Fyn Expression Research Articles

Impairment of circulating endothelial progenitor cells (EPCs) in patients with glucocorticoid-induced avascular necrosis of the femoral head and changes of EPCs after glucocorticoid treatment in vitro

BackgroundAvascular necrosis of the femoral head (ANFH) is a severe complication after high-dose glucocorticoid (GC) administration. The pathogenesis of GC-induced ANFH remains unclear. Though the important role of endothelial progenitor cells (EPCs) in the progression of GC-induced ANFH has been noticed, the effects of GCs on EPCs and the underlying mechanism still need further study.MethodsCirculating EPCs were obtained from the peripheral blood of ANFH patients and healthy controls by Ficoll-density gradient centrifugation. CD133+CD34+ cells with DiI-Ac-LDL uptake and FITC-UEA-1 binding were considered as EPCs. Number and functions of EPCs were analyzed by flow cytometry, chemotaxis assay, and tube formation assay. EPCs from healthy controls were also treated by different concentrations of methylprednisolone and prednisolone in vitro, and cell growth and angiogenic function were evaluated. Expression of CXCR7 and its downstream Akt/GSK-3β/Fyn pathway were also analyzed by western blots after cells treated by methylprednisolone in vitro.ResultsThe number and functions of EPCs in patients with GC-induced ANFH were significantly decreased. In vitro study showed for the first time that except extremely high concentrations, low to medium concentrations of GCs did not have significant effects on EPCs’ growth. Methylprednisolone and prednisolone both inhibited angiogenesis of EPCs even at low concentrations. Mechanism studies found CXCR7 was downregulated in EPCs after methylprednisolone treatment in vitro. Expression and phosphorylation of Akt and GSK-3β were also decreased with an upregulation of Fyn expression after steroid treatment.ConclusionsOur study showed that GC-induced ANFH patients have reduced the number and impaired functions of circulating EPCs. GCs did not show a significant effect on the growth of EPCs in vitro except extremely high concentrations of GCs. However, GCs significantly impaired EPC angiogenic function in vitro, even at low concentrations. Our study also suggested that downregulation of CXCR7 and its downstream Akt/GSK-3β/Fyn pathway in EPCs might be a novel mechanism of how GCs suppress EPCs’ angiogenesis.

NT5DC2 promotes tumorigenicity of glioma stem-like cells by upregulating fyn.

Glioblastoma (GBM) is an incurable primary brain tumor that is highly resistant to current treatments. Glioma stem-like cells (GSCs) are an aggressive population of glioma cells that not only initiate malignant growth, but also promote therapeutic resistance. Thus, targeting GSCs is critical for improving GBM treatment and ensuring complete eradication of the tumor. Here, we show that NT5DC2 (5'-Nucleotidase Domain Containing 2), a functionally unknown protein, plays a crucial role in GSC tumor initiation via upregulating Fyn expression. NT5DC2 is preferentially expressed in GSCs relative to the non-stem tumor cells. Knockdown of NT5DC2 significantly inhibits the GSC tumorsphere formation and cell viability in vitro, and tumorigenesis in vivo, thus, prolonging animal survival. Moreover, disruption of NT5DC2 in GSCs markedly reduces the expression of Fyn, a Src family proto-oncogene that has been implicated in the regulation of GBM progression. Importantly, the expression of NT5DC2 strongly correlated with increased aggression of human gliomas, but not that of other brain tumors. Taken together, our results uncover the function of NT5DC2 in GSC maintenance and highlight NT5DC2 as a promising therapeutic target for GBM.

