scholarly journals Nck-Interacting Ste20 Kinase Couples Eph Receptors to c-Jun N-Terminal Kinase and Integrin Activation

2000 ◽  
Vol 20 (5) ◽  
pp. 1537-1545 ◽  
Author(s):  
Elena Becker ◽  
Uyen Huynh-Do ◽  
Sacha Holland ◽  
Tony Pawson ◽  
Tom O. Daniel ◽  
...  
Keyword(s):  
Tyrosine Kinases ◽  
Kinase Activity ◽  
Sh2 Domain ◽  
Mitogen Activated Protein Kinase ◽  
Eph Receptors ◽  
Tyrosine Kinase Signaling ◽  
Amino Terminal ◽  
Biological Responses ◽  
Mitogen Activated Protein ◽  
Tyrosine Phosphorylated Protein

ABSTRACT The mammalian Ste20 kinase Nck-interacting kinase (NIK) specifically activates the c-Jun amino-terminal kinase (JNK) mitogen-activated protein kinase module. NIK also binds the SH3 domains of the SH2/SH3 adapter protein Nck. To determine whether Nck functions as an adapter to couple NIK to a receptor tyrosine kinase signaling pathway, we determined whether NIK is activated by Eph receptors (EphR). EphRs constitute the largest family of receptor tyrosine kinases (RTK), and members of this family play important roles in patterning of the nervous and vascular systems. In this report, we show that NIK kinase activity is specifically increased in cells stimulated by two EphRs, EphB1 and EphB2. EphB1 kinase activity and phosphorylation of a juxtamembrane tyrosine (Y594), conserved in all Eph receptors, are both critical for NIK activation by EphB1. Although pY594 in the EphB1R has previously been shown to bind the SH2 domain of Nck, we found that stimulation of EphB1 and EphB2 led predominantly to a complex between NIK/Nck, p62 dok , RasGAP, and an unidentified 145-kDa tyrosine-phosphorylated protein. Tyrosine-phosphorylated p62 dok most probably binds directly to the SH2 domain of Nck and RasGAP and indirectly to NIK bound to the SH3 domain of Nck. We found that NIK activation is also critical for coupling EphB1R to biological responses that include the activation of integrins and JNK by EphB1. Taken together, these findings support a model in which the recruitment of the Ste20 kinase NIK to phosphotyrosine-containing proteins by Nck is an important proximal step in the signaling cascade downstream of EphRs.

scholarly journals Role of Mitogen- and Stress-Activated Kinases in Ischemic Injury

2002 ◽  
Vol 22 (6) ◽  
pp. 631-647 ◽  
Author(s):  
Elaine A. Irving ◽  
Mark Bamford
Keyword(s):  
Cell Death ◽  
Cerebral Ischemia ◽  
Protein Kinase ◽  
Signaling Pathways ◽  
Focal Cerebral Ischemia ◽  
Mapk Signaling ◽  
Mitogen Activated Protein Kinase ◽  
Amino Terminal ◽  
Biological Responses ◽  
Mitogen Activated Protein

Protein kinase-mediated signaling cascades constitute the major route by which cells respond to their extracellular environment. Of these, three well-characterized mitogen-activated protein kinase (MAPK) signaling pathways are those that use the extracellular signal-regulated kinase (ERK1/2) or the stress-activated protein kinase (p38/SAPK2 or JNK/SAPK) pathways. Mitogenic stimulation of the MAPK-ERK1/2 pathway modulates the activity of many transcription factors, leading to biological responses such as proliferation and differentiation. In contrast, the p38/SAPK2 and JNK/SAPK (c-Jun amino-terminal kinase/stress-activated protein kinase) pathways are only weakly, if at all, activated by mitogens, but are strongly activated by stress stimuli. There is now a growing body of evidence showing that these kinase signaling pathways become activated following a variety of injury stimuli including focal cerebral ischemia. Whether their activation, however, is merely an epiphenomenon of the process of cell death, or is actually involved in the mechanisms underlying ischemia-induced degeneration, remains to be fully understood. This review provides an overview of the current understanding of kinase pathway activation following cerebral ischemia and discusses the evidence supporting a role for these kinases in the mechanisms underlying ischemia-induced cell death.

scholarly journals Differential inhibition of signaling pathways by dominant-negative SH2/SH3 adapter proteins.

