The binding of von Willebrand factor (VWF) to glycoprotein (GP) Ib-IX-V stimulates transmembrane signaling events that lead to platelet adhesion and aggregation. Recent studies have implied that activation of Src family kinases is involved in GPIb-mediated platelet activation, although the related signal transduction pathway remains poorly defined. This study presents evidence for an important ...

We have studied how prion infection may affect the Src kinase activity in three different neuronal cell lines, ScGT1 and ScN2a, where ScGT1 were generated in our laboratory. By immunoblotting, using clone 28 - a monoclonal antibody recognizing active Src, we have found a 32+/-6.3% and 75+/-7.7% elevation in Src activity in ScGT1 and ScN2a cells, respectively, compared to uninfected cells. Immun...

This work presents a simple, low-cost and reusable label-free method for detecting protein tyrosine kinase activity using a tyrosinase-based amperometric biosensor (tyrosine kinase biosensor). This method is based on the observation that phosphorylation can block the tyrosinase-catalyzed oxidation of tyrosine or tyrosyl residue in peptides. Therefore, the activity of p60c-src protein tyrosine k...

Vacuolar protein sorting 34 (VPS34) contributes to the regulation of the mammalian target of rapamycin complex 1/S6 kinase 1 pathway downstream of nutrient signaling. However, intracellular mechanisms leading to VPS34 activation remain unclear. Here, we report that Src directly phosphorylates VPS34, and that this phosphorylation activates VPS34 lipid kinase activity, leading to Src-Y527F-mediat...

Src and Src-family protein kinases are proto-oncogenes that play key roles in cell morphology, motility, proliferation, and survival. v-Src (a viral protein) is encoded by the chicken oncogene of Rous sarcoma virus, and Src (the cellular homologue) is encoded by a physiological gene, the first of the proto-oncogenes. From the N- to C-terminus, Src contains an N-terminal 14-carbon myristoyl grou...

Myofibroblasts are effector cells in fibrotic disorders that synthesize and remodel the extracellular matrix (ECM). This study investigated the role of the Src kinase pathway in myofibroblast activation in vitro and fibrogenesis in vivo. The profibrotic cytokine, transforming growth factor β1 (TGF-β1), induced rapid activation of Src kinase, which led to myofibroblast differentiation of human l...

We have previously shown that transactivation-proficient hepatitis virus B X protein (HBx) protects Hep 3B cells from transforming growth factor-beta (TGF-beta)-induced apoptosis via activation of the phosphatidylinositol 3-kinase (PI 3-kinase)/Akt signaling pathway. This work further investigated how HBx activates PI 3-kinase. Src activity was elevated in Hep 3B cells following expression of t...

Amplification of the HER-2/neu (ErbB2) gene is observed in approximately 30% of human breast cancers, correlating with a poor clinical prognosis. Src kinases are also involved in the etiology of breast cancer, and their activation was suggested to be necessary for Neu-induced oncogenesis. To address whether Src activity is essential for Neu-mediated tumorigenesis, we used a physiologic inhibito...

Physiological stimuli activate protein kinases for finite periods of time, which is critical for specific biological outcomes. Mimicking this transient biological activity of kinases is challenging due to the limitations of existing methods. Here, we report a strategy enabling transient kinase activation in living cells. Using two protein-engineering approaches, we achieve independent control o...

Ceramide mediates sustained contraction of smooth muscle cells. C2 ceramide induced a rapid increase in Src kinase activity within 15 s, peaked at 1 min, and was sustained up to 8 min. Contraction and Src kinase activity were inhibited in cells incubated in Ca2+-free medium containing 2 mM EGTA and in cells preincubated with herbimycin A, a Src kinase inhibitor. Immunoblotting using a phosphosp...