• 한국자원식물학회:학술대회논문집
• /
• 한국자원식물학회 2021년도 춘계학술대회
• /
• pp.56-56
• /
• 2021

Nypa fruticans Wurmb is a mangrove plant belonging to Araceae family. N. fruticans is typically found in Southeast Asia, and in some parts of Queensland, Australia. N. fruticans has phytochemicals, phenolics, and flavonoids. In this study, we investigated the anti-inflammatory effects of the ethyl acetate fraction of N. fruticans (ENF) on the production and expression of cytokines and inflammatory mediators through the major signal transduction pathways. ENF attenuated the level of cytokines in a dose-dependent manner and decreased the production of nitric oxide (NO). ENF decreased the expression of cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) via alleviating transcription of nuclear factor-kappa B (NF-κB) by an inhibitor of nuclear factor-kappa B (IκB) degradation. Furthermore, mitogen-activated protein kinase (MAPK) signaling pathways (ERK1/2, JNK1/2, and p38) are known to be involved in the inflammatory response. Phosphorylations of ERK1/2, JNK1/2, and p38 were significantly decreased compared with the ENF-untreated control. Conclusively, ENF was related to alleviating various pro-inflammatory mediators through IκB/NF-κB and MAPK signaling pathways, including p65 translocation to the nucleus.

• 한국식물병리학회:학술대회논문집
• /
• 한국식물병리학회 2003년도 정기총회 및 추계학술발표회
• /
• pp.81.2-82
• /
• 2003

Plants have evolved along with pathogens, and they have developed sophisticated defense systems against specific microorganisms to survive. G-protons are considered one of the upstream signaling components working as a key for the defense signal transduction pathway. For activation and inactivation of G-protein, GTP-biding proteins are involved. GTP -binding proteins are found in all organisms. Small GTP-binding proteins, having masses of 21 to 30kD, belong to a superfamily, often named the Ras supefamily because the founding members are encoded by human Ras genes initially discovered as cellular homologs of the viral ras oncogene. Members of this supefamily share several common structural features, including several guanine nucleotide binding domains and an effector binding domain. However, exhibiting a remarkable diversity in both structure and function. They are important molecular switches that cycle between the GDP-bound inactive form into the GTP-bound active form through GDP/GTP replacement. In addition, most GTP-binding proteins cycle between membrane-bound and cytosolic forms. such as the RAC family are cytosolic signal transduction proteins that often are involved in processing of extracellular stimuli. Plant RAC proteins are implicated in regulation of plant cell architecture secondary wall formation, meristem signaling, and defense against pathogens. But their molecular mechanisms and functions are not well known. We isolated a RacB homolog from rice to study its role of defense against pathogens. We introduced the constitutively active and the dominant negative forms of the GTP-hinging protein OsRacB into the wild type rice. The dominant negative foms are using two forms (full-sequence and specific RNA interference with RacB). Employing southern, and protein analysis, we examine to different things between the wild type and the transformed plant. And analyzing biolistic bombardment of onion epidermal cell with GFP-RacB fusion protein revealed association with the nucle.

• Biomolecules & Therapeutics
• /
• 제20권5호
• /
• pp.433-445
• /
• 2012

During the course of evolution, animals encountered the harmful effects of fungi, which are strong pathogens. Therefore, they have developed powerful mechanisms to protect themselves against these fungal invaders. ${\beta}$-Glucans are glucose polymers of a linear ${\beta}$(1,3)-glucan backbone with ${\beta}$(1,6)-linked side chains. The immunostimulatory and antitumor activities of ${\beta}$-glucans have been reported; however, their mechanisms have only begun to be elucidated. Fungal and particulate ${\beta}$-glucans, despite their large size, can be taken up by the M cells of Peyer's patches, and interact with macrophages or dendritic cells (DCs) and activate systemic immune responses to overcome the fungal infection. The sampled ${\beta}$-glucans function as pathogen-associated molecular patterns (PAMPs) and are recognized by pattern recognition receptors (PRRs) on innate immune cells. Dectin-1 receptor systems have been incorporated as the PRRs of ${\beta}$-glucans in the innate immune cells of higher animal systems, which function on the front line against fungal infection, and have been exploited in cancer treatments to enhance systemic immune function. Dectin-1 on macrophages and DCs performs dual functions: internalization of ${\beta}$-glucan-containing particles and transmittance of its signals into the nucleus. This review will depict in detail how the physicochemical nature of ${\beta}$-glucan contributes to its immunostimulating effect in hosts and the potential uses of ${\beta}$-glucan by elucidating the dectin-1 signal transduction pathway. The elucidation of ${\beta}$-glucan and its signaling pathway will undoubtedly open a new research area on its potential therapeutic applications, including as immunostimulants for antifungal and anti-cancer regimens.

