Collagen peptide ingestion alters lipid metabolism-related gene expression and the unfolded protein response in mouse liver.

Ingestion of collagen peptide (CP) elicits beneficial effects on the body, including improvement in blood lipid profiles, but the underlying mechanisms remain unclear. The purpose of this study was to investigate the effects of CP ingestion on the liver, which controls lipid metabolism in the body. Male BALB/cCrSlc mice were bred with the AIN-93M diet containing 14 % casein or the AIN-93M-based low-protein diet containing 10 % casein or a diet containing 6 % casein+4 % CP for 10 weeks (n 12/group). Total, free and esterified cholesterol levels in the blood decreased in the CP group. DNA microarray analysis of the liver revealed that expressions of genes related to lipid metabolic processes such as the PPAR signalling pathway and fatty acid metabolism increased in the CP group compared with the 10 % casein group. The expressions of several genes involved in steroid metabolic process, including Cyp7a1 and Cyp8b1, were decreased, despite being targets of transcriptional regulation by PPAR. These data suggest that lipid metabolism in the liver is altered by CP ingestion, and the decrease in blood cholesterol levels in the CP group is not due to enhancement of the steroid metabolic process. On the other hand, expressions of genes related to the unfolded protein response (UPR) significantly decreased at the mRNA level, suggesting that CP ingestion lowers endoplasmic reticulum stress. Indeed, protein levels of phosphorylated inositol-requiring enzyme 1 decreased after CP ingestion. Taken together, CP affects the broader pathways in the liver - not only lipid metabolism but also UPR.

Searching for novel ATF4 target genes in human hepatoma cells by microarray analysis.

Activating transcription factor 4 (ATF4) is a transcription factor with an important biological activity. ATF4 is induced by various stresses, such as endoplasmic reticulum stress, through the phosphorylation of eukaryotic translation initiation factor 2α. ATF4 is also involved in lipid metabolism. In the present study, we performed a microarray experiment to identify new ATF4 target genes, particularly those involved in lipid metabolism, and identified C12orf39, CSTA, and CALCB as novel ATF4 target genes. An amino acid response element (AARE) as an ATF4-binding site is present in the promoter regions of these genes. In a detailed analysis using luciferase assay, we showed that ATF4 activated C12orf39 promoter activity and that this activation was diminished by deletion or mutation of the AARE sequence in the promoter region. Our results suggest that C12orf39, CSTA, and CALCB are novel ATF4 target genes and that C12orf39 promoter activity is activated by ATF4 through AARE.

Effect of orally administered collagen hydrolysate on gene expression profiles in mouse skin: a DNA microarray analysis.

Dietary collagen hydrolysate has been hypothesized to improve skin barrier function. To investigate the effect of long-term collagen hydrolysate administration on the skin, we evaluated stratum corneum water content and skin elasticity in intrinsically aged mice. Female hairless mice were fed a control diet or a collagen hydrolysate-containing diet for 12 wk. Stratum corneum water content and skin elasticity were gradually decreased in chronologically aged control mice. Intake of collagen hydrolysate significantly suppressed such changes. Moreover, we used DNA microarrays to analyze gene expression in the skin of mice that had been administered collagen hydrolysate. Twelve weeks after the start of collagen intake, no significant differences appeared in the gene expression profile compared with the control group. However, 1 wk after administration, 135 genes were upregulated and 448 genes were downregulated in the collagen group. This suggests that gene changes preceded changes of barrier function and elasticity. We focused on several genes correlated with functional changes in the skin. Gene Ontology terms related to epidermal cell development were significantly enriched in upregulated genes. These skin function-related genes had properties that facilitate epidermal production and differentiation while suppressing dermal degradation. In conclusion, our results suggest that altered gene expression at the early stages after collagen administration affects skin barrier function and mechanical properties. Long-term oral intake of collagen hydrolysate improves skin dysfunction by regulating genes related to production and maintenance of skin tissue.

Administration of a maple syrup extract to mitigate their hepatic inflammation induced by a high-fat diet: a transcriptome analysis.

