Study On Cloning And Tissue Expression Of MEF2Gene Family In Goat

Myocyte Enhancer Factor2(MEF2) is a member of the MADS-Box transcriptional factors, which widely distributed in cardiac, skeletal and smooth muscles, and involved in several physiological processes such as muscle formation, bone and nervous system development, liver fibrosis. In this study, we successfully cloned the coding regions of goat MEF2genes from Nanjiang yellow goat, and quantified their expressions in different tissues and different periods by real-time PCR, subsequently we also addressed the relative relationship between the diameter and density of skeletal muscle. The main results are as follows:(1) The coding sequences of goat MEF2A、MEF2B、MEF2C and MEF2D were successfully cloned and submitted to GenBank (JN967621-JN967624). The lengths of MEF2family were1497bp,1107bp,1302bp and1542bp, which encoded498、368、433and513amino acids respectively. All of these genes contained the MADS-Box and MEF2conserved domains. In addition, MEF2C and MEF2D harbored the HJURP C domain.(2) The bioinformatics analyses indicated their primary secondary structure was random coil, which followed by alpha-helix and beta-sheet. The phylogenetic tree revealed that the goat MEF2amino acid sequences showed high homology to those of mammals. MEF2A and MEF2C were grouped together first, and clustered with MEF2D and MEF2B subsequently.(3) MEF2gene family was widely expressed at all the investigated tissues and different time points, while their expressions showed variant levels quantified by real-time PCR. MEF2A, MEF2B, MEF2C and MEF2D were all highest expressed in skeletal muscle followed by heart, while lowest expressed in liver and kidney. Furthermore, the expressions of MEF2B, MEF2C and MEF2D displayed gender manner (P<0.05or P<0.01).The expression of MEF2A showed an up-down-up trend with aging, which reached the lowest level at the3d after birth in heart, liver, kidney, triceps brachii and longissimus dorsi., while the highest level were found in heart and triceps brachii at the120d. In musculus semimembranous, the expression of MEF2A reached the lowest level at the90d after birth and the highest level at the30d.The expression of MEF2B exhibited an up-down-up trend in heart, liver, kidney and longissimus dorsi with aging, the lowest expression level observed in all tissues (3d) and the highest level in heart, longissimus dorsi (30d) and in liver and kidney (120d). The expression of MEF2B showed an up-down trend In musculus semimembranous and triceps brachii with aging, and reached the highest expression level at the60d and up to the lowest level in musculus semimembranous (3d) and triceps brachii (120d).The expression of MEF2C exhibited gradually increased in heart with aging. The trend in liver and longissimus dorsi showed down-up with aging. The expression of MEF2C in liver reached the lowest level at the60d and the highest level at the120d, while in longissimus dorsi reached the highest level at3d. The MEF2C expression in kidney showed an up-down-up trend with aging, and the expression reached the lowest level at3d and the highest level at120d. In musculus semimembranous, the expression of MEF2C exhibited gradually down-up-down with aging, and the expression reached the lowest level at30d and the highest level at60d.The up-down trend showed in the expression of MEF2D in heart and skeletal muscle with aging. The lowest expression level was observed at3d, the highest expression was in heart (30d), musculus semimembranous (60d), triceps brachii and longissimus dorsi (90d). The MEF2D expression in liver exhibited up-down-up with aging, and the expression reached the highest level at the30d and the lowest level at the60d. The expression of MEF2D in kidney showed a fluctuation with aging.(4) The diameter of goat muscle fiber showed a gradual increase from3d to90d, then decreased gradually, while the density of muscle fiber displayed a durative decline with aging. The expression of MEF2A showed a significant positive correlation with the diameter of muscle fiber in longissimus dorsi and a negative correlation with muscle fiber density (P<0.05). The significant positive correlation was revealed between with MEF2B expression and the diameter and density of muscle fiber in musculus semimembranous (P<0.05). The expression of MEF2C was extremely negative correlation (P<0.01) with muscle fiber diameter and significant positive correlation (P<0.05) with the density in triceps brachii. A significant negative correlation (P<0.05) was observed MEF2D expression and muscle fiber diameter and a significant positive correlation (P<0.05) was found between MEF2D expression and the density of in the three kinds of skeletal muscle.