Cellular dynamics of coenocytic endosperm development in Arabidopsis thaliana.

After double fertilization, the endosperm in the seeds of many flowering plants undergoes repeated mitotic nuclear divisions without cytokinesis, resulting in a large coenocytic endosperm that then cellularizes. Growth during the coenocytic phase is strongly associated with the final seed size; however, a detailed description of the cellular dynamics controlling the unique coenocytic development in flowering plants has remained elusive. By integrating confocal microscopy live-cell imaging and genetics, we have characterized the entire development of the coenocytic endosperm of Arabidopsis thaliana including nuclear divisions, their timing intervals, nuclear movement and cytoskeleton dynamics. Around each nucleus, microtubules organize into aster-shaped structures that drive actin filament (F-actin) organization. Microtubules promote nuclear movement after division, while F-actin restricts it. F-actin is also involved in controlling the size of both the coenocytic endosperm and the mature seed. The characterization of cytoskeleton dynamics in real time throughout the entire coenocyte endosperm period provides foundational knowledge of plant coenocytic development, insights into the coordination of F-actin and microtubules in nuclear dynamics, and new opportunities to increase seed size and our food security.

F-actin regulates the polarized secretion of pollen tube attractants in Arabidopsis synergid cells.

Pollen tube attraction is a key event of sexual reproduction in flowering plants. In the ovule, two synergid cells neighboring the egg cell control pollen tube arrival via the active secretion of attractant peptides such as AtLURE1 and XIUQIU from the filiform apparatus (FA) facing toward the micropyle. Distinctive cell polarity together with longitudinal F-actin and microtubules are hallmarks of the synergid cell in various species, though the functions of these cellular structures are unclear. In this study, we used genetic and pharmacological approaches to indicate the roles of cytoskeletal components in FA formation and pollen tube guidance in Arabidopsis thaliana. Genetic inhibition of microtubule formation reduced invaginations of the plasma membrane but did not abolish micropylar AtLURE1.2 accumulation. By contrast, the expression of a dominant-negative form of ACTIN8 induced disorganization of the FA and loss of polar AtLURE1.2 distribution toward the FA. Interestingly, after pollen tube reception, F-actin became unclear for a few hours in the persistent synergid cell, which may be involved in pausing and resuming pollen tube attraction during early polytubey block. Our data suggest that F-actin plays a central role in maintaining cell polarity and in mediating male-female communication in the synergid cell.

Live-cell imaging reveals the cellular dynamics in seed development.

Seed development in flowering plants is highly complex and governed by three genetically distinct tissues: the fertilization products, the diploid embryo and triploid endosperm, as well as the seed coat that has maternal origin. There are diverse cellular dynamics such as nuclear movement in gamete cells for fertilization, cell polarity establishment for embryo development, and multinuclear endosperm formation. These tissues also coordinate and synchronize the developmental timing for proper seed formation through cell-to-cell communications. Live-cell imaging using advanced microscopy techniques enables us to decipher the dynamics of these events. Especially, the establishment of a less-invasive semi-in vivo live-cell imaging approach has allowed us to perform time-lapse analyses for long period observation of Arabidopsis thaliana intact seed development dynamics. Here we highlight the recent trends of live-cell imaging for seed development and discuss where we are heading.

Artemisia argyi extract alleviates inflammation in a DSS-induced colitis mouse model and enhances immunomodulatory effects in lymphoid tissues.

