scholarly journals Morphological Differentiation of Oligodendrocytes Requires Activation of Fyn Tyrosine Kinase

1999 ◽  
Vol 145 (6) ◽  
pp. 1209-1218 ◽  
Author(s):  
Donna J. Osterhout ◽  
Amy Wolven ◽  
Rebecca M. Wolf ◽  
Marilyn D. Resh ◽  
Moses V. Chao
Keyword(s):  
Tyrosine Kinase ◽  
Kinase Activity ◽  
Kinase Inhibitors ◽  
Morphological Differentiation ◽  
Dominant Negative ◽  
Tyrosine Kinase Activity ◽  
Oligodendrocyte Progenitors ◽  
Differentiated Cells ◽  
Process Formation ◽  
Fyn Tyrosine Kinase

In the central nervous system, myelination of axons occurs when oligodendrocyte progenitors undergo terminal differentiation and initiate process formation and axonal ensheathment. Although it is hypothesized that neuron-oligodendrocyte contact initiates this process, the molecular signals are not known. Here we find that Fyn tyrosine kinase activity is upregulated very early during oligodendrocyte progenitor cell differentiation. Concomitant with this increase is the appearance of several tyrosine phosphorylated proteins present only in differentiated cells. The increased tyrosine kinase activity is specific to Fyn, as other Src family members are not active in oligodendrocytes. To investigate the function of Fyn activation on differentiation, we used Src family tyrosine kinase inhibitors, PP1 and PP2, in cultures of differentiating oligodendrocyte progenitors. Treatment of progenitors with these compounds prevented activation of Fyn and reduced process extension and myelin membrane formation. This inhibition was reversible and not observed with related inactive analogues. A similar effect was observed when a dominant negative Fyn was introduced in progenitor cells. These findings strongly suggest that activation of Fyn is an essential signaling component for the morphological differentiation of oligodendrocytes.

scholarly journals Transmission of growth cone traction force through apCAM–cytoskeletal linkages is regulated by Src family tyrosine kinase activity

2001 ◽  
Vol 155 (3) ◽  
pp. 427-438 ◽  
Author(s):  
Daniel M. Suter ◽  
Paul Forscher
Keyword(s):  
Tyrosine Kinase ◽  
Growth Cone ◽  
Kinase Activity ◽  
Kinase Inhibitors ◽  
Traction Force ◽  
Tyrosine Kinase Activity ◽  
Cellular Mechanisms ◽  
Traction Forces ◽  
Kinase Activation ◽  
Neuronal Growth Cone

Tyrosine kinase activity is known to be important in neuronal growth cone guidance. However, underlying cellular mechanisms are largely unclear. Here, we report how Src family tyrosine kinase activity controls apCAM-mediated growth cone steering by regulating the transmission of traction forces through receptor–cytoskeletal linkages. Increased levels of tyrosine phosphorylation were detected at sites where beads coated with apCAM ligands were physically restrained to induce growth cone steering, but not at unrestrained bead binding sites. Interestingly, the rate and level of phosphotyrosine buildup near restrained beads were decreased by the myosin inhibitor 2,3-butanedione-2-monoxime, suggesting that tension promotes tyrosine kinase activation. While not affecting retrograde F-actin flow rates, genistein and the Src family selective tyrosine kinase inhibitors PP1 and PP2 strongly reduced the growth cone's ability to apply traction forces through apCAM–cytoskeletal linkages, assessed using the restrained bead interaction assay. Furthermore, increased levels of an activated Src family kinase were detected at restrained bead sites during growth cone steering events. Our results suggest a mechanism by which growth cones select pathways by sampling both the molecular nature of the substrate and its ability to withstand the application of traction forces.

scholarly journals ACK Family Tyrosine Kinase Activity Is a Component of Dcdc42 Signaling during Dorsal Closure in Drosophila melanogaster

2002 ◽  
Vol 22 (11) ◽  
pp. 3685-3697 ◽  
Author(s):  
Kai Ping Sem ◽  
Baharak Zahedi ◽  
Ivan Tan ◽  
Maria Deak ◽  
Louis Lim ◽  
...  
Keyword(s):  
Drosophila Melanogaster ◽  
Tyrosine Kinase ◽  
Kinase Activity ◽  
Leading Edge ◽  
Small Gtpase ◽  
Dominant Negative ◽  
Binding Motif ◽  
Dorsal Closure ◽  
Tyrosine Kinase Activity ◽  
Amino Terminal

