Fundamental Research on Soy Protein and Related Components Based on Reactive Sulfur Species
Hideshi IHARA1, Takaaki AKAIKE2, Hidemitsu NAKAJIMA3 and Shingo KASAMATSU*1
1Department of Biological Science, Graduate School of Science,
Osaka Prefecture University, Sakai 599-8531
2Department of Environmental Medicine and Molecular Toxicology, Tohoku University Graduate School of Medicine, Sendai 980-8575
3Department of Veterinary Science, Graduate School of Life and Environmental Sciences, Osaka Prefecture University, Sakai 598-8531
ABSTRACT
We have demonstrated that reactive sulfur species (RSS), such as cysteine persulfide, are generated endogenously in animals and are involved in regulating biologically important processes, including oxidative stress, redox signaling, and sulfur respiration. An increase in the level of RSS in the body is expected to promote health and prevent disease. Because sulfur is obtained from foods, it is important to scientifically evaluate the content and form of RSS in foods. In this research, we conducted the following four fundamental studies on soy protein and related components. (1) We investigated new RSS in soybean using a new alkylating agent that labels the terminal SH group without degrading the RSS. RSS were not detected in natto, which has a higher amount of RSS than soybean seeds. (2) We evaluated the protective effect of RSS by using oxidized glutathione tetrasulfide as a model RSS. We found that genistin, glycitin, Soyaflavon HG, and Hinute AM exhibit RSS-protective effects. (3) We measured RSS in soy protein by labeling the protein with alkylating agents, treating it with protease, and analyzing it by HPLC-MS/MS. We found that many cysteine residues were polythiolated. (4) We performed biochemical and behavioral evaluations of the dementia-preventive effect by using a genetically modified mouse model of Alzheimer's disease. We observed amyloid beta accumulation, gliosis, memory impairment, and decreased levels of RSS in the brain in the mice. Soy Protein Research, Japan 24, 1-5, 2021.
Key words : reactive sulfur species, soy protein, isoflavone, HPLC-MS/MS, Alzheimer's disease
Investigation of Preventive Effects of Plant Proteins, Including Soy Protein Isolate, Against Non-alcoholic Fatty Liver Disease
Hiroshi INOUE*1 and Takanori IDA2
1Metabolism and Nutrition Research Unit, Innovative Integrated Bio-Research Core, Institute for Frontier Science Initiative, Kanazawa University, Ishikawa 920-8641
2Division of Searching and Identification of Bioactive Peptides, Department of Bioactive Peptides, Frontier Science Research Center, University of Miyazaki 889-1692
ABSTRACT
Non-alcoholic fatty liver disease (NAFLD), which is induced by excessive accumulation of fat in the liver, is a major threat to human health because of its increasing prevalence and unfavorable outcomes. Because no pharmacological therapy for NAFLD has yet been established, diet therapy is the main method for preventing and curing NAFLD. In diet therapy for NAFLD. In addition to the amount of diet meal quality such as reconended MUFA and PUFA intake is important in NAFLD dietary therapy. Proteins from plants such as beans are also expected to play a role in the prevention and treatment of NAFLD. We have previously reported that mung bean protein isolate (MPI) decreases hepatic triglyceride accumulation in rodents, similar to soy protein isolate (SPI). β-Conglycinin and 8S globulin are functional elements of SPI and MPI, respectively, and they reduce hepatic expression of lipogenic enzyme genes. However, because the proteins are huge and have no direct contact with hepatocytes, the precise mechanism remains to be elucidated. Dietary proteins are absorbed as amino acids, dipeptides, and tripeptides. We have found that a diet containing a mixture of constituent amino acids from MPI has little effect on hepatic lipogenic gene expression. Therefore, in the present study, to elucidate the mechanism of how SPI and MPI decrease hepatic triglycerides, we looked for the dipeptides that reduce hepatic expression of lipogenic enzyme genes by using fatty acid synthase expression to indicate hepatic lipogenic gene expression in mouse-derived primary hepatocytes. Among 336 synthetic dipeptides, 11 reduced the expression of the fatty acid synthase gene. Although further investigation is needed, these dipeptides may have the potential to decrease hepatic triglycerides and to be therapeutic foodstuffs for NAFLD. Soy Protein Research, Japan 24, 6-13, 2021.
Key words : NAFLD, dipeptide, hepatic lipogenesis, fatty acid synthase, mung bean protein isolate
Modulating Secondary Metabolism and Improving Quality in Soybeans by Light Control: Effects of Red and Blue LED Light on the Isoflavone Biosynthesis Pathway in Soybean Sprouts
Katsuyuki MIYAWAKI*1,2, Kaoru FUJII1, Chihiro NISHIKAWA1 and Aya NAKAI2
1Engineering of Food Production, Field of Bioresource Production Sciences, Faculty of Bioscience and Bioindustry, Tokushima University, Tokushima 770-8513
2Academic Field of Bioresource Sciences, Graduate School of Science and Engineering for Industry and Society, Tokushima University, Tokushima 770-8513
ABSTRACT
Isoflavones and Cblin peptides from soybeans (Glycine max L.) have been reported to prevent osteoporosis and ameliorate the causes of muscle atrophy in microgravity and in bedridden people, respectively. Total isoflavone content is higher in soybean sprouts than in dried seeds and is increased more by exposure to blue light than to fluorescent light; however, the effects of red light and the mechanism for the increase caused by blue light are unknown. In this study, we analyzed the expression of isoflavone-biosynthesis-related genes in soybean sprouts under red or blue LED light to understand how the different light conditions affect the isoflavone synthesis pathway. The relative expression levels of isoflavone synthase genes (IFS1 and IFS2) were increased by blue LED light and decreased by red LED light. Expression levels of the isoflavone reductase gene (IFR) were also changed by the blue and red LED lights. These results indicate that there may be a transcriptional regulation mechanism controlled by light signaling at the expression level of the genes involved in isoflavone synthesis. Soy Protein Research, Japan 24, 14-18, 2021.Soy Protein Research, Japan 24, 14-18, 2021.