Tyrosine phosphorylation activates 6-phosphogluconate dehydrogenase and promotes tumor growth and radiation resistance

6-Phosphogluconate dehydrogenase (6PGD) is a key enzyme that converts 6-phosphogluconate into ribulose-5-phosphate with NADP+ as cofactor in the pentose phosphate pathway (PPP). 6PGD is commonly upregulated and plays important roles in many human cancers, while the mechanism underlying such roles of 6PGD remains elusive. Here we show that upon EGFR activation, 6PGD is phosphorylated at tyrosine (Y) 481 by Src family kinase Fyn. This phosphorylation enhances 6PGD activity by increasing its binding affinity to NADP+ and therefore activates the PPP for NADPH and ribose-5-phosphate, which consequently detoxifies intracellular reactive oxygen species (ROS) and accelerates DNA synthesis. Abrogating 6PGD Y481 phosphorylation (pY481) dramatically attenuates EGF-promoted glioma cell proliferation, tumor growth and resistance to ionizing radiation. In addition, 6PGD pY481 is associated with Fyn expression, the malignancy and prognosis of human glioblastoma. These findings establish a critical role of Fyn-dependent 6PGD phosphorylation in EGF-promoted tumor growth and radiation resistance.

LINC00152 facilitates tumorigenesis in esophageal squamous cell carcinoma via miR-153-3p/FYN axis.

Long non-coding RNAs (LncRNAs) have been found to be associated with the biological behaviors of human cancers. LINC00152 is reported as an oncogene in many kinds of malignancies. However, the functions and mechanisms of LINC00152 involved in esophageal squamous cell carcinoma (ESCC) remain elusive. Our results revealed that LINC00152 expression was up-regulated in ESCC, and correlated with advanced TNM stage, lymph node metastasis, and poor prognosis of ESCC patients. Functionally, LINC00152 knockdown suppressed proliferation, decreased colony forming ability, and induced apoptosis in ESCC cells. Mechanically, LINC00152 functioned as a competing endogenous RNA (ceRNA) to sponge miR-153-3p, thereby facilitating its downstream target FYN. Moreover, miR-153-3p-mediated tumor-suppressive effects were partly reversed following LINC00152 overexpression. Also, FYN knockdown displayed a similar anti-cancerous role in ESCC cells. Taken together, LINC00152 contributed to ESCC progression by down-regulating miR-153-3p and promoting FYN expression, uncovering a novel LINC00152/miR-153-3p/FYN regulatory pathway in ESCC.

Higher Levels of Protein Palmitoylation in the Frontal Cortex across Aging Were Associated with Reference Memory and Executive Function Declines.

Cognitive decline with aging is often due to altered levels of protein expression. The NMDA receptor (NMDAR) and the complex of proteins surrounding the receptor are susceptible to age-related changes in expression. In the frontal cortex of aged mice, there is a significant loss of expression of the GluN2B subunit of the NMDAR, an increase in Fyn expression, and no change in PSD-95. Studies have also found that, in the frontal cortex, phosphorylation of GluN2B subunits and palmitoylation of GluN2 subunits and NMDAR complex proteins are affected by age. In this study, we examined some of the factors that may lead to the differences in the palmitoylation levels of NMDAR complex proteins in the frontal cortex of aged animals. The Morris water maze was used to test spatial learning in 3- and 24-month-old mice. The acyl–biotinyl exchange method was used to precipitate palmitoylated proteins from the frontal cortices and hippocampi of the mice. Additionally, brain lysates from old and young mice were probed for the expression of fatty acid transporter proteins. An age-related increase of palmitoylated GluN2A, GluN2B, Fyn, PSD-95, and APT1 (acyl protein thioesterase 1) in the frontal cortex was associated with poorer reference memory and/or executive functions. These data suggest that there may be a perturbation in the palmitoylation cycle in the frontal cortex of aged mice that contributes to age-related cognitive declines.