BACKGROUND: The incidence of inflammatory bowel disease (IBD), an inflammatory disorder of the gastrointestinal system has increased. IBD, characterized by aberrant immune responses against antigens, is thought to be caused by the invasion of enterobacteria. The pathogenesis of IBD is complicated, hence novel effective therapeutic agents are warranted. Therefore, this study evaluates the potential of Artemisia argyi, a medicinal herb, in alleviating IBD. METHODS: The effectiveness of the A. argyi ethanol extract was verified both in vitro and in vivo. Inflammation was induced in RAW 264.7 cells by 1 µg/mL of lipopolysaccharide (LPS) and by 3% dextran sodium sulfate (DSS) in a DSS-induced colitis mouse model. During the ten-day colitis induction, 200 mg/kg of A. argyi ethanol extract was orally administered to the treatment group. Levels of inflammation-related proteins and genes were analyzed in the colon, serum, and lymphoid tissues, i.e., Peyer's patches (PPs) and spleen. The chemical constituent of the A. argyi ethanol extract was identified using an ultra-high performance liquid chromatography mass spectrometry (UPLC-MS/MS) analysis. RESULTS: A. argyi ethanol extract treatment ameliorated IBD symptoms and reduced the expression of inflammation-related proteins and genes in the colon and serum samples. Furthermore, A. argyi treatment induced the activation of anti-oxidative associated proteins, such as nuclear factor-erythroid factor 2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1); and the treatment have also inhibited nuclear factor-κB (NF-κB), a central mediator of inflammatory responses. A. argyi enhanced the immunomodulatory effects in the PPs and spleen, which may stem from interleukin-10 (IL-10) upregulation. Chemical analysis identified a total of 28 chemical compounds, several of which have been reported to exert anti-inflammatory effects. CONCLUSIONS: The effectiveness of the A. argyi ethanol extract in alleviating IBD was demonstrated; application of the extract successfully mitigated IBD symptoms, and enhanced immunomodulatory responses in lymphoid tissues. These findings suggest A. argyi as a promising herbal medicine for IBD treatment.

Identification of Chemical Compounds from Artemisia gmelinii using UPLC-QTOF-MS/MS and their Regulatory Effects on Immune Responses in DSS-Induced Colitis Mice.

Artemisia gmelinii Web. ex Stechm. (AG), a popular medicinal herb in Asia, has been used as a common food ingredient in Korea and is traditionally known for its anti-inflammatory properties. Therefore, in this study, we aimed to investigate whether AG relieves IBD, a classic chronic inflammatory disease of the gastrointestinal tract. We identified 35 chemical compounds in AG ethanol extract using ultra-high-performance liquid chromatography-quadrupole time-of-flight tandem mass spectrometry. In mice with DSS-induced IBD, AG administration attenuated the disease activity index and the serum and colonic levels of inflammatory cytokines and chemokines. AG treatment decreased nuclear factor-[Formula: see text]B (NF-[Formula: see text]B) signaling, a key mediator of inflammation, in the mouse colons. Additionally, AG extract enhanced immune responses in lymphoid tissues such as spleen and Peyer's patches. Thus, AG consumption potently ameliorated IBD symptoms and improved immune signaling in lymphoid tissues.

Cancer-preventive effect of phenethyl isothiocyanate through tumor microenvironment regulation in a colorectal cancer stem cell xenograft model.

BACKGROUND: Phenethyl isothiocyanate (PEITC) is a glucosinolate derived from cruciferous vegetables and is a cancer-chemopreventive reagent. Cancer stem cells (CSCs) have roles in cancer chemoresistance, invasion, metastasis, and recurrence. Here, we investigated whether PEITC can suppress the properties of CSCs using NCCIT cells and HCT116-derived cancer stem-like cells. Furthermore, we established a CSC xenograft prevention model using nude mice. PURPOSE: The purpose of this study was to examine the actual cancer-preventive effects of PEITC in vitro and in a xenograft prevention model. STUDY DESIGN: We assessed the cancer-preventive effects of PEITC on CSCs using a novel xenograft prevention model. METHODS: NCCIT cells were treated with PEITC, and the expression of pluripotent markers was confirmed by reporter assays, western blotting, and qRT-PCR. In addition, to evaluate the effects of PEITC on CSC properties, sphere cells, which exhibit CSC properties, were established from the HCT116 cells. Furthermore, to examine the inhibitory effects and the underlying mechanism following daily intake of PEITC on CSCs, we performed an animal study in a mouse xenograft model and RNA-sequencing analysis. RESULTS: PEITC significantly reduced the CSC properties, including clonogenicity and the expression of pluripotent factors. Prior to CSC inoculation in vivo, the PEITC pre-treatment group showed a more effective reduction in the tumor growth rate and expression of CSC markers compared to the post-treatment groups. Furthermore, RNA-sequencing results showed that PEITC pre-treatment remarkably suppressed genes related to inflammatory and immune responses and chemokine-related signaling. CONCLUSION: PEITC might contribute to the prevention or delay of colorectal cancer growth by inhibiting CSCs via the regulation of inflammatory chemokines, which can affect the tumor microenvironment. Thus, our study suggests that the daily intake of phytochemicals derived from vegetables or dietary supplements could have cancer-preventive effects through regulation of the host-tumor microenvironment.

