Mylabathula D B, Rice K M, Wang Z, Uddemarri S, Kinnard R S, Blough E R
Department of Biological Sciences, Marshall University, Huntington, WV 25755-1090, USA.
Exp Gerontol. 2006 Feb;41(2):205-14. doi: 10.1016/j.exger.2005.11.001. Epub 2005 Dec 27.
We compared the tissue content, basal phosphorylation, and stretch-induced phosphorylation of the mitogen-activated protein kinase (MAPK) members; extracellular-signal-regulated kinases (ERK 1/2), p38, and c-Jun NH2-terminal kinase (JNK) in the fast-twitch extensor digitorium longus (EDL) and slow-twitch soleus of young adult (6 month), aged (30 month), and very aged (36 month) F344/NNiaHSD X Brown Norway/BiNia (F344/NXBN) rats. The expression and basal phosphorylation of the ERK 1/2, p38, and JNK MAPK proteins were regulated differently with aging in the EDL and soleus. Stretch induced significant phosphorylation of each signaling molecule in both muscle types of young adult and aged animals. In the very aged animals, stretch stimulated ERK 1/2 MAPK phosphorylation; however, EDL stretch failed to induce JNK MAPK phosphorylation, while soleus stretch was unable to induce the phosphorylation of p38 MAPK. The results suggest that skeletal muscle mechanotransduction processes are affected in very aged F344/NXBN rats and that aging alters load-induced signaling in fast- and slow-twitch muscle types differently.
我们比较了年轻成年（6个月）、老年（30个月）和高龄（36个月）的F344/NNiaHSD×Brown Norway/BiNia（F344/NXBN）大鼠的快肌趾长伸肌（EDL）和慢肌比目鱼肌中丝裂原活化蛋白激酶（MAPK）成员，即细胞外信号调节激酶（ERK 1/2）、p38和c-Jun氨基末端激酶（JNK）的组织含量、基础磷酸化和拉伸诱导的磷酸化情况。ERK 1/2、p38和JNK MAPK蛋白的表达及基础磷酸化在EDL和比目鱼肌中随衰老呈现不同的调节方式。拉伸可诱导年轻成年和老年动物两种肌肉类型中各信号分子的显著磷酸化。在高龄动物中，拉伸刺激ERK 1/2 MAPK磷酸化；然而，EDL拉伸未能诱导JNK MAPK磷酸化，而比目鱼肌拉伸无法诱导p38 MAPK磷酸化。结果表明，高龄F344/NXBN大鼠的骨骼肌机械转导过程受到影响，且衰老对快肌和慢肌类型中负荷诱导的信号传导的影响有所不同。