ABSTRACT We have characterized Drosophila melanogaster ACK (DACK), one of two members of the ACK family of nonreceptor tyrosine kinases in Drosophila. The ACKs are likely effectors for the small GTPase Cdc42, but signaling by these proteins remains poorly defined. ACK family tyrosine kinase activity functions downstream of Drosophila Cdc42 during dorsal closure of the embryo, as overexpression of DACK can rescue the dorsal closure defects caused by dominant-negative Dcdc42. Similar to known participants in dorsal closure, DACK is enriched in the leading edge cells of the advancing epidermis, but it does not signal through activation of the Jun amino-terminal kinase cascade operating in these cells. Transcription of DACK is responsive to changes in Dcdc42 signaling specifically at the leading edge and in the amnioserosa, two tissues involved in dorsal closure. Unlike other members of the ACK family, DACK does not contain a conserved Cdc42-binding motif, and transcriptional regulation may be one route by which Dcdc42 can affect DACK function. Expression of wild-type and kinase-dead DACK transgenes in embryos, and in the developing wing and eye, reveals that ACK family tyrosine kinase activity is involved in a range of developmental events similar to that of Dcdc42.

scholarly journals Fast in-vitro screening of FLT3-ITD inhibitors using silkworm-baculovirus protein expression system

2021 ◽  
Author(s):  
Naoki Yamamoto ◽  
Jiro Kikuchi ◽  
Yusuke Furukawa ◽  
Naoya Shibayama
Keyword(s):  
Tyrosine Kinase ◽  
Kinase Activity ◽  
Kinase Inhibitors ◽  
Expression System ◽  
Structural Studies ◽  
Expression And Purification ◽  
Tyrosine Kinase Activity ◽  
Fast Screening ◽  
Baculovirus System

We report expression and purification of a FLT3 protein with ITD mutation (FLT3-ITD) with a steady tyrosine kinase activity using a silkworm-baculovirus system, and its application as a fast screening system of tyrosine kinase inhibitors. The FLT3-ITD protein was expressed in Bombyx mori L. pupae infected by gene-modified nucleopolyhedrovirus, and was purified as an active state. We performed an inhibition assay using 17 potential kinase inhibitors, and succeeded in identifying two potent inhibitors for FLT3-ITD. The result has paved the way for screening FLT3-ITD inhibitors in a fast and easy manner, and also for structural studies.

Tyrosine kinase regulates epithelial sodium transport in A6 cells

1993 ◽  
Vol 264 (1) ◽  
pp. C246-C250 ◽  
Author(s):  
P. S. Matsumoto ◽  
A. Ohara ◽  
P. Duchatelle ◽  
D. C. Eaton
Keyword(s):  
Tyrosine Kinase ◽  
Tyrosine Kinase Inhibitors ◽  
Kinase Activity ◽  
Kinase Inhibitors ◽  
Kinase Inhibitor ◽  
Na Transport ◽  
Tyrosine Kinase Activity ◽  
Open Probability ◽  
Cyclic Monophosphate ◽  
Tyrphostin 23

Insulin increases epithelial Na+ reabsorption, and many of its actions involve tyrosine kinase. We used tyrosine kinase inhibitors to examine the role of tyrosine kinase in the action of insulin. Pretreatment of Na+ transporting cells with tyrosine kinase inhibitors attenuates the subsequent action of insulin, suggesting that the action of insulin on epithelial Na+ transport involves tyrosine kinase activity. In addition to their effect on insulin-induced Na+ transport, the tyrosine kinase inhibitors also significantly reduce Na+ transport in Na(+)-transporting epithelial cells, suggesting that there is a significant tonic tyrosine kinase activity that modulates epithelial Na+ transport. Using patch-clamp methods, we found that one inhibitor, genistein, reduces the number of active Na+ channels in cell-attached patches without significantly affecting the open probability of any remaining channels. The effects of the tyrosine kinase inhibitors are not due to inhibition of protein kinase A (PKA), since H89, a PKA inhibitor, does not affect Na+ transport of control cells (as the tyrosine kinase inhibitors do), and the tyrosine kinase inhibitor, genistein or tyrphostin 23, does not alter the stimulation of ion transport by 8-(4-chlorophenylthio)adenosine 3',5'-cyclic monophosphate, a membrane-permeable adenosine 3',5'-cyclic monophosphate analogue (as H89 does).

