Ginsenoside Rk1 is a novel inhibitor of NMDA receptors in cultured rat hippocampal neurons 490

Nayeon Ryoo,Md. Ataur Rahman,Hongik Hwang,Sung Kwon Ko,Seung-Yeol Nah,Hyoung-Chun Kim,Hyewhon Rhim 고려인삼학회 2020 Journal of Ginseng Research Vol.44 No.3

Background: Ginsenoside Rk1, a saponin component isolated from heat-processed Panax ginseng Meyer,has been implicated in the regulation of antitumor and anti-inflammatory activities. Although ourprevious studies have demonstrated that ginsenoside Rg3 significantly attenuated the activation ofNMDA receptors (NMDARs) in hippocampal neurons, the effects of ginsenosides Rg5 and Rk1, which arederived from heat-mediated dehydration of ginsenoside Rg3, on neuronal NMDARs have not yet beenelucidated. Methods: We examined the regulation of NMDARs by ginsenosides Rg5 and Rk1 in cultured rat hippocampalneurons using fura-2ebased calcium imaging and whole-cell patch-clamp recordings. Results: The results from our investigation showed that ginsenosides Rg3 and Rg5 inhibited NMDARswith similar potencies. However, ginsenoside Rk1 inhibited NMDARs most effectively among the fivecompounds (Rg3, Rg5, Rk1, Rg5/Rk1 mixture, and protopanaxadiol) tested in cultured hippocampalneurons. Its inhibition is independent of the NMDA- and glycine-binding sites, and its action seems toinvolve in an interaction with the polyamine-binding site of the NMDAR channel complex. Conclusion: Taken together, our results suggest that ginsenoside Rk1 might be a novel componentcontributable to the development of ginseng-based therapeutic treatments for neurodegenerativediseases.

Expression and Functional Analysis of Rice Plastidic Maltose Transporter, OsMEX1

Ryoo, Nayeon,Eom, Joon-Seob,Kim, Hyun-Bi,Vo, Bich Thuy,Lee, Sang-Won,Hahn, Tae-Ryong,Jeon, Jong-Seong 한국응용생명화학회 2013 Applied Biological Chemistry (Appl Biol Chem) Vol.56 No.2

In Arabidopsis, maltose is a major product of the transitory starch degradation pathway at night, and its mobilization from the chloroplasts to the cytosol in leaf tissues via a plastidic maltose transporter, AtMEX1, is essential for normal plant growth. However, such a starch utilization pathway has not yet been characterized in rice (Oryza sativa), a monocot model plant. Examination of expression profiles of a rice plastidic maltose transporter, OsMEX1, by real-time polymerase chain reaction showed that it is abundant in the pollen grain-containing stamens of mature flowers. Consistently, high performance liquid chromatography analysis revealed a relatively high maltose content in mature flowers, suggesting that OsMEX1 mainly functions in the tissues. OsMEX1-green fluorescent protein fusion experiment confirmed that OsMEX1 localizes at the chloroplast envelope in both rice and Arabidopsis. Arabidopsis maltose excess1 (mex1) mutant was transformed with OsMEX1 fused to the cauliflower mosaic virus 35S (CaMV35S) promoter. In the resulting transgenic plants, the typical mutant phenotypes of Arabidopsis mex1, such as chlorosis, stunted growth, and maltose and starch deposition at the end of the night, are clearly rescued. This result demonstrates that OsMEX1 functions as a plastidic maltose transporter in Arabidopsis. Our present findings thus suggest that whereas the Arabidopsis MEX1 gene essentially functions in source leaf tissues, its rice counterpart likely has a role in the pollens of mature flowers.

Ginsenoside Rk1 is a novel inhibitor of NMDA receptors in cultured rat hippocampal neurons

Ryoo, Nayeon,Rahman, Md. Ataur,Hwang, Hongik,Ko, Sung Kwon,Nah, Seung-Yeol,Kim, Hyoung-Chun,Rhim, Hyewhon The Korean Society of Ginseng 2020 Journal of Ginseng Research Vol.44 No.3

Background: Ginsenoside Rk1, a saponin component isolated from heat-processed Panax ginseng Meyer, has been implicated in the regulation of antitumor and anti-inflammatory activities. Although our previous studies have demonstrated that ginsenoside Rg3 significantly attenuated the activation of NMDA receptors (NMDARs) in hippocampal neurons, the effects of ginsenosides Rg5 and Rk1, which are derived from heat-mediated dehydration of ginsenoside Rg3, on neuronal NMDARs have not yet been elucidated. Methods: We examined the regulation of NMDARs by ginsenosides Rg5 and Rk1 in cultured rat hippocampal neurons using fura-2-based calcium imaging and whole-cell patch-clamp recordings. Results: The results from our investigation showed that ginsenosides Rg3 and Rg5 inhibited NMDARs with similar potencies. However, ginsenoside Rk1 inhibited NMDARs most effectively among the five compounds (Rg3, Rg5, Rk1, Rg5/Rk1 mixture, and protopanaxadiol) tested in cultured hippocampal neurons. Its inhibition is independent of the NMDA- and glycine-binding sites, and its action seems to involve in an interaction with the polyamine-binding site of the NMDAR channel complex. Conclusion: Taken together, our results suggest that ginsenoside Rk1 might be a novel component contributable to the development of ginseng-based therapeutic treatments for neurodegenerative diseases.

