日本研究小组在利用小鼠进行的实验中发现，通过遏制一种基因的作用，能改善肌肉萎缩的症状。
德岛大学教授田中荣二率领的研究小组发现，myostatin基因会抑制骨骼肌的增加。于是他们利用ＲＮＡ干扰法，抑制该基因发挥作用。研究人员确认，经ＲＮＡ干扰法治疗，患肌肉萎缩症小鼠的颚部骨骼肌的肌肉量增加，咬力也得到增强。
田中荣二指出，目前治疗肌肉萎缩症主要是通过康复疗法等抑制肌肉萎缩，而利用此次成果有望开发出促进肌肉量增加的新疗法。
据介绍，小鼠每接受一次注射，效果能够持续４周左右，而要想改善肌肉萎缩症患者的症状，需要大剂量注射。研究小组准备开发能廉价注射的方法，争取早日用于临床。
相关论文已发表在5月23日一期的美国在线科学杂志《科学公共图书馆—综合》PLoS ONE上。（生物谷Bioon.com）
doi:10.1371/journal.pone.0064719
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Local Applications of Myostatin-siRNA with Atelocollagen Increase Skeletal Muscle Mass and Recovery of Muscle Function
Emi Kawakami, Nobuhiko Kawai, Nao Kinouchi, Hiroyo Mori, Yutaka Ohsawa, Naozumi Ishimaru, Yoshihide Sunada, Sumihare Noji, Eiji Tanaka mail
Background Growing evidence suggests that small-interfering RNA (siRNA) can promote gene silencing in mammalian cells without induction of interferon synthesis or nonspecific gene suppression. Recently, a number of highly specific siRNAs targeted against disease-causing or disease-promoting genes have been developed. In this study, we evaluate the effectiveness of atelocollagen (ATCOL)-mediated application of siRNA targeting myostatin (Mst), a negative regulator of skeletal muscle growth, into skeletal muscles of muscular dystrophy model mice. Methods and Findings We injected a nanoparticle complex containing myostatin-siRNA and ATCOL (Mst-siRNA/ATCOL) into the masseter muscles of mutant caveolin-3 transgenic (mCAV-3Tg) mice, an animal model for muscular dystrophy. Scrambled (scr) -siRNA/ATCOL complex was injected into the contralateral muscles as a control. Two weeks after injection, the masseter muscles were dissected for histometric analyses. To investigate changes in masseter muscle activity by local administration of Mst-siRNA/ATCOL complex, mouse masseter electromyography (EMG) was measured throughout the experimental period via telemetry. After local application of the Mst-siRNA/ATCOL complex, masseter muscles were enlarged, while no significant change was observed on the contralateral side. Histological analysis showed that myofibrils of masseter muscles treated with the Mst-siRNA/ATCOL complex were significantly larger than those of the control side. Real-time PCR analysis revealed a significant downregulation of Mst expression in the treated masseters of mCAV-3Tg mice. In addition, expression of myogenic transcription factors was upregulated in the Mst-siRNA-treated masseter muscle, while expression of adipogenic transcription factors was significantly downregulated. EMG results indicate that masseter muscle activity in mCAV-3Tg mice was increased by local administration of the Mst-siRNA/ATCOL complex. Conclusion These data suggest local administration of Mst-siRNA/ATCOL complex could lead to skeletal muscle hypertrophy and recovery of motor disability in mCAV-3Tg mice. Therefore, ATCOL-mediated application of siRNA is a potential tool for therapeutic use in muscular atrophy diseases.
