School of Kinesiology and Health Science, The Muscle Health Research Centre, York University, Toronto, ON M3J 1P3, Canada.
Appl Physiol Nutr Metab. 2011 Apr;36(2):233-41. doi: 10.1139/h11-004.
Many proteins that function as transcription factors regulate the transcriptional activity of nuclear genes encoding mitochondrial proteins. Several of these are rapidly inducible with contractile activity, followed by a recovery phase. The aim of the present study was to evaluate the expression of a number of rapidly responding gene products to an acute bout of contractile activity followed by a recovery period in both slow- and fast-twitch muscle. Using an in vitro isolated muscle preparation, extensor digitorum longus (EDL) and soleus muscles were stimulated for 15 min, followed by 30 min recovery. Following stimulation, ATP levels were decreased in both the EDL and soleus (25% and 32%, respectively). We found that phosphorylation of p38 MAP kinase was elevated in both muscle types, with a more dramatic 3.5-fold increase observed in the EDL muscle. Peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α) mRNA expression was unchanged as a result of stimulation and recovery, while c-Fos transcript levels were decreased as a result of stimulation, but returned to resting values following recovery. Interestingly, nuclear respiratory factor 1 mRNA levels were unaffected by stimulation, but increased significantly (34%) during the recovery phase. These data suggest that the extent of the induction of transcription factor mRNA to acute exercise, which leads to subsequent muscle adaptations, is transcript specific and dependent on (i) the activation of upstream kinases, (ii) the muscle phenotype, and (iii) the duration of the recovery period.
许多作为转录因子发挥作用的蛋白质调节编码线粒体蛋白质的核基因的转录活性。其中一些在收缩活动后迅速诱导，并随之进入恢复阶段。本研究的目的是评估在急性收缩活动后和恢复期内，快速反应基因产物在慢肌和快肌中的表达情况。使用体外分离的肌肉制备物，刺激伸趾长肌（EDL）和比目鱼肌 15 分钟，然后恢复 30 分钟。刺激后，EDL 和比目鱼肌中的 ATP 水平均降低（分别为 25%和 32%）。我们发现，两种肌肉类型的 p38 MAP 激酶磷酸化水平均升高，EDL 肌肉中的升高更为显著，达到 3.5 倍。过氧化物酶体增殖物激活受体γ共激活因子-1α（PGC-1α）mRNA 表达不受刺激和恢复的影响，而 c-Fos 转录水平因刺激而降低，但在恢复后恢复到静息值。有趣的是，核呼吸因子 1 mRNA 水平不受刺激影响，但在恢复阶段显著增加（34%）。这些数据表明，转录因子 mRNA 对急性运动的诱导程度，进而导致随后的肌肉适应，是转录本特异性的，并取决于（i）上游激酶的激活，（ii）肌肉表型，和（iii）恢复阶段的持续时间。
