Search results for "Tyro"
showing 10 items of 816 documents
Coupling of endothelin receptors to the ERK/MAP kinase pathway. Roles of palmitoylation and G(alpha)q.
2001
Endothelins are potent mitogens that stimulate extracellular signal-regulated kinases (ERK/MAP kinases) through their cognate G-protein-coupled receptors, ET(A) and ET(B). To address the role of post-translational ET receptor modifications such as acylation on ERK activation and to identify relevant downstream effectors coupling the ET receptor to the ERK signaling cascades we have constructed a panel of palmitoylation-deficient ET receptor mutants with differential G(alpha) protein binding capacity. Endothelin-1 stimulation of wild-type ET(A) or ET(B) induced a fivefold to sixfold increase in ERK in COS-7 and CHO cells whereas full-length nonpalmitoylated ET(A) and ET(B) mutants failed to …
Bis(1H-indol-2-yl)methanones are effective inhibitors of FLT3-ITD tyrosine kinase and partially overcome resistance to PKC412A in vitro.
2009
Inhibition of the mutated fms-like tyrosine kinase 3 (FLT3) receptor tyrosine kinase is a promising therapeutic strategy in acute myeloid leukaemia (AML). However, development of resistance to FLT3 tyrosine kinase inhibitors (TKI), such as PKC412A, has been described recently. This observation may have an increasing impact on the duration of response and relapse rates in upcoming clinical trials employing FLT3-TKI. Herein we investigated two representatives of a novel class of FLT3-TKI: Bis(1H-indol-2-yl)methanones. Both compounds effectively induced apoptosis in FLT3-internal tandem duplicate (ITD)-transfected murine myeloid cells and in primary FLT3-ITD positive blasts. Combination of bot…
Induction of collagenase-3 (MMP-13) expression in human skin fibroblasts by three-dimensional collagen is mediated by p38 mitogen-activated protein k…
1999
Collagenase-3 (matrix metalloproteinase-13, MMP-13) is a recently identified human MMP with an exceptionally wide substrate specificity and restricted tissue-specific expression. Here we show that MMP-13 expression is induced in normal human skin fibroblasts cultured within three-dimensional collagen gel resulting in production and proteolytic activation of MMP-13. Induction of MMP-13 mRNAs by collagen gel was potently inhibited by blocking antibodies against alpha1 and alpha2 integrin subunits and augmented by activating antibody against beta1 integrin subunit, indicating that both alpha1 beta1 and alpha2 beta1 integrins mediate the MMP-13-inducing cellular signal generated by three-dimens…
p42 MAPK phosphorylates 80 kDa MARCKS at Ser-113.
1996
Abstract It is demonstrated here that p42 MAPKinase (p42 MAPK) phosphorylates the M yristoylated A lanine- R ich C - K inase S ubstrate (MARCKS) at Ser-113. In permeabilised Swiss 3T3 cells activation of protein kinase C (PKC) leads to p42 MAPK activation, but only the protein kinase C sites in MARCKS become phosphorylated and not Ser-113. The mitogen platelet-derived growth factor (PDGF) elicits the same response. These results demonstrate that while Ser-113 is a substrate for p42 MAPK in vitro and can be phosphorylated in vivo as shown by Taniguchi et al. [(1994) J. Biol. Chem. 269, 18299–18302], its phosphorylation is not subject to acute regulation by p42 MAPK in Swiss 3T3 cells.
Mutations and Deregulation of Ras/Raf/MEK/ERK and PI3K/PTEN/Akt/mTOR Cascades Which Alter Therapy Response.
2012
The Ras/Raf/MEK/ERK and PI3K/PTEN/Akt/mTOR cascades are often activated by genetic alterations in upstream signaling molecules such as receptor tyrosine kinases (RTK). Certain components of these pathways, RAS, NF1, BRAF, MEK1, DUSP5, PP2A, PIK3CA, PIK3R1, PIK3R4, PIK3R5, IRS4, AKT, NFKB1, MTOR, PTEN, TSC1, and TSC2 may also be activated/inactivated by mutations or epigenetic silencing. Upstream mutations in one signaling pathway or even in downstream components of the same pathway can alter the sensitivity of the cells to certain small molecule inhibitors. These pathways have profound effects on proliferative, apoptotic and differentiation pathways. Dysregulation of components of these cas…
Down-regulation of human CYP3A4 by the inflammatory signal interleukin-6: molecular mechanism and transcription factors involved.