Effects of the administration of maple syrup extract (MSX) on hepatic gene expression were investigated in mice fed a high-fat diet. Gene annotation enrichment analysis based on gene ontology revealed some changes in the expression of genes related to lipid metabolism and the immune response in MSX-fed mice. Detailed analysis of these data indicated that MSX ingestion mitigates hepatic inflammation.

Sequential gene expression profiling in the mouse spleen during 14 d feeding with Lactobacillus brevis KB290.

Some lactic acid bacteria play an important role in the immune system with potential benefits to the host. However, detailed mechanisms of immune modulation exerted by probiotics remain to be clarified. Since immune response changes in a time-related manner in some cases, we monitored changes in mRNA levels in the spleen of mice during 14 d feeding with Lactobacillus brevis KB290 (KB290). Female BALB/c mice, aged 9 weeks, commenced a diet containing KB290 (3 × 109 colony-forming units/g) or starch for a period of 1, 4, 7 or 14 d. Cytotoxic activity of the resulting splenocytes against YAC-1 cells was measured using flow cytometry. The activity was found to be significantly higher in the treated group on days 1 and 7. The highest activity appeared on day 4, but was not statistically significantly different. Gene expression profiles were analysed using DNA microarray. Gene Ontology (GO) terms related to the immune process were significantly enriched in the up-regulated gene set on days 1, 4 and 7, and GO terms related to the cellular process were enriched in the down-regulated gene set on days 4 and 7. Although the up-regulated genes involved in antigen processing and presentation for stimulation of CD8+ cytotoxic T cells were not observed on day 14, some genes involved in T-cell and natural killer cell activation remained up-regulated until day 14. For the majority of the genes tested, RT-PCR analysis was used to verify the results obtained from the DNA microarray analysis. The sequential gene expression profiling reflected changes in cytotoxic activity during KB290 feeding.

Post-exercise impact of ingested whey protein hydrolysate on gene expression profiles in rat skeletal muscle: activation of extracellular signal-regulated kinase 1/2 and hypoxia-inducible factor-1α.

We have previously shown that whey protein hydrolysate (WPH) causes a greater increase in muscle protein synthesis than does a mixture of amino acids that is identical in amino acid composition. The present study was conducted to investigate the effect of WPH on gene expression. Male Sprague-Dawley rats subjected to a 2 h swimming exercise were administered either a carbohydrate-amino acid diet or a carbohydrate-WPH diet immediately after exercise. At 1 h after exercise, epitrochlearis muscle mRNA was sampled and subjected to DNA microarray analysis. We found that ingestion of WPH altered 189 genes after considering the false discovery rate. Among the up-regulated genes, eight Gene Ontology (GO) terms were enriched, which included key elements such as Cd24, Ccl2, Ccl7 and Cxcl1 involved in muscle repair after exercise. In contrast, nine GO terms were enriched in gene sets that were down-regulated by the ingestion of WPH, and these GO terms fell into two clusters, 'regulation of ATPase activity' and 'immune response'. Furthermore, we found that WPH activated two upstream proteins, extracellular signal-regulated kinase 1/2 (ERK1/2) and hypoxia-inducible factor-1α (HIF-1α), which might act as key factors for regulating gene expression. These results suggest that ingestion of WPH, compared with ingestion of a mixture of amino acids with an identical amino acid composition, induces greater changes in the post-exercise gene expression profile via activation of the proteins ERK1/2 and HIF-1α.

Oral administration of the AYA strain of Lactobacillus plantarum modulates expression of immunity-related genes in the murine Peyer's patch: a DNA microarray analysis.

We performed comprehensive transcriptome analysis of Peyer's patches to elucidate the effects of oral administration of Lactobacillus plantarum strain AYA in mice. Using microarray analysis, we identified 124 upregulated and 144 downregulated genes for four weeks after the start of dietary supplementation with AYA. Gene Ontology analysis revealed that the genes for immune function were enriched in the upregulated gene set.