1995 ◽  
Vol 15 (12) ◽  
pp. 6829-6837 ◽  
Author(s):  
M Tanaka ◽  
R Gupta ◽  
B J Mayer
Keyword(s):  
Protein Kinase ◽  
Signaling Pathways ◽  
Tyrosine Kinases ◽  
Egf Receptor ◽  
Sh3 Domain ◽  
Sh2 Domain ◽  
Dominant Negative ◽  
Mitogen Activated Protein Kinase ◽  
Erk Activation ◽  
Mitogen Activated Protein

SH2/SH3 adapters are thought to function in signal transduction pathways by coupling inputs from tyrosine kinases to downstream effectors such as Ras. Members of the mitogen-activated protein kinase family are known to be activated by a variety of mitogenic stimuli, including tyrosine kinases such as Abl and the epidermal growth factor (EGF) receptor. We have used activation of the mitogen-activated protein kinase Erk-1 as a model system with which to examine whether various dominant-negative SH2/SH3 adapters (Grb2, Crk, and Nck) could block signaling pathways leading to Erk activation. Activation of Erk-1 by oncogenic Abl was effectively inhibited by Grb2 with mutations in either its SH2 or SH3 domain or by Crk-1 with an SH3 domain mutation. The Crk-1 SH2 mutant was less effective, while Nck SH2 and SH3 mutants had little or no effect on Erk activation. These results suggest that both Crk and Grb2 may contribute to the activation of Erk by oncogenic Abl, whereas Nck is unlikely to participate in this pathway. Next we examined whether combinations of these dominant-negative adapters could inhibit Erk activation more effectively than each mutant alone. When combinations of Crk-1 and Grb2 mutants were analyzed, the combination of the Crk-1 SH3 mutant plus the Grb2 SH3 mutant gave a striking synergistic effect. This finding suggests that in Abl-transformed cells, more than one class of tyrosine-phosphorylated sites (those that bind the Grb2 SH2 domain and those that bind the Crk SH2 domain) can lead to Ras activation. In contrast to results with Abl, Erk activation by EGF was strongly inhibited only by Grb2 mutants; Crk and Nck mutants had little or no effect. This finding suggests that Grb2 is the only adapter involved in the activation of Erk by EGF. Dominant-negative adaptors provide a novel means to identify binding interactions important in vivo for signaling in response to a variety of stimuli.

scholarly journals SHP-2 complex formation with the SHP-2 substrate-1 during C2C12 myogenesis

2001 ◽  
Vol 114 (11) ◽  
pp. 2187-2198
Author(s):  
Maria I. Kontaridis ◽  
Xiangdong Liu ◽  
Lei Zhang ◽  
Anton M. Bennett
Keyword(s):  
Complex Formation ◽  
Tyrosine Kinases ◽  
Tyrosine Phosphatase ◽  
Constitutive Expression ◽  
Sh2 Domain ◽  
Mitogen Activated Protein Kinase ◽  
C2c12 Myoblasts ◽  
Mapk Activity ◽  
Mitogen Activated Protein ◽  
Tyrosyl Phosphorylation

