title: The role of leucine and its metabolites in protein and energy metabolism.
abstract: Leucine (Leu) is a nutritionally essential branched-chain amino acid (BCAA) in animal nutrition. It is usually one of the most abundant amino acids in high-quality protein foods. Leu increases protein synthesis through activation of the mammalian target of rapamycin (mTOR) signaling pathway in skeletal muscle, adipose tissue and placental cells. Leu promotes energy metabolism (glucose uptake, mitochondrial biogenesis, and fatty acid oxidation) to provide energy for protein synthesis, while inhibiting protein degradation. Approximately 80 % of Leu is normally used for protein synthesis, while the remainder is converted to α-ketoisocaproate (α-KIC) and β-hydroxy-β-methylbutyrate (HMB) in skeletal muscle. Therefore, it has been hypothesized that some of the functions of Leu are modulated by its metabolites. Both α-KIC and HMB have recently received considerable attention as nutritional supplements used to increase protein synthesis, inhibit protein degradation, and regulate energy homeostasis in a variety of in vitro and in vivo models. Leu and its metabolites hold great promise to enhance the growth and health of animals (including humans, birds and fish).
authors.affiliation: Scientific Observing and Experimental Station of Animal Nutrition and Feed Science in South-Central, Ministry of Agriculture, Hunan Provincial Engineering Research Center of Healthy Livestock, Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, No. 644 Yuanda Road, Furong District, Changsha, 410125, Hunan, China.|University of Chinese Academy of Sciences, Beijing, 100039, China.
authors.forename: Yehui
authors.initials: Y
authors.lastname: Duan
authors.affiliation: Scientific Observing and Experimental Station of Animal Nutrition and Feed Science in South-Central, Ministry of Agriculture, Hunan Provincial Engineering Research Center of Healthy Livestock, Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, No. 644 Yuanda Road, Furong District, Changsha, 410125, Hunan, China. lifengna@isa.ac.cn.
authors.forename: Fengna
authors.initials: F
authors.lastname: Li
authors.affiliation: Scientific Observing and Experimental Station of Animal Nutrition and Feed Science in South-Central, Ministry of Agriculture, Hunan Provincial Engineering Research Center of Healthy Livestock, Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, No. 644 Yuanda Road, Furong District, Changsha, 410125, Hunan, China.|University of Chinese Academy of Sciences, Beijing, 100039, China.
authors.forename: Yinghui
authors.initials: Y
authors.lastname: Li
authors.affiliation: Scientific Observing and Experimental Station of Animal Nutrition and Feed Science in South-Central, Ministry of Agriculture, Hunan Provincial Engineering Research Center of Healthy Livestock, Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, No. 644 Yuanda Road, Furong District, Changsha, 410125, Hunan, China.
authors.forename: Yulong
authors.initials: Y
authors.lastname: Tang
authors.affiliation: Scientific Observing and Experimental Station of Animal Nutrition and Feed Science in South-Central, Ministry of Agriculture, Hunan Provincial Engineering Research Center of Healthy Livestock, Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, No. 644 Yuanda Road, Furong District, Changsha, 410125, Hunan, China.
authors.forename: Xiangfeng
authors.initials: X
authors.lastname: Kong
authors.affiliation: Scientific Observing and Experimental Station of Animal Nutrition and Feed Science in South-Central, Ministry of Agriculture, Hunan Provincial Engineering Research Center of Healthy Livestock, Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, No. 644 Yuanda Road, Furong District, Changsha, 410125, Hunan, China.
authors.forename: Zemeng
authors.initials: Z
authors.lastname: Feng
authors.affiliation: Department of Nutritional Sciences, Rutgers University, New Brunswick, NJ, 08901, USA.
authors.forename: Tracy G
authors.initials: TG
authors.lastname: Anthony
authors.affiliation: Department of Nutritional Sciences, Rutgers University, New Brunswick, NJ, 08901, USA.
authors.forename: Malcolm
authors.initials: M
authors.lastname: Watford
authors.affiliation: Hubei Collaborative Innovation Center for Animal Nutrition and Feed Safety, Wuhan Polytechnic University, Wuhan, 430023, Hunan, China.
authors.forename: Yongqing
authors.initials: Y
authors.lastname: Hou
authors.affiliation: Hubei Collaborative Innovation Center for Animal Nutrition and Feed Safety, Wuhan Polytechnic University, Wuhan, 430023, Hunan, China.|Department of Animal Science, Texas A&M University, College Station, TX, 77843, USA.
authors.forename: Guoyao
authors.initials: G
authors.lastname: Wu
authors.affiliation: Scientific Observing and Experimental Station of Animal Nutrition and Feed Science in South-Central, Ministry of Agriculture, Hunan Provincial Engineering Research Center of Healthy Livestock, Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, No. 644 Yuanda Road, Furong District, Changsha, 410125, Hunan, China. yinyulong@isa.ac.cn.|Hubei Collaborative Innovation Center for Animal Nutrition and Feed Safety, Wuhan Polytechnic University, Wuhan, 430023, Hunan, China. yinyulong@isa.ac.cn.|School of Biology, Hunan Normal University, Changsha, 410018, Hunan, China. yinyulong@isa.ac.cn.
authors.forename: Yulong
authors.initials: Y
authors.lastname: Yin
mesh_terms: D000818:Animals; D004734:Energy Metabolism; D006801:Humans; D007930:Leucine / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000378:metabolism; D014176:Protein Biosynthesis; D011506:Proteins / Q000378:metabolism
chemical_list: D011506:Proteins; D007930:Leucine
keywords: Energy homeostasis; Leucine; Pigs; Protein metabolism; α-Ketoisocaproate; β-Hydroxy-β-methylbutyrate