Key words : soybean sprouts, isoflavones, LED
Multiomics Integration of Molecular Networks Involved in Soybean Tolerance Against Flooding
Akiko HASHIGUCHI*
Faculty of Medicine, University of Tsukuba, Tsukuba 305-8575
ABSTRACT
Flooding is an environmental stress that causes severe growth inhibition and yield loss in soybean crops. The response mechanisms of soybean to flooding stress have been characterized by a proteomic approach and revealed that an energy consumption metabolic pathway was bypassed. However, the molecular mechanism that regulates tolerance to flooding stress has not yet been fully elucidated. In this study, an analysis of multiomics data was performed using abscisic acid-treated soybeans, which exhibit flooding tolerance. Abscisic acid-induced flooding tolerance signal networks, both metabolic and regulatory, were constructed by integrating layers for metabolites, enzymes, and transcription factors. Signals transduced by changes in post-translational modification were included using nitrosoproteomic and phosphoproteomic data. The networks consisting of 208 reactions revealed that the flooding tolerance metabolic signal was regulated by dozens of metabolites that are involved in feedback regulation after flooding for 3 h. Photosynthesis, ATP synthesis, and other types of carbohydrate metabolism were regulated through changes in S -nitrosylation levels of ribulose bisphosphate carboxylase/oxygenase. In addition, MYB61-mediated transcriptional activation of pectinesterase was detected, suggesting that cell wall remodeling was induced. The regulatory signal network of flooding tolerance regulated genetic information processing, as indicated by changes in the phosphorylation levels of RNA recognition motif domain-containing proteins. These results suggest that modulation of photosynthesis, aerenchyma formation, and RNA editing may be a crucial part of the flooding tolerance signal network. Soy Protein Research, Japan 24, 19-23, 2021.
Key words : soybean, flooding tolerance, ABA, integration of multiomics data, signal network
Food Ink Development of Soy Protein Isolate for 3D Food Printing
Makoto TAKEMASA*
Tokyo Denki University, Graduate School of Science and Engineering, Life Sciences and Engineering, Saitama 350-0394
ABSTRACT
It was found that the food texture changes depending on printing process during food 3d printing. In general, food texture originates from structural heterogeneities at various spatial scales ranging from sub-mm to mm scale. This study demonstrated that there are several ways to control the food texture using 3D printer with soy protein isolate, SPI-based food ink, (1) the volume ratio of space- filling printed; (2) the filling procedure especially in sub-mm to cm scale structure (3) more detailed printing procedure, direction, inter-layer structure in sub-millimeter– scale structure, even in the case of uniform structures in macroscopic scale. Although the current special resolution of 3D food printing is relatively coarse (on the millimeter-scale), in some cases, it could be possible to create sub-millimeter– scale structures as a result of printing conditions and models. The food texture of printed foods was also found to be affected by the inner diameter and length of the nozzle used, the printing speed, and other printing conditions; the mesoscale structures, including molecules and molecular assemblies, of food ink composition. Soy Protein Research, Japan 24, 24-27, 2021.
Key words : food 3D printing, soy protein isolate (SPI), food ink, rheology
Development of Soybean Dietary Fibers Using Nanofiber Technology
Takao NAGANO*
Department of Food Science, Faculty of Bioresources and Environmental Sciences, Ishikawa Prefectural University, Ishikawa 921-8836
ABSTRACT
Okara, a by-product of tofu or soymilk production, is rich in dietary fiber, most of which is insoluble. Thus, improving the physicochemical properties of okara for various applications in foods is of great importance. Wet type grinder (WG) systems are used to produce nanocellulose, which has highly viscous and gel-like forms. Here, okara was ground using a WG system and the effect on soy protein isolate (SPI) gels was investigated. We treated 2% okara with the WG system using different numbers of passes (1-5 times). The particle size distribution of the WG-treated okara decreased and the viscosity increased with the number of passes. The WG- treated okara also dispersed in water homogeneously after 24 h, whereas untreated okara did not. The SPI gels only formed with NaCl and the breaking stress and strain increased with NaCl concentrations up to 0.2%, and then decreased. The addition of 1% WG-treated okara increased the breaking stress and strain of SPI gels as the number of WG passes increased at NaCl concentrations of 1.0% or 1.5%. The breaking stress and strain of SPI gels at 1.0% NaCl also increased with increasing WG-treated okara concentrations up to 1.0%. These results indicate that nanocellulose technologies might improve the physicochemical properties of okara and may be useful for developing protein gel-based foods. Soy Protein Research, Japan 24, 28-32, 2021.
Key words : okara, gel, nanocellulose, soy protein isolate, wet-type grinder
Mechanism of Microenvironment Formation Inhibition by Soybean Components Targeting Tight Junction Proteins
Akira IKARI*
Laboratory of Biochemistry, Department of Biopharmaceutical Sciences, Gifu Pharmaceutical University, Gifu 501-1196
ABSTRACT
Claudins (CLDN) are components of a tight junction in epithelial and endothelial cells. Previously, we reported that CLDN2 expression is high in lung adenocarcinoma tissues and contributes to chemoresistance. The expression of CLDN2 and chemoresistance were suppressed by cyanidin 3-glucoside (Cya3-G), a soybean component. Here, we examined the mechanism of action of Cya3-G by using human lung adenocarcinoma A549 cells. The phosphorylation level of Akt was decreased by Cya3-G. A quartz crystal microbalance assay showed that Cya3-G can bind to Akt but not to PDK1. These results suggest that Cya3-G inhibits the PI3K/ Akt pathway mediated by binding to Akt. The protein stability of CLDN2 was reduced by Cya3-G, but LY-294002, a PI3K/Akt pathway inhibitor, had no effect. The Cya3-G-induced decrease in CLDN2 expression was blocked by SB203580, a p38 inhibitor, whereas anisomycin, a p38 activator, decreased the protein level of CLDN2. The protein stability of CLDN2 was reduced by SB203580, suggesting that CLDN2 protein stability is downregulated by p38. Next, we examined the effect of Cya3-G on anticancer drug-induced toxicity by using spheroid cells. Doxorubicin induced apoptotic cell death, which was enhanced by Cya3-G. The mRNA levels of cancer stem cell markers, including CD133, Oct4, and Nanog, were decreased by Cya3-G. These results indicate that Cya3-G may increase sensitivity to anticancer drugs and prevent recurrence of lung adenocarcinoma. Soy Protein Research, Japan 24, 33-37, 2021.