Myogenesis is a highly ordered process that involves the expression of muscle-specific genes, cell-cell recognition and multinucleated myotube formation. Although protein tyrosine kinases have figured prominently in myogenesis, the involvement of tyrosine phosphatases in this process is unknown. SHP-2 is an SH2 domain-containing tyrosine phosphatase, which positively regulates growth and differentiation. We show that in C2C12 myoblasts, SHP-2 becomes upregulated early on during myogenesis and associates with a 120 kDa tyrosyl-phosphorylated complex. We have identified that the 120 kDa complex consists of the SHP-2 substrate-1 (SHPS-1) and the Grb2-associated binder-1 (Gab-1). SHPS-1, but not Gab-1, undergoes tyrosyl phosphorylation and association with SHP-2 during myogenesis, the kinetics of which correlate with the expression of MyoD. Either constitutive expression or inducible activation of MyoD in 10T½ fibroblasts promotes SHPS-1 tyrosyl phosphorylation and its association with SHP-2. It has been shown that p38 mitogen-activated protein kinase (MAPK) activity is required for the expression/activation of MyoD and MyoD-responsive genes. Inhibition of p38 MAPK by SB203580 in differentiating C2C12 myoblasts blocks MyoD expression, SHPS-1 tyrosyl phosphorylation and the association of SHPS-1 with SHP-2. These data suggest that SHPS-1/SHP-2 complex formation is an integral signaling component of skeletal muscle differentiation.

HIV-1 gp120 and chemokine activation of Pyk2 and mitogen-activated protein kinases in primary macrophages mediated by calcium-dependent, pertussis toxin–insensitive chemokine receptor signaling

Blood ◽  
2001 ◽  
Vol 98 (10) ◽  
pp. 2909-2916 ◽  
Author(s):  
Manuela Del Corno ◽  
Qing-Hua Liu ◽  
Dominique Schols ◽  
Erik de Clercq ◽  
Sandra Gessani ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Pertussis Toxin ◽  
Chemokine Receptor ◽  
Calcium Release ◽  
Mitogen Activated Protein Kinase ◽  
Macrophage Infection ◽  
Amino Terminal ◽  
Crac Channels ◽  
Mitogen Activated Protein ◽  
Hiv 1

Abstract Human immunodeficiency virus type 1 (HIV-1) uses the chemokine receptors CCR5 and CXCR4 as coreceptors for entry. It was recently demonstrated that HIV-1 glycoprotein 120 (gp120) elevated calcium and activated several ionic signaling responses in primary human macrophages, which are important targets for HIV-1 in vivo. This study shows that chemokine receptor engagement by both CCR5-dependent (R5) and CXCR4-dependent (X4) gp120 led to rapid phosphorylation of the focal adhesion-related tyrosine kinase Pyk2 in macrophages. Pyk2 phosphorylation was also induced by macrophage inflammatory protein-1β (MIP-1β) and stromal cell–derived factor-1α, chemokine ligands for CCR5 and CXCR4. Activation was blocked by EGTA and by a potent blocker of calcium release–activated Ca++(CRAC) channels, but was insensitive to pertussis toxin (PTX), implicating CRAC-mediated extracellular Ca++ influx but not Gαi protein-dependent mechanisms. Coreceptor engagement by gp120 and chemokines also activated 2 members of the mitogen-activated protein kinase (MAPK) superfamily, c-Jun amino-terminal kinase/stress-activated protein kinase and p38 MAPK. Furthermore, gp120-stimulated macrophages secreted the chemokines monocyte chemotactic protein-1 and MIP-1β in a manner that was dependent on MAPK activation. Thus, the gp120 signaling cascade in macrophages includes coreceptor binding, PTX-insensitive signal transduction, ionic signaling including Ca++ influx, and activation of Pyk2 and MAPK pathways, and leads to secretion of inflammatory mediators. HIV-1 Env signaling through these pathways may contribute to dysregulation of uninfected macrophage functions, new target cell recruitment, or modulation of macrophage infection.

scholarly journals Stat5 activation enables erythropoiesis in the absence of EpoR and Jak2

Blood ◽  
2008 ◽  
Vol 111 (9) ◽  
pp. 4511-4522 ◽  
Author(s):  
Florian Grebien ◽  
Marc A. Kerenyi ◽  
Boris Kovacic ◽  
Thomas Kolbe ◽  
Verena Becker ◽  
...  
Keyword(s):  
Fetal Liver ◽  
Janus Kinase ◽  
Mitogen Activated Protein Kinase ◽  
Independent Manner ◽  
Hematopoietic Stem ◽  
Tyrosine Kinase Signaling ◽  
Fusion Construct ◽  
Downstream Effector ◽  
Kit Receptor ◽  
Mitogen Activated Protein