Effect of Lactobacillus brevis KB290 on the cell-mediated cytotoxic activity of mouse splenocytes: a DNA microarray analysis.

Lactic acid bacteria confer a variety of health benefits. Here, we investigate the mechanisms by which Lactobacillus brevis KB290 (KB290) enhances cell-mediated cytotoxic activity. Female BALB/c mice aged 9 weeks were fed a diet containing KB290 (3 × 10(9) colony-forming units/g) or starch for 1 d. The resulting cytotoxic activity of splenocytes against YAC-1 cells was measured using flow cytometry and analysed for gene expression using DNA microarray technology. KB290 enhanced the cell-mediated cytotoxic activity of splenocytes. DNA microarray analysis identified 327 up-regulated and 347 down-regulated genes that characterised the KB290 diet group. The up-regulated genes were significantly enriched in Gene Ontology terms related to immunity, and, especially, a positive regulation of T-cell-mediated cytotoxicity existed among these terms. Almost all the genes included in the term encoded major histocompatibility complex (MHC) class I molecules involved in the presentation of antigen to CD8(+) cytotoxic T cells. Marco and Signr1 specific to marginal zone macrophages (MZM), antigen-presenting cells, were also up-regulated. Flow cytometric analysis confirmed that the proportion of MZM was significantly increased by KB290 ingestion. Additionally, the over-represented Kyoto Encyclopedia of Genes and Genomes pathways among the up-regulated genes were those for natural killer (NK) cell-mediated cytotoxicity and antigen processing and presentation. The results for the selected genes associated with NK cells and CD8(+) cytotoxic T cells were confirmed by quantitative RT-PCR. These results suggest that enhanced cytotoxic activity could be caused by the activation of NK cells and/or of CD8(+) cytotoxic T cells stimulated via MHC class I presentation.

Bioinformatics Analysis of the Molecular Networks Associated with the Amelioration of Aberrant Gene Expression by a Tyr-Trp Dipeptide in Brains Treated with the Amyloid-ß Peptide.

Short-chain peptides derived from various protein sources have been shown to exhibit diverse bio-modulatory and health-promoting effects in animal experiments and human trials. We recently reported that the oral administration of the Tyr-Trp (YW) dipeptide to mice markedly enhances noradrenaline metabolism in the brain and ameliorates the working-memory deficits induced by the ß-amyloid 25-35 peptide (Aß25-35). In the current study, we performed multiple bioinformatics analyses of microarray data from Aß25-35/YW-treated brains to determine the mechanism underlying the action of YW in the brain and to infer the molecular mechanisms and networks involved in the protective effect of YW in the brain. We found that YW not only reversed inflammation-related responses but also activated various molecular networks involving a transcriptional regulatory system, which is mediated by the CREB binding protein (CBP), EGR-family proteins, ELK1, and PPAR, and the calcium-signaling pathway, oxidative stress tolerance, and an enzyme involved in de novo l-serine synthesis in brains treated with Aß25-35. This study revealed that YW has a neuroprotective effect against Aß25-35 neuropathy, suggesting that YW is a new functional-food-material peptide.

Ingested maple syrup evokes a possible liver-protecting effect-physiologic and genomic investigations with rats.

Rats fed a 20%-maple syrup diet (maple syrup group) for 11 d showed significantly lower values of the hepatic function markers than those fed a 20%-sugar mix syrup diet (control). The reason was suggested by a DNA microarray analysis which revealed that the expression of genes for the enzymes of ammonia formation were down-regulated in the liver of the maple syrup group.

Dietary iso-α-acids prevent acetaldehyde-induced liver injury through Nrf2-mediated gene expression.

