A proteomic adaptation of small intestinal mucosa in response to dietary protein limitation

Abstract

Dietary protein limitation (PL) is not only beneficial to human health but also applied to minimize nitrogen excretion in livestock production. However, the impact of PL on intestinal physiology is largely unknown. In this study, we identified 5275 quantitative proteins using a porcine model in which pigs suffered PL. A total of 202 proteins |log2 fold-change| > 1 were taken as differentially expressed proteins and subjected to functional and pathway enrichment analysis to reveal proteomic alterations of the jejunal mucosa. Combining with the results of western blotting analysis, we found that protein/carbohydrate digestion, intestinal mucosal tight junction and cell adhesion molecules, and the immune response to foreign antigens were increased in the jejunal mucosa of the pigs upon PL. In contrast, amino acid transport, innate and auto immunity, as well as cell proliferation and apoptosis were reduced. In addition, the expression of functional proteins that involved in DNA replication, transcription and mRNA splicing as well as translation were altered in the jejunal mucosa in response to PL. Furthermore, PL may reduce amino acid transport and cell proliferation through the depression of mTOR pathway. This study provides new insights into the molecular mechanisms underlying the small intestinal response to PL.

Integrated Remodeling of Gut–Liver Metabolism Induced by Moderate Protein Restriction Contributes to Improvement of Insulin Sensitivity

“…Pigs were given free access to feed and water. During the period of the study, the feed intake (kg d –1 ) remained unchanged, and final BW was decreased upon moderate PR as described previously …”

“…Most previous studies focused on extremely protein restrictive diets, in which protein levels were reduced by about 60–100%, or on specific essential amino acid (EAA), such as methionine and branched‐chain AA, which were restricted by 50% or more, far below the estimated average requirement for human and rodents, likely unsustainable and unhealthy due to the severe deficiency of EAA . We demonstrated that moderate PR diets, whose protein levels were reduced by about 20%, shrank circulating AA pool size and profoundly altered the pathways concerning immune function in the small intestine even with the supplementation of crystal EAA in diets . However, the impact of moderate PR without malnutrition on insulin resistance remains unclear.…”

Surplus dietary isoleucine intake enhanced monounsaturated fatty acid synthesis and fat accumulation in skeletal muscle of finishing pigs

“…To explore the alteration of lipogenesis and lipid accumulation in skeletal muscle, the relative protein expression levels of phosphor-adenosine monophosphate-activated protein kinase α (p-AMPKα), AMPKα, phosphor-acetyl coenzyme A (p-ACC), ACC, peroxisome proliferator activated receptor-γ (PPARγ) and CAAT/enhancer binding protein α (C/EBPα) in the LDM were determined by western blot analysis using the protein samples from all individual animals ( n = 6) as described previously [24]. Briefly, equal amounts of samples (50 μg of protein), together with a pre-stained protein ladder (Thermo Fisher, Rockford, IL, USA), were subjected to sodium dodecyl sulfate polyacrylamide gel electrophoresis electrophoresis with glyceraldehyde 3-phosphate dehydrogenase (GAPDH) being run as a loading control.…”

Proteome comparisons reveal influence of different dietary proteins on the development of rat jejunum

“…Diet has a broad influence on the small intestine. For example, protein limitation in diet can upregulate the proteins involved in protein/carbohydrate digestion, intestinal mucosal tight junction and cell adhesion, and the immune response to foreign antigens in the jejunal mucosa of pigs, but downregulate amino acid transport, innate and auto immunity, as well as cell proliferation and apoptosis [38] . In the present study, GO and KEGG pathway analyses indicated that, under the normal dose, intake of chicken protein induced upregulation of respiratory chain, oxidative phosphorylation and oxidoreductase activity, cell junction organization, and regulation of proton transport.…”