Key words : chemosensitivity, claudin-2, cyanidin, lung adenocarcinoma, apoptosis
Improvement of Stress Resilience via Promotion of Oligodendrogenesis by Genistein in Aged Mice
Risako FUJIKAWA and Shozo JINNO*
Department of Anatomy and Neuroscience, Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582
ABSTRACT
Depressive disorders are more frequent in older people than in young people and resilience to psychological stress may play a critical role in the pathophysiology of depression. In this study, we examined the potential effects of the soy isoflavone genistein on the aging-related changes in stress resilience. First, in the elevated plus maze test, we found that exposure to restraint stress (6 h/day, 3 times/ week) for 21 days increased the time spent in the closed arms in middle-aged mice but not in young adult mice. We next tested the alterations in depression-related behaviors and oligodendrogenesis by genistein treatment (30 mg/kg) for 16 days in middle-aged mice. The time spent in the closed arms in the elevated plus maze test was shorter in genistein-treated stressed mice than in vehicle-treated stressed mice. We then examined the spatial densities of oligodendrocyte precursor cells and oligodendrocytes in the hippocampus of middle-aged mice. The densities of these cells were decreased by exposure to restraint stress, whereas they were increased by genistein treatment. In addition, the voxel densities of synaptic boutons on oligodendrocyte precursor cells were decreased by exposure to restraint stress, whereas they were increased by genistein treatment. These findings indicate that genistein may improve the stress resilience of middle-aged mice, which may be associated with the promotion of oligodendrogenesis in the hippocampus. Soy Protein Research, Japan 24, 38-48, 2021.
Key words : words : stress resilience, aging, depression, hippocampus, oligodendrocyte
Effects of Intake Frequency of Various Soybean Products on Motor and Cognitive Function in Older People After 2 Years
Narumi KOJIMA*
Tokyo Metropolitan Institute of Gerontology (TMIG), Tokyo 173-0015
ABSTRACT
We investigated whether motor and cognitive functions are affected by the intake of tofu, miso, and natto in older women. Data from a comprehensive health survey conducted from 2017 to 2018 in 1,365 women aged ≥65 in Tokyo served as the baseline. A follow-up survey was conducted in 2019. The main items measured were intake frequency of tofu, natto, and miso, Mini Mental State Examination- Japanese (MMSE-J), grip strength, knee extension strength, and walking speed. We analyzed the variation in cognitive and motor function by the baseline frequency of soybean product intake, both cross-sectionally and longitudinally, and performed analysis of covariance (ANCOVA). Longitudinal analysis did not find any combination in which the frequency of intake of soybean products had a significant effect on changes in cognitive or motor functions. However, in the cross-sectional analysis using ANCOVA, the variation in the MMSE-J score with the frequency of miso intake was significant (p = 0.036). A higher frequency of miso intake was associated with a lower MMSE-J score (p for trend = 0.002). Furthermore, a higher frequency of miso intake was associated with a higher risk of mild cognitive impairment (p = 0.008). The odds ratio for mild cognitive impairment when miso was eaten almost every day was 1.79 (confidence interval: 1.28-2.51, p = 0.001), taking less frequent intake as the reference. Thus, we found a negative association between the frequency of miso intake and cognitive function. Because we also found a significant relationship between a high frequency of miso intake and high blood pressure in our participants, the mechanism of vascular-related cognitive decline due to high salt intake may be relevant. Soy Protein Research, Japan 24, 49-54, 2021.
Key words : natto, miso, tofu, Mini Mental State Examination
Chemical Epigenetics Using Soybean-derived Ingredients and Its Application to Prevent Osteoporosis
Keizo NISHIKAWA*
1Laboratory of Cell Biology and Metabolic Biochemistry, Department of Medical Life Systems, Granduate School of Life and Medical Sciences, Doshisha University, Kyoto 610-0394
ABSTRACT
In super-aging societies such as Japan, the rapid increase in osteoporosis patients has become a problem. We are working on clarifying the molecular mechanism of osteoclast differentiation, and we have discovered the importance of epigenetic regulation involved in osteoclast differentiation. Furthermore, we have demonstrated the effectiveness of epigenome drug discovery for osteoporosis. In this study, we focused on a new epigenetic regulator, Kdm, and examined its importance in osteoclast regulation. Furthermore, to tackle osteoporosis, we have developed a screening method for identifying food compounds that inhibit Kdm, using a natural compound library containing soybean components. In mammals, there are three paralogs of Kdm-Kdma, Kdmb, and Kdmc-and we generated osteoclast-specific Kdma, Kdmb, and/or Kdmc knockout mice and analyzed the bone phenotypes of these mice. We found that Kdmb and Kdmc regulate osteoclast differentiation redundantly. Furthermore, the screening for new Kdmb inhibitors identified three types of compounds that have a significant inhibitory effect on osteoclast differentiation and one type that has a promoting effect. Soy Protein Research, Japan 24, 55-58, 2021.