2002
The hepatic drug-metabolizing cytochrome P-450 (CYP) enzymes are down-regulated during inflammation. In vitro studies with hepatocytes have shown that the cytokines released during inflammatory responses are largely responsible for this CYP repression. However, the signaling pathways and the cytokine-activated factors involved remain to be properly identified. Our research has focused on the negative regulation of CYP3A4 (the major drug-metabolizing human CYP) by interleukin 6 (IL-6) (the principal regulator of the hepatic acute-phase response). CYP3A4 down-regulation by IL-6 requires activation of the glycoprotein receptor gp130; however, it does not proceed through the JAK/STAT pathway, a…
Different FLT3-ITD Integration Sites Are Associated with Differential Sensitivity to Tyrosine Kinase Inhibitors (TKI) In Vitro.
2010
Abstract Abstract 1709 Introduction: Currently, small molecule FLT3 tyrosine kinase inhibitors (TKIs) are promising therapeutic approaches to overcome the dismal prognosis of AML patients harbouring FLT3-ITD mutations. However, up to 30% of these patients show primary resistance to FLT3-TKIs. Recently, we uncovered a novel mechanism of primary resistance to FLT3 TKIs in a patient displaying an atypical integration site of ITD within the beta2-sheet (ITD_A627E). The data suggested that atypical integration sites of ITDs within the tyrosine kinase domain-1 (TKD1) of FLT3 (beta1-sheet, nucleotide binding loop and beta2-sheet) are associated with rewired signaling and differential responsivenes…
Use of CDC2 from etoposide-treated cells as substrate to assay CDC25 phosphatase activity
1999
International audience; Cyclin-dependent kinases (CDKs) regulate the key transition of the cell cycle in all organisms. In response to Etoposide (VP-16) induced DNA damage, cells undergo a G2-phase arrest resulting in the accumulation of inactive CDK1 (CDC2) kinase complexes. Here we report that upon Etoposide treatment CDC2 is phosphorylated on tyrosine 15 and is dephosphorylated and activated in vitro by recombinant CDC25 phosphatase. We also show that inactive CDC2 kinase from Etoposide-treated cells can be used as a substrate in a sensitive two-step assay of CDC25 phosphatase. This assay, which is very simple to set-up, is based on the monitoring of CDC2 kinase activity after CDC25-depe…
Increased Level of Phosphotyrosine in Human Dendritic Cells under Stimulation with Contact Sensitizers but Not Irritants
1997
In the last years evidence was presented for the activation of dendritic cells (DC) under stimulation with contact sensitizers. Most data were obtained for murine Langerhans cells (LC) whereas in man blood-derived dendritic cells were found to be a more suitable model to study the mechanism of DC activation by haptens. The first observation was the upregulation of MHC class II molecules on murine Langerhans cells in vivo1 followed by their migration from the epidermis into regional lymph nodes2. Very early events during this activation include the upregulation of IL-1s in murine LC3 as well as the endocytotic activation of this cell type4. Based on the last observation attempts were made to…
Tyrosinases from crustaceans form hexamers
2002
Tyrosinases, which are widely distributed among animals, plants and fungi, are involved in many biologically essential functions, including pigmentation, sclerotization, primary immune response and host defence. In the present study, we present a structural and physicochemical characterization of two new tyrosinases from the crustaceans Palinurus elephas (European spiny lobster) and Astacus leptodactylus (freshwater crayfish). In vivo, the purified crustacean tyrosinases occur as hexamers composed of one subunit type with a molecular mass of approx. 71kDa. The tyrosinase hexamers appear to be similar to the haemocyanins, based on electron microscopy. Thus a careful purification protocol was…