Osbaldeston N J, Lee D M, Cox V M, Hesketh J E, Morrison J F, Blair G E, Goldspink D F
Department of Clinical Medicine, University of Leeds, U.K.
Biochem J. 1995 Jun 1;308 ( Pt 2)(Pt 2):465-71. doi: 10.1042/bj3080465.
The levels of c-fos and c-jun mRNA were measured by reverse transcription PCR in the rabbit latissimus dorsi muscle following three separate training regimes, i.e. passive stretch, 10 Hz electrical stimulation or a combination of the two. Both c-fos and c-jun mRNA expression peaked at around 1 h after imposing stretch and at around 4.5-6 h after the initiation of electrical stimulation. The combined stretch/electrical stimulation regime induced biphasic expression of both c-fos and c-jun mRNA, with peaks coinciding temporally with those for the individual regimes. Immunostaining with anti-Fos and anti-Jun antibodies revealed the accumulation of these proteins in both myofibre and interstitial cell nuclei following passive stretch. In contrast, following electrical stimulation the localization of immunoreactive c-Fos and c-Jun proteins was predominantly in interstitial cell nuclei. c-Fos and c-Jun immunoreactivity was also clearly colocalized in a proportion of myonuclei from stretched muscle. These findings suggest that the rapid induction of c-fos and c-jun is an early event in response to mechanical stretch and might trigger [via activator protein-1 (AP-1) transcriptional factors] events leading to muscle fibre hypertrophy. However, the involvement of AP-1 in inducing the phenotypic changes in muscle fibres as a result of electrical stimulation appears less clear.
在三种不同的训练方案（即被动拉伸、10Hz电刺激或两者结合）后，通过逆转录PCR检测兔背阔肌中c-fos和c-jun mRNA的水平。c-fos和c-jun mRNA的表达在施加拉伸后约1小时以及电刺激开始后约4.5 - 6小时达到峰值。拉伸/电刺激联合方案诱导了c-fos和c-jun mRNA的双相表达，其峰值在时间上与单个方案的峰值一致。用抗Fos和抗Jun抗体进行免疫染色显示，被动拉伸后这些蛋白质在肌纤维和间质细胞核中积累。相比之下，电刺激后，免疫反应性c-Fos和c-Jun蛋白主要定位于间质细胞核中。c-Fos和c-Jun免疫反应性在拉伸肌肉的一部分肌核中也明显共定位。这些发现表明，c-fos和c-jun的快速诱导是对机械拉伸反应的早期事件，可能（通过激活蛋白-1（AP-1）转录因子）触发导致肌纤维肥大的事件。然而，AP-1在电刺激导致的肌纤维表型变化中的作用似乎不太明确。
