Publishing type：Research paper (scientific journal)   International / domestic magazine：Domestic journal  

Publishing type：Research paper (scientific journal)  

Abstract

Target identification is a crucial step in elucidating the mechanisms by which functional food components exert their functions. Here, we identified the G-protein-coupled bile acid receptor 1 (GPBAR1, also known as TGR5) as a target of the triterpenoid mogrol, a class of aglycone mogroside derivative from Siraitia grosvenorii. Mogrol, but not mogrosides, activated cAMP-response element-mediated transcription in a TGR5-dependent manner. Additionally, mogrol selectively activated TGR5 but not the other bile acid-responsive receptors (i.e., farnesoid X receptor, vitamin D receptor, or muscarinic acetylcholine receptor M3). Several amino acids in TGR5 (L71A^2.60, W75A^ECL1, Q77A^ECL1, R80A^ECL1, Y89A^3.29, F161A^ECL2, L166A^5.39, Y240A^6.51, S247A^6.58, Y251A^6.62, L262A^7.35, and L266A^7.39) were found to be important for mogrol-induced activation. Mogrol activated insulin secretion under low-glucose conditions in INS-1 pancreatic β-cells, which can be inhibited by a TGR5 inhibitor. Similar effects of mogrol on insulin secretion were observed in the isolated mouse islets. Mogrol administration partially but significantly alleviated hyperglycemia in KKAy diabetic mice by increasing the insulin levels without affecting the β-cell mass or pancreatic insulin content. These results suggest that mogrol stimulates insulin secretion and alleviates hyperglycemia by acting as a TGR5 agonist.

DOI： 10.1038/s41598-024-53380-x

PubMed

Other URL： https://www.nature.com/articles/s41598-024-53380-x

Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

SCOPE: Chalcones are widely present in most plants and have various health beneficial functions. This study investigates the suppressive effect of 13 natural and synthetic chalcones on transformation of aryl hydrocarbon receptor (AhR) induced by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and 3-methylcholanthrene (3-MC) in a cell-free system, Hepa-1c1c7 cells, and liver of ICR mice. METHODS AND RESULTS: In the cell-free system, cardamonin dose-dependently inhibits AhR transformation. Chalcones with substitution on 2' and/or 6' position is important for the suppressive effect, while the substitution on 4' position is negatively for the effect. Moreover, cardamonin and 2'-hydroxychalcone competitively inhibit the binding of [3H]-3-MC to the AhR. In Hepa-1c1c7 cells, cardamonin inhibits AhR transformation and expression of cytochrome P4501A1 (CYP1A1) in a dose-dependent manner through suppressing TCDD-induced phosphorylation of both AhR and AhR nuclear translocator, heterodimerization of them, and nuclear translocation of AhR. In the liver of mice, oral administered cardamonin also inhibits 3-MC-induced AhR translocation and expression of CYP1A1. CONCLUSION: Among used chalcones, a natural chalcone cardamonin competitively binds to AhR and suppresses its transformation. Thus, cardamonin is an effective food factor for suppression of the dioxin-caused biochemical alterations and toxicities.

DOI： 10.1002/mnfr.202400185

PubMed

Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

Pancreatic β-cell mass is a critical determinant of insulin secretion. Severe endoplasmic reticulum (ER) stress causes β-cell apoptosis; however, the mechanisms of progression and suppression are not yet fully understood. Here, we report that the autocrine/paracrine function of insulin reduces ER stress-induced β-cell apoptosis. Insulin reduced the ER-stress inducer tunicamycin- and thapsigargin-induced cell viability loss due to apoptosis in INS-1 β-cells. Moreover, the effect of insulin was greater than that of insulin-like growth factor-1 at physiologically relevant concentrations. Insulin did not attenuate the ER stress-induced increase in unfolded protein response genes. ER stress did not induce cytochrome c release from mitochondria. Mitochondrial hyperpolarization was induced by ER stress and prevented by insulin. The protonophore/mitochondrial oxidative phosphorylation uncoupler, but not the antioxidants N-acetylcysteine and α-tocopherol, exhibited potential cytoprotection during ER stress. Both procaspase-12 and cleaved caspase-12 levels increased under ER stress. The caspase-12 inhibitor Z-ATAD-FMK decreased ER stress-induced apoptosis. Caspase-12 overexpression reduced cell viability, which was diminished in the presence of insulin. Insulin decreased caspase-12 levels at the post-translational stages. These results demonstrate that insulin protects against ER stress-induced β-cell apoptosis in this cell line. Furthermore, mitochondrial hyperpolarization and increased caspase-12 levels are involved in ER stress-induced and insulin-suppressed β-cell apoptosis.

