Integrative transcriptomics and proteomics analysis of longissimus dorsi muscles of Canadian double-muscled Large White pigs

• Comparative transcriptomics and proteomics analyses of pig double-muscled trait
• Construction of interaction network and pathways based on the DEGs and DEPs
• Find key genes and proteins associated with double muscle.
• Wnt, MAPK and TGF-beta pathways take part in muscle hypertrophy.

Canadian double-muscled Large White pigs are characterized by notable muscle mass, showing high daily gain and lean rate and good meat quality. In order to identify the major genes or proteins involved in muscle hyperplasia and hypertrophy, three pairs of full-sib pigs with extreme muscle mass difference from Canadian Large White were selected as experimental animals at 3 months age. The phenotypic differences of longissimus dorsi muscles (LD) were investigated with microarray and proteomics (2-DE, MALDI-TOF-MS), and results were verified by real-time PCR and western bolting respectively. The gene expressing profiling identified 57 and 260 and 147 differently expressed genes (DEGs) from the three pairs respectively with Bayesian statistics and significant analysis of microarrays (SAM) (p < 0.05, q < 0.05, fold > 2). From the network of these DEGs, some major genes were displayed, such as EGF, PPARG, FN1, SERPINE1, MYC, JUN, involved in Wnt, MAPK and TGF-β signal pathway respectively, which mainly participated in cell differentiation and proliferation. In parallel, proteomics analyses revealed 50 differently expressed protein (DEP) spots with mass spectrum, and 33 spots of them were found annotated, which took part in energy metabolism and the structure and contraction of muscle fiber. In brief, our integrated study provides a good foundation for the further study on the genetic mechanism of the double muscle traits in pigs.