Acetaldehyde is the major toxic metabolite of alcohol (ethanol) and enhances fibrosis of the liver through hepatic stellate cells. Additionally, alcohol administration causes the accumulation of reactive oxygen species (ROS), which induce hepatocyte injury-mediated lipid peroxidation. Iso-α-acids, called isohumulones, are bitter acids in beer. The purpose of this study was to investigate the protective effects of iso-α-acids against alcoholic liver injury in hepatocytes in mice. C57BL/6N mice were fed diets containing isomerized hop extract, which mainly consists of iso-α-acids. After 7 days of feeding, acetaldehyde was administered by a single intraperitoneal injection. The acetaldehyde-induced increases in serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels were suppressed by iso-α-acids intake. Hepatic gene expression analyses showed the upregulation of detoxifying enzyme genes, glutathione-S-transferase (GST) and aldehyde dehydrogenase (ALDH). In vitro, iso-α-acids upregulated the enzymatic activities of GST and ALDH and induced the nuclear translocation of nuclear factor-erythroid-2-related factor 2 (Nfe2l2; Nrf2), a master regulator of antioxidant and detoxifying systems. These results suggest that iso-α-acid intake prevents acetaldehyde-induced liver injury by reducing oxidative stress via Nrf2-mediated gene expression.

Effects of Soy Isoflavones, Resistant Starch and Antibiotics on Polycystic Ovary Syndrome (PCOS)-Like Features in Letrozole-Treated Rats.

Polycystic ovary syndrome (PCOS) is the most common endocrine disorder in reproductive-aged women. Recently, various dietary interventions have been used extensively as a novel therapy against PCOS. In the present study, we show that soy isoflavone metabolites and resistant starch, together with gut microbiota modulations, were successful in decreasing the severity of PCOS-like reproductive features while increasing the expression of gut barrier markers and butyric acid in the gut. In the letrozole-induced PCOS model rats, the intake of both 0.05% soy isoflavones and 11% resistant starch, even with letrozole treatment, reduced the severity of menstrual irregularity and polycystic ovaries with a high concentration of soy isoflavones and equol in plasma. Antibiotic cocktail treatment suppressed soy isoflavone metabolism in the gut and showed no considerable effects on reducing the PCOS-like symptoms. The mRNA expression level of occludin significantly increased with soy isoflavone and resistant starch combined treatment. Bacterial genera such as Blautia, Dorea and Clostridium were positively correlated with menstrual irregularity under resistant starch intake. Moreover, the concentration of butyric acid was elevated by resistant starch intake. In conclusion, we propose that both dietary interventions and gut microbiota modulations could be effectively used in reducing the severity of PCOS reproductive features.

Dietary iron-deficient anemia induces a variety of metabolic changes and even apoptosis in rat liver: a DNA microarray study.

Anemia can be induced by dietary iron deficiency, as well as by hemorrhagia. It may also be associated with changes in lipid metabolism. However, no global analysis detailing the consequences of iron deficiency in the liver has yet been conducted. Since the liver is a metabolically important organ and also a major iron-storing organ, we performed a comprehensive transcriptome analysis to determine the effects of iron deficiency on hepatic gene expression. Four-week-old rats were fed an iron-deficient diet, approximately 3 ppm iron, ad libitum for 16 days. These rats were compared with similar rats pair-fed a control diet with a normal iron level, 48 ppm iron. The 16-day iron-deficient diet apparently induced anemia. On day 17, the rats were killed under anesthesia, and their livers were dissected for DNA microarray analysis. We identified 600 upregulated and 500 downregulated probe sets that characterized the iron-deficient diet group. In the upregulated probe sets, genes involved in cholesterol, amino acid, and glucose metabolism were significantly enriched, while genes related to lipid metabolism were significantly enriched in the downregulated probe sets. We also found that genes for caspases 3 and 12, which mediate endoplasmic reticulum (ER)-specific apoptosis, were upregulated in the iron-deficient group. Combined, these results suggest that iron deficiency exerts various influences, not only on nutrient metabolism but also on apoptosis, as a consequence of ER stress in the liver.

The hepatic genes for immunoproteasome are upregulated by refeeding after fasting in the rat.