DOI： 10.14814/phy2.16106

PubMed

Publishing type：Research paper (scientific journal)   International / domestic magazine：Domestic journal  

<p>Quercetin is a natural flavonol and has various health beneficial functions. Our pervious study demonstrated that long-term feeding (13 weeks) of quercetin and its glycosides, isoquercitrin, rutin, and enzymatically modified isoquercitrin, which is a mixture of quercetin monoglycoside and its oligoglycosides, prevented hyperglycemia and adiposity in mice fed a high-fat diet but not standard diet. It is, however, unclear whether a single admin­istration of these compounds prevent postprandial hyperglycemia or not. In the present study, we estimated their prevention effect on acute hyperglycemia by an oral glucose tolerance test in ICR mice and investigated its mechanism. It was found that quercetin glycosides, but not the aglycone, suppressed acute hyperglycemia and isoquercitrin showed the strongest effect among the glycosides. As the underlying mechanism, quercetin glycosides promoted translocation of glucose transporter 4 to the plasma membrane of skeletal muscle of mice through phosphorylation of ‍adenosine monophosphate-activated protein kinase and its upstream Ca²⁺/calmodulin-dependent protein kinase kinase β without activating the insulin- and JAK/STAT-signal pathways. In conclusion, single oral administration of quercetin glycosides prevented a blood sugar spike by promoting glucose transporter 4 ‍translocation through activating the CAMKKβ/AMPK signaling pathway.</p>

DOI： 10.3164/jcbn.23-30

PubMed

CiNii Research

Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

Mung beans are among the important edible legumes cultivated in Asia, Southern Europe, and Northern America. Mung beans contain 20-30% proteins with high digestibility and possess biological activities, but detailed health beneficial functions are not fully understood yet. In this study, we report the isolation and identification of active peptides from mung beans which promote glucose uptake and elucidate their mechanism in L6 myotubes. HTL, FLSSTEAQQSY, and TLVNPDGRDSY were isolated and identified as active peptides. These peptides promoted the translocation of glucose transporter 4 (GLUT4) to the plasma membrane. The tripeptide HTL promoted glucose uptake through the activation of adenosine monophosphate-activated protein kinase, while the oligopeptides FLSSTEAQQSY and TLVNPDGRDSY through the activation of the PI3K/Akt pathway. Furthermore, these peptides promoted the phosphorylation of Jak2 via interaction with the leptin receptor. Thus, mung bean is a promising functional food for the prevention of hyperglycemia and type 2 diabetes through promoting glucose uptake accompanied by JAK2 activation in the muscle cells.

DOI： 10.1039/d3fo00836c

PubMed

Authorship：Lead author   Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

DOI： 10.3390/ijms24109035

PubMed

Authorship：Lead author   Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

SCOPE: Acetaldehyde is a highly toxic primary metabolite of ethanol, and converted to non-toxic acetic acid by aldehyde dehydrogenase (ALDH). Accumulation of acetaldehyde causes significant damage to our body. Aged garlic extract (AGE) is a functional food material and possesses various health beneficial effects. In this study, we investigated whether AGE contributes to acetaldehyde detoxification through ALDH induction and its underlying mechanism. METHODS AND RESULTS: C57BL/6J mice were orally administrated 10 - 1000 mg/kg BW of AGE for 1week before ethanol administration. AGE suppressed ethanol-caused accumulation of acetaldehyde level in the plasma through inducing mitochondrial ALDH2 but not cytosolic ALDH1A1. AGE also induced antioxidant enzymes, heme oxigenase-1 and NAD(P)H:quinone oxidoreductase 1, resulting in prevention of lipid peroxidation in the liver. In HepG2 cells, AGE prevented ethanol- and acetaldehyde-caused cytotoxicity. AGE induced mitochondrial ALDH2 through activating nuclear factor-erythroid 2-related factor 2 (Nrf2). AGE inhibited protein degradation of Nrf2 and enhanced protein degradation of kelch-like ECH-associated protein 1. Furthermore, S-allyl cysteine and S-allyl mercaptocysteine as the bioactive compounds in AGE also induce ALDH2 and Nrf2. CONCLUSION: AGE prevented acetaldehyde-induced hepatotoxicity through enhancing acetaldehyde detoxification through Nrf2-dependent induction of mitochondrial ALDH2. This article is protected by copyright. All rights reserved.

DOI： 10.1002/mnfr.202200627

PubMed

Publishing type：Research paper (scientific journal)  

DOI： 10.1021/acs.jafc.2c06791

PubMed

Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

Thermoregulation is a process by which core body temperature is maintained in mammals. Males typically have a lower body temperature than females. However, the effects of androgens, sex hormones that show higher levels in males, on adrenergic receptor-mediated thermogenesis remains unclear. Here, we demonstrate that androgen-androgen receptor (AR) signaling suppresses the β-adrenergic agonist-induced rise of core body temperature using castrated and AR knockout (ARKO) male mice. Furthermore, in vitro mechanistic studies show that activated AR inhibits cAMP response element (CRE)-mediated transcription by suppressing cAMP response element-binding protein (CREB) phosphorylation. The elevation of body temperature induced by the β-adrenergic agonist CL316243 was higher in ARKO and castrated mice than in control mice. Similarly, CL316243 induced a greater increase in Uncoupling protein 1 (Ucp1) expression and CREB phosphorylation in the brown adipose tissue (BAT) of ARKO mice than in that of controls. We determined that activation of AR by dihydrotestosterone suppressed β3-agonist- or forskolin-induced CRE-mediated transcription, which was prevented by AR antagonist bicalutamide. AR activation also suppressed CREB phosphorylation induced by forskolin. Moreover, we found AR nuclear localization, but not transcriptional activity, was necessary for the suppression of CRE-mediated transcription. Finally, modified mammalian two-hybrid and immunoprecipitation analyses suggest nuclear AR and CREB form a protein complex both in the presence and absence of dihydrotestosterone and forskolin. These results suggest androgen-AR signaling suppresses β-adrenoceptor-induced UCP1-mediated BAT thermogenesis by suppressing CREB phosphorylation, presumably owing to a protein complex with AR and CREB. This mechanism explains sex differences in body temperature, at least partially.

