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Syk 525

Christoph Köhler, Vivien Fuhr, Maja Dinekov
PURPOSE: Spleen tyrosine kinase (Syk) has been shown to phosphorylate tyrosine 18 of tau in vitro. It has been proposed that increased immunoreactivity for double-phosphorylated Syk in hippocampal neurons of Alzheimer's disease cases indicates a not yet defined neurodegenerative process. To investigate this possibility we have studied Syk and tau phosphorylated at tyrosine 18 (pTyr18) in transgenic mice and human hippocampi. METHODS: We performed immunohistochemistry, immunofluorescence labeling and Western blotting and compared the distribution of Syk double-phosphorylated at tyrosines 525 and 526 and pTyr18 in human tau transgenic pR5 mice and human hippocampi with low and high Braak stages for neurofibrillary tangle pathology...
December 15, 2017: Brain Research
Xin Liu, Xue-ying Song, Xiao-ping Zhang, Ying-lun Han, Ting Zhu, Rong Xiao, Qing-wei Li
In recent years, the antigen recognition mechanism based on variable lymphocyte receptors (VLRs) was found in agnathan lamprey. To illuminate the genetic basis of immune response of lymphocyte-like cells in the mucosal immune system of lamprey and explore the evolutionary relationship of adaptive immune responses between the jawless and jawed vertebrates, we constructed cDNA libraries of lamprey (Lampetra japonica) gills before and after stimulation, and then performed high-throughput transcriptome sequencing and analysis...
November 2015: Yi Chuan, Hereditas
Jessica Ryan, Frank Y Ma, Yingjie Han, Elyce Ozols, John Kanellis, Greg H Tesch, David J Nikolic-Paterson
Antibody-dependent activation of myeloid cells within the glomerulus plays a central role in rapidly progressive forms of glomerulonephritis. The spleen tyrosine kinase (Syk) is expressed by all leukocytes, except mature T cells, and is required for signalling via the B-cell receptor, Fc receptors, and some integrins. Syk has been proposed as a therapeutic target in glomerulonephritis. However, little is known of Syk activation in human kidney disease, while studies in experimental glomerulonephritis using non-selective Syk inhibitors require validation via conditional gene deletion...
January 2016: Journal of Pathology
Lorena Buitrago, Dheeraj Bhavanasi, Carol Dangelmaier, Bhanu Kanth Manne, Rachit Badolia, Alessandra Borgognone, Alexander Y Tsygankov, Steven E McKenzie, Satya P Kunapuli
Protein kinase C (PKC) isoforms differentially regulate platelet functional responses downstream of glycoprotein VI (GPVI) signaling, but the role of PKCs regulating upstream effectors such as Syk is not known. We investigated the role of PKC on Syk tyrosine phosphorylation using the pan-PKC inhibitor GF109203X (GFX). GPVI-mediated phosphorylation on Syk Tyr-323, Tyr-352, and Tyr-525/526 was rapidly dephosphorylated, but GFX treatment inhibited this dephosphorylation on Tyr-525/526 in human platelets but not in wild type murine platelets...
October 4, 2013: Journal of Biological Chemistry
Jessica Ryan, Frank Y Ma, John Kanellis, Mercedes Delgado, Kate Blease, David J Nikolic-Paterson
Glomerular antibody deposition induces acute neutrophil-mediated glomerular injury via activation of c-Jun amino terminal kinase (JNK) and p38 mitogen-activated protein kinase (MAPK). However, the link between antibody deposition and activation of JNK/p38 MAPK signalling is unclear. This study tested the postulate that spleen tyrosine kinase (Syk), which is activated via Fcγ-receptor ligation, is required for activation of JNK and p38 signalling and acute neutrophil-mediated glomerular injury. We used a Syk inhibitor (SYKi) in rat nephrotoxic serum nephritis (NTN) in which neutrophil-mediated glomerular injury is dependent upon JNK and p38 signalling...