Considering that animals maintain energy homeostasis in response to nutrient levels, experiments were done to elucidate the temporal effects of refeeding after fasting on gene expression profiles in the rat liver. Using DNA microarray technology, we first compared gene expression profiles in the livers of rats allowed to feed for 6 h after fasting for 18 h and those in 24-h fasting rats, and found that the expression levels of energy metabolism-related genes in the two groups were different. In addition, refeeding induced upregulation of the genes encoding immunoproteasome components. Finally, immunoblot analysis confirmed changes in protein levels, suggesting that refeeding after fasting enhanced immune function.

Effect of flavonol glycoside in mulberry (Morus alba L.) leaf on glucose metabolism and oxidative stress in liver in diet-induced obese mice.

BACKGROUND: Mulberry therapies on type 2 diabetic patients or streptozotocin-induced diabetic rats have been reported to improve fasting blood glucose levels. We investigated the effects of dietary consumption of mulberry-leaf powder and purified quercetin 3-(6-malonylglucoside), the quantitatively major flavonol glycoside in mulberry leaves, on glucose and lipid metabolism in high-fat diet-induced obese mice. Male C57BL/6J mice aged 8 weeks were assigned to three groups (control, mulberry leaf powder (MLP), and quercetin 3-(6-malonylglucoside) (Q3MG)) and treated with their respective diets for 8 weeks. RESULTS: We found that dietary supplementation of 10 g MLP kg(-1) or 1 g Q3MG kg(-1) in high-fat diet effectively suppressed blood glucose levels. We also noted increased expression of glycolysis-related genes and suppression of thiobarbituric acid reactive substances concentrations in the liver of Q3MG group compared to control mice. CONCLUSION: Dietary consumption of Q3MG, the quantitatively major flavonol glycoside in mulberry leaves, improved hyperglycemia in obese mice and reduced oxidative stress in the liver.

A maple syrup extract alleviates liver injury in type 2 diabetic model mice.

A recent study showed that 54% of type 2 diabetes (T2D) patients have nonalcoholic fatty liver disease, which is a risk factor for aggravation diabetic symptoms. Previous studies suggested components in maple syrup alleviated liver injury and found polyphenols as food components to improve the symptoms and complications of diabetes. Therefore, we hypothesized that a polyphenol fraction in maple syrup improves the symptoms and complications of diabetes. To address the hypothesis, we investigated the effects of a polyphenol-rich maple syrup extract (MSE) on a T2D model mice. KK-Ay mice were fed a normal or 0.1% MSE-supplemented diet for 43 days. The results showed that the levels of serum alanine aminotransferase and aspartate aminotransferase were significantly reduced in mice that ingested MSE. Hepatic genes related to lipogenesis and lipolysis were down- and upregulated, respectively, in mice that ingested MSE. These results suggest that MSE intake alleviates liver injury and suppresses lipid accumulation in the livers of T2D mice.

Tyr-Trp administration facilitates brain norepinephrine metabolism and ameliorates a short-term memory deficit in a mouse model of Alzheimer's disease.

The physiological actions of orally ingested peptides on the brain remain poorly understood. This study examined the effects of 39 orally administered synthetic Tyr-containing dipeptides on the enhancement of brain norepinephrine metabolism in mice by comparing the concentration of 3-methoxy-4-hydroxyphenylethyleneglycol (MHPG). Although Tyr-Tyr administration increased blood and cerebral cortex (Cx) Tyr concentrations the most, Tyr-Trp increased Cx MHPG concentration the most. The oral administration of Tyr-Trp ameliorated a short-term memory deficit of a mouse model of cognitive dysfunction induced by amyloid beta peptide 25-35. Gene expression profiling of mouse brain using a microarray indicated that Tyr-Trp administration led to a wide variety of changes in mRNA levels, including the upregulation of genes encoding molecules involved in catecholamine metabolism. A comparative metabolome analysis of the Cx of mice given Tyr-Trp or Tyr-Tyr demonstrated that Tyr-Trp administration yielded higher concentrations of Trp and kynurenine pathway metabolites than Tyr-Tyr administration, as well as higher L-dopa levels, which is the initial product of catecholamine metabolism. Catecholamines were not significantly increased in the Cx of the Tyr-Tyr group compared with the Tyr-Trp group, despite a marked increase in Tyr. Presumably, Tyr-Trp administration enhances catecholamine synthesis and metabolism via the upregulation of genes involved in Tyr and Trp metabolism as well as metabolites of Tyr and Trp. These findings strongly suggest that orally ingested Tyr-Trp modulates the brain metabolome involved in catecholamine metabolism and contributes to higher brain function.

