Kimura Noriyuki, Kumamoto Toshihide, Oniki Takahiro, Nomura Miwa, Nakamura Kenichiro, Abe Yoshitake, Hazama Yusuke, Ueyama Hidetsugu
Department of Neurology and Neuromuscular Disorders, Faculty of Medicine, Oita University, Idaigaoka 1-1, Hasama, Yufu, Oita 879-5593, Japan.
Muscle Nerve. 2009 Apr;39(4):521-8. doi: 10.1002/mus.21223.
Previous studies have documented the presence of rimmed vacuoles, atrophic fibers, and increased lysosomal cathepsin activity in skeletal muscle from animal models of chloroquine-induced myopathy, suggesting that muscle fibers in this type of myopathy may be degraded via the lysosomal-proteolysis pathway. Given recent evidence of abnormal ubiquitin accumulation in rimmed vacuoles, in this study we chose to examine the significance of the ubiquitin-proteasome proteolytic system in the process of muscle fiber destruction in experimental chloroquine myopathy. Expression of ubiquitin, 26S proteasome proteins, and ubiquitin ligases, such as muscle-specific RING finger-1 (MuRF-1) and atrogin-1/muscle atrophy F-box protein (MAFbx), was analyzed in innervated and denervated rat soleus muscles after treatment with either saline or chloroquine. Abnormal accumulation of rimmed vacuoles was observed only in chloroquine-treated denervated muscles. Ubiquitin and proteasome immunostaining, and ubiquitin, MuRF-1, and atrogin-1/MAFbx mRNAs were significantly increased in denervated soleus muscles from saline- and chloroquine-treated rats when compared with contralateral innervated muscles. Further, ubiquitin and ubiquitin ligase mRNA levels were higher in denervated muscles from chloroquine-treated rats when compared with saline-treated rats. These data demonstrate increased proteasomes and ubiquitin in denervated muscles from chloroquine-treated rats and suggest that the ubiquitin-proteasome proteolysis pathway as well as the lysosomal-proteolysis pathway mediate muscle fiber destruction in experimental chloroquine myopathy.
先前的研究已证明，在氯喹诱导的肌病动物模型的骨骼肌中存在边缘空泡、萎缩纤维以及溶酶体组织蛋白酶活性增加的现象，这表明此类肌病中的肌纤维可能通过溶酶体 - 蛋白水解途径降解。鉴于最近有证据表明边缘空泡中存在异常泛素积累，在本研究中，我们选择研究泛素 - 蛋白酶体蛋白水解系统在实验性氯喹肌病中肌纤维破坏过程中的意义。在用生理盐水或氯喹处理后，分析了去神经支配和未去神经支配的大鼠比目鱼肌中泛素、26S蛋白酶体蛋白以及泛素连接酶（如肌肉特异性环状结构域蛋白 -1（MuRF -1）和atrogin -1/肌肉萎缩F -盒蛋白（MAFbx））的表达。仅在氯喹处理的去神经支配肌肉中观察到边缘空泡的异常积累。与对侧未去神经支配的肌肉相比，生理盐水和氯喹处理的大鼠去神经支配的比目鱼肌中泛素和蛋白酶体免疫染色以及泛素、MuRF -1和atrogin -1/MAFbx mRNA显著增加。此外，与生理盐水处理的大鼠相比，氯喹处理的大鼠去神经支配肌肉中泛素和泛素连接酶mRNA水平更高。这些数据表明氯喹处理的大鼠去神经支配肌肉中蛋白酶体和泛素增加，并表明泛素 - 蛋白酶体蛋白水解途径以及溶酶体 - 蛋白水解途径介导了实验性氯喹肌病中的肌纤维破坏。