Effect of norgalanthamine on renal injury induced by carbon tetrachloride in mice

Nayeon Yang,Myungsoon Ko,Minhwa Jang,Eunjun Jang,Dowook Yu,Wootaek Hong,Seongbeom Bae,Jieun Ryoo,Taekyun Shin,Meejung Ahn 한국실험동물학회 2021 한국실험동물학회 학술발표대회 논문집 Vol.2021 No.7

Norgalanthamine is a major component of Crinum asiaticum var. japonicum that exhibits several biological activities. This study evaluated the anti-inflammatory and anti-oxidative properties of norgalanthamine in mice with carbon tetrachloride (CCl4)-induced renal injury. Norgalanthamine (1 and 10 mg/kg) was orally administered to mice for 7 or 14 days, after which renal injury was induced by CCl4 (1.5 ml/kg, i.p.). The vehicle and positive controls consisted of phosphate-buffered saline and silymarin (100 mg/kg), respectively. In CCl4-injured mice, norgalanthamine pretreatment significantly reversed the increases in serum alanine aminotransferase, aspartate aminotransferase, and total bilirubin levels, and the decrease in the serum glucose level. The histopathological evaluation and Iba-1 immunoreactivity also supported the protective effects of norgalanthamine against CCl4-induced kidney injury. These results suggest that norgalanthamine ameliorates oxidative renal injury, possibly through reducing enhancing antioxidant enzymes, and suppressing infiltrated macrophages.

Activation of Rice Yellow Stripe1-Like 16 (OsYSL16) Enhances Iron Efficiency

이시철,안진흥,Nayeon Ryoo,전종성,Mary Lou Guerinot 한국분자세포생물학회 2012 Molecules and cells Vol.33 No.2

Graminaceous plants release ferric-chelating phytoside-rophores that bind to iron. These ferric-phytosiderophore complexes are transported across the plasma membrane by a protein produced from Yellow Stripe 1 (YS1). Here, we report the characterization of OsYSL16, one of the YS1-like genes in rice. Real-time analysis revealed that this gene was constitutively expressed irrespective of metal status. Promoter fusions of OsYSL16 to -glucuronidase (GUS) showed that OsYSL16 was highly expressed in the vascular tissues of the root, leaf, and spikelet, and in leaf mesophyll cells. The OsYSL16-green fluorescence protein (GFP) fusion protein was localized to the plasma membrane. From a pool of rice T-DNA insertional lines, we identified two independent activation-tagging mutants in OsYSL16. On an Fe-deficient medium, those mutants retained rela-tively high chlorophyll concentrations compared with the wild-type (WT) controls, indicating that they are more tolerant to a lack of iron. The Fe concentration in shoots was also higher in the OsYSL16 activation lines than in the WT. During germination, the rate of Fe-utilization from the seeds was higher in the OsYSL16 activation lines than in the WT seeds. Our results suggest that the function of OsYSL16 in Fe-homeostasis is to enable distribution of iron within a plant.

Activation of rice Yellow Stripe1-Like 16 (OsYSL16) enhances iron efficiency

Lee, Sichul,Ryoo, Nayeon,Jeon, Jong-Seong,Guerinot, Mary Lou,An, Gynheung Springer-Verlag 2012 Molecules and cells Vol.33 No.2

Role of the rice hexokinases OsHXK5 and OsHXK6 as glucose sensors.

Cho, Jung-Il,Ryoo, Nayeon,Eom, Joon-Seob,Lee, Dae-Woo,Kim, Hyun-Bi,Jeong, Seok-Won,Lee, Youn-Hyung,Kwon, Yong-Kook,Cho, Man-Ho,Bhoo, Seong Hee,Hahn, Tae-Ryong,Park, Youn-Il,Hwang, Ildoo,Sheen, Jen,Jeo American Society of Plant Physiologists 2009 Plant Physiology Vol.149 No.2

