title: Signaling Pathways Related to Protein Synthesis and Amino Acid Concentration in Pig Skeletal Muscles Depend on the Dietary Protein Level, Genotype and Developmental Stages.
abstract: Muscle growth is regulated by the homeostatic balance of the biosynthesis and degradation of muscle proteins. To elucidate the molecular interactions among diet, pig genotype, and physiological stage, we examined the effect of dietary protein concentration, pig genotype, and physiological stages on amino acid (AA) pools, protein deposition, and related signaling pathways in different types of skeletal muscles. The study used 48 Landrace pigs and 48 pure-bred Bama mini-pigs assigned to each of 2 dietary treatments: lower/GB (Chinese conventional diet)- or higher/NRC (National Research Council)-protein diet. Diets were fed from 5 weeks of age to respective market weights of each genotype. Samples of biceps femoris muscle (BFM, type I) and longissimus dorsi muscle (LDM, type II) were collected at nursery, growing, and finishing phases according to the physiological stage of each genotype, to determine the AA concentrations, mRNA levels for growth-related genes in muscles, and protein abundances of mechanistic target of rapamycin (mTOR) signaling pathway. Our data showed that the concentrations of most AAs in LDM and BFM of pigs increased (P<0.05) gradually with increasing age. Bama mini-pigs had generally higher (P<0.05) muscle concentrations of flavor-related AA, including Met, Phe, Tyr, Pro, and Ser, compared with Landrace pigs. The mRNA levels for myogenic determining factor, myogenin, myocyte-specific enhancer binding factor 2 A, and myostatin of Bama mini-pigs were higher (P<0.05) than those of Landrace pigs, while total and phosphorylated protein levels for protein kinase B, mTOR, and p70 ribosomal protein S6 kinases (p70S6K), and ratios of p-mTOR/mTOR, p-AKT/AKT, and p-p70S6K/p70S6K were lower (P<0.05). There was a significant pig genotype-dependent effect of dietary protein on the levels for mTOR and p70S6K. When compared with the higher protein-NRC diet, the lower protein-GB diet increased (P<0.05) the levels for mTOR and p70S6K in Bama mini-pigs, but repressed (P<0.05) the level for p70S6K in Landrace pigs. The higher protein-NRC diet increased ratio of p-mTOR/mTOR in Landrace pigs. These findings indicated that the dynamic consequences of AA profile and protein deposition in muscle tissues are the concerted effort of distinctive genotype, nutrient status, age, and muscle type. Our results provide valuable information for animal feeding strategy.
authors.affiliation: Key Laboratory of Agro-ecological Processes in Subtropical Region, Chinese Academy of Sciences, Changsha, Hunan, China; Hunan Animal Science and Veterinary Medicine Research Institute, Changsha, China; University of Chinese Academy of Sciences, Beijing, China.
authors.forename: Yingying
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Key Laboratory of Agro-ecological Processes in Subtropical Region, Chinese Academy of Sciences, Changsha, Hunan, China.
authors.forename: Fengna
authors.initials: F
authors.lastname: Li
authors.affiliation: Key Laboratory of Agro-ecological Processes in Subtropical Region, Chinese Academy of Sciences, Changsha, Hunan, China.
authors.forename: Xiangfeng
authors.initials: X
authors.lastname: Kong
authors.affiliation: Key Laboratory of Agro-ecological Processes in Subtropical Region, Chinese Academy of Sciences, Changsha, Hunan, China.
authors.forename: Bie
authors.initials: B
authors.lastname: Tan
authors.affiliation: Key Laboratory of Agro-ecological Processes in Subtropical Region, Chinese Academy of Sciences, Changsha, Hunan, China; University of Chinese Academy of Sciences, Beijing, China.
authors.forename: Yinghui
authors.initials: Y
authors.lastname: Li
authors.affiliation: Key Laboratory of Agro-ecological Processes in Subtropical Region, Chinese Academy of Sciences, Changsha, Hunan, China; University of Chinese Academy of Sciences, Beijing, China.
authors.forename: Yehui
authors.initials: Y
authors.lastname: Duan
authors.affiliation: INRA, CNRH-IdF, AgroParisTech, UMR 914 Nutrition Physiology and Ingestive Behavior, Paris, France.
authors.forename: François
authors.initials: F
authors.lastname: Blachier
authors.affiliation: Department of Biochemistry and Molecular Biology, University of New Mexico, Albuquerque, United States of America.
authors.forename: Chien-An A
authors.initials: CA
authors.lastname: Hu
authors.affiliation: Key Laboratory of Agro-ecological Processes in Subtropical Region, Chinese Academy of Sciences, Changsha, Hunan, China; School of Biology, Hunan Normal Univesity, Hunan, Changsha City, 410018, China; Changsha Lvye Biotechnology Limited Company, Guangdong Hinapharm Group and WangDa Academician Workstation, Hunan, Changsha City, 41019, P. R. China.
authors.forename: Yulong
authors.initials: Y
authors.lastname: Yin
mesh_terms: D000596:Amino Acids / Q000032:analysis* / Q000378:metabolism; D000821:Animal Feed; D000818:Animals; D002851:Chromatography, High Pressure Liquid; D004032:Diet; D005838:Genotype; D009124:Muscle Proteins / Q000235:genetics / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000254:growth & development / Q000378:metabolism*; D012313:RNA / Q000302:isolation & purification / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction; D038762:Ribosomal Protein S6 Kinases, 70-kDa / Q000378:metabolism; D015398:Signal Transduction; D013552:Swine; D013556:Swine, Miniature / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D058570:TOR Serine-Threonine Kinases / Q000378:metabolism; D013997:Time Factors; D059467:Transcriptome
chemical_list: D000596:Amino Acids; D009124:Muscle Proteins; D012333:RNA, Messenger; D012313:RNA; D038762:Ribosomal Protein S6 Kinases, 70-kDa; D058570:TOR Serine-Threonine Kinases