• Archives of Pharmacal Research
• /
• 제29권10호
• /
• pp.890-897
• /
• 2006

In inflammatory responses, induction of cytokines and other immune regulator genes in macrophages by pathogen-associated signal such as lipopolysaccharide (LPS) plays a crucial role. In this study, the gene expression profile changes by LPS treatment in the macrophage/monocyte lineage cell line RAW264.7 was investigated. A 60-mer oligonucleotide microarray of which probes target 32381 mouse genes was used. A reverse transcription-in vitro translation labeling protocol and a chemileuminescence detection system were employed. The mRNA expression levels in RAW264.7 cells treated for 6 h with LPS and the control vehicle were compared. 747 genes were up-regulated and 523 genes were down-regulated by more than 2 folds. 320 genes showing more than 4-fold change by LPS treatment were further classified for the biological process, molecular function, and signaling pathway. The biological process categories that showed high number of increased genes include the immunity and defense, the nucleic acid metabolism, the protein metabolism and modification, and the signal transduction process. The chemokine-cytokine signaling, interleukin signaling, Toll receptor signaling, and apoptosis signaling pathways involved high number of genes differentially expressed in response to LPS. These expression profile data provide more comprehensive information on LPS-target genes in RAW264.7 cells, which will be useful in comparing gene expression changes induced by extracts and compounds from anti-inflammatory medicinal herbs.

• Biomolecules & Therapeutics
• /
• 제32권1호
• /
• pp.56-64
• /
• 2024

Biased signaling or functional selectivity refers to the ability of an agonist or receptor to selectively activate a subset of transducers such as G protein and arrestin in the case of G protein-coupled receptors (GPCRs). Although signaling through arrestin has been reported from various GPCRs, only a few studies have examined side-by-side how it differs from signaling via G protein. In this study, two signaling pathways were compared using dopamine D₂ receptor (D₂R) mutants engineered via the evolutionary tracer method to selectively transduce signals through G protein or arrestin (D₂G and D₂Arr, respectively). D₂G mediated the inhibition of cAMP production and ERK activation in the cytoplasm. D₂Arr, in contrast, mediated receptor endocytosis accompanied by arrestin ubiquitination and ERK activation in the nucleus as well as in the cytoplasm. D₂Arr-mediated ERK activation occurred in a manner dependent on arrestin3 but not arrestin2, accompanied by the nuclear translocation of arrestin3 via importin1. D₂R-mediated ERK activation, which occurred in both the cytosol and nucleus, was limited to the cytosol when cellular arrestin3 was depleted. This finding supports the results obtained with D₂Arr and D₂G. Taken together, these observations indicate that biased signal transduction pathways activate distinct downstream mechanisms and that the subcellular regions in which they occur could be different when the same effectors are involved. These findings broaden our understanding on the relation between biased receptors and the corresponding downstream signaling, which is critical for elucidating the functional roles of biased pathways.

• Biotechnology and Bioprocess Engineering:BBE
• /
• 제10권5호
• /
• pp.444-450
• /
• 2005

Epidermal growth factor (EGF) activates many intracellular effector molecules, which subsequently influence the expression levels of many genes involved in cell growth, apoptosis and signal transduction, etc. In this study, the early response of gene expressions due to EGF treatment was monitored using oligonucleotide DNA microarrays in rat schwannoma cell lines. An immunoblotting experiment showed the successful activation of EGF receptors and an effector protein, STAT5, due to EGF treatment. The microarray study showed that 35 genes were significantly induced and 2 were repressed within 60 min after the treatment. The list of induced genes included early growth response 1, suppressor of cytokine signaling 3, c-fos, interferon regulatory factor 1 and early growth response 2, etc. According to the microarray data, six of these were induced by more than 10-fold, and showed at least two different induction patterns, indicating complicated regulatory mechanisms in the EGF signal transduction.

• BMB Reports
• /
• 제32권2호
• /
• pp.196-202
• /
• 1999

The existence of the Ras-independent signal transduction pathway of insulin leading to DNA synthesis was investigated in Rat-1 fibroblasts overexpressing human insulin receptor (HIRc-B) using the single-cell microinjection technique. Microinjection of a dominant-negative mutant $Ras^{N17}$ protein into quiescent HIRc-B cells inhibited the DNA synthesis stimulated by insulin. Microinjection of oncogenic H-$Ras^{V12}$ protein ($H-Ras^{V12}$) (0.1 mg/ml) induced DNA synthesis by 35%, whereas that of control-injected IgG was induced by 20%. When the marginal amount of oncogenic H-$Ras^{V12}$ protein was coinjected with a dominant-negative mutant of the H-Ras protein ($Ras^{N17}$), DNA synthesis was 35% and 74% in the absence and presence of insulin, respectively. This full recovery of DNA synthesis by insulin suggests the existence of the Ras-independent pathway. The same recovery was observed in the cells coinjected with either H-$Ras^{V12}$ plus H-$Ras^{N17}$ plus SH2 domain of the p85 subunit of PI3-kinase ($p85^{SH2-N}$) or H-$Ras^{V12}$ plus H-$Ras^{N17}$ plus interfering anti-Shc antibody. When co-injected with a dominant-negative H-$Ras^{N17}$, the DNA synthesis induced by the Ras-independent pathway was blocked. These results indicate that the Ras-independent pathway of insulin leading to DNA synthesis exists, bypassing the p85 of PI3-kinase and Shc protein, and requires Rac1 protein.