Cytokine Profile and Expression of FYN, ZAP-70 and LAT During Concanavalin A Stimulation in Patients with Resistant Bronchial Asthma

Background: Bronchial asthma (BA) is one of the most spreading chronic lung pathology in the world. The disease is characterized by high heterogeneity of clinical phenotypes including resistant forms which provoke significant clinical problem. Immune shift from Th2 to alternative immunological response is considered to be a mechanism of drug-resistance in BA treatment but this issue is not considerably studied yet. Aims: Detection of distinctive patterns in cytokine secretion and genetic expression (ZAP-70, FYN and LAT) of naïve and concanavalin A stimulated lymphocytes in patients with resistant BA. Materials and methods: The study enrolled ten patients in each group: subjects with treatment resistant BA, severe BA, and controls (30 in total). During the experiment, all patients with BA received treatment according to the condition. For each participant lymphocytes isolation from venous blood was performed. Cells were cultured with concanavalin A and without stimulation. Concentrations of cytokines IL-2, IL-12, TNF-α, IL-4, IL-5, and IL-6 in supernatants were measured with ELISA. Reverse transcription polymerase chain reaction was used to detect the mRNA expression of LAT, ZAP-70, and FYN genes. Results: Significant disease contribution to the lymphocyte secretion profile was established without concanavalin A stimulation: increased levels of IL-2 and IL-4 was observed in lymphocytes of patients with resistant BA if compared to the results of gorup with severe BA. Patients with resistant BA were characterized by weak cytokine response to the stimulation: only TNF-α and IL-5 levels were significantly increased whereas in group with severe BA all cytokines concentrations increased except IL-12, in controls — except IL-12 and IL-2. Significant FYN upregulation was identified in resistant BA group if compared with other groups, and in severe BA patients if compared with controls. The concanavalin A-stimulated cells showed increased expression of ZAP-70 in cells of patients with resistant BA compared to control group. Conclusions: Lymphocytes from patients with resistant BA are characterized by lack of cytokine response to concanavalin A stimulation, alteration of cytokine secretion, and genetic expression profile similar to cells with low sensitivity to apoptosis. The FYN gene is a perspective target for finding approaches to overcome resistance to steroid drugs in bronchial asthma.

Fyn Regulates Binding Partners of Cyclic-AMP Dependent Protein Kinase A.

The cAMP-dependent protein kinase A (PKA) is a serine/threonine kinase involved in many fundamental cellular processes, including migration and proliferation. Recently, we found that the Src family kinase Fyn phosphorylates the catalytic subunit of PKA (PKA-C) at Y69, thereby increasing PKA kinase activity. We also showed that Fyn induced the phosphorylation of cellular proteins within the PKA preferred target motif. This led to the hypothesis that Fyn could affect proteins in complex with PKA. To test this, we employed a quantitative mass spectrometry approach to identify Fyn-dependent binding partners in complex with PKA-C. We found Fyn enhanced the binding of PKA-C to several cytoskeletal regulators that localize to the centrosome and Golgi apparatus. Three of these Fyn-induced PKA interactors, AKAP9, PDE4DIP, and CDK5RAP2, were validated biochemically and were shown to exist in complex with Fyn and PKA in a glioblastoma cell line. Intriguingly, the complexes formed between PKA-C and these known AKAPs were dependent upon Fyn catalytic activity and expression levels. In addition, we identified Fyn-regulated phosphorylation sites on proteins in complex with PKA-C. We also identified and biochemically validated a novel PKA-C interactor, LARP4, which complexed with PKA in the absence of Fyn. These results demonstrate the ability of Fyn to influence the docking of PKA to specific cellular scaffolds and suggest that Fyn may affect the downstream substrates targeted by PKA.

MiR-125a-3p is responsible for chemosensitivity in PDAC by inhibiting epithelial-mesenchymal transition via Fyn