DOI： 10.1016/j.jbc.2022.102619

PubMed

Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

Physical inactivity due to prolonged sedentary behavior induces obesity. Therefore, we investigated whether housing mice in small cages to mimic sedentary behavior induced obesity and whether dietary oleamide (cis-9,10-octadeceneamide) suppressed the induced obesity. A single oral administration of oleamide (50 mg/kg) to mice resulted in the accumulation of the exogenous oleamide in abdominal visceral fat. Next, mice were housed in small cages and oleamide (50 mg/kg/d) was orally administered for 12 weeks. Housing mice in small cages impaired glucose tolerance and increased food efficiency. It also increased body weight and abdominal fat mass. Dietary oleamide improved the impairment and inhibited their increases in mice housed in small cages. Furthermore, dietary oleamide suppressed the mRNA expression of inflammation-related factors in abdominal fat of mice housed in small cages. Hence, these results indicate that although housing mice in small cages induces obesity and increases abdominal fat mass, dietary oleamide suppresses the obesity.

DOI： 10.1093/bbb/zbac082

PubMed

Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

Pectolinarigenin (PG) and its glycoside pectolinarin (PN) were reported to have various health beneficial functions such as anti-inflammatory and anti-carcinogenic activities. It has also been reported that PG and PN have radical scavenging ability as direct antioxidant activity. However, the indirect antioxidant activity of PG and PN by inducing antioxidant enzymes in hepatocytes is not fully understood yet. In this study, we investigated whether PG and PN increase expression of antioxidant enzymes through the nuclear factor-erythroid-2-related factor 2 (Nrf2)-mediated pathway in human hepatoma HepG2 cells and the liver of male ICR mice. PG, but not PN, induced antioxidant enzymes, namely heme oxigenase-1, NAD(P)H:quinone oxidoreductase 1, and aldo-keto reductase family 1 member B10, in HepG2 cells. As for the induction mechanism of these enzymes, PG-induced nuclear accumulation of Nrf2 increased antioxidant response element (ARE)-mediated transcriptional activity and suppressed degradation of Nrf2 through modification of Kelch-like EXH-associated protein 1. Oral administration of PG also induced nuclear accumulation Nrf2 and expression of antioxidant enzymes in the liver of mice. Therefore, PG, but not PN, exhibits the indirect antioxidant activity by inducing antioxidant enzymes through the Nrf2/ARE pathway and may protect liver from oxidative stress.

DOI： 10.3390/antiox11040675

PubMed

Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

Curcumin is a yellow pigment in turmeric (Curcuma longa) with various physiological effects in the body. To elucidate the molecular mechanisms by which bioactive compounds exert their function, identification of their molecular targets is crucial. In this study, we show that curcumin activates G protein-coupled receptor 97 (GPR97). Curcumin dose-dependently activated serum-response element-, but not serum-response factor-response element-, nuclear factor of activated T-cell-response element-, or cAMP-response element-, mediated transcription in cells overexpressed with GPR97. The structure-activity relationship indicated that (i) the double-bonds of the central 7-carbon chain were essential for activation; (ii) a methoxy group on the aromatic ring was required for maximal activity; (iii) the addition of glucuronic acid moiety or a methoxy group to the aromatic ring, but not the methylation of the aromatic p-hydroxy group, eliminated the activity; (iv) the stability of curcumin would be related to receptor activation. Both mutant GPR97(T250A) lacking the cleavage at GPCR proteolysis site and mutant GPR97(ΔN) lacking the N-terminal extracellular region were activated by curcumin and its related compounds similar to wild-type GPR97. In contrast, the synthetic glucocorticoid beclomethasone dipropionate and l-Phe activated wild-type GPR97 and GPR97(T250A), but not GPR97(ΔN). Moreover, curcumin exerted an additive effect on the activation of wild-type GPR97 with beclomethasone dipropionate, but not with l-Phe. Taken together, these results indicate that curcumin activates GPR97 coupled to Gi/Go subunit, and suggest that curcumin and glucocorticoid activate GPR97 in a different manner.

