Comparison of the estrogenic potencies of standardized soy extracts by immature rat uterotrophic bioassay.

Soy phytoestrogens, isoflavones, are a primary class of plant-based estrogen alternatives being sold over the counter nowadays. Genistein, daidzein and glycitein are the major isoflavones found in soybeans, as aglycones and glycosides. Each isoflavone shows distinctive estrogenic activity and pharmacokinetics. Soy dry extracts, employed as pharmaceutical raw material for manufacturing isoflavone supplements, are standardized to contain 40% of total isoflavones, but the amount of each isoflavone is highly diverse. The influence of these compositional differences on the estrogenic potency of soy extracts was evaluated by uterotrophic bioassay. Five commercial samples of standardized soy dry extract, homogeneously suspended in arachis oil, were administered per os in serial doses (125-4150 mg/kg bw/day) to immature female rats for 3 days. Soy extract samples with considerable diversity in isoflavone composition revealed different estrogenic potencies. Our results indicate a need of standardization of the individual isoflavone content in soy extracts.     

High isoflavone content and estrogenic activity of 25 year-old Glycine max tissue cultures

Soy isoflavones are phytoestrogens which have been associated with several health benefits. In the present study, we report the production of isoflavones in a collection of 40 strains of soya cell cultures established in 1975. A large variability in the isoflavone composition was observed and high-producing strains, with an isoflavone content of up to 46.3 mg g(-1) dry wt., were found. In comparison with soybeans, many callus strains had a higher isoflavone concentration (10-40 times) and a different ratio of genistin to daidzin forms. The highest producing strain was transferred to liquid medium in an Erlenmeyer flask and in a 10 l stirred-tank bioreactor where high isoflavone content (7% dry wt.), concentration (880 mg l(-1)) and a maximum productivity estimated to 60 mg l(-1) d(-1) were obtained. We further studied the estrogenic activity of pure compounds compared to plant cell culture extracts in the estrogen-responsive human endometrial Ishikawa cell line. Estrogen was confirmed to be 1000-10,000 times more active than isoflavones. The estrogenic activity of the extracts correlated to their isoflavone content. The activity of the malonyl isoflavones, assessed here for the first time, was lower than the aglycones. Taken together, these results suggest that soya cell cultures can be used as an alternative source to soybeans to provide high concentrations of bioactive isoflavones.     

Pharmacological activities of Genistein,an isoflavone from soy (Glycine max): part II--anti-cholesterol activity,effects on osteoporosis & menopausal symptoms

Phytoestrogens represent a family of plant compounds such as isoflavones, flavones and lignans. A wide range of commonly consumed foods contains appreciable amounts of different phytoestrogens such as isoflavones and lignans. Soy and its products are particularly good sources of isoflavones and lignans. The evidence reviewed here represents the beneficial effects of most potential and promising isoflavone, Genistein in various types of diseases such as osteoporosis, cardiovascular diseases, menopausal symptoms by accumulating evidence from molecular and cellular biology experiments, animal studies, and, to a limited extent, human clinical trials. This review suggests that phytoestrogens may potentially confer health benefits related to various diseases such as cardiovascular disorder, menopausal symptoms, and osteoporosis.     

Novel major quantitative trait loci regulating the content of isoflavone in soybean seeds

Despite their medicinal, pharmaceutical, and nutritional importance of isoflavones, the genetic basis controlling the amounts of isoflavones in soybean seeds is still not well understood. The main obstacle is the great variability in the content of isoflavone in seeds harvested from different environments. In this study, quantitative trait loci (QTL) for the content of different isoflavones including daidzein, genistein, and glycitein were investigated in a population of recombinant inbred lines derived from the cross of “Hwangkeum” (Glycine max) by “IT182932” (Glycine soja). Seeds analyzed were harvested in three different experimental environments. QTL analyses for isoflavone content were conducted by composite interval mapping across a genomewide genetic map. Two major QTL were mapped to soybean chromosomes 5 and 8, which were designated QDZGT1 and QDZGT2, respectively. Both loci have not been previously reported in other isoflavone sources. The results from this study will be useful in cloning genes that can control the contents of isoflavones in soybean and for the development of soybean lines containing a high or low isoflavone content.     