Intake of a Mixture of Sake Cake and Rice Malt Increases Mucin Levels and Changes in Intestinal Microbiota in Mice.

Amazake is a traditional Japanese beverage. Its main ingredients are sake cake and rice malt. In this study, we examined the effect of sake cake and rice malt on the intestinal barrier function and gut microbiota. BALB/c mice were fed a control diet or a diet containing a mixture of sake cake and rice malt powder (SRP) for four weeks. Fecal IgA values did not change between groups, but the fecal mucin level was significantly greater in the SRP-fed group. Gene expression analysis in the ileum by real-time PCR demonstrated Muc2 expression did not change, while the Muc3 expression was upregulated in the SRP-fed group. Furthermore, microbiota analysis demonstrated a change by SRP intake at the family level, and the proportion of Lactobacillaceae significantly increased in the SRP-fed group. At the genus level, the proportion of Lactobacillus also significantly increased in the SRP-fed group. These results suggest that the intake of a mixture of sake cake and rice malt improves intestinal barrier function by increasing mucin levels and inducing changes in intestinal microbiota.

A maple syrup extract alters lipid metabolism in obese type 2 diabetic model mice.

BACKGROUND: Some polyphenols are known to improve the symptoms of diabetes. In the present study, we investigated the effects of a polyphenol-rich extract of maple syrup (MSx) on a diabetic mouse model. METHODS: KK-A y mice were fed a normal or 0.05% MSx-supplemented diet for 42 days. Body weight, food intake, serum biochemical parameters, and fecal total bile acid were measured. Gene expression of liver and epididymal white adipose tissue (WAT) and cecal microbiota were analyzed. Data were analyzed with an unpaired two-tailed Student's t test or Welch's t test according to the results of the F test. RESULTS: Serum low-density lipoprotein cholesterol levels were significantly reduced in mice that consumed MSx. Hepatic genes related to fatty acid degradation and cholesterol catabolism were upregulated in mice that consumed MSx. In contrast, the expression of genes related to lipid metabolism in WAT was unaffected by the intake of MSx. There were no significant differences between the two groups in terms of total bile acid level in the feces and the relative abundance of bacteria in the cecum. CONCLUSION: Our results primarily indicate that MSx can help alleviate one of the symptoms of dyslipidemia.

The Anti-Arthritis Effect of Olive-Derived Maslinic Acid in Mice is Due to its Promotion of Tissue Formation and its Anti-Inflammatory Effects.

SCOPE: A previous study demonstrated that intake of olive pomace extract containing maslinic acid (MA), a triterpene, effectively prevents and alleviates arthritis in animals and humans. Here, the molecular mechanisms involved in the anti-arthritis effect of MA have been elucidated by determining gene expression changes induced by olive-derived MA intake in collagen antibody-induced arthritis (CAIA) mice. METHODS AND RESULTS: Mice are divided into the untreated (CT), CAIA (CA), and CAIA administered MA (CA + MA) groups. The CA + MA mice are fed MA at a daily dose of 200 mg kg-1 of body weight from day 1. CAIA is then induced on day 8 and evaluated on day 12. Arthritis symptoms are alleviated, and the gene expression of inflammatory cytokines is reduced in the CA + MA group compared with the CA group. A DNA microarray analysis of synovial membranes reveals that MA alters the expression levels of genes related to inflammation, including glucocorticoid responses, immune responses, and the extracellular matrix. CONCLUSIONS: The preventive effect of MA on arthritis is attributable to the promotion of tissue formation as well as suppression of inflammation in the synovium via inactivation of Toll-like receptor signaling and downregulation of leukotrienes through the glucocorticoid receptor.