Key words : osteoclast, epigenetic regulation, osteoporosis, bone, food ingredient
The Effect of Soy Isoflavone on Sarcopenic Obesity Through Regulation of Muscle Fat Metabolism
Kaoruko IIDA* and Moe MATSUMOTO
Department of Nutrition and Food Science, Graduate School of Humanities and Sciences, Ochanomizu University, Tokyo 112-8610
ABSTRACT
Aim: Intramuscular fat accumulation has been considered to be implicated in the etiology of sarcopenic obesity. We have previously reported that soy isoflavone daidzein regulates expression of genes involved in fatty acid oxidation (FAO) in muscle cells via ERRα-related pathway. This study therefore aimed to clarify whether daidzein inhibit lipid accumulation in muscular cells and tissues thereby preventing muscle atrophy. Methods: C2C12 myoblasts were differentiated and then treated with fatty acids (FA) in the absence or presence of daidzein and XCT790, an ERRα specific inhibitor. Diet-induced obese C57BL/6J mice were divided into 3 groups and in two groups mice were subjected to hindlimb suspension (HS). The mice in one of two HS-groups were fed a high-fat high-sucrose diet containing daidzein (2.0 g/kg chow) and those in other two groups were fed a regular high-fat high-sucrose diet (n = 8 in each group). Results: Daidzein decreased fat accumulation assessed by oil-red-o staining in FA-treated C2C12 myotubes. This decline was eliminated by XCT790. Fat deposit in gastrocnemius muscles showed a decreased tendency in mice treated with daidzein compared with its control. In addition, daidzein treatment significantly improved HS-induced decline in muscle fiber area. In the muscles of mice receiving HS, there were significant decreases in the expression of genes related to FAO and mitochondrial biogenesis. Daidzein treatment tended to inverse this decrease in the expression of ERRα. Conclusion: Daidzein decreased fat accumulation induced by FA in vitro and by HS in vivo. Daidzein also improved muscle atrophy after HS in obese mice. Although the mechanism remains unclear, these findings suggest that daidzein may prevent sarcopenic obesity as a therapeutic approach. Soy Protein Research, Japan 24, 59-66, 2021.
Key words : daidzein, fat accumulation, muscles atrophy, obesity
Use of Artificial Intelligence to Integrate and Systematize Clinical Evidence for Protein Intake
Tomohide YAMADA*
Department of Diabetes and Metabolic Diseases, The Graduate school of Medicine, The University of Tokyo 113-8655
ABSTRACT
Evidence-based medicine involves determining a treatment that matches the needs of each patient by integrating the best and latest available scientific evidence and clinical skills. Systematic review and meta-analysis involve searching databases and performing statistical analysis to integrate the results of multiple independent studies and obtain the highest-quality evidence, which provides the foundation of clinical guidelines. In this work, we intended to use artificial intelligence (AI) to reduce the time required to perform a systematic review as well as to improve the precision of methods for conducting systematic reviews and meta-analyses. Specifically, we used AI to identify groups of people at high risk of 5-year mortality who have benefited from protein intake. Our approach considered differences in genetics, epigenetics, the microbiome, and other environmental factors, including other nutrients, environmental toxicants, pharmaceuticals, disease status, and physical activity. The objectives and planned outcomes of this project are to reduce the time required to perform a systematic review by employing AI and to improve the precision of method. The aim is to make comprehensive searches of medical articles for reviews 10 times faster than the current speed. Our results could help to facilitate the acquisition of evidence for clinical guidelines in all disease fields, not just those related to protein intake. Soy Protein Research, Japan 24, 67-74, 2021.
Key words : precision nutrition, artificial intelligence, systematic review, life-related diseases
Protection of Circadian Clock-related Brain Functions by Dietary Soy Isoflavones
Shinobu YASUO*
Laboratory of Regulation in Metabolism and Behavior, Faculty of Agriculture, Kyushu University, Fukuoka 819-0395
ABSTRACT
Inappropriate timing of food intake, including skipping breakfast and eating late, is associated with disruption of the circadian clock and increases the risk of various diseases. In a previous study, we found that mice subjected to evening time- restricted feeding (TRF) exhibited poorer memory performance and lower dendritic spine density in the hippocampus compared with mice subjected to morning TRF. Here, we examined whether the effect of evening TRF was mitigated by a diet containing soy isoflavones, which have estrogen-like properties that might improve cognition and modulate synaptic plasticity. In the Barnes maze test, short-term memory in mice subjected to evening TRF was improved by a soy isoflavone diet. These mice also exhibited higher expression of several synaptic genes and higher dendritic spine density in the hippocampus compared with mice fed a control diet and subjected to evening TRF. These results suggest that dietary intake of soy isoflavones may prevent and mitigate cognitive/synaptic deficits caused by inappropriate meal timing. Soy Protein Research, Japan 24, 75-80, 2021.
Key words : soy protein, dietary rhythm, hippocampus, synapse, memory
Effect of Dietary β-conglycinin, a Soy Protein Component, on Soy-protein-susceptible Indigenous Gut Bacteria
Takashi KUDA*
Laboratory of Food Microbiology, Department of Food Science and Technology, Tokyo University of Marine Science and Technology, Tokyo 108-8477
ABSTRACT
β-Conglycinin (β-CG), a principal protein component of soybeans, exhibits antioxidant, antibacterial, and immunomodulatory properties. In this study, the presence of β-CG-susceptible indigenous gut bacteria (SIB) was examined in Institute of Cancer Research mice fed either 20% (w/w) soy protein (SP), β-CG, or milk casein (MC) for 14 days. Body weight, liver weight, and plasma glucose levels were lower in the β-CG group compared with the MC group. The cecal microbiome was analyzed using 16S rRNA gene (V4) amplicon sequencing, the QIIME2 bioinformatics pipeline, and the SILVA database. Although Muribaculum sp.- and Roseburia-like bacteria were abundant, Eisenbergiella-, Desulfovibrionaceae-, Mucispirillum schaedleri-, and Bacteroides massiliensis-like bacteria were less frequent in the SP and BC groups. Furthermore, there were more Tidjanibacter massiliensis-, Duncaniella sp.-, and Enterorhabdus-like bacteria in the BC group than in the MC and SP groups. Adlercreutzia caecimuris (formerly named Enterorhabdus caecimuris) was isolated and characterized using blood liver agar plates. These bacteria, which are β-CG-SIB, may exert interactive effects on the consumption of soybeans or SP, thereby influencing the health of the host. Soy Protein Research, Japan 24, 81-90, 2021.