Soy isoflavones and cognitive function

There is growing interest in the physiological functions of soy isoflavones, especially in whether they affect cognitive function and have beneficial effects on neurodegenerative diseases. Here we review the recent evidence from clinical and experimental studies supporting a role for soy isoflavones in cognitive function. Soy isoflavones may mimic the actions and functions of estrogens on brain, and they have been shown to have positive effects on the cognitive function in females; however, studies on their effects on spatial memory have not provided consistent results in males. Although data from humans, cultures, and animal models are currently insufficient for elucidating the metabolism of soy isoflavone actions on cognitive function and the nervous system, we suggest two putative pathways; (1) an estrogen receptor-mediated pathway and (2) via the inhibition of tyrosine kinase, in particular by genistein, which is one of the soy isoflavones. Although soy isoflavones appear to have a positive effect on brain function, further research is needed to determine not only the efficacy but also the safety of soy isoflavones on the nervous system and cognitive function.     

Macrophage adhesion on fibronectin evokes an increase in the elastic property of the cell membrane and cytoskeleton: an atomic force microscopy study

Interactions between cells and microenvironments are essential to cellular functions such as survival, exocytosis and differentiation. Cell adhesion to the extracellular matrix (ECM) evokes a variety of biophysical changes in cellular organization, including modification of the cytoskeleton and plasma membrane. In fact, the cytoskeleton and plasma membrane are structures that mediate adherent contacts with the ECM; therefore, they are closely correlated. Considering that the mechanical properties of the cell could be affected by cell adhesion-induced changes in the cytoskeleton, the purpose of this study was to investigate the influence of the ECM on the elastic properties of fixed macrophage cells using atomic force microscopy. The results showed that there was an increase (~50 %) in the Young’s modulus of macrophages adhered to an ECM-coated substrate as compared with an uncoated glass substrate. In addition, cytochalasin D-treated cells had a 1.8-fold reduction of the Young’s modulus of the cells, indicating the contribution of the actin cytoskeleton to the elastic properties of the cell. Our findings show that cell adhesion influences the mechanical properties of the plasma membrane, providing new information toward understanding the influence of the ECM on elastic alterations of macrophage cell membranes.     

Dynamic and structural signatures of lamellar actomyosin force generation

The regulation of cellular traction forces on the extracellular matrix is critical to cell adhesion, migration, proliferation, and differentiation. Diverse lamellar actin organizations ranging from contractile lamellar networks to stress fibers are observed in adherent cells. Although lamellar organization is thought to reflect the extent of cellular force generation, understanding of the physical behaviors of the lamellar actin cytoskeleton is lacking. To elucidate these properties, we visualized the actomyosin dynamics and organization in U2OS cells over a broad range of forces. At low forces, contractile lamellar networks predominate and force generation is strongly correlated to actomyosin retrograde flow dynamics with nominal change in organization. Lamellar networks build ～60% of cellular tension over rapid time scales. At high forces, reorganization of the lamellar network into stress fibers results in moderate changes in cellular tension over slower time scales. As stress fibers build and tension increases, myosin band spacing decreases and α-actinin bands form. On soft matrices, force generation by lamellar networks is unaffected, whereas tension-dependent stress fiber assembly is abrogated. These data elucidate the dynamic and structural signatures of the actomyosin cytoskeleton at different levels of tension and set a foundation for quantitative models of cell and tissue mechanics.     

The Negative Effect of Soy Extract on Erythrocyte Membrane Fluidity: An Electron Paramagnetic Resonance Study

A decrease of erythrocyte membrane fluidity can contribute to the pathophysiology of hypertension. Soy products, which are used as alternative therapeutics in some cardiovascular conditions, contain various isoflavones (genistein, daidzein, and their glucosides, genistin and daidzin), which can incorporate cellular membrane and change its fluidity. The aim of this study was to examine the effects of soy extract (which generally corresponds to the soy products of isoflavone composition) on erythrocyte membrane fluidity at graded depths. We used electron paramagnetic resonance spectroscopy and fatty acid spin probes (5-DS and 12-DS), the spectra of which are dependent on membrane fluidity. After being treated with soy extract, erythrocytes showed a significant (P = 0.016) decrease of membrane fluidity near the hydrophilic surface, while there were no significant changes of fluidity in deeper hydrophobic membrane regions. These results suggest that soy products containing high levels of genistein and isoflavone glucosides may not be suitable for use in hypertension because they decrease erythrocyte membrane fluidity.     