• Journal of Photoscience
• /
• 제4권1호
• /
• pp.23-30
• /
• 1997

Leaf movements in nyctinastic plants are produced by changes in the turgor of extensor and flexor cells, collectively called motor cells, in opposing regions of the leaf movement organ, the pulvinus. In Samanea saman, a tropical tree of the legume family, extensor cells shrink and flexor cells swell to bend the pulvinus and fold the leaf at night, whereas extensor cells swell and flexor cells shrink to straighten the pulvinus and extend the leaf in the daytime. These changes are caused by ion fluxes primarily of potassium and chloride, across the plasma membrane of the motor cells. These ion fluxes are regulated by exogenous light signals and an endogenous biolgical clock. Inward-directed K$^+$ channels are closed in extensor and open in flexor cells in the dark period, while these channels are open in extensor and closed in flexor cells in the light period. Blue light opens the closed K$^+$ channels in extensor and closes the open them in flexor cells during darkness. Illumination of red light followed by darkness induces to open the closed K$^+$ channels in flexor and to close the open K$^+$ channels in extensor cells in the light. The dynamics of K$^+$ channels in motor cells that are controlled by light signals are consistent with the behavior of the pulvini in intact plants. Therefore, these cell types are an attractive model system to elucidate regulations of ion transports and their signal transduction pathways in plants. This review is focused on light-controlled ion movements and regulatory mechanisms involved in phosphoinositide signaling in leaf movements in nyctinastic plants.

• International Journal of Oral Biology
• /
• 제46권1호
• /
• pp.51-59
• /
• 2021

Periodontal disease is an inflammatory disease that affects the destruction of the bone supporting the tooth and connective tissues surrounding it. Periodontal ligament fibroblasts (PDLFs) induce overexpression of matrix metalloproteinase (MMP) involved in periodontal disease's inflammatory destruction. Osteoclasts take part in physiological bone remodeling, but they are also involved in bone destruction in many kinds of bone diseases, including osteoporosis and periodontal disease. This study examined the effect of baicalin on proteolytic enzymes' production and secretion of inflammatory cytokines in PDLFs and RAW 264.7 cells under the lipopolysaccharide (LPS)-induced inflammatory conditions. Baicalin inhibited the expression of the protein, MMP-1 and MMP-2, without affecting PDLFs' cell viability, suggesting its possibility because of the inhibition of phosphorylation activation of mitogen-activated protein kinase's p38, and the signal transduction process of nuclear factor κB (NFκB)-related protein. Also, baicalin reduced the expression of MMP-8 and MMP-9 in RAW 264.7 cells. This reduction is thought to be due to the inhibition of the signal transduction process of NFκB-related proteins affected by inhibiting p65RelA phosphorylation. Also, baicalin inhibited the secretion of nitric oxide and interleukin-6 induced by LPS in RAW 264.7 cells. These results suggest that baicalin inhibits connective tissue destruction in periodontal disease. The inhibition of periodontal tissue destruction may be a therapeutic strategy for treating inflammatory periodontal-diseased patients.

• BMB Reports
• /
• 제31권4호
• /
• pp.370-376
• /
• 1998

Src-Homology 2 (SH2) domains have a capacity to bind phosphotyrosine-containing sequence context and play essential roles in various cellular signaling pathways. Due to the specific nature of the binding between SH2 domains and their counterpart proteins, inhibitors of SID domain binding have drawn extensive attention as a potential candidate for therapeutic agents. Here, we describe the binding assay system to screen for the ligands or blockers of the SH2 domains with an emphasis on the $p56^{lck}$ SH2 domain. In our assay system, SID domains expressed and purified as fusion proteins to Glutathione-S-transferase (GST) were covalently attached to 96-well microtitre plates through amide bond formation, which were subsequently allowed to bind the biotinylated phosphotyrosine (pY)containing synthetic pep tides. The binding of biotinylated pY peptides was detected by the horseradish peroxidase (HRP)-conjugated streptavidin. Using the various combinations of SH2 domain-pY peptides, we observed that: (1) The binding of pY-peptides to its counterpart SH2 domain is concentration-dependent and saturable; (2) The binding is highly specific for a particular combination of SH2 domain-pY peptide pair; and (3) The binding of Lck SH2-cognate pY-peptides is specifically competed by the nonbiotinylated peptides with expected relative affinity. These results indicate that the established assay system detects the SH2-pY peptide interaction with reproducible sensitivity and specificity and is suitable for screening the specific inhibitors of $p56^{lck}$ SH2 function.