• Molecules and Cells
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• v.41 no.6
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• pp.545-552
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• 2018

Spleen tyrosine kinase (SYK) is a cytosolic non-receptor protein tyrosine kinase. Because SYK mediates key receptor signaling pathways involving the B cell receptor and Fc receptors, SYK is an attractive target for autoimmune disease and cancer treatments. To date, representative oral SYK inhibitors, including fostamatinib (R406 or R788), entospletinib (GS-9973), cerdulatinib (PRT062070), and TAK-659, have been assessed in clinical trials. Here, we report the crystal structures of SYK in complex with two newly developed inhibitors possessing 4-aminopyrido[4,3-D]pyrimidine moieties (SKI-G-618 and SKI-O-85). One SYK inhibitor (SKI-G-618) exhibited moderate inhibitory activity against SYK, whereas the other inhibitor (SKI-O-85) exhibited a low inhibitory profile against SYK. Binding mode analysis indicates that a highly potent SYK inhibitor might be developed by modifying and optimizing the functional groups that interact with Leu377, Gly378, and Val385 in the G-loop and the nearby region in SYK. In agreement with our structural analysis, one of our SYK inhibitor (SKI-G-618) shows strong inhibitory activities on the ${\beta}$-hexosaminidase release and phosphorylation of SYK/Vav in RBL-2H3 cells. Taken together, our findings have important implications for the design of high affinity SYK inhibitors.

• IMMUNE NETWORK
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• v.21 no.2
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• pp.16.1-16.8
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• 2021

Patients with severe coronavirus disease 2019 (COVID-19) demonstrate dysregulated immune responses including exacerbated neutrophil functions. Massive neutrophil infiltrations accompanying neutrophil extracellular trap (NET) formations are also observed in patients with severe COVID-19. However, the mechanism underlying severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-induced NET formation has not yet been elucidated. Here we show that 2 viral proteins encoded by SARS-CoV-2, the nucleocapsid protein and the whole spike protein, induce NET formation from neutrophils. NET formation was ROSindependent and was completely inhibited by the spleen tyrosine kinase inhibition. The inhibition of p38 MAPK, protein kinase C, and JNK signaling pathways also inhibited viral protein-induced NET formation. Our findings demonstrate one method by which SARSCoV-2 evades innate immunity and provide a potential target for therapeutics to treat patients with severe COVID-19.

• Biomolecules & Therapeutics
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• v.31 no.6
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• pp.611-618
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• 2023

Rhizome of Alisma orientale has been used as a traditional medicine for treating kidney diseases in East Asian countries. Its inhibitory effects on hypersensitivity responses have been reported for methanol extracts, with alisol B 23-acetate (AB23Ac) being the most active constituent among six terpenes in inhibiting the direct passive Arthus reaction. However, whether AB23Ac has efficacy against allergic asthma has not been tested to date. The in vivo efficacy of AB23Ac in an ovalbumin (OVA)-induced allergic asthma mouse model was evaluated by administrating AB23Ac before OVA sensitization or OVA challenge in BALB/c mice. AB23Ac suppressed antigen-induced degranulation of RBL-2H3 mast cells in a concentration-dependent manner. The administration of AB23Ac both before OVA sensitization and OVA challenge greatly lowered pulmonary resistance and the increase in immune cell counts and inflammatory responses around the peribronchial and perivascular regions. In addition, the inflammatory cytokine levels of Th1/Th2/Th17 cells in the bronchoalveolar lavage fluid decreased in the AB23Ac-treated groups. AB23Ac reduced the number of PAS-stained cells in the lungs. Furthermore, a computer modeling study indicated that AB23Ac can bind tightly to spleen tyrosine kinase (Syk). These results suggest that AB23Ac may ameliorate allergic asthma by suppressing immune responses in dendritic cells during sensitization and in mast cells during challenge periods.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.5
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• pp.3001-3003
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• 2013

Objective: Spleen tyrosine kinase (Syk) is closely related to tumor invasion and metastasis, and has been shown to have potential inhibitory effects in tumors. In this study, we constructed a eukaryotic expression vector for Syk and analyzed its effects on invasive ability of the A549 non-small cell lung cancer cell line in vitro. Methods: A fragment of Syk was obtained by RT-PCR from human lung cancer cells and cloned into the expression vector pLNCXSyk. After restriction endonuclease digestion, PCR and DNA sequencing confirmation, the recombinant Syk expression plasmid was transfected into A549 human lung cancer cells using lipofectamine protocols. After selection, the cells stably expressed Syk. Detection of Syk expression of the cells by RT-PCR, and invasive ability were examined. Results: The eukaryotic expression plamid pLNCXSyk was constructed and expressed stably in the A549 human lung cancer cells. The RT-PCR results showed that Syk mRNA expression was upregulated significantly (P<0.05). Lower invasion through a basal membrane were apparent after transfection (P<0.05). Conclusions: A eukaryotic expression plasmid to cause Syk expression in lung cancer cells can obviously inhibit their invasive ability in vitro.