Pay attention to membrane tension: Mechanobiology of the cell surface

The cell surface is a mechanobiological unit that encompasses the plasma membrane, its interacting proteins, and the complex underlying cytoskeleton. Recently, attention has been directed to the mechanics of the plasma membrane, and in particular membrane tension, which has been linked to diverse cellular processes such as cell migration and membrane trafficking. However, how tension across the plasma membrane is regulated and propagated is still not completely understood. Here, we review recent efforts to study the interplay between membrane tension and the cytoskeletal machinery and how they control cell form and function. We focus on factors that have been proposed to affect the propagation of membrane tension and as such could determine whether it can act as a global or local regulator of cell behavior. Finally, we discuss the limitations of the available tool kit as new approaches that reveal its dynamics in cells are needed to decipher how membrane tension regulates diverse cellular processes.     

How does the extracellular matrix direct gene expression?

Based on the existing literature, a model is presented that postulates a “dynamic reciprocity” between the extracellular matrix (ECM) on the one hand and the cytoskeleton and the nuclear matrix on the other hand. The ECM is postulated to exert physical and chemical influences on the geometry and the biochemistry of the cell via transmembrane receptors so as to alter the pattern of gene expression by changing the association of the cytoskeleton with the mRNA and the interaction of the chromatin with the nuclear matrix. This, in turn, would affect the ECM, which would affect the cell, which…     

Dietary soy isoflavone-aglycone lowers food intake in female rats with and without ovariectomy

Objective: Estrogens downregulate eating behavior, and soy isoflavones are known to be estrogenic agents. We aimed to examine whether the estrogenic property of soy isoflavones can affect food intake and body weight. Methods and Procedures: Seven‐week‐old male, female, and ovariectomized (OVX) Sprague‐Dawley rats were given free access to a diet containing 100–300 mg total isoflavone/kg diet, or to a control diet, either with or without concurrent administration of estradiol by subcutaneous implantation. Results: Dietary soy isoflavone was shown to lower food intake in female rats, whether or not the animals had undergone ovariectomy. Administration of estradiol lowered the food intake in male rats and in OVX female rats. The decrease in weekly food intake in female rats led to a reduction in their weekly gain in body weight. Dietary soy isoflavone significantly increased the concentration of serum isoflavones, especially equol (a metabolite of daidzein), regardless of gender or ovariectomy. Dietary soy isoflavone did not affect either serum estradiol concentration or uterine and didymus weights, but estradiol administration improved the uterine atrophy in OVX rats, and decreased the didymus weight in male rats. Discussion: Soy isoflavone lowers the food intake in female rats, but not in the male animals. Contrary to the hypothesis currently in vogue, the reduction in food intake caused by soy isoflavone may not be a purely estrogenic effect. This follows from the finding that the effects of soy isoflavones on food intake and on the reproductive organs differ from the corresponding effects produced by estrogen.     

N-Ethylmaleimide-sensitive Factor Attachment Protein α (αSNAP) Regulates Matrix Adhesion and Integrin Processing in Human Epithelial Cells