Yellow loosestrife (Lysimachia vulgaris var. davurica) ameliorates liver fibrosis in db/db mice with methionine- and choline-deficient diet-induced nonalcoholic steatohepatitis.

BACKGROUND: Nonalcoholic steatohepatitis (NASH), a liver disease caused by a nonalcoholic fatty liver, is increasing in incidence worldwide. Owing to the complexity of its pathogenic mechanisms, there are no therapeutic agents for this disease yet. The ideal drug for NASH needs to concurrently decrease hepatic lipid accumulation and exert anti-inflammatory, antifibrotic, and antioxidative effects in the liver. Because of their multipurpose therapeutic effects, we considered that medicinal herbs are suitable for treating patients with NASH. METHODS: We determined the efficacy of the alcoholic extract of Lysimachia vulgaris var. davurica (LV), an edible medicinal herb, for NASH treatment. For inducing NASH, C57BLKS/J lar-Leprdb/Leprdb (db/db) male mice were fed with a methionine-choline deficient (MCD) diet ad libitum. After 3 weeks, the LV extract and a positive control (GFT505) were administered to mice by oral gavage for 3 weeks with a continued MCD diet as needed. RESULTS: In mice with diet-induced NASH, the LV extract could relieve the disease symptoms; that is, the extract ameliorated hepatic lipid accumulation and also showed antioxidative and anti-inflammatory effects. The LV extract also activated nuclear factor E2-related factor 2 (Nrf2) expression, leading to the upregulation of antioxidants and detoxification signaling. Moreover, the extract presented remarkable efficacy in alleviating liver fibrosis compared with GFT505. This difference was caused by significant LV extract-mediated reduction in the mRNA expression of fibrotic genes like the alpha-smooth muscle actin and collagen type 3 alpha 1. Reduction of fibrotic genes may thus relate with the downregulation of transforming growth factor beta (TGFß)/Smad signaling by LV extract administration. CONCLUSIONS: Lipid accumulation and inflammatory responses in the liver were alleviated by feeding LV extract to NASH-induced mice. Moreover, the LV extract strongly prevented liver fibrosis by blocking TGFß/Smad signaling. Hence, LV showed sufficient potency for use as a therapeutic agent against NASH.

Cellular dynamics of double fertilization and early embryogenesis in flowering plants.

Flowering plants (angiosperms) perform a unique double fertilization in which two sperm cells fuse with two female gamete cells in the embryo sac to develop a seed. Furthermore, during land plant evolution, the mode of sexual reproduction has been modified dramatically from motile sperm in the early-diverging land plants, such as mosses and ferns as well as some gymnosperms (Ginkgo and cycads) to nonmotile sperm that are delivered to female gametes by the pollen tube in flowering plants. Recent studies have revealed the cellular dynamics and molecular mechanisms for the complex series of double fertilization processes and elucidated differences and similarities between animals and plants. Here, together with a brief comparison with animals, we review the current understanding of flowering plant zygote dynamics, covering from gamete nuclear migration, karyogamy, and polyspermy block, to zygotic genome activation as well as asymmetrical division of the zygote. Further analyses of the detailed molecular and cellular mechanisms of flowering plant fertilization should shed light on the evolution of the unique sexual reproduction of flowering plants.

Gymnaster Koraiensis Extract Alleviated Metabolic Syndrome Symptoms and Stimulated UCP1-Independent Energy Consumption via AMPK Activation in White Adipose Tissue.

