Proteomic analysis of chemically transformed NIH-3T3 cells reveals novel mechanisms of action of amaranth lunasin-like peptide.

Food-derived biopeptides can interact with genes and proteins to preserve health and prevent the development of diseases. Lunasin is a soybean cancer-preventive peptide that has been well characterized; however, few studies have been carried out to characterize the function of amaranth lunasin-like peptide (AhLun). The aim of this work was to analyze the proteomic profile changes in NIH-3T3 cells when they are chemically transformed with the carcinogen 3-methylcholanthrene (3MC) in the absence or presence of AhLun. The addition of AhLun into the culture medium did not affect the cell morphology; however, as a chemopreventive agent, it significantly reduced anisokaryosis formation when cells were treated with 3MC. Changes in protein accumulation in NIH-3T3 cells were evaluated by gel-based proteomics analysis. Differentially accumulated protein spots that exhibited at least a twofold change in spot intensity (p < 0.05), when compared with control cells, were analyzed by LC-MS/MS. Successfully identified proteins were grouped into six main categories according to their localization and function (nuclear, ribosomal, mitochondrial, metabolism, cytoskeletal, and miscellaneous). The gel-based proteomic approach for the evaluation of the chemopreventive potential of AhLun reveals novel pathways of action and provides new clues about the possible mechanisms of action of this bioactive peptide present in amaranth seeds.

The proteome map of the escamolera ant (Liometopum apiculatum Mayr) larvae reveals immunogenic proteins and several hexamerin proteoforms.

The larvae of escamolera ant (Liometopum apiculatum Mayr) have been considered a delicacy since Pre-Hispanic times. The increased demand for this stew has led to massive collection of ant nests. Yet biological aspects of L. apiculatum larvae remain unknown, and mapping the proteome of this species is important for understanding its biological characteristics. Two-dimensional gel electrophoresis (2-DE) followed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis was used to characterize the larvae proteome profile. From 380 protein spots analyzed, 174 were identified by LC-MS/MS and homology search against the Hymenoptera subset of the NCBInr protein database using the Mascot search engine. Peptide de novo sequencing and homology-based alignment allowed the identification of 36 additional protein spots. Identified proteins were classified by cellular location, molecular function, and biological process according to the Gene Ontology annotation. Immunity- and defense-related proteins were identified including PPIases, FK506, PEBP, and chitinases. Several hexamerin proteoforms were identified and the cDNA of the most abundant protein detected in the 2-DE map was isolated and characterized. L. apiculatum hexamerin (LaHEX, GeneBank accession no. MH256667) contains an open reading frame of 2199 bp encoding a polypeptide of 733 amino acid residues with a calculated molecular mass of 82.41 kDa. LaHEX protein is more similar to HEX110 than HEX70 from Apis mellifera. Down-regulation of LaHEX was observed throughout ant development. This work represents the first proteome map as well as the first hexamerin characterized from L. apiculatum larvae.

Consumption of Amaranth Induces the Accumulation of the Antioxidant Protein Paraoxonase/Arylesterase 1 and Modulates Dipeptidyl Peptidase IV Activity in Plasma of Streptozotocin-Induced Hyperglycemic Rats.

BACKGROUND/AIM: Amaranth is a source of several bioactive compounds, among which peptides with inhibitory activity upon dipeptidyl peptidase IV (DPP-IV) have been reported. However, there is no information about the action of amaranth DPP-IV-inhibitory peptides using in vivo models. The aim of this work was to evaluate the effect of amaranth consumption on plasma and kidney DPP-IV activity as well the changes in plasma proteome profile of streptozotocin (STZ)-induced hyperglycemic rats. METHODS: Rats were fed for 12 weeks with a diet containing 20% popped amaranth grain. Kidneys and blood samples were collected for lipid profile, DPP-IV activity and expression, and proteomic analysis. RESULTS: Total cholesterol and DPP-IV activity in plasma was increased in hyperglycemic rats, but this effect was reverted by amaranth consumption. Triacylglycerols were increased in the hyperglycemic group fed amaranth, and the highest levels of high-density lipoproteins were also observed in this group. These data correlated with the accumulation of apolipoprotein A-II in plasma. Accumulation of the antioxidant protein paraoxonase/arylesterase 1 in STZ-induced hyperglycemic rats was observed when amaranth was supplied in the diet. CONCLUSION: This study provides new insights into the molecular mechanisms by which amaranth exerts its beneficial health action in a hyperglycemic state.

In vitro inhibition of dipeptidyl peptidase IV by peptides derived from the hydrolysis of amaranth (Amaranthus hypochondriacus L.) proteins.

Bioactive compounds present in foods could potentially have beneficial effects on human health. In this study we report the in vitro inhibitory capacity of peptides released from amaranth seed proteins after enzymatic digestion, against dipeptidyl peptidase IV (DPPIV); an enzyme known to deactivate incretins, hormones involved in insulin secretion. Other seeds, such as soybean, black bean, and wheat were also tested. The highest inhibition of DPPIV was observed with amaranth peptides released after simulated gastrointestinal digestion, showing an IC(50) of 1.1mg/mL in a dose-dependent manner. In silico tryptic digestion of amaranth globulins was carried out releasing peptides larger than 13 residues. Some of these peptides were used for the in silico prediction of their binding modes with DPPIV. Docking models showed that the possible mechanism of globulin peptides to inhibit DPPIV was through blocking the active dimer formation. Peptides were also found inside the major cavity where the natural substrates reach the catalytic site of the enzyme. This is the first report of the identification of inhibitory DPPIV peptides from amaranth hydrolysates and the prediction of their binding modes at the molecular level, leading to their possible use as functional food ingredients in the prevention of diabetes.