• YAKHAK HOEJI
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• v.56 no.1
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• pp.26-34
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• 2012

Mast cells play an important role in early and late phase allergic reactions through allergen and IgE-dependent release of histamine, proteases, prostaglandins, and several multifunctional cytokines. In this study, we investigated whether Cudrania tricuspidata extract (CTE) suppresses IgE-mediated allergic responses in mast cells, an allergic animal model, and its mechanism of action in mast cells. We found that CTE inhibited IgE-mediated degranulation and cytokine production in rat basophilic leukemia (RBL)-2H3 mast cells and bone marrow-derived mast cells (BMMC), as well as passive cutaneous anaphylaxis (PCA) in mice. With regard to its mechanism of action, CTE suppressed the activating phosphorylation of spleen tyrosine kinase (Syk), a key enzyme in mast cell signaling processes and that of LAT, a downstream adaptor molecule of Syk in $Fc{\varepsilon}RI$-mediated signal pathways. CTE also suppressed the activating phosphorylation of mitogen-activated protein (MAP) kinases and Akt. The present results strongly suggest that the anti-allergic activity of CTE is mediated through inhibiting degranulation and allergic cytokine secretion by inhibition of Syk kinase in mast cells. Therefore, CTE may be useful for the treatment of allergic diseases.

• Korean Journal of Pharmacognosy
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• v.44 no.2
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• pp.118-124
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• 2013

Mast cells is the key effector cells for IgE-mediated allergic responses. In this study, we investigated whether Rhus trichocarpa extract (RT) inhibited IgE-mediated allergic responses in mast cells and an allergic animal model. We further tried to find its mechanism of action in mast cells. We found that RT suppressed antigen-stimulated degranulation and production of TNF-${\alpha}$ and IL-4 in rat basophilic leukemia (RBL)-2H3 mast cells and bone marrow-derived mast cells (BMMC), as well as IgE-mediated passive cutaneous anaphylaxis (PCA) in mice. As the mechanism of action of RT, it inhibited the activation of spleen tyrosine kinase (Syk), a pivotal signaling molecule for activation of mast cells and that of LAT, a downstream adaptor molecule of Syk in $Fc{\varepsilon}RI$-mediated signal pathways. RT also suppressed the activation of mitogen-activated protein (MAP) kinases and Akt. The current results demonstrated for the first time that RT has the anti-allergic effect through inhibiting degranulation and secretion of cytokines by suppression of Syk in antigen-stimulated mast cells. Therefore, RT might be useful for allergic diseases.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.5
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• pp.3309-3314
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• 2013

Spleen tyrosine kinase (SYK) is a non-receptor type cytoplasmic protein and a known tumor suppressor gene in breast cancer. Polymorphisms in SYK have been reported to be associated with cell invasion/cell morality and an increased risk of cancer development. In this case control study, all exons of the SYK gene and its exon/ intron boundaries were amplified in 200 breast cancer cases and 100 matched controls and then analyzed by single stranded conformational polymorphism. Amplified products showing altered mobility patterns were sequenced and analyzed. Twelve variations were identified in exonic and intronic regions of DNA encoding SH2 domain and kinase domain of the SYK gene. All of these mutations are novel. Among them, 5 missense mutations were observed in exon 15 while one missense mutation was found in exon 8. In addition to these mutations, six mutations were also identified in intronic regions. We found a significant association between SYK mutations and breast cancer and observed that Glu241Arg, a missense mutation is associated with an increase risk of ~7 fold (OR=6.7, 95% CI=1.54-28.8), Thr581Pro (missense mutation) is associated with increased risk of ~16 fold (OR=15.5, 95%CI=2.07-115.45) and 63367 T>G (missense mutation) is associated with increased risk of ~13 fold (OR=12.8, 95%CI=1.71-96.71) for breast cancer. Significant associations were observed for each of these variations with both late menopause (p<0.01) and early menarche (p<0.005) cases when compared to controls. Our findings suggest that the polymorphic gene SYK may contribute to the development of breast cancer in at least the Pakistani population. This study provides an insight view of SYK which may provide a significant finding for the pharmaceutical and biotechnology industry.