SCOPE: Metabolic syndrome and obesity are rising worldwide concerns that are accompanied by adverse health consequences. Here, it is hypothesized that the ethanol extract from Gymnaster koraiensis (GK), an edible Korean plant known for its anti-cancer and hepatoprotective properties, could attenuate metabolic syndrome-related symptoms in high-fat dietary-induced obese (DIO) mice. METHODS AND RESULTS: Administration of 100 mg kg-1 GK extract to DIO mice effectively reduces body and white adipose tissue (WAT) weight. It also reduces cardiovascular disease risk and improves insulin resistance by lowering the fasting blood glucose levels and mitigating oxidative stress and inflammation. Moreover, supplementation with GK causes elevated energy expenditure in WAT by increasing the mitochondrial oxidative capacity and lipid catabolism through upregulated adenosine monophosphate-activated protein kinase (AMPK) signaling. Orlistat is used as a positive control drug due to its widespread use in previous studies. It is found that GK extract causes weight loss, similar to Orlistat, and it additionally shows unique functions, such as upregulation of energy consumption in WAT. CONCLUSION: GK extract treatment prominently reduces obesity and its associated metabolic complications, such as hyperlipidemia, hyperglycemia, and insulin resistance. Hence, It can be used as a promising multi-target functional food that can improve metabolic syndrome-related symptoms.

Reduction of Hepatic Lipogenesis by Loliolide and Pinoresinol from Lysimachia vulgaris via Degrading Liver X Receptors.

The liver X receptors (LXRs) are major regulators of lipogenesis, and their reduced activation by an inhibitor could be a treatment strategy for fatty liver disease. Small molecules originating from dietary food are considered suitable and attractive drug candidates for humans in terms of safety. In this study, an edible plant, Lysimachia vulgaris (LV), used as a traditional and medicinal food in East Asia was evaluated for lipogenesis decreasing effects. Activity-guided fractionation was performed, and the isolated compounds were identified using spectroscopic methods. We conducted in vitro real-time polymerase chain reaction (PCR) and Western blotting as well as histological and biochemical analyses following in vivo treatments. Using a high-fat diet animal model, we confirmed that LV extracts (LVE) decreased lipogenic metabolism and restored liver function to control levels. To identify active components, we conducted activity-guided fractionation and then isolated compounds. Two compounds, loliolide and pinoresinol, were identified in the dichloromethane fraction, and they significantly attenuated the expression levels of lipogenic factors including sterol regulatory element-binding protein (SREBP)-1, stearoyl-CoA desaturase 1 (SCD1), fatty acid synthase (FAS), and acetyl-CoA carboxylase (ACC). Importantly, loliolide and pinoresinol significantly accelerated the protein degradation of LXRs by enhanced ubiquitination, which inhibited lipogenesis. These results suggest that loliolide and pinoresinol might be potential candidate supplementary treatments for nonalcoholic fatty liver disease (NAFLD) by reducing lipogenesis through increased ubiquitination of LXRs.

Physalin A regulates the Nrf2 pathway through ERK and p38 for induction of detoxifying enzymes.

BACKGROUND: Physalin A isolated from Physalis alkekengi var. franchetii has been known to have many pharmacological properties. However, its effect through the Nrf2 pathway has not yet been elucidated. In the present study, we determined the effects of physalin A on cancer chemoprevention via the Nrf2 pathway. METHODS: Experiments were performed in Hepa-1c1c7 and HepG2 cells. The quinone reductase (QR) activity assay was used to assess the activity of physalin A and other compounds isolated from P. alkekengi. The antioxidant response element (ARE) reporter assay was used to determine physalin A induced transcription of Nrf2 target genes, whereas the oligonucleotide pull-down assay was used to investigate Nrf2 binding to the AREs post physalin A treatment. Real-time PCR and western blotting were performed to determine the expression of Nrf2 target genes. Immunocytochemistry was used to determine Nrf2 localization after treatment with physalin A. Kinase inhibitors were used to test the involvement of Nrf2-targeting kinases and the role of ERK and p38 phosphorylation was confirmed using western blotting. RESULTS: Physalin A significantly induced QR activity. As an upstream effector of QR, Nrf2 induced genes containing the ARE, which encode various antioxidants and detoxification enzymes. We observed that physalin A increased the expression of Nrf2 and its target genes in HepG2 cells. Moreover, we observed that physalin A-induced Nrf2 activation was regulated by ERK and p38 kinase in HepG2 cells. CONCLUSIONS: Taken together, we showed that physalin A increased detoxifying enzyme expression via activation of Nrf2 and its target genes. These results imply that physalin A could be a potential chemopreventive agent for liver diseases, as well as cancer.