The role of Src family kinases in starfish egg fertilisation

Zygote ◽  
1999 ◽  
Vol 8 (S1) ◽  
pp. S16-S17 ◽  
Author(s):  
Andrew F. Giusti ◽  
Kathy R. Foltz ◽  
Laurinda. A. Jaffe
Keyword(s):  
Tyrosine Kinase ◽  
Kinase Activity ◽  
Kinase Inhibitors ◽  
Calcium Ionophore ◽  
Calcium Ionophore A23187 ◽  
Free Calcium ◽  
Ionophore A23187 ◽  
Tyrosine Kinase Activity ◽  
Sh2 Domains ◽  
Upstream Regulator

A common early feature in the activation of all eggs during fertilisation is an increase in the level of intra-cellular free calcium (Ca2+) that, in most species, propagates as a wave across the egg (reviewed in Strieker, 1999). In echinoderms, this Ca2+ release is the result of a signal transduction cascade that requires phospholipase Cγ (PLCγ)-mediated production of inositol trisphosphate (IP3) (Carroll et al., 1997, 1999). PLCγ is most commonly regulated by tyrosine phosphorylation (Rhee & Bae, 1997), indicating that a tyrosine kinase is a likely upstream regulator of PLCγ enzymatic activity at fertilisation. In support of this hypothesis, an increase in tyrosine kinase activity and an increase in tyrosine-phosphorylated proteins at fertilisation has been observed in echinoderm eggs (Satoh & Garbers, 1985; Ciapa & Epel, 1991; Kinsey, 1997). Moreover, the tyrosine kinase inhibitors genistein (Shen et al., 1999) and PP1 (Abassi et al., 2000) have been used to show that in sea urchin eggs a tyrosine kinase activity is required for normal Ca2+ release in response to fertilisation.In eggs of the starfish Asterina miniata, a Src-type tyrosine kinase has been identified as a potential regulator of PLCγ activity at fertilisation (Giusti et al., 1999a). This kinase exhibits a rapid fertilisation-dependent association specifically with the Src Homology 2 (SH2) domains of PLCγ. Moreover, the timing of this association correlates with an increase in the tyrosine kinase activity bound to the PLCγ SH2 domains, and neither the Src kinase nor the associated kinase activity was observed to associate with the PLCγ SH2 domains after treating eggs with the calcium ionophore A23187 (Giusti et al., 1999a). These data identify an egg Src family kinase as a potential upstream regulator of PLCγ during starfish egg fertilisation.

Down-Modulation of P210bcr/abl Induces Apoptosis/Differentiation in K562 Leukemic Blast Cells

1997 ◽  
Vol 83 (4) ◽  
pp. 756-761 ◽  
Author(s):  
Arunkumar B. Deora ◽  
Michelle B. Miranda ◽  
S.G. Anand Rao
Keyword(s):  
Tyrosine Kinase ◽  
Kinase Activity ◽  
Kinase Inhibitors ◽  
K562 Cells ◽  
Erythroid Differentiation ◽  
Leukemic Blast ◽  
Tyrosine Kinase Activity ◽  
Abl Tyrosine Kinase ◽  
Blast Cells ◽  
Induced Apoptosis

Aims and background K562 cells are growth factor independent and neither function as stem cells nor differentiate into functional end cells. They are blast cells. There is evidence that the constitutively expressed bcr-abl tyrosine kinase might be responsible for the maintenance of the blast state of CML cells. We have studied the effect of two tyrosine kinase inhibitors, quercetin and genistein, on K562 cells. Methods K562 cells were treated with quercetin/genistein for a period of 72 hrs and then subjected to staining for apoptosis and erythroid differentiation and Western blotting with c-abl and phosphotyrosine monoclonal antibodies. Results The IC50 value was found to be 9.2 μg/ml for quercetin and 11.8 μg/ml for genistein. Quercetin-treated cells did not show any differentiation but showed 68% apoptosis as compared to 7% in control. Genistein-treated cells showed 16% apoptosis and 15% erythroid differentiation. Quercetin reduced the level of p210 by 74% and its phosphotyrosine content by 67.6%. Genistein reduced p210 by 77.8% and its phosphotyrosine content by 16%. Conclusion Both quercetin and genistein are able to down-modulate the tyrosine kinase activity of p210 as well as bring about a decrease in the content of the protein with different effects: quercetin induced apoptosis while genistein brought about both differentiation and apoptosis.

