Kyoto University, Japan.
Acta Physiol (Oxf). 2009 Apr;195(4):483-94. doi: 10.1111/j.1748-1716.2008.01944.x.
The dystrophin-glycoprotein complex (DGC) and focal adhesion complex (FAC) are transmembrane structures in muscle fibres that link the intracellular cytoskeleton to the extracellular matrix. DGC and FAC proteins are abundant in slow-type muscles, indicating the structural reinforcement which play a pivotal role in continuous force output to maintain posture for long periods. The aim of the present study was to examine the expression of these structures across fast-type muscles containing different myosin heavy chain (MHC) isoform patterns which reflect the fatigue-resistant characteristics of skeletal muscle.
We measured the expression of dystrophin and beta1 integrin (representative proteins of DGC and FAC respectively) in plantaris, extensor digitorum longus, tibialis anterior, red and white portions of gastrocnemius, superficial portion of vastus lateralis and diaphragm, in comparison with soleus (SOL) and cardiac muscle from rats.
The expression of dystrophin and beta1 integrin correlated positively with the percentage of type I, IIa and IIx MHC isoforms and negatively with that of type IIb MHC isoform in fast-type skeletal muscles, and their expression was abundant in SOL and cardiac muscle.
Our results support the idea that DGC and FAC are among the factors that explain the fatigue-resistant property not only of slow-type but also of fast-type skeletal muscles.
肌纤维中的质膜结构——肌营养不良糖蛋白复合物（DGC）和黏着斑复合物（FAC）将细胞内的细胞骨架与细胞外基质连接起来。DGC 和 FAC 蛋白在慢肌中含量丰富，这表明它们在持续输出力量以维持长时间姿势方面起着至关重要的结构加固作用。本研究旨在检测这些结构在不同肌球蛋白重链（MHC）同工型模式的快肌中的表达情况，这些同工型模式反映了骨骼肌的抗疲劳特性。
我们测量了比目鱼肌、趾长伸肌、胫骨前肌、腓肠肌红肌和白肌部分、股外侧肌浅部和横膈肌中肌营养不良蛋白和β1 整合素（分别代表 DGC 和 FAC 的代表性蛋白）的表达情况，并与大鼠的比目鱼肌和心肌进行了比较。
在快肌中，DGC 和 FAC 的表达与 I 型、IIa 型和 IIx 型 MHC 同工型的百分比呈正相关，与 IIb 型 MHC 同工型的百分比呈负相关，并且在比目鱼肌和心肌中表达丰富。
我们的结果支持这样一种观点，即 DGC 和 FAC 是解释不仅是慢肌，而且是快肌抗疲劳特性的因素之一。