<P>The Arabidopsis (Arabidopsis thaliana) hexokinase 1 (AtHXK1) is recognized as an important glucose (Glc) sensor. However, the function of hexokinases as Glc sensors has not been clearly demonstrated in other plant species, including rice (Oryza sativa). To investigate the functions of rice hexokinase isoforms, we characterized OsHXK5 and OsHXK6, which are evolutionarily related to AtHXK1. Transient expression analyses using GFP fusion constructs revealed that OsHXK5 and OsHXK6 are associated with mitochondria. Interestingly, the OsHXK5DeltamTP-GFP and OsHXK6DeltamTP-GFP fusion proteins, which lack N-terminal mitochondrial targeting peptides, were present mainly in the nucleus with a small amount of the proteins seen in the cytosol. In addition, the OsHXK5NLS-GFP and OsHXK6NLS-GFP fusion proteins harboring nuclear localization signals were targeted predominantly in the nucleus, suggesting that these OsHXKs retain a dual-targeting ability to mitochondria and nuclei. In transient expression assays using promoterluciferase fusion constructs, these two OsHXKs and their catalytically inactive alleles dramatically enhanced the Glc-dependent repression of the maize (Zea mays) Rubisco small subunit (RbcS) and rice alpha-amylase genes in mesophyll protoplasts of maize and rice. Notably, the expression of OsHXK5, OsHXK6, or their mutant alleles complemented the Arabidopsis glucose insensitive2-1 mutant, thereby resulting in wild-type characteristics in seedling development, Glc-dependent gene expression, and plant growth. Furthermore, transgenic rice plants overexpressing OsHXK5 or OsHXK6 exhibited hypersensitive plant growth retardation and enhanced repression of the photosynthetic gene RbcS in response to Glc treatment. These results provide evidence that rice OsHXK5 and OsHXK6 can function as Glc sensors.</P>

Development of a simple and efficient system for excising selectable markers in Arabidopsis using a minimal promoter::Cre fusion construct

Kim, Hyun-Bi,Cho, Jung-Il,Ryoo, Nayeon,Qu, Shaohong,Wang, Guo-Liang,Jeon, Jong-Seong Springer-Verlag 2012 Molecules and cells Vol.33 No.1

Monitoring of Intracellular Tau Aggregation Regulated by OGA/OGT Inhibitors

Lim, Sungsu,Haque, Md. Mamunul,Nam, Ghilsoo,Ryoo, Nayeon,Rhim, Hyewhon,Kim, Yun Kyung MDPI 2015 INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES Vol.16 No.9

<P>Abnormal phosphorylation of tau has been considered as a key pathogenic mechanism inducing tau aggregation in multiple neurodegenerative disorders, collectively called tauopathies. Recent evidence showed that tau phosphorylation sites are protected with <I>O</I>-linked β-<I>N</I>-acetylglucosamine (<I>O</I>-GlcNAc) in normal brain. In pathological condition, tau is de-glycosylated and becomes a substrate for kinases. Despite the importance of <I>O</I>-GlcNAcylation in tau pathology, <I>O</I>-GlcNAc transferase (OGT), and an enzyme catalyzing <I>O</I>-GlcNAc to tau, has not been carefully investigated in the context of tau aggregation. Here, we investigated intracellular tau aggregation regulated by BZX2, an inhibitor of OGT. Upon the inhibition of OGT, tau phosphorylation increased 2.0-fold at Ser199 and 1.5-fold at Ser396, resulting in increased tau aggregation. Moreover, the BZX2 induced tau aggregation was efficiently reduced by the treatment of Thiamet G, an inhibitor of <I>O</I>-GlcNAcase (OGA). Our results demonstrated the protective role of OGT in tau aggregation and also suggest the counter-regulatory mechanism of OGA and OGT in tau pathology.</P>

Development of a Simple and Efficient System for Excising Selectable Markers in Arabidopsis Using a Minimal Promoter::Cre Fusion Construct

Hyun-Bi Kim,전종성,Jung-Il Cho,Nayeon Ryoo,Shaohong Qu,Guo-Liang Wang 한국분자세포생물학회 2012 Molecules and cells Vol.33 No.1

The development of rapid and efficient strategies to gen-erate selectable marker-free transgenic plants could help increase the consumer acceptance of genetically modified (GM) plants. To produce marker-free transgenic plants without conditional treatment or the genetic crossing of offspring, we have developed a rapid and convenient DNA excision method mediated by the Cre/loxP recombination system under the control of a -46 minimal CaMV 35S promoter. The results of a transient expression assay showed that -46 minimal promoter::Cre recombinase (-46::Cre) can cause the loxP-specific excision of a selectable marker, thereby connecting the 35S promoter and -glucuronidase (GUS) reporter gene. Analysis of stable transgenic Arabidopsis plants indicated a positive correlation between loxP-specific DNA excision and GUS expression. PCR and DNA gel-blot analysis further revealed that nine of the 10 tested T1 transgenic lines carried both excised and non-excised constructs in their genomes. In the subsequent T2 generation plants, over 30% of the individuals for each line were marker-free plants harboring the excised construct only. These results demonstrate that the -46::Cre fusion construct can be efficiently and easily utilized for producing marker-free transgenic plants.