scholarly journals JAK2 Tyrosine Kinase Phosphorylates and Is Negatively Regulated by Centrosomal Protein Ninein

2014 ◽  
Vol 35 (1) ◽  
pp. 111-131 ◽  
Author(s):  
Jennifer Jay ◽  
Alan Hammer ◽  
Andrea Nestor-Kalinoski ◽  
Maria Diakonova
Keyword(s):  
Tyrosine Kinase ◽  
Kinase Activity ◽  
Cytokine Signaling ◽  
Centrosomal Protein ◽  
C Terminus ◽  
Dependent Inhibition ◽  
Important Regulator ◽  
Terminal Amino ◽  
Tyrosyl Phosphorylation

JAK2 is a cytoplasmic tyrosine kinase critical for cytokine signaling. In this study, we have identified a novel centrosome-associated complex containing ninein and JAK2. We have found that active JAK2 localizes around the mother centrioles, where it partly colocalizes with ninein, a protein involved in microtubule (MT) nucleation and anchoring. We demonstrated that JAK2 is an important regulator of centrosome function. Depletion of JAK2 or use of JAK2-null cells causes defects in MT anchoring and increased numbers of cells with mitotic defects; however, MT nucleation is unaffected. We showed that JAK2 directly phosphorylates the N terminus of ninein while the C terminus of ninein inhibits JAK2 kinase activityin vitro. Overexpressed wild-type (WT) or C-terminal (amino acids 1179 to 1931) ninein inhibits JAK2. This ninein-dependent inhibition of JAK2 significantly decreases prolactin- and interferon gamma (IFN-γ)-induced tyrosyl phosphorylation of STAT1 and STAT5. Downregulation of ninein enhances JAK2 activation. These results indicate that JAK2 is a novel member of centrosome-associated complex and that this localization regulates both centrosomal function and JAK2 kinase activity, thus controlling cytokine-activated molecular pathways.

scholarly journals Constitutive Association of BRCA1 and c-Abl and Its ATM-Dependent Disruption after Irradiation

2002 ◽  
Vol 22 (12) ◽  
pp. 4020-4032 ◽  
Author(s):  
Nicolas Foray ◽  
Didier Marot ◽  
Voahangy Randrianarison ◽  
Nicole Dalla Venezia ◽  
Didier Picard ◽  
...  
Keyword(s):  
Tyrosine Kinase ◽  
Kinase Activity ◽  
Direct Interaction ◽  
Cell Cycle Checkpoint ◽  
Dependent Manner ◽  
Tyrosine Kinase Activity ◽  
Abl Tyrosine Kinase ◽  
C Terminus

ABSTRACT BRCA1 plays an important role in mechanisms of response to double-strand breaks, participating in genome surveillance, DNA repair, and cell cycle checkpoint arrests. Here, we identify a constitutive BRCA1-c-Abl complex and provide evidence for a direct interaction between the PXXP motif in the C terminus of BRCA1 and the SH3 domain of c-Abl. Following exposure to ionizing radiation (IR), the BRCA1-c-Abl complex is disrupted in an ATM-dependent manner, which correlates temporally with ATM-dependent phosphorylation of BRCA1 and ATM-dependent enhancement of the tyrosine kinase activity of c-Abl. The BRCA1-c-Abl interaction is affected by radiation-induced modification to both BRCA1 and c-Abl. We show that the C terminus of BRCA1 is phosphorylated by c-Abl in vitro. In vivo, BRCA1 is phosphorylated at tyrosine residues in an ATM-dependent, radiation-dependent manner. Tyrosine phosphorylation of BRCA1, however, is not required for the disruption of the BRCA1-c-Abl complex. BRCA1-mutated cells exhibit constitutively high c-Abl kinase activity that is not further increased on exposure to IR. We suggest a model in which BRCA1 acts in concert with ATM to regulate c-Abl tyrosine kinase activity.