Igalan induces detoxifying enzymes mediated by the Nrf2 pathway in HepG2 cells.

Igalan is one of the sesquiterpene lactones found in Inula helenium L., which is used as the traditional medicine to treat inflammatory diseases. However, the pharmacological effects of igalan have not been characterized. In this study, we isolated igalan from I. helenium L. and evaluated the effects of igalan on signaling pathways and expression of target genes in HepG2 cells. Igalan activated the nuclear factor erythroid 2-related factor 2 (Nrf2) pathway by increasing the inactive form of GSK3ß, the phosphorylated form of AKT, and the nuclear accumulation of Nrf2. Thus, target genes of Nrf2 such as HO-1 and NQO1 increased in HepG2 cells. Moreover, igalan inhibited the tumor necrosis factor-α (TNF-α)-induced nuclear factor-κB activation and suppressed the expression of its target genes, including TNF-α, interleukin (IL)-6, and IL-8 in HepG2 cells. Our results indicate the potential of igalan as an activator of cellular defense mechanisms and a detoxifying agent.

Phenethyl isothiocyanate suppresses cancer stem cell properties in vitro and in a xenograft model.

BACKGROUND: Cancer stem cells (CSCs) are a subset of cells within the bulk of a tumor that have the ability to self-renew and differentiate, and are thus associated with cancer invasion, metastasis, and recurrence. Phenethyl isothiocyanate (PEITC) is a natural compound found in cruciferous vegetables such as broccoli and is used as a cancer chemopreventive agent; however, its effects on CSCs are little known. PURPOSE: To evaluate the effect of PEITC on CSCs in this study by examining CSC properties. METHODS: NCCIT human embryonic carcinoma cells were treated with PEITC, and the expression of pluripotency factors Oct4, Sox-2, and Nanog were evaluated by luciferase assay and western blot. Effect of PEITC on self-renewal capacity and clonogenicity were assessed with the sphere formation, soft agar assay, and clonogenic assay in an epithelial cell adhesion molecule (EpCAM)-expressing CSC model derived from HCT116 colon cancer cells using a cell sorting system. The effect of PEITC was also investigated in a mouse xenograft model obtained by injecting nude mice with EpCAM-expressing cells. RESULTS: We found that PEITC treatment suppressed expression of the all three pluripotency factors in the NCCIT cells, in which pluripotency factors are highly expressed. Moreover, PEITC suppressed the self-renewal capacity and clonogenicity in the EpCAM-expressing CSC model. EpCAM was used as a specific CSC marker in this study. Importantly, PEITC markedly suppressed both tumor growth and expression of three pluripotency factors in a mouse xenograft model. CONCLUSION: These results demonstrate that PEITC might be able to slow down or prevent cancer recurrence by suppressing CSC stemness.

The chimeric repressor for the GATA4 transcription factor improves tolerance to nitrogen deficiency in Arabidopsis.

Nitrogen limits crop yield, but application of nitrogen fertilizer can cause environmental problems and much fertilizer is lost without being absorbed by plants. Increasing nitrogen use efficiency in plants may help overcome these problems and is, therefore, an important and active subject of agricultural research. Here, we report that the expression of the chimeric repressor for the GATA4 transcription factor (35S:GATA4-SRDX) improved tolerance to nitrogen deficiency in Arabidopsis thaliana. 35S:GATA4-SRDX seedlings were significantly larger than wild type under nitrogen-sufficient and -deficient conditions (10 and 0.5 mM NH4NO3, respectively). 35S:GATA4-SRDX plants exhibited shorter primary roots, fewer lateral roots, and higher root hair density compared with wild type. The expression levels of NITRATE TRANSPORTER 2.1, ASPARAGINE SYNTHETASE and NITRATE REDUCTASE 1 were significantly higher in roots of 35S:GATA4-SRDX plants than in wild type under nitrogen-sufficient conditions. Under nitrogen-deficient conditions, the expression of genes for cytosolic glutamine synthetases was upregulated in shoots of 35S:GATA4-SRDX plants compared with wild type. This upregulation of nitrogen transporter and nitrogen assimilation-related genes might confer tolerance to nitrogen deficiency in 35S:GATA4-SRDX plants.