DOI： 10.1016/j.bbrc.2022.01.075

PubMed

Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

Non-alcoholic fatty liver disease (NAFLD) and its advanced stage, non-alcoholic steatohepatitis (NASH), are a major health issue throughout the world. Certain food components such as polyphenols are expected to possess preventive effects on NAFLD and NASH. In this study, the preventive effects of black soybean polyphenols were examined by using three NAFLD/NASH animal models. In a choline-deficient and L-amino acid-defined high-fat diet-induced NASH model, the intake of black soybean polyphenols decreased oxidative stress, but failed in attenuating liver injury and decreasing the expression of alpha-smooth muscle actin (α-SMA). In a Western diet with sucrose and fructose containing sweetened water-induced NAFLD model, black soybean polyphenols suppressed hepatic lipid accumulation, oxidative stress, aminotransferase activities in the plasma, inflammatory cytokine expression, and α-SMA expression accompanied by modulation of lipid metabolism. In a combination of Western diet and carbon tetrachloride model, black soybean polyphenols also suppressed hepatic lipid accumulation, oxidative stress, aminotransferase activities in the plasma, and α-SMA expression. In conclusion, black soybean is an attractive food for the prevention of NAFLD and NASH due to its strong antioxidant activity.

DOI： 10.1039/d1fo03541j

PubMed

Publishing type：Research paper (scientific journal)   Kind of work：Joint Work   International / domestic magazine：International journal  

DOI： 10.1038/s41538-021-00119-x.

Authorship：Lead author   Publishing type：Research paper (scientific journal)  

DOI： 10.3164/jcbn.21-163

Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

Skeletal muscle atrophy causes decreased physical activity and increased risk of metabolic diseases. We investigated the effects of oleamide (cis-9,10-octadecanamide) treatment on skeletal muscle health. The plasma concentration of endogenous oleamide was approximately 30 nM in the male ddY mice under normal physiological conditions. When the stable isotope-labelled oleamide was orally administered to male ddY mice (50 mg/kg), the plasma concentration of exogenous oleamide reached approximately 170 nM after 1 h. Male ddY mice were housed in small cages (one-sixth of normal size) to enforce sedentary behaviour and orally administered oleamide (50 mg/kg/day) for 4 weeks. Housing in small cages decreased tibialis anterior (TA) muscle mass and the cross-sectional area (CSA) of the myofibres in TA muscle. Dietary oleamide alleviated the decreases in TA muscle and resulted in plasma oleamide concentration of approximately 120 nM in mice housed in small cages. Housing in small cages had no influence on the phosphorylation levels of Akt, mTOR, and p70S6K in TA muscle; nevertheless, oleamide increased the phosphorylation levels of the proteins. Housing in small cages increased the expression of LC3-II and p62, but not LC3-I, in TA muscle, and oleamide reduced LC3-I, LC3-II, and p62 expression levels. In C2C12 myotubes, oleamide increased myotube diameter at ≥ 100 nM. Furthermore, the mTOR inhibitor, Torin 1, suppressed oleamide-induced increases in myotube diameter and protein synthesis. These results indicate that dietary oleamide rescued TA muscle atrophy in mice housed in small cages, possibly by activating the PI3K/Akt/mTOR signalling pathway and restoring autophagy flux.

DOI： 10.1017/S0007114520004304

PubMed

Authorship：Lead author   Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

Kaempferol possesses various health-promoting functions including antihyperglycemic activity, but its underlying molecular mechanism is poorly understood. Glucose transporter 4 (GLUT4) plays an important role in the uptake of blood glucose into muscle cells after its translocation to the plasma membrane. In this study, we demonstrated that kaempferol at 1.0 nM or more significantly increased the uptake of 2-[3H]- deoxy-d-glucose by 1.3-1.4-fold in L6 myotubes. Kaempferol at 10 pM or more also significantly increased GLUT4 translocation by 1.3-1.6-fold. Kaempferol at 1.0 nM significantly increased the phosphorylation of adenosine monophosphate-activated protein kinase (AMPK) by 2.9-fold, liver kinase B1 and Janus kinase 2 (JAK2) by 1.9-fold, and signal transducer and activator of transcription 3 by 3.7-fold. In addition, kaempferol increased phosphorylation of phosphoinositide 3-kinase (PI3K) by 1.8-fold but not the insulin receptor. Small interfering RNA (siRNA) for AMPK, JAK2, or PI3K canceled kaempferol-induced glucose uptake and GLUT4 translocation. Furthermore, siRNA for JAK2 canceled kaempferol-induced phosphorylation of AMPK and PI3K. These results indicate that a JAK2-depdendent pathway regulates kaempferol-induced glucose uptake and GLUT4 translocation in L6 myotubes and that kaempferol may be an effective compound for the prevention of hyperglycemia.

DOI： 10.1021/acs.jafc.0c05236

PubMed

Authorship：Lead author   Publishing type：Research paper (scientific journal)   Kind of work：Joint Work   International / domestic magazine：International journal  

Publishing type：Research paper (scientific journal)   International / domestic magazine：Domestic journal  