BackgroundPancreatic ductal adenocarcinoma (PDAC) is one of the most lethal cancers and resistance to cytotoxic chemotherapy is the major cause of mortality in PDAC patients. miR-125a-3p was found to be down-regulated in PDAC cells; however, the function of miR-125a-3p in PDAC has been elusive. Here, we explored the role of miR-125a-3p in chemosensitivity in PDAC cells. MethodsWe used qRT-PCR to detect miR-125a-3p expression in two PDAC cell lines. And we measured cell viability and apoptosis by MTT assay and flow cytometry, respectively. Scratch wound healing assay and transwell invasion assay were used to test the effects of miR-125a-3p and Fyn on cell EMT process. In addition, we validated the interaction of miR-125a-3p and Fyn by dual luciferase reporter assay. qRT-PCR and western blot were used to detect the mRNA and protein expressions of E-cadhrein, N-cadhrein, Snail and Fyn. ResultsWe found that miR-125a-3p was down-regulated in a time-dependent manner following treatment with gemcitabine in PDAC cells. Meanwhile, we found that overexpression of miR-125a-3p significantly increased chemosensitivity to gemcitabine and suppressed epithelial-mesenchymal transition (EMT) of PDAC cells. Mechanistically, miR-125a-3p directly targeted Fyn and decreased the expression of Fyn that functions to promote EMT process in PDAC. Furthermore, overexpression of Fyn could partially reverse the effects of miR-125a-3p on chemosensitivity to gemcitabine. ConclusionOur study is the first to show that miR-125a-3p is responsible for chemosensitivity in PDAC and could inhibit epithelial-mesenchymal transition by directly targeting Fyn. This provides a novel potential therapeutic strategy to overcome chemoresistance in PDAC.

PO-462 Investigating the potential anti-cancer properties of a novel src family kinase inhibitor in triple negative breast cancer

IntroductionThe Src Family Kinases (SFKs) are key mediators in various oncogenic pathways and are commonly activated in many forms of cancer. Of the nine members of SFKs, increasing reports suggest aberrant activation of Lyn and Fyn in breast cancer. Bioinformatics analysis reveals that Lyn and Fyn expression are strongly associated with the claudin-low TNBC patient group. Due to the current lack of targeted therapy for the TNBC subtype, it becomes worthwhile to investigate the potential of Lyn and Fyn as novel therapeutic targets. While preclinical studies involving current SFK inhibitors were promising, subsequent clinical trials have shown limited clinical benefits. In this project, we developed a novel in-house SFK inhibitor (Drug X) that specifically targets Lyn and Fyn kinases.Material and methodsPatient data analysis, Ligand-based computation, Proteome Profiler Array, in vivo mouse Pharmacokinetics and Pharmacodynamics studies, Bioinformatics analysis, Affymetrix Microarray, Secretome Analysis, Cell viability assays, Flow cytometry, Western blot, qPCR, Immunofluorescence, Transwell assays, 3D Matrigel Assays, and Tube-formation assay.Results and discussionsProteome Profiler Array results validated the ligand-based target prediction analyses of Drug X in vitro. Mouse studies show that Drug X is well-tolerated and exhibited significant tumour burden load reduction. Pharmacokinetics of Drug X was characterised. Overall, Drug X showed moderate systemic clearance, high volume of distribution and moderate oral bioavailability. Downstream functional studies were performed, and Drug X was found to induce apoptosis via the intrinsic pathway. Also, Drug X could down-regulate the mesenchymal properties of mesenchymal-like TNBC cell lines via the modulation of key EMT-related genes. Preliminary in vitro and in vivo rat aortic ring assay data also suggested that Drug X could harbour potent anti-angiogenic effects.ConclusionBased on in vitro and in vivo experiments, preliminary findings have supported that Drug X could potentially be a promising novel drug candidate for TNBC treatment and on-going efforts are being made to further elucidate the underlying mechanisms of Drug X in modulating the key oncogenic processes – namely from the angle of apoptosis, EMT and angiogenesis.

