日本語フィールド
著者：Masanao Machida, kohel Takeda, Shin Fuzimaki, Sachiko ikemune, Sachie Nesori, Hidenori Kiyosawa, Tohru Takemasa題名：RNA overshoot Accompanies Recovery of Delayed Plantaris Muscle Growth Resulting from Juvenile Hindlimb Suspension発表情報：Advances in Exercise and Sports Physiology 巻: 19 号: 2 ページ: 39-46キーワード：skeletal muscle, muscle growth概要：成長期のおける身体的不活動による骨格筋の成長不全からの回復過程の分子メカニズムを解明することを目的に、本実験を行った。具体的には、成長期のマウスに後肢懸垂を実施し、骨格筋の成長不全のマウスを作成した。その後、後肢懸垂を解除し、その回復過程の骨格筋の反応について、特にRNAの変化とそれを制御するシグナル伝達について解析した。その結果、成長不全からの回復期には、RNAの過剰発現が引き起こされている事を明らかとした。抄録：Delay in the growth of skeletal muscle resulting from physical inactivity during the juvenile period may affect the subsequent quality of life. Therefore, it is important to clarify whether recovery of this muscle growth delay can be achieved by physical training thereafter. In the present study, mice were subjected to hindlimb suspension from 5 to 8 weeks of age to induce a delay of muscle growth and reloading from 8 weeks of age to recovery of muscle. Growth of the plantaris muscle, which is composed of fast-twitch fibers, was monitored at 5, 8, 11 and 14 weeks of age. This revealed that the growth of the plantaris had completely recovered from this delay by 11 weeks of age. Moreover, the recovery was accompanied by a significant increase of RNA content relative to control muscle. Since ribosomal RNA accounts for the majority of total RNA, it was thought that the machinery for protein synthesis had become activated in the recovering muscle. In addition, phosphorylated ribosomal protein S6, which is an important factor for efficient translation, was increased at the same time. These results suggested that protein synthesis was enhanced in recovering muscle. In addition, the recovering muscle showed activation of the Erk pathway, one of the pathways controlling the expression of ribosomal RNA. These results suggest that loss of skeletal muscle due to unloading during the juvenile period can be completely recovered by reloading, and that this recovery might require an increase of RNA content mediated by the Erk pathway.英語フィールド
Author：Masanao Machida, kohel Takeda, Shin Fuzimaki, Sachiko ikemune, Sachie Nesori, Hidenori Kiyosawa, Tohru TakemasaTitle：RNA overshoot Accompanies Recovery of Delayed Plantaris Muscle Growth Resulting from Juvenile Hindlimb SuspensionAnnouncement information:Advances in Exercise and Sports Physiology Vol: 19 Issue: 2 Page: 39-46Keyword：skeletal muscle, muscle growthAn abstract：Delay in the growth of skeletal muscle resulting from physical inactivity during the juvenile period may affect the subsequent quality of life. Therefore, it is important to clarify whether recovery of this muscle growth delay can be achieved by physical training thereafter. In the present study, mice were subjected to hindlimb suspension from 5 to 8 weeks of age to induce a delay of muscle growth and reloading from 8 weeks of age to recovery of muscle. Growth of the plantaris muscle, which is composed of fast-twitch fibers, was monitored at 5, 8, 11 and 14 weeks of age. This revealed that the growth of the plantaris had completely recovered from this delay by 11 weeks of age. Moreover, the recovery was accompanied by a significant increase of RNA content relative to control muscle. Since ribosomal RNA accounts for the majority of total RNA, it was thought that the machinery for protein synthesis had become activated in the recovering muscle. In addition, phosphorylated ribosomal protein S6, which is an important factor for efficient translation, was increased at the same time. These results suggested that protein synthesis was enhanced in recovering muscle. In addition, the recovering muscle showed activation of the Erk pathway, one of the pathways controlling the expression of ribosomal RNA. These results suggest that loss of skeletal muscle due to unloading during the juvenile period can be completely recovered by reloading, and that this recovery might require an increase of RNA content mediated by the Erk pathway.