scholarly journals C-Terminus or Juxtamembrane Deletions in the Insulin Receptor do not Affect the Glucose-Dependent Inhibition of the Tyrosine Kinase Activity

2008 ◽  
Vol 227 (3) ◽  
pp. 787-791
Author(s):  
Luitgard Mosthaf ◽  
Lucia Berti ◽  
Monika Kellerer ◽  
Joanne Mushack ◽  
Eva Seffer ◽  
...  
Keyword(s):  
Tyrosine Kinase ◽  
Insulin Receptor ◽  
Kinase Activity ◽  
Tyrosine Kinase Activity ◽  
C Terminus ◽  
Dependent Inhibition

scholarly journals Regulation of Jak2 Function by Phosphorylation of Tyr317 and Tyr637 during Cytokine Signaling

2009 ◽  
Vol 29 (12) ◽  
pp. 3367-3378 ◽  
Author(s):  
Scott A. Robertson ◽  
Rositsa I. Koleva ◽  
Lawrence S. Argetsinger ◽  
Christin Carter-Su ◽  
Jarrod A. Marto ◽  
...  
Keyword(s):  
Tyrosine Kinase ◽  
Kinase Activity ◽  
Feedback Inhibition ◽  
Dominant Role ◽  
Kinase Domain ◽  
Cytokine Signaling ◽  
Tyrosine Kinase Domain ◽  
Phosphorylation Sites ◽  
Cytokine Stimulation

ABSTRACT Jak2, the cognate tyrosine kinase for numerous cytokine receptors, undergoes multisite phosphorylation during cytokine stimulation. To understand the role of phosphorylation in Jak2 regulation, we used mass spectrometry to identify numerous Jak2 phosphorylation sites and characterize their significance for Jak2 function. Two sites outside of the tyrosine kinase domain, Tyr317 in the FERM domain and Tyr637 in the JH2 domain, exhibited strong regulation of Jak2 activity. Mutation of Tyr317 promotes increased Jak2 activity, and the phosphorylation of Tyr317 during cytokine signaling requires prior activation loop phosphorylation, which is consistent with a role for Tyr317 in the feedback inhibition of Jak2 kinase activity after receptor stimulation. Comparison to several previously identified regulatory phosphorylation sites on Jak2 revealed a dominant role for Tyr317 in the attenuation of Jak2 signaling. In contrast, mutation of Tyr637 decreased Jak2 signaling and activity and partially suppressed the activating JH2 V617F mutation, suggesting a role for Tyr637 phosphorylation in the release of JH2 domain-mediated suppression of Jak2 kinase activity during cytokine stimulation. The phosphorylation of Tyr317 and Tyr637 act in concert with other regulatory events to maintain appropriate control of Jak2 activity and cytokine signaling.

scholarly journals Topology of Streptococcus pneumoniae CpsC, a Polysaccharide Copolymerase and Bacterial Protein Tyrosine Kinase Adaptor Protein

2014 ◽  
Vol 197 (1) ◽  
pp. 120-127 ◽  
Author(s):  
Jonathan J. Whittall ◽  
Renato Morona ◽  
Alistair J. Standish
Keyword(s):  
Streptococcus Pneumoniae ◽  
Tyrosine Kinase ◽  
Tyrosine Kinases ◽  
Kinase Activity ◽  
Tyrosine Phosphatase ◽  
Adaptor Protein ◽  
Tyrosine Kinase Activity ◽  
Content Type ◽  
Protein Tyrosine ◽  
C Terminus