Turmeric and its components have various health beneficial functions. However, little is known about function of bisacurone, which is one of the sesquiterpenes in turmeric, at the compound level. In this study, we investigated the preventive effect of bisacurone on hepatic lipid accumulation and its mechanism in HepG2 cells and ICR mice. In HepG2 cells, bisacurone significantly inhibited fatty acid-induced intracellular lipid accumulation in a dose-dependent manner. Bisacurone at 10 µM increased protein expression of peroxisome proliferator-activated receptor α and carnitine palmitoyltransferase-1A accompanied by phosphorylation of AMP-activated protein kinase. In the liver of ICR mice, bisacurone decreased total lipids, triglyceride, and cholesterol contents. Bisacurone at 10 mg/kg body weight increased phosphorylation of AMP-activated protein kinase, and its downstream acetyl-CoA carboxylase as a rate-limiting enzyme for lipogenesis, while it decreased the nuclear translocation level of sterol regulatory element-binding protein 1 and carbohydrate-responsive element-binding protein as the major transcription factors for lipogenesis. On the other hand, bisacurone promoted lipolysis by up-expression of peroxisome proliferator-activated receptor α and carnitine palmitoyltransferase-1A. Thus, bisacurone might be a valuable food factor for preventing hepatic lipid accumulation by inhibiting lipogenesis and promoting lipolysis through phosphorylation of AMP-activated protein kinase.

DOI： 10.3164/jcbn.20-16

PubMed

Publishing type：Research paper (scientific journal)   International / domestic magazine：Domestic journal  

Quercetin and its glycosides possess various health beneficial functions, but comparative study of them on energy metabolism in different tissues are not well studied. In this study, we investigated AMP-activated protein kinase regulated glucose metabolism in the skeletal muscle and lipid metabolism in the white adipose tissue and liver to compare the effectiveness of quercetin and its glycosides, namely isoquercitrin, rutin, and enzymatically modified isoquercitrin, in male ICR mice. The mice were fed a standard or high-fat diet supplemented with 0.1% quercetin and its glycosides for 13 weeks. Quercetin glycosides, but not quercetin, decreased body weight gain and fat accumulation in the mesenteric adipose tissue in high-fat groups. All compounds decreased high-fat diet-increased plasma glucose and insulin levels. Moreover, all compounds significantly increased AMP-activated protein kinase phosphorylation in either standard or high-fat diet-fed mice in all tissues tested. As its downstream events, all compounds induced glucose transporter 4 translocation in the muscle. In the white adipose tissue and liver, all compounds increased lipogenesis while decreased lipolysis. Moreover, all compounds increased browning markers and decreased differentiation markers in adipose tissue. Therefore, quercetin and its glycosides are promising food components for prevention of adiposity and hyperglycemia through modulating AMP-activated protein kinase-driven pathways.

DOI： 10.3164/jcbn.20-47

PubMed

Authorship：Lead author,　Corresponding author   Publishing type：Research paper (scientific journal)   International / domestic magazine：Domestic journal  

Urban particulate matters (PM) exposure is significantly correlated with extrinsic skin aging signs and skin cancer incidence. PM contains polycyclic aromatic hydrocarbons, and they act as the agonists of aryl hydrocarbon receptor (AhR). Activation of AhR promotes generation of intracellular reactive oxygen species (ROS) and inflammation. Enzymatically synthesized glycogen (ESG), which is synthesized from starch, possesses various functions, such as anti-tumor, anti-obesity and antioxidant. However, the effects of ESG on PM-induced skin inflammation remain unclear. In this study, we investigated whether ESG has a protective effect on PM-induced oxidative stress and inflammation in human epidermal keratinocytes. ESG inhibited PM-induced expression of inflammatory cytokines IL6, TNFA and PTGS2. ESG also inhibited PM-induced phosphorylation of MAPKs and ROS accumulation. However, ESG had no effect on PM-induced expression of CYP1A1, one of the target proteins of AhR. On the other hand, ESG increased nuclear translocation of Nrf2 and expression of antioxidant proteins, HO-1 and NQO1. These results suggest that ESG suppressed PM-induced inflammation by decreasing ROS accumulation through the Nrf2 pathway.

DOI： 10.3164/jcbn.20-43

PubMed

Publishing type：Research paper (scientific journal)   International / domestic magazine：Domestic journal  

Enzymatically synthesized glycogen is a product from starch. Enzymatically synthesized glycogen has been reported to possess various health beneficial effects such as anti-oxidative and anti-inflammatory effects. In this study, we investigated the effect of enzymatically synthesized glycogen on ultraviolet B-induced oxidative stress and apoptosis in normal human epidermal keratinocytes. Treatment with enzymatically synthesized glycogen suppressed ultraviolet B-induced reactive oxygen species, caspase-3 activity, and DNA fragmentation in normal human epidermal keratinocytes. Furthermore, enzymatically synthesized glycogen increased in the expression level of heme oxygenase-1, NAD(P)H: quinone oxidoreductase 1, and NF-E2-related factor 2, a transcriptional factor for heme oxygenase-1 and NAD(P)H: quinone oxidoreductase 1. Although enzymatically synthesized glycogen did not increase in its mRNA expression level of NF-E2-related factor 2, enzymatically synthesized glycogen retained its protein degradation. Knockdown of heme oxygenase-1 and NAD(P)H: quinone oxidoreductase 1 canceled enzymatically synthesized glycogen-suppressed reactive oxygen species accumulation in normal human epidermal keratinocytes. It is, therefore, concluded that enzymatically synthesized glycogen inhibited ultraviolet B-induced oxidative stress through increasing the expression level of heme oxygenase-1 and NAD(P)H: quinone oxidoreductase 1 through the NF-E2-related factor 2 pathway in normal human epidermal keratinocytes.