Key words : soy protein, β-conglycinin, gut microbiome, Adlercreutzia caecimuris, ICR mice
Anti-inflammatory Effect of Soy Isoflavones on Innate Lymphoid Cells in Visceral Adipose Tissue
Masahide HAMAGUCHI*
Department of Endocrinology and Metabolism, Kyoto Prefectural University of Medicine, Kyoto 602-8566
ABSTRACT
The westernization of the Asian diet is linked to increases in the prevalence of patients with type 2 diabetes mellitus and is also thought to disturb gut microbiota. However, the effect of habitual food intake associated with dysbiosis in patients with type 2 diabetes is not fully understood. In this cross-sectional study, we identified a cluster of gut microbiota associated with a high prevalence of type 2 diabetes in hospital out-patients with or without diabetes mellitus, enrolled from November 2016 to December 2017. 16S rRNA analysis was performed to obtain operational taxonomic units, which were converted into two-dimensional data by t-distributed stochastic neighbor embedding (tSNE) and were clustered by the k-means methods (k = 4). Habitual diet intakes were evaluated by a brief self-administered dietary history questionnaire. We examined the gut microbiota of 383 patients with type 2 diabetes mellitus and 115 patients without diabetes mellitus. The proportion of patients with type 2 diabetes in the four groups clusterized by tSNE analysis was 86.8% in the Red group (112/129), 69.8% in the Blue group (81/116), 75.6% in the Green group (90/119), and 74.6% in the Yellow group (100/134). There were no differences in sex, age, or body mass index between the groups. The Red group had a higher percentage of Actinobacteria and a lower percentage of Firmicutes at the phylum level compared with the other groups. Furthermore, at the genus level, the proportion of Bifidobacterium and Lactobacillus was higher, and that of Blautia and Phascolarctobacterim was lower in the Red group. Furthermore, type 2 diabetic patients in the Red group were characterized by a high rate of alpha-glucosidase inhibitor and glinide use and a low intake of fermented soybean foods such as miso soup in their dietary habits. In conclusion, the gut microbiota pattern of the Red group, which contained the largest number of type 2 diabetic patients in this study, may indicate characteristic changes in gut microbiota associated with type 2 diabetes in Japan. In addition, certain diabetes drugs and fermented foods may be involved in this change in gut microbiota. Soy Protein Research, Japan 24, 91-98, 2021.
Key words : gut microbiota, diabetes mellitus, type 2 diabetes mellitus, soy protein, habitual food intake
Evaluation of Lipid and Glucose Regulation by the Combination of Soy Protein β-conglycinin and n-3 Polyunsaturated Fatty Acids
Masashi HOSOKAWA*
Laboratory of Bioresources Chemistry, Division of Marine Life Science, Faculty of Fisheries Sciences, Hokkaido University, Hokkaido 041-8611
ABSTRACT
Soybean β-conglycinin (β-CG), which is a constituent of storage proteins, has many physiological effects. Dietary n-3 polyunsaturated fatty acids (PUFAs) such as EPA and DHA have a triacylglycerol-lowering effect among other health benefits. In this study, we investigated the combined effect of β-CG and n-3 PUFA-containing oil (PUFA oil) on the lipid and glucose parameters of diabetic/obese KK-Ay mice. Serum cholesterol and triacylglycerol were significantly lower in mice fed β-CG than in those fed casein. Furthermore, 3% and 5% PUFA oil in each protein diet reduced serum cholesterol and triacylglycerol levels. Hepatic lipids in the mice were decreased by β-CG or PUFA oil whereas their combined effect was not observed. The combination of PUFA oil and β-CG increased DHA markedly in the hepatic lipid composition. Oleic acid was significantly decreased by β-CG and PUFA oil via the downregulation of stearoyl-CoA desaturase mRNA. After 7 days of feeding, the blood glucose level was decreased by β-CG compared with casein but PUFA oil had no effect. The combined effect of β-CG and 5% PUFA oil on the suppression of blood glucose elevation appeared after 21 days of feeding. These results demonstrate the combined effect of β-CG and fish oil on the lipid and blood glucose parameters of diabetic/obese KK-Ay mice. Soy Protein Research, Japan 24, 99-104, 2021.
Key words : β-conglycinin, n-3 polyunsaturated fatty acid, lipid metabolism, blood glucose, KK-Ay mice
Effect of β-conglycinin Intake Combined with Exercise on the Induction of Brown-like Adipocyte Formation
Takanori TSUDA*
College of Bioscience and Biotechnology, Graduate School of Bioscience and Biotechnology, Chubu University, Aichi 487-8501
ABSTRACT
Induction of brown-like adipocytes in white adipose tissue (WAT) is a potential therapeutic target for the treatment of obesity and related disorders owing to the ability of these cells to release excess energy via induction of thermogenesis associated with uncoupling protein 1 (UCP1). Soy protein β-conglycinin (βCon) has serum lipid-lowering and anti-obesity effects. Exercise (EX) has various benefits for overall metabolic health and can also induce the formation of brown-like adipocyte in WAT. Therefore, we hypothesized that combining βCon intake with EX might induce brown-like adipocyte formation in WAT. Our previous findings indicated that 1/2 βCon diet intake alone did not significantly induce brown-like adipocyte formation in mice. In the present study, we examined whether intake of 1/2 β Con diet combined with EX induced the formation of the brown-like adipocytes in inguinal white adipose tissue (iWAT) in mice. Hematoxylin and eosin staining of iWAT from the EX + 1/2 βCon group showed distinct multilocular adipocytes, and the significant induction of UCP1 protein expression in iWAT was observed in the EX + 1/2 βCon group compared with the EX group. Furthermore, the plasma FGF21 concentration of the EX + 1/2 βCon group was significantly higher than that of the EX group. These findings suggested that FGF21 may be associated with the brown-like adipocyte formation induced by EX combined with 1/2 βCon diet intake in mice. Soy Protein Research, Japan 24, 105-108, 2021.