December 2011: Laboratory Investigation; a Journal of Technical Methods and Pathology
Xianwen Chen, Lige Ren, Soochong Kim, Nicholas Carpino, James L Daniel, Satya P Kunapuli, Alexander Y Tsygankov, Dehua Pei
TULA-1 (UBASH3A/STS-2) and TULA-2 (p70/STS-1) represent a novel class of protein-tyrosine phosphatases. Previous studies suggest that TULA-2 is sequence-selective toward phosphotyrosyl (Tyr(P)) peptides. In this work the substrate specificity of TULA-1 and -2 was systematically evaluated by screening a combinatorial Tyr(P) peptide library. Although TULA-1 showed no detectable activity toward any of the Tyr(P) peptides in the library, TULA-2 recognizes two distinct classes of Tyr(P) substrates. On the N-terminal side of Tyr(P), the class I substrates contain a proline at the Tyr(P)-1 position, a hydrophilic residue at the Tyr(P)-2 position, and aromatic hydrophobic residues at positions Tyr(P)-3 and beyond...
October 8, 2010: Journal of Biological Chemistry
Deepika Singh, Reema Rani, Resmi Rajendran, Namrata Jit Kaur, Abhinav Pandey, Puneet Chopra, Tarun Jain, Manish Kumar Jain, Sonam Grover, Ranjana Arya, Kulvinder Singh Saini
Spleen tyrosine kinase (Syk) is an important non-receptor tyrosine kinase and its aberrant regulation is associated with a variety of allergic disorders and autoimmune diseases. To identify small molecule inhibitors of Syk in high-throughput assays, recombinant Syk protein is needed in bulk quantity. We studied the expression of recombinant human Syk in three heterologous systems: E. coli, baculovirus expression vector system (BEVS), and the cellular slime mold Dictyostelium discoideum (Dd). Syk activity was higher in the BEVS as compared to the Dd expression host, whereas in E...
February 2010: Biotechnology Journal
Laura Carsetti, Luca Laurenti, Stefania Gobessi, Pablo G Longo, Giuseppe Leone, Dimitar G Efremov
The Syk kinase is regarded as a promising target for the treatment of antigen-driven B-cell malignancies, considering its essential role in propagating antigenic stimuli through the B-cell receptor (BCR). In certain common B-cell malignancies Syk is activated even in the absence of BCR engagement, suggesting a wider role for this kinase in lymphomagenesis. In this paper, we have profiled molecular differences between BCR-induced and constitutive Syk activation in terms of phosphorylation of regulatory tyrosine residues, downstream signaling properties and capacity to sustain B-cell proliferation...
July 2009: Cellular Signalling
Bryan N Kahner, Robert T Dorsam, Soochong Kim, Haripriya Shankar, Daisuke Kitamura, Satya P Kunapuli
Thrombin-induced platelet activation leads to tyrosine phosphorylation of hematopoietic lineage cell-specific protein-1 (HS1), a 75 kDa adapter protein expressed exclusively in cells of hematopoietic lineage. We have shown HS1 to be a functionally important signaling molecule downstream of PAR-4 and GPVI collagen receptor. We have thus begun to elucidate PAR signaling pathway of HS1 phosphorylation, and its functional implications. PAR-1 and PAR-4 activating peptides (SFLLRN and AYPGKF, respectively) induced HS1 phosphorylation in a Gq-dependent manner as shown by incubation with the Gq inhibitor, YM254890...
December 2008: Platelets
Henry E Speich, Svetozar Grgurevich, Teddi J Kueter, Angela D Earhart, Steven M Slack, Lisa K Jennings
Atherosclerotic plaques can lead to partial vascular occlusions that produce abnormally high levels of arterial wall shear stress. Such pathophysiological shear stress can promote shear-induced platelet aggregation (SIPA), which has been linked to acute myocardial infarction, unstable angina, and stroke. This study investigated the role of the tyrosine kinase Syk in shear-induced human platelet signaling. The extent of Syk tyrosine phosphorylation induced by pathophysiological levels of shear stress (100 dyn/cm(2)) was significantly greater than that resulting from physiological shear stress (10 dyn/cm(2))...