Integrin-based adhesion to the extracellular matrix (ECM) plays critical roles in controlling differentiation, survival, and motility of epithelial cells. Cells attach to the ECM via dynamic structures called focal adhesions (FA). FA undergo constant remodeling mediated by vesicle trafficking and fusion. A soluble N-ethylmaleimide-sensitive factor (NSF) attachment protein α (αSNAP) is an essential mediator of membrane fusion; however, its roles in regulating ECM adhesion and cell motility remain unexplored. In this study, we found that siRNA-mediated knockdown of αSNAP induced detachment of intestinal epithelial cells, whereas overexpression of αSNAP increased ECM adhesion and inhibited cell invasion. Loss of αSNAP impaired Golgi-dependent glycosylation and trafficking of β1 integrin and decreased phosphorylation of focal adhesion kinase (FAK) and paxillin resulting in FA disassembly. These effects of αSNAP depletion on ECM adhesion were independent of apoptosis and NSF. In agreement with our previous reports that Golgi fragmentation mediates cellular effects of αSNAP knockdown, we found that either pharmacologic or genetic disruption of the Golgi recapitulated all the effects of αSNAP depletion on ECM adhesion. Furthermore, our data implicates β1 integrin, FAK, and paxillin in mediating the observed pro-adhesive effects of αSNAP. These results reveal novel roles for αSNAP in regulating ECM adhesion and motility of epithelial cells.     

Cloud storage for endosomes

Coordinated regulation of vesicle trafficking is critical for the proper functioning of a cell. The bulk of cellular transport vesicles are sequestered in a “perinuclear cloud”, with only a small fraction released to the cell periphery. Jongsma et al ( 2016 ) found that the ER‐associated E3 ubiquitin ligase RNF26 is responsible for establishing and maintaining the architecture of the perinuclear cloud and that this spatiotemporal positioning is critical for effective regulation of the endocytic and exocytic systems.     

Effects of soy protein and isoflavone on hepatic fatty acid synthesis and oxidation and mRNA expression of uncoupling proteins and peroxisome proliferator-activated receptor gamma in adipose tissues of rats

Soy protein rich in isoflavones profoundly affects lipid metabolism in experimental animals. To distinguish the roles of the protein and isoflavone components of a soy protein preparation in regulating lipid metabolism, we compared the effects of diets containing methanol-washed soy protein low in isoflavone supplemented with a 0-, 0.5- and 4-g/kg isoflavone preparation on hepatic fatty acid metabolism and adipose tissue gene expression in rats. Diets containing soy protein irrespective of the isoflavone levels decreased the activities and mRNA expression of enzymes involved in hepatic fatty acid synthesis to similar levels. Methanol-washed soy protein compared to casein increased the mRNA expression of peroxisome proliferator-activated receptor (PPAR) alpha, and supplementing the soy protein diet with isoflavone further increased this parameter dose-dependently. However, methanol-washed soy protein compared to casein was totally ineffective in altering the activities and mRNA levels of enzymes involved in fatty acid oxidation. Supplementation of soy protein diets with isoflavone slightly increased these parameters. The mRNA level of uncoupling protein (UCP) 1 in brown adipose tissue was significantly increased and mRNA levels of UCP2 and 3, and PPARgamma2 tended to be higher in rats fed methanol-washed soy protein not supplemented with isoflavone than in the animals fed casein. Adding isoflavone to the soy protein diets dose-dependently increased these parameters. These results suggested that the protein rather than isoflavone component is primarily responsible for the physiological activity of soy protein rich in isoflavones in reducing hepatic lipogenesis. However, isoflavones may have a role in regulating heptic fatty acid oxidation and adipose tissue gene expression.     

Multi-level control of actin dynamics by protein kinase D

Dynamic actin remodeling is fundamental to processes such as cell motility, vesicle trafficking, and cytokinesis. Protein kinase D (PKD) is a serine–threonine kinase known to be involved in diverse biological functions ranging from vesicle fission at the Golgi complex to regulation of cell motility and invasion. This review addresses the role of PKD in the organization of the actin cytoskeleton with a particular emphasis on the substrates associated with this function. We further highlight the multi-level control of actin dynamics by PKD and suggest that the tight spatio-temporal control of PKD activity is critical for the coordination of directed cell migration.     

Crosstalk of cell polarity signaling pathways

Cell polarity, the asymmetric organization of cellular components along one or multiple axes, is present in most cells. From budding yeast cell polarization induced by pheromone signaling, oocyte polarization at fertilization to polarized epithelia and neuronal cells in multicellular organisms, similar mechanisms are used to determine cell polarity. Crucial role in this process is played by signaling lipid molecules, small Rho family GTPases and Par proteins. All these signaling circuits finally govern the cytoskeleton, which is responsible for oriented cell migration, cell shape changes, and polarized membrane and organelle trafficking. Thus, typically in the process of cell polarization, most cellular constituents become polarized, including plasma membrane lipid composition, ion concentrations, membrane receptors, and proteins in general, mRNA, vesicle trafficking, or intracellular organelles. This review gives a brief overview how these systems talk to each other both during initial symmetry breaking and within the signaling feedback loop mechanisms used to preserve the polarized state.     