Circular RNA expression profiles of mouse ovaries during postnatal development and the function of circular RNA epidermal growth factor receptor in granulosa cells

PurposeCircular RNAs (circRNAs) are a class of noncoding RNAs that can regulate gene expression at the post-transcriptional level. The contribution of circRNAs in the regulation of granulosa cells (GCs) functions is not yet clear. The aim of this study was to analyze circRNA expression in adult and neonate ovaries, uncover the biological roles of circ_0002861 (circEGFR) and identify the mechanism by which it modulates follicular development. Basic ProceduresThe circRNA expression profiles of adult and neonatal mouse ovaries were explored by high-throughput sequencing. The function of circEGFR was measured by RNA fluorescence in situ hybridization, overexpression, knockdown, RNA immunoprecipitation and luciferase reporter assays in GCs. Main FindingsNumerous differentially expressed circRNAs were identified in adult and neonatal ovaries. Through circRNAs expression patterns and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis, estrogen signaling was found to be upregulated in adult ovaries compared with neonate ovaries. Further analysis revealed that the expression of circEGFR (circ_0002861, ID: mmu_circ_0002861 in circBase) was increased in adult ovaries compared with neonate ovaries. circEGFR is formed by splicing from exons 14 and 15 of the epidermal growth factor receptor (EGFR) gene to produce a covalently linked 249-nucleotide circRNA. Overexpression of circEGFR increased estradiol (E2) production and GCs growth, whereas circEGFR knockdown enhanced progesterone production and inhibited (E2) secretion by GCs. Bioinformatic screening identified several binding sites for miR-125a-3p in the circEGFR sequence. RNA immunoprecipitation and luciferase reporter assays demonstrated that circEGFR may act as a sponge for miR-125a-3p, thus modulating Fyn expression. Principal ConclusionsThese findings illustrate that circEGFR may play a vital role in ovarian GCs by modulating Fyn via competitive binding with miR-125a-3p. Our results suggest potential applications of circEGFR in reproductive and steroid-related disorder therapy.

Tyrosine kinase Fyn promotes osteoarthritis by activating the β-catenin pathway

ObjectivesTo investigate the role of tyrosine kinase Fyn in the development of osteoarthritis (OA) and the underlying mechanisms, and to define whether targeting Fyn could prevent OA in mice.MethodsCartilage samples...

The Role of Neuropilin-1-FYN Interaction in Odontoblast Differentiation of Dental Pulp Stem Cells.

Abnormal odontoblast differentiation of dental pulp stem cells (DPSCs) caused by inflammation is closely related to the development of dental caries. Neuropilin-1 (NRP1) is one of the members of neuropilin family. It can combine with disparate ligands involved in regulating cell differentiation. FYN belongs to the protein-tyrosine kinase family, which has been implicated in the control of cell growth, and the effect can be further strengthened by inflammatory factors. In our studies, we verified that NRP1 can form complexes with FYN and have the correlation changes in odontoblast differentiation of DPSCs. Therefore, we surmise that in the progress of dental caries, NRP1 interacts with FYN, by expanding inflammation and inhibition of odontoblast differentiation of DPSCs through nuclear factor kappa B (NF-κB) signaling pathway. In this subject, we first investigated the expression and interaction of NRP1 and FYN in DPSCs. And then, we researched the effect of this complex controlling downstream signal pathway in normal or inflammation stimulated DPSCs. Finally, we analyzed the relationship between this role and odontoblast differentiation of DPSCs. This research will provide the molecular mechanism of inflammation factors of dental caries through activating NF-κB signal regulating odontoblast differentiation in DPSCs for finding new potential drug targets for the clinical treatment of dental caries.

Tyrosine kinase Fyn regulates iNOS expression in LPS-stimulated astrocytes via modulation of ERK phosphorylation

