CAJ | 학술논문

太空飞行所致的肌萎缩和重力感知的分子机制至今尚不清楚.研究太空飞行对秀丽隐杆线虫(C.elegans)体壁肌细胞结构和功能的影响.经过近15大太空飞行后对其生存率和运动能力进行了观察,并检测了5个重要的肌相关基凶的表达和3种蛋白质含量.太空研究是在动物的整体水平进行的,而不是就单个细胞的研究.经历太空飞行后线虫生存率没有明显变化,但运动频率变慢,爬行轨迹也发生了改变,提示线虫运动功能出现障碍,这些数据揭示:微重力下秀丽线虫肌肉发育发生了变化.肌球蛋白A(myosin A)免疫荧光染色观察发现,太空飞行组肌纤维面积缩小,肌细胞致密体(dense-body)荧光亮度下降.这些形态学观察直接提示太空组线虫出现了肌萎缩.但是,肌动蛋白(F-actin)荧光染色显示两组并无明显差别.基因表达水平的分析结果显示,在太空飞行组动物中dys-1表达明显上调,同时h1h-1,myo-3,unc-54和egl-19基因表达下调.抗肌萎缩蛋白(dystrophin,由dys-1编码)是抗肌萎缩蛋白-糖白复合物(DGC)的主要组成成分,而该复合物在微重力下增多,提示肌细胞是为了接受更多的力学刺激以维持细胞内外的力学平衡,所以该复合物在肌细胞的重力感知中起关键作用.基因h1h-1,myo-3,unc-54和egl-19表达下调,说明它们分别从结构和功能两个途径促进了微重力性肌萎缩的发生.最后,Western blot结果提示,太空组线虫体壁肌内肌球蛋白A减少,进一步确证了太空飞行中线虫有肌萎缩发生.
태공비행소치적기위축화중력감지적분자궤제지금상불청초.연구태공비행대수려은간선충(C.elegans)체벽기세포결구화공능적영향.경과근15대태공비행후대기생존솔화운동능력진행료관찰,병검측료5개중요적기상관기흉적표체화3충단백질함량.태공연구시재동물적정체수평진행적,이불시취단개세포적연구.경력태공비행후선충생존솔몰유명현변화,단운동빈솔변만,파행궤적야발생료개변,제시선충운동공능출현장애,저사수거게시:미중력하수려선충기육발육발생료변화.기구단백A(myosin A)면역형광염색관찰발현,태공비행조기섬유면적축소,기세포치밀체(dense-body)형광량도하강.저사형태학관찰직접제시태공조선충출현료기위축.단시,기동단백(F-actin)형광염색현시량조병무명현차별.기인표체수평적분석결과현시,재태공비행조동물중dys-1표체명현상조,동시h1h-1,myo-3,unc-54화egl-19기인표체하조.항기위축단백(dystrophin,유dys-1편마)시항기위축단백-당백복합물(DGC)적주요조성성분,이해복합물재미중력하증다,제시기세포시위료접수경다적역학자격이유지세포내외적역학평형,소이해복합물재기세포적중력감지중기관건작용.기인h1h-1,myo-3,unc-54화egl-19표체하조,설명타문분별종결구화공능량개도경촉진료미중력성기위축적발생.최후,Western blot결과제시,태공조선충체벽기내기구단백A감소,진일보학증료태공비행중선충유기위축발생.
The molecular mechanism underlying muscular atrophy and gravisensing during spaceflight is still unknown. The major effects of spaceflight on body-wall muscles of Caenorhabditis elegans (C. elegans) in the structures and functions wore examined, and five important muscle-related genes and three proteins were studied after nearly 15-day spaceflight. The changes for the wall-muscles were observed in situ. Decreased muscle fiber size was observed with myosin immunofluorescence and duller dense-body staining in flight samples, which suggested that muscular atrophy had happened during spaceflight. However, F-actin staining showed no differences between the spaceflight group and ground control group. Otherwise, after returning to the earth the C eleganu displayed reduced rate of movement with a lower ratio (height/width) in crawl trace wave, which indicated a functional defect. These results demonstrated that C. elegans muscular development was changed in response to microgravity, and changes also occurred at the level of gene transcription and protein translation. Expression of dys-I increased significantly in body-wall muscles, while hlh-1, myo-3, uric-54 and eg1-19 RNA levels decreased after spaceflight. Dystrophin (encoded by dys-1) is one of important components in dystrophin-glycoprotein complex (DGC). Increased dys-I expression after flight implied that the muscular cell would accept more gravity signals by DGC in mierogravity in order to keep mechanical balance within the cells. It is concluded that DGC was involved into the mechanical transduction in body-wall muscles of C. elegans when gravity varied, which potentially played a vital role in gravisensing. The changes ofhlh-l, myo-3, tmc-54 and egl-19 suggested that they had the effects of promoting microgravity-induced muscular atrophy in strcture and function aspects. Result of Western blotting showed that the level of myosin A in spaceflight group decreased, further confirmed that atrophy happened during flight.