Soy extract has different effects compared with the isolated isoflavones on the proteome of homocysteine-stressed endothelial cells

The Relationship Between Nutrition and Atherosclerosis

Atherosclerosis is the basic pathological process of many diseases, such as coronary atherosclerosis and stroke. Nutrients can affect the occurrence and development of atherosclerosis. At present, in nutrition science, the research on atherosclerosis focuses on which nutrients play an important role in its prevention strategy, and what are the possible mechanisms of its action. In the current study, the process of atherosclerosis can be affected by adjusting the proportion of nutrients in the diet. In this review, we pay attention to the effects of phytosterols, omega-3-polyunsaturated fatty acids, polyphenol, vitamin, and other nutrients on atherosclerosis, pay attention to their current epidemiological status, current nutritional research results, and prevention or a possible mechanism to reduce the risk of development of atherosclerosis. So that more personalized nutritional approaches may be more effective in terms of nutritional intervention responses to atherosclerosis.

Evidence for interactions between homocysteine and genistein: insights into stroke risk and potential treatment

Elevated plasma homocysteine (2-amino-4-sulfanylbutanoic acid) level is a risk factor for stroke. Moreover, it has been suggested that high levels of homocysteine in the acute phase of an ischemic stroke can predict mortality, especially in stroke patients with the large-vessel atherosclerosis subtype. In clinical studies, supplementation with genistein (5, 7-dihydroxy-3- (4-hydroxyphenyl)-4H-1-benzopyran-4-one) decreased plasma homocysteine levels considerably. Therefore, genistein could be considered as a potential drug for prevention and/or treatment of stroke. However, the mechanism of the effect of genistein on homocysteine level remains to be elucidated. In this report, direct functional interactions between homocysteine and genistein are demonstrated in in vitro experimental systems for determination of methylenetetrahydrofolate reductase (MetF) and glutathione peroxidase (GPx) activities, reconstructed with purified compounds, and in a simple in vivo system, based on measurement of growth rate of Vibrio harveyi and Bacillus subtilis cultures. Results of molecular modelling indicated that homocysteine can directly interact with genistein. Therefore, genistein-mediated decrease in plasma levels of homocysteine, and alleviation of biochemical and physiological effects of one of these compounds by another, might be ascribed to formation of homocysteine-genistein complexes in which biological activities of these molecules are abolished or alleviated.

The effect of soy or isoflavones on homocysteine levels: a meta-analysis of randomised controlled trials

BACKGROUND

The present study aimed to evaluate the effect of soy or isoflavones on blood homocysteine levels via a systematic review and meta-analysis.

METHODS

Pubmed, Embase, Web of Science and the Cochrane Library (up to 16 December 2015) were used for the literature review. Only randomised controlled trials were included. The primary outcome was the standard mean difference (SMD) of blood homocysteine levels between the experimental and control groups.

RESULTS

Nineteen randomised controlled studies were included for qualitative analysis. Eighteen studies were included in the data synthesis. Soy or isoflavones were found to have no effect on homocysteine levels, with a SMD of -0.21 (95% confidence interval = -0.43 to 0.00, I² =67.7%, random effect model). No publication bias was found among those studies (P = 0.296 for Egger's test, and P = 0.198 for Begg's test).

CONCLUSIONS

Soy or isoflavones were not found to be associated with a reduction in homocysteine levels. Further studies might still be needed in carefully selected populations.

Proteomic analysis identifies cytoskeleton-interacting proteins as major downstream targets of altered folate status in the aorta of adult rat

SCOPE

Mild folate deficiency and subsequently elevated plasma level of homocysteine are associated with an increased risk for vascular diseases in adults. Conversely, high intakes of folic acid (FA) may have beneficial effects on vascular function, presumably in part through homocysteine lowering. However, these effects have not yet been translated in terms of prevention or treatment of vascular pathologies. Besides, the complex biologic perturbation induced by variations of the folate supply is still not fully deciphered. We thus carried out a proteomic analysis of the aorta of adult rats after a dietary FA depletion or supplementation.

METHODS AND RESULTS

Nine month-old rats were fed a FA-depleted, FA-supplemented or control diet for 8 weeks. Total proteins from adventitia-free aortas were separated by 2DE and differentially expressed proteins were identified by MS. FA depletion or supplementation resulted in significantly changed abundance of 29 spots (p < 0.05), of which 20 proteins were identified. Bioinformatic analysis revealed that most of these proteins are involved in cytoskeleton-related processes important to cell function/maintenance, assembly/organization, and movement.