The high concentrations of nitric oxide (NO) produced by inducible nitric oxide synthase (iNOS) in activated glial cells in response to neuroinflammatory stimuli have neurotoxic effects on the brain. At basal levels, iNOS expression is low, and proinflammatory stimuli induce iNOS expression in astrocytes, microglia, and oligodendrocytes. Fyn, a non-receptor tyrosine kinase, regulates iNOS expression in several types of immune cells. However, its role in stimulated astrocytes is less clear. In this study, we investigated the role of Fyn in the regulation of lipopolysaccharide (LPS)-induced iNOS expression in astrocytes from mice and rats. Intracerebroventricular LPS injections in cortical regions enhanced iNOS mRNA and protein levels, which were increased in Fyn-deficient mice. Accordingly, LPS-induced nitrite production was enhanced in primary astrocytes cultured from Fyn-deficient mice or rats. Similar results were observed in cultured astrocytes after the siRNA-induced knockdown of Fyn expression. Finally, we observed increased LPS-induced extracellular signal-regulated protein kinase (ERK) activation in Fyn-deficient astrocytes. These results suggested that Fyn has a regulatory role in iNOS expression in astrocytes during neuroinflammatory responses.

Upregulation of Tyrosine Kinase FYN in Human Thyroid Carcinoma: Role in Modulating Tumor Cell Proliferation, Invasion, and Migration.

Tyrosine kinase FYN-a member of the SRC family of kinases-is associated with mediating mitogenic signals and regulating cell cycle entry, growth, and proliferation. It was hypothesized that FYN is upregulated in thyroid carcinoma, which plays a critical role in tumorigenesis. FYN expression level in thyroid carcinoma tissue and tumor cell lines was determined. Also, the effects of FYN on thyroid cancer (TC) growth, signaling, cell cycle, and apoptosis were evaluated in vitro. FYN was knocked down in thyroid cancer cells (TPC-1) by siRNA to investigate the effects on cell proliferation, invasion, and migration. First, FYN was upregulated both in thyroid carcinoma tissue and in tumor cell lines. Loss of FYN by siRNA weakened proliferation, invasion, and migration of PTC-1 cells. Furthermore, it was demonstrated that knockdown of FYN can inhibit the G0/G1 phase of cell cycle. It was also observed that reduced expression of FYN could increase the level of NF-κB/P65 and IκBα. This study was the first to demonstrate critical positive regulation of thyroid tumorigenesis by FYN, which could be a potential target gene for thyroid carcinoma treatment. In addition, findings from this study highlighted the potential role of FYN inhibitors in TC therapy.

The Effect of Myricetin Flavonoid on the Expression of Fyn Gene in Melanoma Cells (A375)

Background: Malignant melanoma as one of the most common cancers is currently spreading worldwide. Regarding after-effect of advanced treatments, using natural products has attracted much attention. Flavonoids, polyphenol compounds rich in diet, are being considered for their therapeutic preventive features. Fyn gene, a member of the protein tyrosine kinase oncogene family, has become an important target for therapy goals. Objectives: The aim of this study was to assess Fyn gene expression after treatment of melanoma cells with myricetin. Methods: In this study, the melanoma cells were treated with different concentrations of myricetin (0 to 100 �M) and their viability was determined by the methylthiazolyl diphenyl-tetrazolium bromide (MTT) assay, also the expression of Fyn gene in treated cells with selected concentrations of myricetin (0, 20, 40, 50, and 60 �M) was detected by real time quantitative polymerase chain reaction (qPCR). Results: The current investigation showed that treatment of A375 melanoma cells with the dietary flavonoid myricetin (3, 5, 7- trihydroxy-2-(3, 4, 5,-trihydroxy phenyl)-4- chromenone), resulted in decreased cell viability and increased expression of Fyn gene. The MTT assay analysis of exposed cells with different concentrations of myricetin showed that up to 25 �Mof myricetin had no cytotoxicity effect on A375 cells, also with increasing of myricetin concentration, the repression of cell proliferation developed as well. Conclusions: Real time qPCR analysis of Fyn expression in exposed cells with various concentration of myricetin leads to overexpression of this gene, dose dependently. Through this research, it was determined that myricetin with its anti-proliferative potential could suppress the development of cancer cells. On the other hand, since Fyn kinase could be involved in tumorigenesis of some cancer cells, it could be concluded that myricetin could effect the carcinogenicity of Fyn function in melanoma cells. Keywords: Melanoma, A375, Myricetin, Fyn Gene

