Ubipuitin-Proteasome System Impairment Caused by a Missense Cardiac Myosin-binding Protein C Mutation and Associated with Cardiac Dysfunction in Hypertrophic Cardiomyopathy
Ubipuitin-Proteasome System Impairment Caused by a Missense Cardiac Myosin-binding Protein C Mutation and Associated with Cardiac Dysfunction in Hypertrophic Cardiomyopathy
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DOI：
10.1016/j.jmb.2008.09.070
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发表时间：
2008-12-26
影响因子：
5.6
通讯作者：
Hisatome, Ichiro
中科院分区：
文献类型：
--
作者：
Bahrudin, Udin;Morisaki, Hiroko;Hisatome, Ichiro
泛素-蛋白酶体系统是截短的心肌肌球蛋白结合蛋白C消失的原因，其活性的抑制导致心功能不全。本研究探讨肥厚型心肌病(HCM)患者心肌肌球蛋白结合蛋白C基因(MYBPC3)错义突变是否导致其蛋白质不稳定，导致UPS受损，并与心功能不全有关。用变性高效液相色谱和测序鉴定了日本人肥厚型心肌炎患者的突变。在COS-7细胞和新生大鼠心肌细胞中进行异源表达，以检测蛋白稳定性和蛋白酶体活性。超声心动图测定心功能。本研究发现了5个新的MYBPC3突变：E344K、Delta K814、Delta 2864-2865GC、Q998E和T1046M。与野生型和其他突变型相比，E334K蛋白水平显著降低，降解速度更快，具有更高的多泛素水平，在蛋白酶体抑制剂MG132(50 mM，6h)处理的细胞中，E334K蛋白水平增加。其334位氨基酸的电荷影响其稳定性，而E334K不影响其磷酸化。在COS-7细胞和新生大鼠心肌细胞中，E334K蛋白降低了细胞内20 S蛋白酶体的活性，增加了促凋亡/抗凋亡蛋白的比例，促进了心肌细胞的凋亡。携带E334K突变的患者表现出明显的左心功能障碍和扩张。结论是MYBPC3错义突变E334K通过UPS破坏其蛋白的稳定性，并可能通过损害泛素-蛋白酶体系统而导致肥厚性心肌病心功能不全。(C)2008爱思唯尔有限公司。保留所有权利。
The ubiquitin-proteasome system is responsible for the disappearance of truncated cardiac myosin-binding protein C, and the suppression of its activity contributes to cardiac dysfunction. This study investigated whether missense cardiac myosin-binding protein C gene (MYBPC3) mutation in hypertrophic cardiomyopathy (HCM) leads to destabilization of its protein, causes UPS impairment, and is associated with cardiac dysfunction. Mutations were identified in Japanese HCM patients using denaturing HPLC and sequencing. Heterologous expression was investigated in COS-7 cells as well as neonatal rat cardiac myocytes to examine protein stability and proteasome activity. The cardiac function was measured using echocardiography. Five novel MYBPC3 mutations-E344K, Delta K814, Delta 2864-2865GC, Q998E, and T1046M-were identified in this study. Compared with the wild type and other mutations, the E334K protein level was significantly lower, it was degraded faster, it had a higher level of poly-ubiquination, and increased in cells pretreated with the proteasome inhibitor MG132 (50 mu M, 6 h). The electrical charge of its amino acid at position 334 influenced its stability, but E334K did not affect its phosphorylation. The E334K protein reduced cellular 20 S proteasome activity, increased the proapoptotic/antiapoptotic protein ratio, and enhanced apoptosis in transfected Cos-7 cells and neonatal rat cardiac myocytes. Patients carrying the E334K mutation presented significant left ventricular dysfunction and dilation. The conclusion is the missense MYBPC3 mutation E334K destabilizes its protein through UPS and may contribute to cardiac dysfunction in HCM through impairment of the ubiquitin-proteasome system. (C) 2008 Elsevier Ltd. All rights reserved.