Key words : brown-like adipocyte, β-conglycinin, exercise, uncoupling protein 1
Molecular Mechanisms of Soy Isoflavone Action in Skeletal Muscle
Yasutomi KAMEI*
Laboratory of Molecular Nutrition, Graduate School of Life and Environmental Sciences, Kyoto Prefectural University, Kyoto 606-8522
ABSTRACT
Skeletal muscle plays important roles in exercise, glucose uptake, and energy expenditure. Muscle atrophy and dysfunction leads to obesity, metabolic diseases, decreased quality of life, and shortened healthy longevity. We have shown that soy isoflavones enhance the transcriptional activity of PGC-1β, an important regulator of energy expenditure in skeletal muscle. In this study, we examined the role of soy isoflavones in preventing and alleviating obesity and in increasing skeletal muscle function. We found that PGC-1β expression was decreased during muscle atrophy. We previously reported that the transcription factor FOXO1 negatively regulates PGC-1β gene expression in skeletal muscle. During atrophy, isoflavone usage was decreased in skeletal muscle; thus, increased isoflavone intake may improve muscle function. We treated C2C12 myoblasts (overexpressing PGC-1β) with isoflavones, and we observed increased lipid metabolism-related gene expression. Thus, we found that the isoflavones increase energy expenditure via the PGC-1β pathway. We used PGC-1α KO mice to examine whether isoflavone intake reduces obesity. Isoflavone intake marginally decreased white adipose tissue weight in mice fed a high-fat diet. However, there were no marked differences between wild-type and PGC-1α KO mice. In future work, conditions in which PGC-1α expression in skeletal muscle is enhanced, such as exercise, should be examined. Soy Protein Research, Japan 24, 109-117, 2021.
Key words : isoflavone, skeletal muscle, obesity, energy expenditure, PGC-1β
Regulation of Muscle Glycogen Metabolism by the Soy Isoflavone Genistein
Takahiko SHIMIZU*
Aging Stress Response Research Project Team, National Center for Geriatrics and Gerontology (NCGG), Aichi 474-8511
ABSTRACT
SOD2 is an antioxidant enzyme localized in mitochondria. Muscle-specific Sod2- deficient mice showed a marked decrease in forced running ability associated with overproduction of muscle mitochondrial superoxide. The amount of ATP in skeletal muscle decreased significantly, suggesting a decrease in running performance due to a decrease in muscle ATP. In addition to the decrease in mitochondrial respiratory enzyme activity, there was an accumulation of muscle glycogen. Glycogen metabolism is defined by anabolic and catabolic activities. The muscle glycogen synthase activity was similar to that of wild-type mice, but the muscle glycogen phosphorylase (GP-M) activity was significantly reduced. The decrease in glycolytic ATP production caused by the impairment of glycogen use is an additive phenotype. When an SOD mimic was administered to the mutant mice, the amount of muscle ATP was restored and the running time was significantly extended. When polyphenols were evaluated using the in vivo system, the soy isoflavone genistein significantly prolonged the running time. Biochemical analysis showed that genistein administration increased muscle ATP levels and decreased muscle glycogen accumulation. GP-M activity showed an increasing trend but this was not significant. These results suggested that genistein acted directly or indirectly on GP-M activity to restore glycogen use and to improve athletic performance by increasing muscle ATP. Soy Protein Research, Japan 24, 118-123, 2021.
Key words : genistein, mitochondria, SOD2, ROS, glycogen metabolism
Development of Anti-aging Material based on Matrix of Dipeptide and Activity of Ghrelin Signaling
Kousaku OHINATA* and Ken SHIMIZU
Graduate School of Agriculture, Kyoto University, Kyoto 611-0011
ABSTRACT
We have previously reported that a chymotrypsin digest of β-conglycinin, a major soy seed storage protein, increases ghrelin sensitivity. In this study, we searched for ghrelin sensitivity-stimulating peptides present in the digest, based on the structure-activity relationship of dipeptides that stimulate ghrelin sensitivity and comprehensive peptide analysis of the digest. We found that an 11-amino acid peptide present in the digest increased Ca2+ flux in response to ghrelin application in ghrelin receptor-transfected CHO cells. Although, the peptide did not stimulate ghrelin secretion in vitro and in vivo, it did increase food intake in non-fasted mice after administration. Thus, this peptide is the first example of a ghrelin sensitivity- stimulating peptide derived from food protein. Soy Protein Research, Japan 24, 124- 127, 2021.