2, 6-dichlorobenzonitrile Causes Multiple Effects on Pollen Tube Growth beyond Altering Cellulose Synthesis in Pinus bungeana Zucc

Cellulose is an important component of cell wall, yet its location and function in pollen tubes remain speculative. In this paper, we studied the role of cellulose synthesis in pollen tube elongation in Pinus bungeana Zucc. by using the specific inhibitor, 2, 6-dichlorobenzonitrile (DCB). In the presence of DCB, the growth rate and morphology of pollen tubes were distinctly changed. The organization of cytoskeleton and vesicle trafficking were also disturbed. Ultrastructure of pollen tubes treated with DCB was characterized by the loose tube wall and damaged organelles. DCB treatment induced distinct changes in tube wall components. Fluorescence labeling results showed that callose, and acidic pectin accumulated in the tip regions, whereas there was less cellulose when treated with DCB. These results were confirmed by FTIR microspectroscopic analysis. In summary, our findings showed that inhibition of cellulose synthesis by DCB affected the organization of cytoskeleton and vesicle trafficking in pollen tubes, and induced changes in the tube wall chemical composition in a dose-dependent manner. These results confirm that cellulose is involved in the establishment of growth direction of pollen tubes, and plays important role in the cell wall construction during pollen tube development despite its lower quantity.     

The emergence of ECM mechanics and cytoskeletal tension as important regulators of cell function

The ability to harvest and maintain viable cells from mammalian tissues represented a critical advance in biomedical research, enabling individual cells to be cultured and studied in molecular detail. However, in these traditional cultures, cells are grown on rigid glass or polystyrene substrates, the mechanical properties of which often do not match those of the in vivo tissue from which the cells were originally derived. This mechanical mismatch likely contributes to abrupt changes in cellular phenotype. In fact, it has been proposed that mechanical changes in the cellular microenvironment may alone be responsible for driving specific cellular behaviors. Recent multidisciplinary efforts from basic scientists and engineers have begun to address this hypothesis more explicitly by probing the effects of ECM mechanics on cell and tissue function. Understanding the consequences of such mechanical changes is physiologically relevant in the context of a number of tissues in which altered mechanics may either correlate with or play an important role in the onset of pathology. Examples include changes in the compliance of blood vessels associated with atherosclerosis and intimal hyperplasia, as well as changes in the mechanical properties of developing tumors. Compelling evidence from 2-D in vitro model systems has shown that substrate mechanical properties induce changes in cell shape, migration, proliferation, and differentiation, but it remains to be seen whether or not these same effects translate to 3-D systems or in vivo. Furthermore, the molecular “mechanotransduction” mechanisms by which cells respond to changes in ECM mechanics remain unclear. Here, we provide some historical context for this emerging area of research, and discuss recent evidence that regulation of cytoskeletal tension by changes in ECM mechanics (either directly or indirectly) may provide a critical switch that controls cell function.     

The effects of soy protein in women and men with elevated plasma lipids

Fifty four postmenopausal women with elevated cholesterol were recruited for a randomised, double-blind controlled trial of soy protein containing isoflavones. (ISP+) or a soy protein with a low isoflavone content (ISP-), taken daily for 12 weeks. There was an overall reduction after 12 weeks in total cholesterol (TC), LDL cholesterol (LDL-C), sex hormone binding globulin (SHBG), and luteinizing hormone (LH). There were no significant differences between treatment groups. In a separate study 27 male subjects with a TC > 5.5 mmol/l were given ISP+ for 12 weeks. In this male study there was a significant increase in HDL cholesterol (HDL-C) and SHBG. Soy protein has a cholesterol lowering effect in both women and men. These studies suggest that this effect is independent of isoflavones. Soy protein also reduces SHBG levels in both sexes.