DOI： 10.3164/jcbn.20-44

PubMed

Publishing type：Research paper (scientific journal)   International / domestic magazine：Domestic journal  

The patients of type I allergic diseases were increased in the developed countries. Recently, many studies have focused on food factors with anti-allergic activities. Enzymatically synthesized glycogen, a polysaccharide with a multi-branched α-1,4 and α-1,6 linkages, is a commercially available product from natural plant starch, and has immunostimulation activity. However, effect of enzymatically synthesized glycogen on the anti-allergic activity was unclear yet. In this study, we investigated that enzymatically synthesized glycogen inhibited allergic and inflammatory responses using a co-culture system consisting of Caco-2 and RBL-2H3 cells. Enzymatically synthesized glycogen inhibited antigen-induced β-hexosaminidase release and production of TNF-α and IL-6 in RBL-2H3 cells in the co-culture system. Furthermore, enzymatically synthesized glycogen inhibited antigen-induced phosphorylation of tyrosine kinases, phospholipase C γ1/2, mitogen-activated protein kinases and Akt. Anti-allergic and anti-inflammatory activities of enzymatically synthesized glycogen were indirect action through stimulating Caco-2 cells, but not by the direct interaction with RBL-2H3 cells, because enzymatically synthesized glycogen did not permeate Caco-2 cells. These findings suggest that enzymatically synthesized glycogen is an effective food ingredient for prevention of type I allergy through stimulating the intestinal cells.

DOI： 10.3164/jcbn.20-33

PubMed

Authorship：Lead author   Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

In the body, alcohol dehydrogenase rapidly converts ethanol to its toxic metabolite, acetaldehyde, which is further metabolized to non-toxic acetic acid by aldehyde dehydrogenase (ALDH). 6-(methylsulfinyl)hexyl isothiocyanate (6-MSITC), a major bioactive compound in Wasabi (Wasabia japonica) has various physiological effects such as anti-oxidative, anti-inflammatory and anti-cancer effects. However, the effect of 6-MSITC on alcohol metabolism has not been studied. In this study, we investigated the effects of 6-MSITC on hepatic ALDH activity and protein expression both in vitro and in vivo. 6-MSITC inhibited ethanol- and acetaldehyde-induced cytotoxicity. Treatment with 6-MSITC to HepG2 cells enhanced ALDH activity through the induction of mitochondrial ALDH2 expression, but not cytosolic ALDH1A1. Knockdown of Nrf2 canceled the 6-MSITC-induced ALDH2 expression, indicating that Nrf2 regulated ALDH2 expression. Moreover, 6-MSITC increased the nuclear translocation of Nrf2 and the expression levels of HO-1 and SOD2, Nrf2-regulated phase II drug-metabolizing enzymes. Oral administration of 6-MSITC increased the mitochondrial ALDH2 activity and its expression in the liver of C57BL/6J mice. These results suggested that 6-MSITC is possible to protect acetaldehyde toxicity in hepatocytes by induction of mitochondrial ALDH2 expression through Nrf2/ARE pathway.

DOI： 10.1016/j.abb.2020.108329

PubMed

Authorship：Lead author   Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

The expression of drug-metabolizing enzymes is deeply involved in chemical-induced cancer progression and prevention. The aryl hydrocarbon receptor (AhR) induces phase I, and certain phase II drug-metabolizing enzymes after the binding of ligands, such as 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). We have previously demonstrated that luteolin inhibited TCDD-induced AhR transformation, and modulated the expression of drug-metabolizing enzymes through not only the AhR, but also the nuclear factor-erythroid-2-related factor 2 (Nrf2). We have examined the effect of kaempferol on the expression of drug-metabolizing enzymes through modulation of the AhR- and Nrf2-pathways, and the effect of co-treatment with kaempferol and luteolin. Kaempferol dose-dependently inhibited not only the TCDD-induced expression of phase I and phase II drug-metabolizing enzymes, but also the tertiary butylhydroquinone (t-BHQ)-induced expression of phase II drug-metabolizing enzymes, by modulating the AhR- and Nrf2-pathways. Co-treatment with kaempferol and luteolin enhanced the inhibitory effect on the expression of drug-metabolizing enzymes, compared with either kaempferol or luteolin alone. Moreover, co-treatment with kaempferol and luteolin increased the cellular levels of kaempferol without affecting the levels of luteolin. An in vivo study was also performed and the results demonstrated that co-treatment with kaempferol and luteolin enhanced the inhibition of benzo[a]pyrene-induced drug-metabolizing enzymes compared with either kaempferol or luteolin alone, in the liver of ICR mice. These results suggest that luteolin promoted the incorporation of kaempferol into hepatocytes and enhanced the inhibitory effect of kaempferol on chemical-induced drug-metabolizing enzymes. Thus, luteolin enhances the kaempferol-inhibited expression of drug-metabolizing enzymes.