CONCLUSION

Our proteomic study supports that expression of proteins essential to vascular structure and, presumably, function is modulated by high intake as well as deprivation of FA.

Matrin 3 co-immunoprecipitates with the heat shock proteins glucose-regulated protein 78 (GRP78), GRP75 and glutathione S-transferase π isoform 2 (GSTπ2) in thymoma cells

Here, we report evidence that matrin 3 (MATR3), a highly conserved inner nuclear matrix phosphoprotein, whose function is largely unknown, interacts specifically with the heat shock proteins glucose-regulated protein 78 (GRP78), GRP75 and glutathione S-transferase π isoform 2 (GSTπ2). Using immunoprecipitation experiments of lysates obtained from control and tributyltin oxide (TBTO)-treated thymoma cell line (EL4), we identified MATR3 and its partners by MS/MS analysis and confirmed by immunoblot. We also show that MATR3 undergoes degradation as reported before and that this cleavage process, which is inhibited by the broad-spectrum caspase inhibitor, z-VAD-FMK, is more marked in TBTO-treated cells. Further, we found that the heat shock protein glucose-regulated protein 78 was downregulated in the TBTO-treated cells. The GRP78 protein is known to protect cells from apoptosis by complexing with procaspase 7 thereby preventing caspase activation cascade. By immunoblot analysis, we found that the levels of procaspases-3 and -7 were lower in TBTO-treated cells; in contrast, the level of p20, the active form of caspase 3, was relatively higher in the treated cells compared to that of control cells. We propose that the TBTO-mediated downregulation of GRP78 triggers the caspase cascade pathway leading to MATR3 degradation.

The immunosuppressant tributyltin oxide blocks the mTOR pathway, like rapamycin, albeit by a different mechanism

We treated the thymoma cell line (EL4) with two model immunosuppressants, rapamycin and tributyltin oxide (TBTO), and compared their effects on the expression levels of proteins that are downstream targets of mTOR kinase 1 (mammalian target of rapamycin, known also as mechanistic target of rapamycin): p70 ribosomal S6 kinase1 and 4E-binding protein 1, a repressor of the cap-binding protein eIF4E. In addition, we evaluated the levels of ribosomal protein S6, p-eIF4B, substrates of p70S6 kinase1, matrin 3 and ribonucleotide reductase, subunit RRM2. The levels of these proteins were evaluated in cell lysates by immunoblot. We found that both compounds inhibited the phosphorylation state of p70S6 kinase 1 and its substrates; however, TBTO, in contrast to rapamycin, reduced the level of the total p70S6k1. Besides, we detected a band with a molecular weight of c. 32 kDa only in the TBTO-treated lysates. This band was detected with a monoclonal antibody specific for S6k1, suggesting that this band might be a degradation product of the kinase. Further, TBTO and rapamycin differentially affected 4E-binding protein 1; the former compound stimulated its phosphorylation state whereas the latter inhibited it. The two immunosuppressants did not affect the level of ribonucleotide reductase, but TBTO downregulated matrin3, in agreement with a previous report, whereas rapamycin had no effect on the expression level of this latter protein. We conclude that TBTO inhibits, like rapamycin, the p70 S6 kinase 1 pathway, but with a different mechanism. However, in contrast to rapamycin, which inhibits the cap-dependent translation, TBTO increases the phosphorylation of 4E-binding protein1.

Genistein attenuates vascular endothelial impairment in ovariectomized hyperhomocysteinemic rats

Hyperhomocysteinemia (HHcy) is a well-known independent risk factor for vascular diseases in the general population. This study was to explore the effect of genistein (GST), a natural bioactive compound derived from legumes, on HHcy-induced vascular endothelial impairment in ovariectomized rats in vivo. Thirty-two adult female Wistar rats were assigned randomly into four groups (n = 8): (a) Con: control; (b) Met: 2.5% methionine diet; (c) OVX + Met: ovariectomy + 2.5% methionine diet; (d) OVX + Met + GST: ovariectomy + 2.5% methionine diet + supplementation with genistein. After 12 wk of different treatment, the rats' blood, toracic aortas and liver samples were collected for analysis. Results showed that high-methionine diet induced both elevation of plasma Hcy and endothelial dysfunction, and ovariectomy deteriorated these injuries. Significant improvement of both functional and morphological changes of vascular endothelium was observed in OVX + Met + GST group; meanwhile the plasma Hcy levels decreased remarkably. There were significant elevations of plasma ET-1 and liver MDA levels in ovariectomized HHcy rats, and supplementation with genistein could attenuate these changes. These results implied that genistein could lower the elevated Hcy levels, and prevent the development of endothelial impairment in ovariectomized HHcy rats. This finding may shed a novel light on the anti-atherogenic activities of genistein in HHcy patients.