• BMB Reports
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• v.40 no.5
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• pp.749-756
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• 2007

Phosphorylation on serine/threonine or tyrosine residues of target proteins is an essential and significant regulatory mechanism in signal transduction during many cellular and life processes, including spermatogenesis, oogenesis and fertilization. In the present work, we reported the isolation and characterization of mouse testis-specific serine/threonine kinase 5 (Tssk5), which contains four alternatively spliced variants including, Tssk5$\alpha$, Tssk5$\beta$, Tssk5$\gamma$ and Tssk5$\delta$. Moreover, the locus of Tssk5 is on chromosome 14qC3 and the four variants had a similar high expression in the testis and the heart; however, had a low expression in other tissues, except for Tssk5$\alpha$ which also had comparably high expression in the spleen. Each variant of Tssk5 expression began in the testis 16 days after birth. Aside from TSSK5$\alpha$, the other isoforms have an insertion of ten amino acid residues (RLTPSLSAAG) in region VIb (HRD domain) (His-Arg-Asp). Moreover, only TSSK5$\alpha$ exhibited kinase activity and consistently, a further Luciferase Reporter Assay demonstrated that TSSK5$\beta$, TSSK5$\gamma$ and TSSK5$\delta$ cannot be stimulated at the CREB/CRE responsive pathway in comparison to TSSK5$\alpha$. These findings suggest that TSSK5$\beta$, TSSK5$\gamma$, TSSK5$\delta$ may be pseudokinases due to the insertion, which may damage the structure responsible for active kinase activity. Pull-down assay experiments indicated that TSSK5$\beta$, TSSK5 $\gamma$ and TSSK5$\delta$ can directly interact with TSSK5$\alpha$. In summary, these four isoforms with similar expression patterns may be involved in spermatogenesis through a coordinative way in testis.

• Journal of Acupuncture Research
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• v.19 no.6
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• pp.111-124
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• 2002

A line of study reported that electroacupuncture(EA) modulate natural killer cell(NK Cell) activities. One report suggested that EA enhanced splenic interferon-gamma($IFN-{\gamma}$), interleukin-2(IL-2), and NK cell activity in Sprague-Dawley rats. Another study suggested that $IFN-{\gamma}$ mediates the up-regulation of NK cell activity, and endogenous ${\beta}$-endorphin secretion also play a role in the up-regulation of NK cell activity induced by EA stimulation. In order to better understand the molecular regulation underlying the activation of NK cell induced by EA, we have utilized cDNA microarray to elucidate how EA alters program of gene expression of spleen in rats. First, we divided three groups, group I was EA group treated with EA in restriction holder, group II was sham group with only holder stress, and last group III was control group with no treatment. We measured NK cell activity after EA stimulation three times for 2 days using $^{51}Cr$ release assay. Second, Biotin-labeled cDNA probes synthesized from EA group and sham group, were competitively hybridized to the microarray that contained variable genes. Such high-throughput screening has identified a number of EA-responsive gene candidates. Of these, we found that EA induced a subset of genes of genes that functionally could modulatory effects on NK cell activity. Genes(vascular cell adhesion molecule-1, protein-tyrosine kinase, CD94 mRNA) related to boost NK cell activity, were increased by EA And, genes(protein-tyrosine-phospatase mRNA, protein-tyrosine phosphatase(SHP-1) mRNA) related to inhibit NK cell activity, were decreased by EA. These EA-responsive genes may provide key insights from which to understand mechanisms of activation of NK cell induced by EA.

• Animal Bioscience
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• v.35 no.8
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• pp.1235-1249
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• 2022

Objective: The purpose of this study was to evaluate the protection of glutamate (GLU) against the impairment in intestinal barrier function induced by lipopolysaccharide (LPS) stress in weaned pigs. Methods: Twenty-four weaned pigs were divided into four treatments containing: i) non-challenged control, ii) LPS-challenged control, iii) LPS+1.0% GLU, and iv) LPS+2.0% GLU. On day 28, pigs were treated with LPS or saline. Blood samples were collected at 0, 2, and 4 h post-injection. After blood samples collection at 4 h, all pigs were slaughtered, and spleen, mesenteric lymph nodes, liver and intestinal samples were obtained. Results: Dietary GLU supplementation inhibited the LPS-induced oxidative stress in pigs, as demonstrated by reduced malondialdehyde level and increased glutathione level in jejunum. Diets supplemented with GLU enhanced villus height, villus height/crypt depth and claudin-1 expression, attenuated intestinal histology and ultrastructure impairment induced by LPS. Moreover, GLU supplementation reversed intestinal intraepithelial lymphocyte number decrease and mast cell number increase induced by LPS stress. GLU reduced serum cortisol concentration at 4 h after LPS stress and downregulated the mRNA expression of intestinal corticotropin-releasing factor signal (corticotrophin-releasing factor [CRF], CRF receptor 1 [CRFR1], glucocorticoid receptor, tryptase, nerve growth factor, tyrosine kinase receptor A), and prevented mast cell activation. GLU upregulated the mRNA expression of intestinal transforming growth factor β. Conclusion: These findings indicate that GLU attenuates LPS-induced intestinal mucosal barrier injury, which is associated with modulating CRF signaling pathway.