DOI： 10.1039/c9fo02951f

PubMed

Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

The gut microbiota is involved in metabolic disorders induced by androgen deficiency after sexual maturation in males (late-onset hypogonadism). However, its role in the energy metabolism of congenital androgen deficiency (e.g., androgen-insensitive syndrome) remains elusive. Here, we examined the link between the gut microbiota and metabolic disease symptoms in androgen receptor knockout (ARKO) mouse by administering high-fat diet (HFD) and/or antibiotics. HFD-fed male, but not standard diet-fed male or HFD-fed female, ARKO mice exhibited increased feed efficiency, obesity with increased visceral adipocyte mass and hypertrophy, hepatic steatosis, glucose intolerance, insulin resistance, and loss of thigh muscle. In contrast, subcutaneous fat mass accumulated in ARKO mice irrespective of the diet and sex. Notably, all HFD-dependent metabolic disorders observed in ARKO males were abolished after antibiotics administration. The ratios of fecal weight-to-food weight and cecum weight-to-body weight were specifically reduced by ARKO in HFD-fed males. 16S rRNA sequencing of fecal microbiota from HFD-fed male mice revealed differences in microbiota composition between control and ARKO mice. Several genera or species (e.g., Turicibacter and Lactobacillus reuteri, respectively) were enriched in ARKO mice, and antibiotics treatment spoiled the changes. Furthermore, the life span of HFD-fed ARKO males was shorter than that of control mice, indicating that androgen deficiency causes metabolic dysfunctions leading to early death. These findings also suggest that AR signaling plays a role in the prevention of metabolic dysfunctions, presumably by influencing the gut microbiome, and improve our understanding of health consequences in subjects with hypogonadism and androgen insensitivity.

DOI： 10.1152/ajpendo.00461.2019

PubMed

Authorship：Lead author   Publishing type：Research paper (scientific journal)   Kind of work：Joint Work   International / domestic magazine：International journal  

DOI： 10.1371/journal.pone.0231403.

Authorship：Lead author   Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

Skeletal muscle secretes biologically active proteins that contribute to muscle hypertrophy in response to either exercise or dietary intake. The identification of skeletal muscle-secreted proteins that induces hypertrophy can provide critical information regarding skeletal muscle health. Dietary provitamin A, β-carotene, induces hypertrophy of the soleus muscle in mice. Here, we hypothesized that skeletal muscle produces hypertrophy-inducible secretory proteins via dietary β-carotene. Knockdown of retinoic acid receptor (RAR) γ inhibited the β-carotene-induced increase soleus muscle mass in mice. Using RNA sequencing, bioinformatic analyses, and literature searching, we predicted transglutaminase 2 (TG2) to be an all-trans retinoic acid (ATRA)-induced secretory protein in cultured C2C12 myotubes. Tg2 mRNA expression increased in ATRA- or β-carotene-stimulated myotubes and in the soleus muscle of β-carotene-treated mice. Knockdown of RARγ inhibited β-carotene-increased mRNA expression of Tg2 in the soleus muscle. ATRA increased endogenous TG2 levels in conditioned medium from myotubes. Extracellular TG2 promoted the phosphorylation of Akt, mechanistic target of rapamycin (mTOR), and ribosomal p70 S6 kinase (p70S6K), and inhibitors of mTOR, phosphatidylinositol 3-kinase, and Src (rapamycin, LY294002, and Src I1, respectively) inhibited TG2-increased phosphorylation of mTOR and p70S6K. Furthermore, extracellular TG2 promoted protein synthesis and hypertrophy in myotubes. TG2 mutant lacking transglutaminase activity exerted the same effects as wild-type TG2. Knockdown of G protein-coupled receptor 56 (GPR56) inhibited the effects of TG2 on mTOR signaling, protein synthesis, and hypertrophy. These results indicated that TG2 expression was upregulated through ATRA-mediated RARγ and that extracellular TG2 induced myotube hypertrophy by activating mTOR signaling-mediated protein synthesis through GPR56, independent of transglutaminase activity.

DOI： 10.1016/j.bbamcr.2019.118563

PubMed

Authorship：Lead author   Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

The flavon luteolin has various health-promoting activities including cardiovascular protection, anti-inflammatory activity and anticancer activity. A serum concentration of about 100 nM luteolin is reached by dietary habit. However, little is known about the function of luteolin over its physiological concentration range. In this study, we investigated whether a physiological concentration of luteolin could activate nuclear factor-erythroid-2-related factor 2 (Nrf2)-mediated expression of phase II drug-metabolizing enzymes in human hepatoma HepG2 cells. Interestingly, less than 1 nM of luteolin could induce phase II drug-metabolizing enzymes, such as GSTs, HO-1, and NQO1. Both 1 and 100 nM luteolin increased expression and activity of ALDH2, which metabolized toxic acetaldehyde into nontoxic acetic acid. Luteolin increased nuclear accumulation of Nrf2 and enhanced the ARE-binding complex through increasing the stability of the Nrf2 protein. Luteolin increased phosphorylation of Nrf2 at Ser40, and MEK inhibitors (U0126 and PD98059) canceled luteolin-induced phosphorylation of Nrf2. Furthermore, luteolin increased modified Keap1. In conclusion, a physiological concentration of luteolin induces the expression of phase II drug-metabolizing enzymes by enhancement of Nrf2 nuclear accumulation through MEK1/2-ERK1/2-mediated phosphorylation of Nrf2, increasing Nrf2 stability and inducing a conformational change of Keap1.