Matrin 3 binds and stabilizes mRNA

Matrin 3 (MATR3) is a highly conserved, inner nuclear matrix protein with two zinc finger domains and two RNA recognition motifs (RRM), whose function is largely unknown. Recently we found MATR3 to be phosphorylated by the protein kinase ATM, which activates the cellular response to double strand breaks in the DNA. Here, we show that MATR3 interacts in an RNA-dependent manner with several proteins with established roles in RNA processing, and maintains its interaction with RNA via its RRM2 domain. Deep sequencing of the bound RNA (RIP-seq) identified several small noncoding RNA species. Using microarray analysis to explore MATR3′s role in transcription, we identified 77 transcripts whose amounts depended on the presence of MATR3. We validated this finding with nine transcripts which were also bound to the MATR3 complex. Finally, we demonstrated the importance of MATR3 for maintaining the stability of several of these mRNA species and conclude that it has a role in mRNA stabilization. The data suggest that the cellular level of MATR3, known to be highly regulated, modulates the stability of a group of gene transcripts.

7-difluoromethyl-5,4'-dimethoxygenistein, a novel agent protecting against vascular endothelial injury caused by oxidative stress

1. Genistein is known to protect the vascular endothelium. However, genistein exhibits poor bioavailability, which limits its use in the treatment of cardiovascular diseases. 7-Difluoromethyl-5,4'-dimethoxygenistein (dFMGEN), prepared by the difluoromethylation and alkylation of genistein, is a new active chemical entity. The protective effects of dFMGEN against vascular endothelial injury caused by oxidative stress were investigated in the present study. 2. Human umbilical vein endothelial cells were treated with either genistein (10 micromol/L) or various concentrations of dFMGEN (0.1, 0.3, 1, 3 and 10 micromol/L) for 30 min before exposure to 1 mmol/L H(2)O(2) for 24 h. The generation of reactive oxygen species (ROS) was assessed by fluorescence flow cytometry, the release of lactate dehydrogenase (LDH) was examined by biochemical assay, cell viability was measured by the 3-(4,5-dimethyl-2 thiazoyl)-2,5-diphenyl-2H-tetrazolium bromide assay, cell apoptosis was detected by flow cytometry and the expression of caspase 3 was examined by western blot analysis. 3. Pretreatment with 0.1, 0.3, 1, 3 and 10 micromol/L dFMGEN decreased the generation of ROS and the release of LDH in H(2)O(2)-exposed vascular endothelial cells, enhanced cell viability in a concentration-dependent manner over the concentration range 0.1-10 micromol/L, suppressed H(2)O(2)-induced apoptosis of vascular endothelial cells and downregulated the expression of caspase 3. The protective effect of 10 micromol/L dFMGEN against oxidative stress-induced endothelial injury was stronger than that of 10 micromol/L genistein. 4. The results of the present study suggest that dFMGEN can protect against vascular endothelial injury caused by oxidative stress.

Advances in Nutrigenomics research: novel and future analytical approaches to investigate the biological activity of natural compounds and food functions

In recent years, nutrition research has moved from classical epidemiology and physiology to molecular biology and genetics. Following this trend, Nutrigenomics has emerged as a novel and multidisciplinary research field in nutritional science that aims to elucidate how diet can influence human health. It is already well known that bioactive food compounds can interact with genes affecting transcription factors, protein expression and metabolite production. The study of these complex interactions requires the development of advanced analytical approaches combined with bioinformatics. Thus, to carry out these studies Transcriptomics, Proteomics and Metabolomics approaches are employed together with an adequate integration of the information that they provide. In this article, an overview of the current methodologies and a thorough revision of the advances in analytical technologies and their possibilities for future developments and applications in the field of Nutrigenomics is provided.