Plant-based Food Cyanidin-3-Glucoside Modulates Human Platelet Glycoprotein VI Signaling and Inhibits Platelet Activation and Thrombus Formation

Background: Platelets play an important role in hemostasis, thrombosis, and atherosclerosis. Glycoprotein VI (GPVI) is a major platelet receptor that interacts with exposed collagen on injured vessel walls. Our previous studies have shown that anthocyanins (a type of natural plant pigment) attenuate platelet function; however, whether anthocyanins affect collagen-induced GPVI signaling remains unknown.Objective: The objective of this study was to explore the effects of cyanidin-3-glucoside (Cy-3-g, one of the major bioactive compounds in anthocyanins) on platelet activation and thrombosis and the GPVI signaling pathway.Methods: Platelets from healthy men and women were isolated and incubated with different concentrations (0, 0.5, 5, and 50 μM) of Cy-3-g. The expression of activated integrin αIIbβ3, P-selectin, CD63, and CD40L, fibrinogen binding to platelets, and platelet aggregation were evaluated in vitro. Platelet adhesion and aggregation in whole blood under flow conditions were assessed in collagen-coated perfusion chambers. Thrombosis and hemostasis were assessed in 3-4-wk-old male C57BL/6J mice through FeCl3-induced intravital microscopy and tail bleeding time. The effect of Cy-3-g on collagen-induced human platelet GPVI signaling was explored with Western blot.Results: Cy-3-g attenuated platelet function in a dose-dependent manner. The 0.5-μM dose of Cy-3-g inhibited (P < 0.05) human platelet adhesion and aggregation to collagen at both venous (-54.02%) and arterial (-22.90%) shear stresses. The 5-μM dose inhibited (P < 0.05) collagen-induced human platelet activation (PAC-1: -48.21%, P-selectin: -50.63%), secretion (CD63: -73.89%, CD40L: -43.70%), fibrinogen binding (-56.79%), and aggregation (-17.81%). The 5-μM dose attenuated (P < 0.01) thrombus growth (-66.67%) without prolonging bleeding time in mice. The 50-μM dose downregulated (P < 0.05) collagen-induced GPVI signaling in human platelets and significantly decreased phosphorylation of Syk-linker for activation of T cells (LAT)-SLP76 (Syk: -39.08%, LAT: -32.25%, SLP76: -40.00%) and the expression of Lyn (-31.89%), Fyn (-36.27%), and phospholipase C-γ2 (-39.08%).Conclusions: Cy-3-g inhibits human platelet activation, aggregation, secretion, and thrombus formation, and downregulates the collagen-GPVI signaling pathway. Supplementation of Cy-3-g may have protective effects against atherothrombosis.

Methylmercury augments Nrf2 activity by downregulation of the Src family kinase Fyn

Methylmercury (MeHg) is a potent developmental neurotoxicant that induces an oxidative stress response in the brain. It has been demonstrated that MeHg exposure increases nuclear factor erythroid 2-related factor 2 (Nrf2) activity. Nrf2 is a transcription factor that translocates to the nucleus in response to oxidative stress, and upregulates phase II detoxifying enzymes. Although, Nrf2 activity is augmented subsequent to MeHg exposure, it has yet to be established whether Nrf2 moves into the nucleus as a result. Furthermore, the potential effect MeHg might have on the non-receptor tyrosine kinase, Fyn, has not been addressed. Fyn phosphorylates Nrf2 in the nucleus, resulting in its inactivation, and consequent downregulation of the oxidative stress response. Here, we observe Nrf2 translocates to the nucleus subsequent to MeHg-induced oxidative stress. This response is concomitant with reduced Fyn expression and nuclear localization. Moreover, we detected an increase in phosphorylated Akt and glycogen synthase kinase 3 beta (GSK-3β) at activating and inhibitory sites, respectively. Akt phosphorylates and inhibits GSK-3β, which subsequently prevents Fyn phosphorylation to signal nuclear import. Our results demonstrate MeHg downregulates Fyn to maintain Nrf2 activity, and further illuminate a potential mechanism by which MeHg elicits neurotoxicity.