Abstract Erythropoiesis requires erythropoietin (Epo) and stem cell factor (SCF) signaling via their receptors EpoR and c-Kit. EpoR, like many other receptors involved in hematopoiesis, acts via the kinase Jak2. Deletion of EpoR or Janus kinase 2 (Jak2) causes embryonic lethality as a result of defective erythropoiesis. The contribution of distinct EpoR/Jak2-induced signaling pathways (mitogen-activated protein kinase, phosphatidylinositol 3-kinase, signal transducer and activator of transcription 5 [Stat5]) to functional erythropoiesis is incompletely understood. Here we demonstrate that expression of a constitutively activated Stat5a mutant (cS5) was sufficient to relieve the proliferation defect of Jak2−/− and EpoR−/− cells in an Epo-independent manner. In addition, tamoxifen-induced DNA binding of a Stat5a–estrogen receptor (ER)* fusion construct enabled erythropoiesis in the absence of Epo. Furthermore, c-Kit was able to enhance signaling through the Jak2-Stat5 axis, particularly in lymphoid and myeloid progenitors. Although abundance of hematopoietic stem cells was 2.5-fold reduced in Jak2−/− fetal livers, transplantation of Jak2−/−-cS5 fetal liver cells into irradiated mice gave rise to mature erythroid and myeloid cells of donor origin up to 6 months after transplantation. Cytokine- and c-Kit pathways do not function independently of each other in hematopoiesis but cooperate to attain full Jak2/Stat5 activation. In conclusion, activated Stat5 is a critical downstream effector of Jak2 in erythropoiesis/myelopoiesis, and Jak2 functionally links cytokine- with c-Kit-receptor tyrosine kinase signaling.

scholarly journals A Rare p.T599dup BRAF Mutant NSCLC in a Non-Smoker

2020 ◽  
Vol 28 (1) ◽  
pp. 196-202
Author(s):  
Alla Turshudzhyan ◽  
James Vredenburgh
Keyword(s):  
Lung Cancer ◽  
Targeted Therapies ◽  
Kinase Activity ◽  
Mitogen Activated Protein Kinase ◽  
Braf Mutations ◽  
Activating Mutations ◽  
Extracellular Signal ◽  
Activating Mutation ◽  
Mitogen Activated Protein ◽  
Murine Sarcoma

V-RAF murine sarcoma viral oncogene homolog B1 (BRAF) mutated non-small-cell lung cancer (NSCLC) is an exceptionally rare form of lung cancer, found only in one to two percent of patients with an NSCLC diagnosis. BRAF NSCLC traditionally affects former or active smokers. BRAF mutations have always been of special interest to the oncological community, as they offer potential for targeted therapies. BRAF mutation spectrum includes mutations that are of both V600 and non-V600 types. BRAF V600 is an activating mutation, which results in high kinase activity and overproduction of active oncoproteins such as rapidly accelerated fibrosarcoma (RAF). This makes them susceptible to targeted therapies with RAF inhibitors. There has been little evidence, however, regarding efficacy of RAF inhibitors towards non-activating mutations that have intermediate to low kinase activity, such as non-V600 BRAF mutations. While several approaches have been investigated to overcome the limitations of RAF inhibitors, such as use of mitogen-activated protein kinase kinase (MEK) and extracellular signal-regulated kinase (ERK) inhibitors or combination of MEK and RAF inhibitors, none of them have been proven to have a superior efficacy for low kinase activity non-V600 BRAF tumors. We present a case of an extremely rare variant of NSCLC BRAF p.T599dup mutation in a non-smoker that responded to a targeted combination therapy with RAF and MEK inhibitors. The patient responded well to therapy that usually targets high kinase activity V600 mutations. Our hope is to bring more attention to non-V600 mutations and document their responses to existing and new therapies.

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