Isoflavone genistein protects human vascular endothelial cells against tumor necrosis factor-alpha-induced apoptosis through the p38beta mitogen-activated protein kinase

Isoflavone genistein may have beneficial effects on vascular function, but the mechanism is unclear. Here, we investigated whether genistein protects vascular endothelial cells against apoptosis induced by tumor necrosis factor-alpha. We show that genistein significantly inhibited TNF-alpha-induced apoptosis in human aortic endothelial cells as determined by caspase-3 activation, 7-amino actinomycin D staining, in situ apoptotic cell detection and DNA laddering. The anti-apoptotic effect of genistein was associated with an enhanced expression of Bcl-2 protein and its promoter activity. Inhibition of extracellular signal-regulated kinase 1/2, protein kinase A, or estrogen receptors had no effect on the cytoprotective effect of genistein. However, inhibition of p38 mitogen-activated protein kinase (p38) completely abolished this genistein effect. Accordingly, stimulation of HAECs with genistein resulted in rapid activation of p38beta, but not p38alpha. These findings provide the evidence that genistein acts as a survival factor for vascular ECs to protect cells against apoptosis via activation of p38beta. Preservation of the functional integrity of the endothelial monolayer may represent an important mechanism by which genistein exerts its vasculoprotective effect.

Regulation of cellular signals from nutritional molecules: a specific role for phytochemicals, beyond antioxidant activity

Phytochemicals (PhC) are a ubiquitous class of plant secondary metabolites. A "recommended" human diet should warrant a high proportion of energy from fruits and vegetables, therefore providing, among other factors, a huge intake of PhC, in general considered "health promoting" by virtue of their antioxidant activity and positive modulation, either directly or indirectly, of the cellular and tissue redox balance. Diet acts through multiple pathways and the association between the consumption of specific food items and the risk of degenerative diseases is extremely complex. Recent literature suggests that molecules having a chemical structure compatible with a putative antioxidant capacity can actually "perform" activities and roles independent of such capacity, interacting with cellular functions at different levels, such as affecting enzyme activities, binding to membrane or nuclear receptors as either an elective ligand or a ligand mimic. Inductive or signaling effects may occur at concentrations much lower than that required for effective antioxidant activity. Therefore, the "antioxidant hypothesis" is to be considered in some cases an intellectual "shortcut" possibly biasing the real understanding of the molecular mechanisms underlying the beneficial effects of various classes of food items. In the past few years, many exciting new indications elucidating the mechanisms of polyphenols have been published. Here, we summarize the current knowledge of the mechanisms by which specific molecules of nutritional interest, and in particular polyphenols, play a role in cellular response and in preventing pathologies. In particular, their direct interaction with nuclear receptors and their ability to modulate the activity of key enzymes involved in cell signaling and antioxidant responses are presented and discussed.

Proteomic methodological recommendations for studies involving human plasma, platelets, and peripheral blood mononuclear cells

This study was designed to develop, optimize and validate protocols for blood processing prior to proteomic analysis of plasma, platelets and peripheral blood mononuclear cells (PBMC) and to determine analytical variation of a single sample of depleted plasma, platelet and PBMC proteins within and between four laboratories each using their own standard operating protocols for 2D gel electrophoresis. Plasma depleted either using the Beckman Coulter IgY-12 proteome partitioning kit or the Amersham albumin and IgG depletion columns gave good quality gels, but reproducibility appeared better with the single-use immuno-affinity column. The use of the Millipore Filter Device for protein concentration gave a 16% ( p < 0.005) higher recovery of protein in flow-through sample compared with acetone precipitation. The use of OptiPrep gave the lowest level of platelet contamination (1:0.8) during the isolation of PBMC from blood. Several proteins (among which are alpha-tropomyosin, fibrinogen and coagulation factor XIII A) were identified that may be used as biomarkers of platelet contamination in future studies. When identifying preselected spots, at least three out of the four centers found similar identities for 10 out of the 10 plasma proteins, 8 out of the 10 platelet proteins and 8 out of the 10 PBMC proteins. The discrepancy in spot identifications has been described before and may be explained by the mis-selection of spots due to laboratory-to-laboratory variation in gel formats, low scores on the peptide analysis leading to no or only tentative identifications, or incomplete resolution of different proteins in what appears as a single abundant spot. The average within-laboratory coefficient of variation (CV) for each of the matched spots after automatic matching using either PDQuest or ProteomWeaver software ranged between 18 and 69% for depleted plasma proteins, between 21 and 55% for platelet proteins, and between 22 and 38% for PBMC proteins. Subsequent manual matching improved the CV with on average between 1 and 16%. The average between laboratory CV for each of the matched spots after automatic matching ranged between 4 and 54% for depleted plasma proteins, between 5 and 60% for platelet proteins, and between 18 and 70% for PBMC proteins. This variation must be considered when designing sufficiently powered studies that use proteomics tools for biomarker discovery. The use of tricine in the running buffer for the second dimension appears to enhance the resolution of proteins especially in the high molecular weight range.