Key words : β-conglycinin, peptide, ghrelin sensitivity, anorexia of aging, anti-aging
A Novel Target Molecule for the Soybean Protein β-conglycinin
Makoto SHIMIZU*
Nutri-Life Science Laboratory, Department of Applied Biological Chemistry, The University of Tokyo, Tokyo 113-8657
ABSTRACT
Soybean protein β-conglycinin (β-CG) has several beneficial effects, including anti-obesity effects. Our previous study found that β-CG consumption markedly increased the gene expression of fibroblast growth factor 21 (Fgf21), which exerts the anti-obesity effect. Most of the anti-obesity effects of β-CG were abolished by FGF21 deficiency, suggesting that β-CG exerts its beneficial effects through FGF21. Because expression of several activating transcription factor 4 (ATF4) target genes including Fgf21, ATF4 is a potential regulator of Fgf21 expression by β-CG consumption. However, ATF4 was not activated by β-CG consumption, suggesting other potential regulators. Activating transcription factor 5 (ATF5) is a liver-selective transcription factor and has a similar structure, DNA-binding element, and target genes to ATF4. We recently found that ATF5 also regulates Fgf21 expression. In this study, we investigated the role of ATF5 in regulating Fgf21 expression by β-CG consumption. When C57/BL/6 wild mice were fed with a β-CG diet, the expression of Atf5 and Fgf21 was significantly increased, and the expression of some ATF5 target genes was also increased. To investigate the role of ATF5, wild type or ATF5-deficient mice were fed with a casein diet or a β-CG diet. Gene expression analysis showed that increases in Fgf21 expression caused by β-CG consumption were not abolished by ATF5 deficiency. Both the plasma level of FGF21 and hepatic expression of ATF5 target genes were increased in both wild type and ATF5 deficient mice by the β-CG diet. These results indicate that β-CG stimulates Fgf21 expression without involving ATF5. Soy Protein Research, Japan 24, 128-133, 2021.
Key words : β-conglycinin, FGF21, gene expression, ATF4, ATF5
Screening of the Human Olfactory Receptor Response to Hexanal, the Causative Compound of the Grassy Smell in Soybean Products
Yuko TERADA* and Keisuke ITO
School of Food and Nutritional Sciences, University of Shizuoka, Shizuoka 422-8526
ABSTRACT
Hexanal, which is the causative compound of the unpleasant grassy smell in soybeans, presents a major obstacle to the use of soy products in food. Humans detect smells via approximately 400 kinds of human olfactory receptors (hORs) in the nasal olfactory epithelium. Thus, determining which hORs respond to hexanal would enable the development of smell masking agents that inhibit hexanal- responsive receptors. We previously established a hOR assay system using a cAMP-dependent luciferase and identified OR2W1 as a hexanal-responsive receptor. However, assessment of 400 hORs assay takes excessive time. Thus, in this study, we developed a faster method for screen hexanal-responsive receptors among the 400 hORs. First, we established a GFP reporter assay system that detects the elevated intracellular cAMP level induced by hOR activation. Next, we developed a receptor screening method that combines the GFP reporter assay system with a cell sorting system. In the screening method, the GFP-reporter plasmid and 400 hOR expression plasmids are transfected into HEK cells. Following the administration of odorant compounds to the transfected cells, the GFP-positive cells are collected using the cell sorter. After three rounds of selection, the hOR genes that responded to the odorant compounds are determined by DNA sequencing. Using this screening method, we identified nine hORs as candidate hexanal- responsive receptors. In future work, confirming whether these hORs respond to hexanal would advance the development of smell masking agents at a receptor level. Soy Protein Research, Japan 24, 134-138, 2021.
Key words : hexanal, human olfactory receptor, reporter assay, screening system
Structural Analysis of Soybean Seed Storage Protein by Small-angle Scattering
Aya OKUDA*
Institute for Integrated Radiation and Nuclear Science, Kyoto University, Osaka 590-0494
ABSTRACT
The major components of soybean seed storage protein, glycinin and β-conglycinin, form aggregates and gels via disulfide bonds and intermolecular interactions, giving them properties that make them remarkably well-suited to food processing. The structures of these proteins change during food processing depending on physical and chemical conditions such as pressure, pH, and salt concentration, leading to the emergence of various physical properties. Therefore, clarifying the relationship between these structures and properties is important for developing new food processing technologies using soybean protein. Small-angle scattering techniques are useful for observing the nanoscale structure of proteins, which contributes to their physical properties. The soybean seed storage proteins β-conglycinin (7S) and glycinin (11S) contain multiple subunits. In this study, the structures of the single subunits (pro7S α', pro11S A1aB1b) were observed by small-angle X-ray scattering (SAXS) using recombinant proteins from the E. coli expression system. In addition, monodisperse samples containing no contaminants are necessary for rigorous scattering experiments. Therefore, the conditions for obtaining high-purity recombinant protein samples free of contaminants using various types of column chromatography were investigated. The high-purity protein samples were used to examine the NaCl concentration-dependent dissociation/association and structural changes with SAXS. The results suggested that these recombinant proteins form complexes based on trimeric structures. Soy Protein Research, Japan 24, 139-143, 2021.
Key words : soybean seed storage protein, glycinin, β-conglycinin, small-angle X-ray scattering (SAXS)
Effects of Soy Protein Intake on Glucose Metabolism in Subcutaneous Fat Tissue of Rats
Hirokazu TANIGUCHI*
Division of Applied Life Sciences, Graduate School of Life and Environmental Sciences, Kyoto Prefectural University, Kyoto 606-8522
ABSTRACT
Adipose tissue insulin resistance is associated with fatty liver disease, and fibroblast growth factor 21 (FGF21) stimulates glucose uptake in adipose tissue. FGF21 secretion is induced by soy protein intake; thus, in this study, we evaluated whether habitual soy protein intake affects FGF21 and adipose tissue glucose metabolism. Sixteen male F344/NSlc rats were fed casein or soy protein diets for 12 weeks. To examine diurnal changes in circulating FGF21 concentration, blood sampling was performed four times at 6-h intervals (2:00, 8:00, 14:00, and 20:00). 2-Deoxyglucose was injected, and the glucose uptake in subcutaneous adipose tissue was measured. After the feeding periods, relative liver weight, hepatic fat content, and plasma total cholesterol level were significantly lower in the rats fed the soy protein diet (p < 0.05). The plasma FGF21 levels were significantly higher in the light periods (8:00 and 14:00) than in the dark periods (20:00 and 2:00) in both groups. However, the rats fed the soy protein diet showed a significantly lower plasma FGF21 level in the dark periods (p < 0.05) and a significantly higher level in the light periods compared with rats fed a casein diet (p < 0.05). 2-Deoxyglucose uptake in the subcutaneous adipose tissue was the same in both groups. In conclusion, habitual soy protein intake prevents fatty liver disease and cholesterolemia, and affects diurnal FGF21 rhythm. However, a soy protein diet did not affect adipose tissue glucose uptake. Soy Protein Research, Japan 24, 144-149, 2021.
