Transcriptomic profiling of skeletal muscle microRNA involved in muscle fiber type specification

为了阐明miRNA在牛肌肉类型特化和维持中的作用，我们试图通过大规模平行测序来确定3头日本黑牛半腱肌（STD）和咬肌（MS）之间差异表达的miRNA。肌球蛋白重链（MyHC）亚型的差异基因表达证实，STD和MS分别是MyHC-2x-和MyHC-1-丰富的肌肉。共获得192个已知的miRNA和20个潜在的新的牛miRNA。鉴定了在每块肌肉中差异超过2倍的差异表达的miRNA。特别是，miR-196 a和miR-885仅在STD肌肉中表达，这通过定量逆转录-PCR验证（分别为P=0.045和P<0.001），而与STD相比，慢型定向miR-208 b在MS中高度表达（假发现率<0.05）。此外，16个潜在的新的miRNA被映射，并通过计算分析确认其前体结构。

To elucidate roles of miRNA in bovine muscle type specification and maintenance, we sought to determine differentially expressed miRNA between semitendinosus (STD) and masseter (MS) muscles from 3 Japanese black cattle by massively parallel sequencing. Differential gene expression of myosin heavy chain (MyHC) isoforms confirmed that STD and MS were MyHC-2x- and MyHC-1-abundant muscles, respectively. In total, 192 known miRNA and 20 potential new bovine miRNA were obtained from the sequencing. The differentially expressed miRNA with more than 2-fold difference in each muscle were identified. In particular, miR-196a and miR-885 were exclusively expressed in STD muscle, which was validated by quantitative reverse transcription-PCR (P=0.045 and P<0.001, respectively), whereas a slow type-directing miR-208b was highly expressed in MS compared with STD (false discovery rate<0.05). In addition, 16 potential novel miRNA were mapped and confirmed for their precursor structures by computational analyses.