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.

N-Acetyl-L-cysteine Protects the Enterocyte against Oxidative Damage by Modulation of Mitochondrial Function

“…These data indicate that H 2 O 2 induces mitochondrial ROS production and then leads to DNA damage in IPEC-J2 cells. The report by Yi et al indicated that NAC increased the growth of IPEC-1 cells and suggested that NAC at low concentrations (<1 mM) could stimulate cell growth [20]. In line with these results, this experiment showed that addition of NAC at 500–1000  μ M to 100  μ M H 2 O 2 treatment increased the cell viability.…”

“…Similarly, supplement of NAC has been reported to improve growth performance and energy status, reduce inflammation, and ameliorate tissue damage [12]. Recently, Yi et al have found that NAC could stimulate protein synthesis and inhibit proteolysis in IPEC-1 cells [20]. In the present study, we found that NAC could not only ameliorate H 2 O 2 -induced cell growth inhibition, but also attenuate mitochondrial dysfunction in H 2 O 2 -treated cells.…”

Dietary Supplementation with Oleum Cinnamomi Improves Intestinal Functions in Piglets

“…Total RNA was quantified using the NanoDrop ® ND-1000A UV-VIS spectrophotometer (Thermo Scientific, Wilmington, DE, USA) at an OD of 260 nm, and its purity was assessed by determining the OD260/OD280 ratio. All of the samples had an OD260/OD280 ratio above 1.8 corresponding to 90–100% pure nucleic acids [ 21 , 38 ]. Meanwhile, RNA integrity in each sample was determined using 1% denatured agarose gel electrophoresis.…”

Targeting redox regulation to treat substance use disorder using N‐acetylcysteine

“…In a cell culture study using PC12 cells and sympathetic neurons deprived of neuotrophic factors, NAC supplementation was able to promote cell survival using a transcriptiondependent mechanism (Yan et al, 1995). Similarly, the results of a gene expression study in enterocytes suggested that NAC also increases protein synthesis (Yi et al, 2016). However, the role of NAC in protein homeostasis extends beyond protein synthesis to include protection against toxicity-induced protein degradation.…”