Key words : glucose uptake, insulin resistance, FGF21, fatty liver, cholesterolemia
Improving Zinc Absorption by Using Soybean Components
Ayako HASHIMOTO*
Department of Food and Nutrition, Faculty of Home Economics, Kyoto Women's University, Kyoto 605-8501
ABSTRACT
Zinc deficiency is a global public health problem, with about 20% of the world's population estimated to be zinc deficient. To prevent zinc deficiency, we explored a new strategy for increasing dietary zinc absorption. In the small intestine, the zinc transporters ZIP4 and ZNT1 play a primary role in dietary zinc absorption. ZIP4 is involved in zinc uptake into enterocytes at the apical surface and ZNT1 exports zinc from enterocytes into the blood. Thus, food components that increase ZIP4 and ZNT1 expression might potentially increase dietary zinc absorption. In previous studies, we identified soyasaponin Bb as an active component that increased ZIP4 expression and cellular zinc levels. In this study, we screened soybean extracts and identified components that increase ZIP4 or ZNT1 expression. These results suggest that soybeans might be used to increase dietary zinc absorption and thus improve zinc nutritional status. Soy Protein Research, Japan 24, 150-153, 2021.
Key words : zinc absorption, zinc transporter, ZIP4, ZNT1, soybean components
Soy and Isoflavone Intake and Lifestyle and Health Awareness in Japanese Workers
Mariko NAKAMOTO*1, Sarasa MORI1, Emi SHUTO1, Akiko NAKAMOTO1, Akiko HATA2, Nanako AKI2, Yosuke SHIKAMA2,3, Yukiko BANDO2, Takako ICHIHARA4, Takako MINAGAWA5, Ayako TAMURA6, Yumi KUWAMURA7, Makoto FUNAKI2 and Tohru SAKAI1
1Department of Public Health and Applied Nutrition, Institute of Biomedical Sciences, the University of Tokushima Graduate School, Tokushima 770-8503
2Clinical Research Center for Diabetes, Tokushima University Hospital, Tokushima 770-8503
3National Center for Geriatrics and Gerontology, Research Institute, Department of Oral Disease Research, Aichi 474-8511
4Department of Nursing, Faculty of Medicine, Kagawa University, Kagawa 761-0793
5Department of Medical Treatment Recovery Care Nursing, Institute of Biomedical Sciences, the University of Tokushima Graduate School, Tokushima 770-8503
6Department of Nursing, Faculty of Nursing, Shikoku University, Tokushima 771-1192
7Department of Women's Health Nursing, Institute of Biomedical Sciences, the University of Tokushima Graduate School, Tokushima 770-8503
ABSTRACT
In this study, we describe the contributions of different soy foods to daily isoflavone intake and the secular changes in total isoflavone intake over 7 years in Japanese workers. In addition, we examined the lifestyle and health awareness characteristics that contribute to the behavior affecting isoflavone intake. The participants were 534 men and 172 women aged 20 to 64 years who participated in a baseline survey and follow-up survey. We obtained anthropometric data, blood samples, and information on lifestyle characteristics, including dietary intake and dietary behavior and current medical histories, using a self-administered questionnaire. The average amount of dietary isoflavone intake was higher in women than in men. Most of the isoflavones were ingested from tofu, miso, and natto in both men and women. Over 7 years, the average amount of isoflavone intake increased in men, whereas there was no change in women. Dietary skipping in women was associated with increased isoflavone intake over 7 years, and midnight snacking in men was associated with decreased isoflavone intake over 7 years. These findings suggest that there were gender differences in the secular change in total isoflavone intake over 7 years, as well as in characteristics associated with isoflavone intake behavior in Japanese workers. Soy Protein Research, Japan 24, 154-161, 2021. Soy Protein Research, Japan 24, 154-161, 2021.
Key words : soy, isoflavones, lifestyle behavior, lifestyle conscious, Japanese workers
Effect of a Soy Protein Diet on the Regulation of Sugar Preference in Mice
Sho MATSUI*
Laboratory of Nutrition Chemistry, Division of Food Science and Biotechnology Graduate School of Agriculture, Kyoto University, Kyoto 606-8502
ABSTRACT
Increasing rates of diabetes and obesity are attributed to increased consumption of carbohydrate-rich diets and sugar-sweetened beverages. Fibroblast growth factor (FGF) 21 is a hormone that controls the preference for simple sugar, and its expression is increased by consuming soy β-conglycinin, a major component of soy protein. However, it has not been examined whether consuming a soy protein diet controls the preference for simple sugar. In this study, 5-week-old male C57BL/6 mice were fed a high soy-protein diet (HSoyD) for 7 or 14 days and the effect on simple sugar preference and the blood FGF21 level were investigated in those mice. In addition, the expression of sugar preference-regulating genes in the hypothalamus was examined in mice fed HSoyD for 14 days. The mice fed HSoyD for 14 days showed a significant suppression of simple sugar preference compared with those fed a high casein-protein diet. The FGF21 level was not altered in the mice fed the HSoyD after 7 or 14 days. The mRNA expression of neuropeptide Y (NPY), which is involved in the regulation of sugar preference, in the hypothalamus was significantly suppressed by HSoyD intake. These results suggest feeding soy protein suppresses simple sugar preference via downregulating NPY in the hypothalamus. Soy Protein Research, Japan 24, 162-165, 2021.
Key words : FGF21, preference, Npy, simple sugar