In Gram-positive bacteria, tyrosine kinases are split into two proteins, the cytoplasmic tyrosine kinase and a transmembrane adaptor protein. InStreptococcus pneumoniae, this transmembrane adaptor is CpsC, with the C terminus of CpsC critical for interaction and subsequent tyrosine kinase activity of CpsD. Topology predictions suggest that CpsC has two transmembrane domains, with the N and C termini present in the cytoplasm. In order to investigate CpsC topology, we used a chromosomal hemagglutinin (HA)-tagged Cps2C protein inS. pneumoniaestrain D39. Incubation of both protoplasts and membranes with carboxypeptidase B (CP-B) resulted in complete degradation of HA-Cps2C in all cases, indicating that the C terminus of Cps2C was likely extracytoplasmic and hence that the protein's topology was not as predicted. Similar results were seen with membranes fromS. pneumoniaestrain TIGR4, indicating that Cps4C also showed similar topology. A chromosomally encoded fusion of HA-Cps2C and Cps2D was not degraded by CP-B, suggesting that the fusion fixed the C terminus within the cytoplasm. However, capsule synthesis was unaltered by this fusion. Detection of the CpsC C terminus by flow cytometry indicated that it was extracytoplasmic in approximately 30% of cells. Interestingly, a mutant in the protein tyrosine phosphatase CpsB had a significantly greater proportion of positive cells, although this effect was independent of its phosphatase activity. Our data indicate that CpsC possesses a varied topology, with the C terminus flipping across the cytoplasmic membrane, where it interacts with CpsD in order to regulate tyrosine kinase activity.

Modulation of pp60c-src activity and cellular localization during differentiation of human trophoblast cells in culture

1993 ◽  
Vol 105 (3) ◽  
pp. 629-636 ◽  
Author(s):  
C. Rebut-Bonneton ◽  
S. Boutemy-Roulier ◽  
D. Evain-Brion
Keyword(s):  
Tyrosine Kinase ◽  
Cellular Localization ◽  
Kinase Activity ◽  
Cell Aggregation ◽  
Trophoblast Cells ◽  
Tyrosine Kinase Activity ◽  
Human Trophoblast ◽  
Human Trophoblast Cells ◽  
E Cadherin

The morphological and functional differentiation of human trophoblast cells ends with the formation of terminally differentiated multinucleated syncytial trophoblasts. This in vivo differentiation is mimicked in vitro during the primary culture of extravillous cytotrophoblasts: isolated mononuclear cytotrophoblasts aggregate and fuse to form syncytia. This in vitro differentiation is associated with an increase in epidermal growth factor receptor (EGF-R) expression and a transitory increase in E-cadherin expression during cell aggregation. In the present study, we investigated the expression of pp60c-src during morphological differentiation of trophoblast cells. Cultures were terminated at various time intervals and pp60c-src was analysed by immunocytochemistry using a specific antibody. In addition, pp60c-src was investigated by western blot analysis and its tyrosine kinase activity was measured concomitantly. In mononuclear cytotrophoblasts, pp60c-src was localized at cell-matrix contacts and during the aggregation of cytotrophoblasts, pp60c-src was distributed on the cell surface at points of cell-cell contact being colocalized with EGF-R and E-cadherin. The kinase activity of the pp60c-src protein increased significantly at day 2 when cells were completely aggregated and started to fuse, and remained elevated while cells underwent further differentiation. Inhibition of pp60c-src by herbimycin A at 0.25 to 1 microgram/ml during the first day of culture was associated with a decreased expression of tyrosine kinase activity of EGF-R and an increase in E-cadherin expression. These data suggest that pp60c-src is involved in the modulation of trophoblast cell aggregation and fusion leading to syncytial formation.

Reduction of tyrosine kinase activity and protein tyrosine dephosphorylation by anoxic stimulation in vitro

Neuroscience ◽  
1997 ◽  
Vol 82 (1) ◽  
pp. 161-170 ◽  
Author(s):  
J.L Braunton ◽  
V Wong ◽  
W Wang ◽  
M.W Salter ◽  
J Roder ◽  
...  
Keyword(s):  
Tyrosine Kinase ◽  
Kinase Activity ◽  
Tyrosine Kinase Activity ◽  
Protein Tyrosine

scholarly journals Activation of the c-abl oncogene by viral transduction or chromosomal translocation generates altered c-abl proteins with similar in vitro kinase properties.

