title: N-acetylcysteine stimulates protein synthesis in enterocytes independently of glutathione synthesis.
abstract: Dietary supplementation with N-acetylcysteine (NAC) has been reported to improve intestinal health and treat gastrointestinal diseases. However, the underlying mechanisms are not fully understood. According to previous reports, NAC was thought to exert its effect through glutathione synthesis. This study tested the hypothesis that NAC enhances enterocyte growth and protein synthesis independently of cellular glutathione synthesis. Intestinal porcine epithelial cells were cultured for 3 days in Dulbecco's modified Eagle medium containing 0 or 100 μM NAC. To determine a possible role for GSH (the reduced form of glutathione) in mediating the effect of NAC on cell growth and protein synthesis, additional experiments were conducted using culture medium containing 100 μM GSH, 100 μM GSH ethyl ester (GSHee), diethylmaleate (a GSH-depletion agent; 10 μM), or a GSH-synthesis inhibitor (buthionine sulfoximine, BSO; 20 μM). NAC increased cell proliferation, GSH concentration, and protein synthesis, while inhibiting proteolysis. GSHee enhanced cell proliferation and GSH concentration without affecting protein synthesis but inhibited proteolysis. Conversely, BSO or diethylmaleate reduced cell proliferation and GSH concentration without affecting protein synthesis, while promoting protein degradation. At the signaling level, NAC augmented the protein abundance of total mTOR, phosphorylated mTOR, and phosphorylated 70S6 kinase as well as mRNA levels for mTOR and p70S6 kinase in IPEC-1 cells. Collectively, these results indicate that NAC upregulates expression of mTOR signaling proteins to stimulate protein synthesis in enterocytes independently of GSH generation. Our findings provide a hitherto unrecognized biochemical mechanism for beneficial effects of NAC in intestinal cells.
authors.affiliation: Hubei Collaborative Innovation Center for Animal Nutrition and Feed Safety, Hubei Key Laboratory of Animal Nutrition and Feed Science, Wuhan Polytechnic University, Wuhan, 430023, China.
authors.forename: Dan
authors.initials: D
authors.lastname: Yi
authors.affiliation: Hubei Collaborative Innovation Center for Animal Nutrition and Feed Safety, Hubei Key Laboratory of Animal Nutrition and Feed Science, Wuhan Polytechnic University, Wuhan, 430023, China. houyq@aliyun.com.
authors.forename: Yongqing
authors.initials: Y
authors.lastname: Hou
authors.affiliation: Hubei Collaborative Innovation Center for Animal Nutrition and Feed Safety, Hubei Key Laboratory of Animal Nutrition and Feed Science, Wuhan Polytechnic University, Wuhan, 430023, China.
authors.forename: Lei
authors.initials: L
authors.lastname: Wang
authors.affiliation: Hubei Collaborative Innovation Center for Animal Nutrition and Feed Safety, Hubei Key Laboratory of Animal Nutrition and Feed Science, Wuhan Polytechnic University, Wuhan, 430023, China.
authors.forename: Minhui
authors.initials: M
authors.lastname: Long
authors.affiliation: Department of Animal Science, Texas A&M University, College Station, TX, 77843, USA.
authors.forename: Shengdi
authors.initials: S
authors.lastname: Hu
authors.affiliation: Hubei Collaborative Innovation Center for Animal Nutrition and Feed Safety, Hubei Key Laboratory of Animal Nutrition and Feed Science, Wuhan Polytechnic University, Wuhan, 430023, China.
authors.forename: Huimin
authors.initials: H
authors.lastname: Mei
authors.affiliation: Hubei Collaborative Innovation Center for Animal Nutrition and Feed Safety, Hubei Key Laboratory of Animal Nutrition and Feed Science, Wuhan Polytechnic University, Wuhan, 430023, China.
authors.forename: Liqiong
authors.initials: L
authors.lastname: Yan
authors.affiliation: Hubei Collaborative Innovation Center for Animal Nutrition and Feed Safety, Hubei Key Laboratory of Animal Nutrition and Feed Science, Wuhan Polytechnic University, Wuhan, 430023, China.|Department of Biochemistry and Molecular Biology, University of New Mexico School of Medicine, Albuquerque, NM, 87131, USA.
authors.forename: Chien-An Andy
authors.initials: CA
authors.lastname: Hu
authors.affiliation: Hubei Collaborative Innovation Center for Animal Nutrition and Feed Safety, Hubei Key Laboratory of Animal Nutrition and Feed Science, Wuhan Polytechnic University, Wuhan, 430023, China.|Department of Animal Science, Texas A&M University, College Station, TX, 77843, USA.
authors.forename: Guoyao
authors.initials: G
authors.lastname: Wu
mesh_terms: D000111:Acetylcysteine / Q000494:pharmacology*; D000818:Animals; D019328:Buthionine Sulfoximine / Q000494:pharmacology; D002460:Cell Line; D049109:Cell Proliferation / Q000187:drug effects*; D003545:Cysteine / Q000378:metabolism; D020895:Enterocytes / Q000378:metabolism*; D039642:Eukaryotic Initiation Factors / Q000378:metabolism; D005978:Glutathione / Q000031:analogs & derivatives / Q000378:metabolism* / Q000494:pharmacology; D008298:Maleates / Q000494:pharmacology; D014176:Protein Biosynthesis / Q000187:drug effects*; D060888:Real-Time Polymerase Chain Reaction; D034421:Sus scrofa; D058570:TOR Serine-Threonine Kinases / Q000378:metabolism
chemical_list: D039642:Eukaryotic Initiation Factors; D008298:Maleates; D019328:Buthionine Sulfoximine; C042431:S-ethyl glutathione; D058570:TOR Serine-Threonine Kinases; C014476:diethyl maleate; D005978:Glutathione; D003545:Cysteine; D000111:Acetylcysteine
keywords: Glutathione; Intestinal cells; N-acetylcysteine; Protein synthesis