A Milk Diet Partly Containing Soy Protein Does Not Change Growth but Regulates Jejunal Proteins in Young Goats

Soy protein is known to alter intestinal function and structure. We determined in young goats whether a diet partly containing soy protein differently affects intestinal morphology and the jejunal and hepatic proteome as compared with a milk diet. Fourteen male 2-wk-old White German dairy goat kids were fed comparable diets based on whole cow's milk in which 35% of the crude protein was casein (milk protein group; MP) or soy protein supplemented by indispensable AA (SPAA) for 34 d (n = 7/group). Body weight gain and food efficiency were not different. Jejunal and hepatic tissue was collected to determine intestinal morphology by microscopy and protein repertoire by 2-dimensional gel electrophoresis and mass spectrometry. Jejunal crypt depth was reduced and villus height to crypt depth ratio was higher in SPAA than in milk protein. Out of 131 proteins identified, 32 proteins were found to be differently expressed in both groups. In SPAA, down-regulated jejunal proteins were involved in processes related to cytoskeleton generation, protein, lipid, and energy metabolism. Downregulated hepatic proteins were related to glycolysis and Krebs cycle. Thirteen proteins were upregulated in SPAA. Among these, 2 hepatic proteins were related to carbohydrate breakdown. The other 11 jejunal proteins were involved in cytoskeleton assembly, proteolysis, and carbohydrate breakdown. In addition, glutathione-S-transferase was found to be upregulated in the medial jejunum. In conclusion, a SPAA diet as compared with a milk diet was related to changes in jejunal morphology and jejunal proteins relevant for protein turnover, energy metabolism, and cytoskeleton assembly with no apparent impact on animal BW gain.

Dietary isoflavones in the prevention of cardiovascular disease--a molecular perspective

The Food and Drugs Administration has approved a health claim for soy based on clinical trials and epidemiological data indicating that high soy consumption is associated with a lower risk of coronary artery disease. Soy products contain a group of compounds called isoflavones, with genistein and daidzein being the most abundant. A number of cardioprotective benefits have been attributed to dietary isoflavones including a reduction in LDL cholesterol, an inhibition of pro-inflammatory cytokines, cell adhesion proteins and inducible nitric oxide production, potential reduction in the susceptibility of the LDL particle to oxidation, inhibition of platelet aggregation and an improvement in vascular reactivity. There is increasing interest in the use of nutrigenomic methods to understand the mechanisms by which isoflavones induce these changes, and in the use of nutrigenetics to understand why the effects vary between individuals. Nutrigenomics is a rapidly growing field making use of molecular biology methodologies, such as microarray technology and proteomics, to study how specific nutrients or diets affect gene expression and cellular protein levels. The analysis of differential gene expression and protein levels in endothelial cells, macrophages and smooth muscle cells is critical to elucidating the sequence of events leading to the formation of atherosclerotic lesions, and to understanding the potential anti-atherogenic properties of soy isoflavones. An increasing number of studies demonstrate a significant impact of genetic variation on changes in cardiovascular risk factors in response to dietary intervention. Nutrigenetic effects of this type have recently been reported for dietary isoflavones, and may help to explain some of the disparities in the current literature concerning isoflavones and cardiovascular health.

Proteome analysis suggests that mitochondrial dysfunction in stressed endothelial cells is reversed by a soy extract and isolated isoflavones

Apoptosis is a driving force in atherosclerosis development. A soy extract or a combination of the soy isoflavones genistein and daidzein inhibited apoptosis induced by oxidized LDL in endothelial cells. Proteome analysis revealed that the LDL-induced alterations of numerous proteins were reversed by the extract and the genistein/daidzein mixture but only three protein entities, all functionally linked to mitochondrial dysfunction, were regulated in common by both treatments.