Enhanced biglycan gene expression in the adipose tissues of obese women and its association with obesity-related genes and metabolic parameters.

Extracellular matrix (ECM) remodeling dynamically occurs to accommodate adipose tissue expansion during obesity. One non-fibrillar component of ECM, biglycan, is released from the matrix in response to tissue stress; the soluble form of biglycan binds to toll-like receptor 2/4 on macrophages, causing proinflammatory cytokine secretion. To investigate the pattern and regulatory properties of biglycan expression in human adipose tissues in the context of obesity and its related diseases, we recruited 21 non-diabetic obese women, 11 type 2 diabetic obese women, and 59 normal-weight women. Regardless of the presence of diabetes, obese patients had significantly higher biglycan mRNA in both visceral and subcutaneous adipose tissue. Biglycan mRNA was noticeably higher in non-adipocytes than adipocytes and significantly decreased during adipogenesis. Adipose tissue biglycan mRNA positively correlated with adiposity indices and insulin resistance parameters; however, this relationship disappeared after adjusting for BMI. In both fat depots, biglycan mRNA strongly correlated with the expression of genes related to inflammation and endoplasmic reticulum stress. In addition, culture of human preadipocytes and differentiated adipocytes under conditions mimicking the local microenvironments of obese adipose tissues significantly increased biglycan mRNA expression. Our data indicate that biglycan gene expression is increased in obese adipose tissues by altered local conditions.

Tanshinone IIA induces mitochondria dependent apoptosis in prostate cancer cells in association with an inhibition of phosphoinositide 3-kinase/AKT pathway.

Tanshinone IIA (Tan IIA; 14,16-epoxy-20-nor-5(10),6,8,13,15-abietapentaene-11,12-dione), a phytochemical derived from the roots of Salvia miltiorrhiza BUNGE, has been reported to posses anti-angiogenic, anti-oxidant, anti-inflammatory and apoptotic activities. However, the cancer growth inhibitory/cytocidal effects and molecular mechanisms in prostate cancer cells have not been well studied. In the present study, we demonstrate that Tan IIA significantly decreased the viable cell number of LNCaP (phosphate and tensin homolog (PTEN) mutant, high AKT, wild type p53) prostate cancer cells more sensitively than against the PC-3 (PTEN null, high AKT, p53 null) prostate cancer cells. Tan IIA significantly increased TdT-mediated dUTP nick-end labeling (TUNEL) positive index and sub-G1 DNA contents of treated cells, consistent with apoptosis. Tan IIA treatment led to cleavage activation of pro-caspases-9 and 3, but not pro-caspase-8, and cleavage of poly (ADP ribose) polymerase (PARP), a caspase-3 substrate. Additionally, Tan IIA treatment induced cytochrome c release from the mitochondria into the cytosol and reduced mitochondrial membrane potential and suppressed the expression of mitochondria protective Bcl-2 family protein Mcl-1(L). Tan IIA reduced the expression of phosphoinositide 3-kinase (PI3K) p85 subunit, and the phosphorylation of AKT and mammalian target of rapamycin (mTOR) in a concentration-dependent manner. Moreover, the combination of Tan IIA and LY294002, a specific PI3K inhibitor, enhanced PARP cleavage of LNCaP and PC-3, but not in MDA-MB-231 breast cancer cells which do not contain detectable active AKT. The findings suggest that Tan IIA-induced apoptosis involves mitochondria intrinsic caspase activation cascade and an inhibition of the PI3K/AKT survival pathway.