Comparative Analyses by Sequencing of Transcriptomes during Skeletal Muscle Development between Pig Breeds Differing in Muscle Growth Rate and Fatness

Abstract

Understanding the dynamics of muscle transcriptome during development and between breeds differing in muscle growth is necessary to uncover the complex mechanism underlying muscle development. Herein, we present the first transcriptome-wide longissimus dorsi muscle development research concerning Lantang (LT, obese) and Landrace (LR, lean) pig breeds during 10 time-points from 35 days-post-coitus (dpc) to 180 days-post-natum (dpn) using Solexa/Illumina's Genome Analyzer. The data demonstrated that myogenesis was almost completed before 77 dpc, but the muscle phenotypes were still changed from 77 dpc to 28 dpn. Comparative analysis of the two breeds suggested that myogenesis started earlier but progressed more slowly in LT than in LR, the stages ranging from 49 dpc to 77 dpc are critical for formation of different muscle phenotypes. 595 differentially expressed myogenesis genes were identified, and their roles in myogenesis were discussed. Furthermore, GSK3B, IKBKB, ACVR1, ITGA and STMN1 might contribute to later myogenesis and more muscle fibers in LR than LT. Some myogenesis inhibitors (ID1, ID2, CABIN1, MSTN, SMAD4, CTNNA1, NOTCH2, GPC3 and HMOX1) were higher expressed in LT than in LR, which might contribute to more slow muscle differentiation in LT than in LR. We also identified several genes which might contribute to intramuscular adipose differentiation. Most important, we further proposed a novel model in which MyoD and MEF2A controls the balance between intramuscular adipogenesis and myogenesis by regulating CEBP family; Myf5 and MEF2C are essential during the whole myogenesis process while MEF2D affects muscle growth and maturation. The MRFs and MEF2 families are also critical for the phenotypic differences between the two pig breeds. Overall, this study contributes to elucidating the mechanism underlying muscle development, which could provide valuable information for pig meat quality improvement.The raw data have been submitted to Gene Expression Omnibus (GEO) under series GSE25406.

Effect of average litter weight in pigs on growth performance, carcass characteristics and meat quality of the offspring as depending on birth weight

“…Because the early stages of gestation mark the onset of myogenesis (Zhao et al, 2011), it is reasonable to assume that differences in placental efficiency caused by different prenatal survival patterns will affect myogenesis and ultimately postnatal growth efficiency (Dwyer et al, 1993).…”

Promoter Variant-Dependent mRNA Expression of theMEF2AinLongissimus DorsiMuscle in Cattle

“…Zhao et al (2011) confirmed that muscle regulatory factor (MRF) and MEF2 families are critical for the phenotypic differences between two pig breeds and proposed a novel model myogenesis. According to these authors, MyoD and MEF2A control the balance between intermuscular adiopogenesis and myogenesis by regulating the CCAAT/enhancerbinding protein (CEBP) family, while MEF2C and Myf5 are important during the whole myogenesis process and MEF2D affects muscle growth and maturation.…”

Association of novel polymorphisms in the bovine myocyte enhancer factor 2D (MEF2D) gene with carcass traits of Polish Holstein-Friesian cattle

“…Many studies have shown that MEF2 transcripts were predominantly expressed in the muscle tissues of humans, mice, and pigs (Naya and Olson 1999;Potthoff et al, 2007;Liu et al, 2011). In skeletal muscle cells in culture, MEF2D has been reported to be expressed in proliferating myoblasts prior to the onset of differentiation (Breitbart et al, 1993) and to play a crucial role in muscle growth and maturation during porcine myogenesis (Zhao et al, 2011). Moreover, it has been reported that MEF2 proteins regulate the promoter activity of several negative regulators of myogenesis, e.g.…”

“…Several experimental approaches have revealed that MEF2 factors play an important role in the regulation of gluconeogenesis and adipocyte differentiation by regulating the expression of target genes, such as glucose transporter protein 4 (GLUT4) (Thai et al, 1998;Silva et al, 2005) and CCAAT/enhancer-binding protein α (C/EBPα) (Zhao et al, 2011) in skeletal muscle, heart, and adipose tissue. It has been shown that the level of GLUT4 expression is dependent on the binding of the MEF2A-MEF2D heterodimer complex to the MEF2 DNA-binding site in human and mice GLUT4 promoters; since a reduction in MEF2 expression is correlated with reduced GLUT4 promoter activity (Mora et al, 2001;Santalucia et al, 2001).…”