Institute of Biochemistry, Faculty of General Medicine, University of Szeged, Dóm tér 9., 6720 Szeged, Hungary (JAB, TK, AKP, EZ, LD, LM).
J Histochem Cytochem. 2013 Dec;61(12):889-900. doi: 10.1369/0022155413503661. Epub 2013 Aug 26.
Myostatin is an important negative regulator of skeletal muscle growth. The hypermuscular Compact (Cmpt) mice carry a 12-bp natural mutation in the myostatin propeptide, with additional modifier genes being responsible for the phenotype. Muscle cellularity of the fast-type tibialis anterior (TA) and extensor digitorum longus (EDL) as well as the mixed-type soleus (SOL) muscles of Cmpt and wild-type mice was examined by immunohistochemical staining of the myosin heavy chain (MHC) proteins. In addition, transcript levels of MHC isoforms were quantified by qPCR. Based on our results, all investigated muscles of Cmpt mice were significantly larger compared with that of wild-type mice, as characterized by fiber hyperplasia of different grades. Fiber hypertrophy was not present in TA; however, EDL muscles showed specific IIB fiber hypertrophy while the (I and IIA) fibers of SOL muscles were generally hypertrophied. Both the fast TA and EDL muscles of Cmpt mice contained significantly more glycolytic IIB fibers accompanied by a decreased number of IIX and IIA fibers; however, this was not the case for SOL muscles. In summary, despite the variances found in muscle cellularity between the different myostatin mutant mice, similar glycolytic shifts were observed in Cmpt fast muscles as in muscles from myostatin knockout mice.
肌肉生长抑制素（Myostatin）是一种重要的负向调节骨骼肌生长的因子。高度肌肉发达的 Compact（Cmpt）小鼠携带肌生成抑制素前肽中的 12 个碱基对的天然突变，额外的修饰基因负责该表型。通过肌球蛋白重链（MHC）蛋白的免疫组织化学染色，检查了 Cmpt 和野生型小鼠的快型胫骨前肌（TA）和趾长伸肌（EDL）以及混合型比目鱼肌（SOL）的肌肉细胞。此外，通过 qPCR 定量了 MHC 同工型的转录水平。根据我们的结果，与野生型小鼠相比，Cmpt 小鼠的所有研究肌肉均明显增大，其特征是不同程度的纤维增生。TA 中不存在纤维肥大；然而，EDL 肌肉表现出特定的 IIB 纤维肥大，而 SOL 肌肉的（I 和 IIA）纤维则普遍肥大。Cmpt 小鼠的快肌 TA 和 EDL 均含有明显更多的糖酵解 IIB 纤维，同时 IIX 和 IIA 纤维数量减少；然而，这在 SOL 肌肉中并非如此。总之，尽管不同肌生成抑制素突变小鼠之间的肌肉细胞存在差异，但在 Cmpt 快肌中观察到与肌生成抑制素敲除小鼠肌肉相似的糖酵解变化。
