in HF progression. Recombinant cRLC was cloned and expressed. Recombinant RLC was differentially phosphorylated in-vitro using cardiac myosin light chain kinase (cMLCK) and ZIP kinase. Recombinant RLC species were exchanged into permeabilised cardiac trabeculae to perform mechanical measurements during shortening (slack test and force-velocity experimentation protocols). We observed a decrease in peak power, velocity at peak power (VPP) and peak isometric force of contraction when reducing RLC phosphorylation. Conversely, enriching RLC phosphorylation increased peak power, VPP and peak maximal unloaded shortening velocity (VMAX) in comparison to control. Conclusions: Altering cRLC phosphorylation has a significant impact on the mechanical function of cardiac muscle and is dramatically altered during HF progression. These results highlight the importance of understanding thick filament regulation and specifically the ability of cRLC phosphorylation to regulate cardiac muscle function.1583-Pos Board B475 Removal of Proximal IG Domains of Titin in Soleus Muscle Results in Differential Splicing of Titin MRNA Danielle E. Buck, Charles S. Chung, John E. Smith, Henk L. Granzier. University of Arizona, Tucson, AZ, USA. Titin is the largest protein known that functions as a molecular spring in striated muscle. Its elastic properties are acquired through differential splicing of spring-like domains of titin including the immunoglobuline-like (IG) and PEVK. Our lab has recently created a novel mouse model in which nine of the proximal IG domains (titin exons 30-38, 90kDa reduction in protein size) have been deleted (IG KO). Surprisingly in the skeletal muscles from IG KO mice, titin was found to undergo additional differential splicing to yield smaller titin isoforms. These changes in splicing were found to be developmentally regulated and occur to different extents in various muscles. Most prominently, in the adult soleus muscle, two smaller titin isoforms were present in the IG KO (3.42 MDa 5 0.008 and 3.24 MDa 5 0.027 respectively) as compared to one larger isoform found in wild-type mice (3.61 MDa 5 0.057). Titin microarray analysis revealed IG KO mice had significant downregulation of exons in the PEVK region in addition to the lack of exons 30-38 as compared to wild-type. Consistent with a decrease in titin size, IG KO soleus muscles produced an increased passive tension (19%, p= 0.02) at 20% above slack length of the muscle as probed by intact mechanics. However, maximal active tension in the soleus and other muscles were not significantly different in the wildtype as compared to IG KO. Two titin binding proteins were found to be differentially expressed by Affymetrix Array, CARP (7.23 fold increased in IG KO, p< 0.001) and myomesin (2.13 fold decreased in IG KO, p< 0.001). The reason for the differential expression of titin binding proteins and the muscle specific changes in alternative splicing need to be further studied.
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肌球蛋白轻链
影响因子：
64.8
作者：
A. Weeds
通讯作者：
A. Weeds
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DOI：
10.1152/ajpheart.1990.259.4.h1118
发表时间：
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期刊：
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