Regulation of GVBD in mouse oocytes by miR-125a-3p and Fyn kinase through modulation of actin filaments

Meiotically arrested oocytes are characterized by the presence of the nuclear structure known as germinal-vesicle (GV), the breakdown of which (GVBD) is associated with resumption of meiosis. Fyn is a pivotal factor in resumption of the first meiotic division; its inhibition markedly decreases the fraction of oocytes undergoing GVBD. Here, we reveal that in mouse oocytes Fyn is post-transcriptionally regulated by miR-125a-3p. We demonstrate that in oocytes resuming meiosis miR-125a-3p and Fyn exhibit a reciprocal expression pattern; miR-125a-3p decreases alongside with an increase in Fyn expression. Microinjection of miR-125a-3p inhibits GVBD, an effect that is markedly reduced by Fyn over-expression, and impairs the organization of the actin rim surrounding the nucleus. Lower rate of GVBD is also observed in oocytes exposed to cytochalasin-D or blebbistatin, which interfere with actin polymerization and contractility of actin bundles, respectively. By down-regulating Fyn in HEK-293T cells, miR-125a-3p reduces the interaction between actin and A-type lamins, which constitute the nuclear-lamina. Our findings suggest a mechanism, by which a decrease in miR-125a-3p during oocyte maturation facilitates GVBD by allowing Fyn up-regulation and the resulting stabilization of the interaction between actin and A-type lamins.

Epidermal growth factor receptor in glioblastoma.

Mutations in the epidermal growth factor receptor (EGFR) are commonly occurring in glioblastoma. Enhanced activation of EGFR can occur through a variety of different mechanisms, both ligand-dependent and ligand-independent. Numerous evidence has suggested that EGFR is overexpressed in most of primary glioblastomas and some of the secondary glioblastomas and is characteristic of more aggressive glioblastoma phenotypes. Additionally, recent studies have revealed that wild-type EGFR, and to a greater extent hyper-activating EGFR mutants induced a substantial upregulation of Fyn expression. Furthermore, it was determined that Fyn expression is upregulated across a panel of patient-derived glioblastoma stem cells (GSCs) relative to normal progenitor controls. Moreover, researchers are continuously involved in elucidation of novel mechanism linking EGFR EGFR-expressing glioblastoma. The present review highlights current aspects of EGFR receptor in glioblastoma and concludes that the concept of EGFR signaling and related receptors and associated factors is evolving, however, it needs detailed evaluation for future clinical applications in cancer patients.

Mechanistic insight into the suppressive effects of stem cell factor during IgE-mediated activation in bone marrow-derived mast cells.

Abstract Treatment of bone marrow derived mast cells (BMMCs) with stem cell factor (SCF) is common practice when differentiating mast cells for experimentation. The enhanced growing potential from including SCF during mast cell culture and differentiation allows for easier maintenance and quicker experiments. Recent publications have begun to identify potentially negative effects of treatment with SCF regarding mast cell activation. The mechanism of SCF inhibition on mast cell activation is mostly unknown, but BMMCs derived with the addition of SCF function differently than untreated cells when mast cells are primed and subsequently activated. This study provides insight into the specific targets of SCF treatment and the impact SCF has on the ability of mast cells to activate. Running ELISAs in conjunction with real-time qPCR, we identified differentially expressed proteins involved in FCɛRI signaling and mast cell activation in BMMCs exposed to SCF. We examine the effects of SCF on Fyn, Lyn, Syk and Stat5 protein expression compared to mast cells raised without SCF. These data are also placed in the context of other immunosuppressive mechanism, (e.g. TGFβ). The presented data allow researchers to better understand the implications that may result from SCF treatment of BMMCs, especially with respect to examining IgE-mediated functions.