scholarly journals Intracellular delivery of anti-BCR/ABL antibody by PLGA nanoparticles suppresses the oncogenesis of chronic myeloid leukemia cells

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Guoyun Jiang ◽  
Zhenglan Huang ◽  
Ying Yuan ◽  
Kun Tao ◽  
Wenli Feng
Keyword(s):  
Chronic Myeloid Leukemia ◽  
Tyrosine Kinase ◽  
Myeloid Leukemia ◽  
Kinase Activity ◽  
Kinase Inhibitors ◽  
Fusion Gene ◽  
Intracellular Delivery ◽  
Tyrosine Kinase Activity

Abstract Background The pathogenesis of chronic myeloid leukemia (CML) is the formation of the BCR/ABL protein, which is encoded by the bcr/abl fusion gene, possessing abnormal tyrosine kinase activity. Despite the wide application of tyrosine kinase inhibitors (TKIs) in CML treatment, TKIs drug resistance or intolerance limits their further usage in a subset of patients. Furthermore, TKIs inhibit the tyrosine kinase activity of the BCR/ABL oncoprotein while failing to eliminate the pathologenic oncoprotein. To develop alternative strategies for CML treatment using therapeutic antibodies, and to address the issue that antibodies cannot pass through cell membranes, we have established a novel intracellular delivery of anti-BCR/ABL antibodies, which serves as a prerequisite for CML therapy. Methods Anti-BCR/ABL antibodies were encapsulated in poly(d, l-lactide-co-glycolide) nanoparticles (PLGA NPs) by a double emulsion method, and transferrin was labeled on the surface of the nanoparticles (Ab@Tf-Cou6-PLGA NPs). The characteristics of nanoparticles were measured by dynamic light scattering (DLS) and transmission electron microscopy (TEM). Cellular uptake of nanoparticles was measured by flow cytometry (FCM). The effect of nanoparticles on the apoptosis and proliferation of CML cells was testified by FCM and CCK-8 assay. In addition, the anti-cancer impact of nanoparticles was evaluated in mouse models of CML. Results The results demonstrated that the Ab@Tf-Cou6-PLGA NPs functioned as an intracellular deliverer of antibodies, and exhibited an excellent effect on degrading BCR/ABL oncoprotein in CML cells via the Trim-Away pathway. Treatment with Ab@Tf-Cou6-PLGA NPs inhibited the proliferation and induced the apoptosis of CML cells in vitro as well as impaired the oncogenesis ability of CML cells in vivo. Conclusions In conclusion, our study indicated that this approach achieved safe and efficient intracellular delivery of antibodies and degraded BCR/ABL oncoprotein via the Trim-Away pathway, which provides a promising therapeutic strategy for CML patients, particularly those with TKI resistance.

Identification of surrogate markers for determining drug activity using proteomics

2003 ◽  
Vol 31 (6) ◽  
pp. 1488-1490 ◽  
Author(s):  
C.M. McClelland ◽  
W.J. Gullick
Keyword(s):  
Tyrosine Kinase ◽  
Tyrosine Kinase Inhibitors ◽  
Kinase Activity ◽  
Kinase Inhibitors ◽  
Drug Evaluation ◽  
New Drugs ◽  
Hydroxyl Groups ◽  
Surrogate Markers ◽  
Tyrosine Kinase Activity ◽  
Drug Activity

In a high proportion of human carcinomas overexpression of the EGFR (epidermal growth factor receptor), a receptor tyrosine kinase, represents a potential target for cancer treatment. EGFR is induced to dimerize through ligand binding which activates the tyrosine kinase activity of the receptor. This catalyses the transfer of ATP's γ-phosphate to hydroxyl groups of tyrosine residues on the receptor, creating binding sites that recruit downstream signalling proteins. New drugs, SMTKIs (small-molecule tyrosine kinase inhibitors), have been designed to inhibit the tyrosine kinase activity of the receptor, producing an anti-tumour effect. The development of surrogate markers to determine the drug activity of these new inhibitors would be of great benefit in drug evaluation and in the subsequent management of patient disease. This review describes current treatments of cancer using tyrosine kinase inhibitors and the use of proteomic analysis to identify possible markers of activity of these new drugs.

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