1985 ◽  
Vol 5 (1) ◽  
pp. 204-213 ◽  
Author(s):  
R L Davis ◽  
J B Konopka ◽  
O N Witte
Keyword(s):  
Tyrosine Kinase ◽  
Kinase Activity ◽  
Leukemia Virus ◽  
Leukemia Cell ◽  
Chromosomal Translocation ◽  
Leukemia Cell Line ◽  
Tyrosine Kinase Activity ◽  
Serine Kinase ◽  
Abelson Murine Leukemia Virus

The v-abl protein of Abelson murine leukemia virus is a tyrosine-specific kinase. Its normal cellular homolog, murine c-abl, does not possess detectable tyrosine kinase activity in vitro. Previously, we have detected tyrosine kinase activity in vitro for an altered c-abl gene product (c-abl P210) in the K562 human chronic myelogenous leukemia cell line. The expression of this variant c-abl gene product correlates with chromosomal translocation and amplification of the c-abl gene in K562 cells. Like v-abl, c-abl P210 is a fusion protein containing non-abl sequences near the amino terminus of c-abl. We compared the in vitro tyrosine kinase activity of c-abl P210 with that of wild-type murine v-abl. The remarkable similarities of these two proteins with respect to cis-acting autophosphorylation, trans-acting phosphorylation of exogenous substrates, and kinase inhibition, using site-directed abl-specific antisera, suggested that c-abl P210 could function similarly to v-abl in vivo. In addition, c-abl P210 possessed an associated serine kinase activity in immunoprecipitates. The serine kinase activity was not inhibited by site-directed, abl-specific antisera that inhibit the tyrosine kinase activity, suggesting that the serine kinase activity is not an intrinsic property of c-abl P210. Thus, the activation of the c-abl gene in a human leukemia cell line may have functional consequences analogous to activation of the c-abl gene in Abelson murine leukemia virus.

scholarly journals Mammary tumors expressing the neu proto-oncogene possess elevated c-Src tyrosine kinase activity.

1994 ◽  
Vol 14 (1) ◽  
pp. 735-743 ◽  
Author(s):  
S K Muthuswamy ◽  
P M Siegel ◽  
D L Dankort ◽  
M A Webster ◽  
W J Muller
Keyword(s):  
Signal Transduction ◽  
Tyrosine Kinase ◽  
Kinase Activity ◽  
Specific Activity ◽  
Fusion Gene ◽  
Mammary Tumorigenesis ◽  
Mammary Tumors ◽  
Tyrosine Kinase Activity ◽  
Src Tyrosine Kinase

Amplification and overexpression of the neu (c-erbB2) proto-oncogene has been implicated in the pathogenesis of 20 to 30% of human breast cancers. Although the activation of Neu receptor tyrosine kinase appears to be a pivotal step during mammary tumorigenesis, the mechanism by which Neu signals cell proliferation is unclear. Molecules bearing a domain shared by the c-Src proto-oncogene (Src homology 2) are thought to be involved in signal transduction from activated receptor tyrosine kinases such as Neu. To test whether c-Src was implicated in Neu-mediated signal transduction, we measured the activity of the c-Src tyrosine kinase in tissue extracts from either mammary tumors or adjacent mammary epithelium derived from transgenic mice expressing a mouse mammary tumor virus promoter/enhancer/unactivated neu fusion gene. The Neu-induced mammary tumors possessed six- to eightfold-higher c-Src kinase activity than the adjacent epithelium. The increase in c-Src tyrosine kinase activity was not due to an increase in the levels of c-Src but rather was a result of the elevation of its specific activity. Moreover, activation of c-Src was correlated with its ability to complex tyrosine-phosphorylated Neu both in vitro and in vivo. Together, these observations suggest that activation of the c-Src tyrosine kinase during mammary tumorigenesis may occur through a direct interaction with activated Neu.

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