Pig embryonic muscle iTRAQ analysis

Here, we performed the first iTRAQ-based proteomic analysis of early embryonic longissimus dorsi muscle from Landrance (LR) and miniature pig (Wuzhishan WZS) ranging from 21 to 42 days post coitus (dpc). 4431 proteins were identified. In both WZS and LR, the largest amount of differentially expressed proteins (DEPs) were found between 28 and 35 dpc. 252 breed-DEPs were selected by GO analysis, including 8 myofibrillar proteins. Only MYHCⅠ/IIA mRNA were detected due to early embryonic stages, and significantly higher expression of them were found in WZS during these 4 stages. MYHCⅠ was first found in WZS at 28 dpc and expressed in both breeds at later stages, while MYHCII protein was not detected until 35 dpc in both breeds. Thus, 33 myogenic breed-DEPs selected from last two stages were analyzed by STRING, which showed that some myofibrillar proteins (MYH1, TPM4, MYH10, et.al) and functional proteins (CSRP2, CASQ2, OTC, et.al), together with candidate myogenic proteins (H3F3A, HDGFRP2, et.al), probably participate in the regulatory network of myofiber formation. Thus, our study provides new data on myofiber type development during early embryo stages, which contributes to the improved understanding in the regulation mechanism of early myogenesis in agricultural animals.