title: The effects of reduced dietary protein level on amino acid transporters and mTOR signaling pathway in pigs.
abstract: Amino acid transporter plays an important role in regulating mTOR signaling pathway. This study investigated the effects of reduced dietary protein levels on amino acid transporters and mTOR signaling pathway. A total of 54 weaning pigs were randomly allocated into a 3 × 3 factorial design, followed by slaughtering the pigs separately after 10-, 25- and 45-day feeding, with 18 pigs from each feeding period divided into three subgroups for treatment with three different protein-level diets: 20% crude protein (CP) diet (normal recommended, high protein, HP), 17% CP diet (medium protein, MP) and 14% CP diet (low protein, LP). The results indicated that reduced dietary protein level decreased the weight of longissimus dorsi. Additionally, quantitative PCR chip analysis showed that mRNA expression of amino acid transporters SLC38A2, SLC1A7, SLC7A1, SLC7A5, SLC16A10 and SLC3A2 in the LP group were significantly (P < 0.05) higher than those in the MP or HP group, and the phosphorylation of mTOR and S6K1 decreased in the LP group after 25-day feeding. Furthermore, the vitro experimental results further confirmed that the mRNA levels for SLC7A1, SLC7A5, SLC3A2, SLC38A2 and SLC36A1 were increased and the phosphorylation of mTOR and S6K1 was decreased when the concentration of amino acids in C2C12 myoblasts was reduced. All these results indicated that the LP diet induced a high expression of amino acid transporters and the inhibition of the mTOR activity, which resulting in restriction on protein synthesis and longissimus dorsi growth.
authors.affiliation: Agricultural Ministry Key Laboratory of Swine Breeding and Genetics, Key Laboratory of Agricultural Animal Genetics, Breeding, and Reproduction of Ministry of Education, Huazhong Agricultural University, Wuhan, China; The Cooperative Innovation Center for Sustainable Pig Production, Wuhan, China.
authors.forename: Dan
authors.initials: D
authors.lastname: Wang
authors.affiliation: Agricultural Ministry Key Laboratory of Swine Breeding and Genetics, Key Laboratory of Agricultural Animal Genetics, Breeding, and Reproduction of Ministry of Education, Huazhong Agricultural University, Wuhan, China; The Cooperative Innovation Center for Sustainable Pig Production, Wuhan, China.
authors.forename: Xuebin
authors.initials: X
authors.lastname: Wan
authors.affiliation: Department of Animal Nutrition, Huazhong Agricultural University, Wuhan, China.
authors.forename: Jian
authors.initials: J
authors.lastname: Peng
authors.affiliation: Hubei Key Laboratory of Animal Embryo Engineering and Molecular Breeding, Institute of Animal Husbandry and Veterinary, Hubei Academy of Agricultural Science, Wuhan, China.
authors.forename: Qi
authors.initials: Q
authors.lastname: Xiong
authors.affiliation: Agricultural Ministry Key Laboratory of Swine Breeding and Genetics, Key Laboratory of Agricultural Animal Genetics, Breeding, and Reproduction of Ministry of Education, Huazhong Agricultural University, Wuhan, China; The Cooperative Innovation Center for Sustainable Pig Production, Wuhan, China.
authors.forename: Hongdan
authors.initials: H
authors.lastname: Niu
authors.affiliation: Agricultural Ministry Key Laboratory of Swine Breeding and Genetics, Key Laboratory of Agricultural Animal Genetics, Breeding, and Reproduction of Ministry of Education, Huazhong Agricultural University, Wuhan, China; The Cooperative Innovation Center for Sustainable Pig Production, Wuhan, China.
authors.forename: Huanan
authors.initials: H
authors.lastname: Li
authors.affiliation: Agricultural Ministry Key Laboratory of Swine Breeding and Genetics, Key Laboratory of Agricultural Animal Genetics, Breeding, and Reproduction of Ministry of Education, Huazhong Agricultural University, Wuhan, China; The Cooperative Innovation Center for Sustainable Pig Production, Wuhan, China. Electronic address: chaijin@mail.hzau.edu.cn.
authors.forename: Jin
authors.initials: J
authors.lastname: Chai
authors.affiliation: Agricultural Ministry Key Laboratory of Swine Breeding and Genetics, Key Laboratory of Agricultural Animal Genetics, Breeding, and Reproduction of Ministry of Education, Huazhong Agricultural University, Wuhan, China; The Cooperative Innovation Center for Sustainable Pig Production, Wuhan, China. Electronic address: jiangsiwen@mail.hzau.edu.cn.
authors.forename: Siwen
authors.initials: S
authors.lastname: Jiang
mesh_terms: D026905:Amino Acid Transport Systems / Q000235:genetics* / Q000378:metabolism; D000818:Animals; D001835:Body Weight; D018753:Diet, Protein-Restricted; D005786:Gene Expression Regulation; D014176:Protein Biosynthesis; D012333:RNA, Messenger / Q000235:genetics; D015398:Signal Transduction; D034421:Sus scrofa / Q000235:genetics / Q000254:growth & development / Q000502:physiology*; D058570:TOR Serine-Threonine Kinases / Q000378:metabolism*
chemical_list: D026905:Amino Acid Transport Systems; D012333:RNA, Messenger; D058570:TOR Serine-Threonine Kinases
keywords: Amino acids transporter; Longissimus dorsi weight; Quantitative PCR chip; Reduced dietary protein; mTOR signaling pathway