October 2008: American Journal of Physiology. Cell Physiology
A L Feldman, D X Sun, M E Law, A J Novak, A D Attygalle, E C Thorland, S R Fink, J A Vrana, B L Caron, W G Morice, E D Remstein, K L Grogg, P J Kurtin, W R Macon, A Dogan
Peripheral T-cell lymphomas (PTCLs) are fatal in the majority of patients and novel treatments, such as protein tyrosine kinase (PTK) inhibition, are needed. The recent finding of SYK/ITK translocations in rare PTCLs led us to examine the expression of Syk PTK in 141 PTCLs. Syk was positive by immunohistochemistry (IHC) in 133 PTCLs (94%), whereas normal T cells were negative. Western blot on frozen tissue (n=6) and flow cytometry on cell suspensions (n=4) correlated with IHC results in paraffin. Additionally, western blot demonstrated that Syk-positive PTCLs show tyrosine (525/526) phosphorylation, known to be required for Syk activation...
June 2008: Leukemia: Official Journal of the Leukemia Society of America, Leukemia Research Fund, U.K
Kaiser M Bijli, Fabeha Fazal, Mohd Minhajuddin, Arshad Rahman
Protein kinase C-delta (PKC-delta) plays a pivotal role in mediating thrombin-induced NF-kappaB activation and ICAM-1 expression in endothelial cells. However, the downstream mechanisms mediating its function are unclear. In this study, we show that PKC-delta-mediated activation of protein-tyrosine kinase Syk plays an important role in thrombin signaling of NF-kappaB activation and intercellular adhesion molecule-1 (ICAM-1) expression in endothelial cells. Stimulation of human vascular endothelial cells with thrombin resulted in a time-dependent phosphorylation of Syk on tyrosine 525 and 526, an indication of Syk activation...
May 23, 2008: Journal of Biological Chemistry
S Qin, P B Chock
Using Btk-deficient DT40 cells and the transfectants expressing wild-type Btk or Btk mutants in either kinase (Arg(525) to Gln), Src homology 2 (SH2, Arg(307) to Ala), or pleckstrin homology (PH, Arg(28) to Cys) domains, we investigated the roles and structure-function relationships of Btk in hydrogen peroxide-induced calcium mobilization. Our genetic evidence showed that Btk deficiency resulted in a significant reduction in hydrogen peroxide-induced calcium response. This impaired calcium signaling is correlated with the complete elimination of IP3 production and the significantly reduced tyrosine phosphorylation of PLCgamma2 in Btk-deficient DT40 cells...
July 10, 2001: Biochemistry
H L Li, M S Forman, T Kurosaki, E Puré
The tyrosine kinases Syk and Lyn are activated in B lymphocytes following antibody induced cross-linking of the B cell receptor for antigen (BCR). It has been suggested that activation of Syk is dependent on Lyn. We tested this hypothesis by comparing the phosphorylation and activation of several downstream effector molecules in parental DT40, DT40Syk- and DT40Lyn- B cells. The phosphorylation and activation of p90Rsk was ablated in Syk-deficient B cells but unaffected in Lyn-deficient B cells while the phosphorylation/activation of Ras GTPase activating protein (Ras GAP) and mitogen activated protein (MAP) kinase required both Syk and Lyn...
July 18, 1997: Journal of Biological Chemistry
C L Law, K A Chandran, S P Sidorenko, E A Clark
Antigen receptor ligation on lymphocytes activates protein tyrosine kinases and phospholipase C-gamma (PLC-gamma) isoforms. Glutathione S-transferase fusion proteins containing the C-terminal Src-homology 2 [SH2(C)] domain of PLC-gamma1 bound to tyrosyl phosphorylated Syk. Syk isolated from antigen receptor-activated B cells phosphorylated PLC-gamma1 on Tyr-771 and the key regulatory residue Tyr-783 in vitro, whereas Lyn from the same B cells phosphorylated PLC-gamma1 only on Tyr-771. The ability of Syk to phosphorylate PLC-gamma1 required antigen receptor ligation, while Lyn was constitutively active...
April 1996: Molecular and Cellular Biology
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