DOI： 10.1016/j.abb.2019.01.012

PubMed

Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

Skeletal muscle plays a critical role in locomotion and energy metabolism. Maintenance or enhancement of skeletal muscle mass contributes to the improvement of mobility and prevents the development of metabolic diseases. The extracts from Kaempferia parviflora rhizomes contain at least ten methoxyflavone derivatives that exhibit enhancing effects on ATP production and glucose uptake in skeletal muscle cells. In the present study, we investigated the effects of ten K. parviflora-derived methoxyflavone derivatives (six 5,7-dimethoxyflavone (DMF) derivatives and four 5-hydroxy-7-methoxyflavone (HMF) derivatives) on skeletal muscle hypertrophy. Murine C2C12 myotubes and senescence-accelerated mouse-prone 1 (SAMP1) mice treated with methoxyflavones were used as experimental models to determine the effects of HMF derivatives on myotube diameter and size and muscle mass. The four HMF derivatives, but not the six DMF derivatives, increased myotube diameter. The 5-hydroxyflavone, 7-methoxyflavone, and 5,7-dihydroxyflavone had no influence on myotube size, a result that differed from HMF. Dietary administration of the mixture composed of the four HMF derivatives resulted in increase in the soleus muscle size and mass in SAMP1 mice. HMF derivatives also promoted protein synthesis in myotubes, and treatment with the intracellular Ca2+ chelator BAPTA-AM, which depletes intracellular Ca2+ levels, inhibited this promotion. Furthermore, BAPTA-AM inhibited HMF-promoted protein synthesis even when myotubes were incubated in Ca2+-free medium. These results indicate that HMF derivatives induce myotube hypertrophy and that both the 5-hydroxyl group and the 7-methoxy group in the flavones are necessary for myotube hypertrophy. Furthermore, these results suggest that HMF-induced protein synthesis requires intracellular Ca2+, but not extracellular Ca2+.

DOI： 10.1002/fsn3.891

PubMed

Authorship：Lead author   Publishing type：Research paper (scientific journal)   Kind of work：Joint Work   International / domestic magazine：International journal  

DOI： 10.3892/mmr.2018.8603.

Publishing type：Research paper (scientific journal)   Kind of work：Joint Work   International / domestic magazine：International journal  

DOI： 10.1002/cbin.10845.

Publishing type：Research paper (scientific journal)   Kind of work：Joint Work   International / domestic magazine：International journal  

DOI： 10.1016/j.jnutbio.2017.07.017.

Authorship：Lead author   Publishing type：Research paper (scientific journal)   Kind of work：Joint Work   International / domestic magazine：International journal  

DOI： 10.1016/j.bbrc.2016.08.114.

Publishing type：Research paper (scientific journal)   Kind of work：Joint Work   International / domestic magazine：International journal  

DOI： 10.1002/1873-3468.12265.

Publishing type：Research paper (scientific journal)   Kind of work：Joint Work   International / domestic magazine：International journal  

DOI： 10.1038/srep23001.

Authorship：Lead author   Publishing type：Research paper (scientific journal)   Kind of work：Joint Work   International / domestic magazine：Domestic journal  

DOI： 10.3177/jnsv.61.481.

Publishing type：Research paper (scientific journal)   Kind of work：Joint Work   International / domestic magazine：International journal  

DOI： 10.1530/JOE-15-0128.

Publishing type：Research paper (scientific journal)   Kind of work：Joint Work   International / domestic magazine：International journal  

DOI： 10.1017/S0007114512003297.

生体外異物であるダイオキシン類による毒性はアリール炭化水素受容体(AhR)を介した作用であるため,AhRの活性化を抑制することが毒性の緩和につながる。ダイオキシン類の毒性の緩和は転写因子nuclear factor-erythroid 2-related factor 2(Nrf2)を介した薬物代謝第II相酵素の誘導も有効である。Nrf2の活性化はダイオキシン類の曝露以外の環境ストレスに対する生体防御機能も高める。そのため,AhRを抑制しNrf2を活性化する食品因子の探索を行ってきた。筆者はこれまでに,フラボノイドであるルテオリンとケンフェロールの共作用がAhRの活性抑制効果を増強すること,日常的な食事から摂取可能な量のルテオリンがNrf2を活性化することを明らかにした。また,AhRの活性化が引き起こす肝臓への脂肪蓄積が,概日リズムの乱れに起因することと,ルテオリンとケンフェロールによる抑制効果を見出した。これらのことから,ルテオリンとケンフェロールは薬物代謝系を介した生体外異物に対する生体防御機能に関して,有効性が明らかとなった。(著者抄録)

Authorship：Lead author  

Authorship：Lead author  

Authorship：Lead author  

Authorship：Lead author  

Presentation type：Symposium, workshop panel (nominated)