scholarly journals Dual regulation of neuronal morphogenesis by a δ-catenin–cortactin complex and Rho

2003 ◽  
Vol 162 (1) ◽  
pp. 99-111 ◽  
Author(s):  
Maria Cruz Martinez ◽  
Tomoyo Ochiishi ◽  
Michael Majewski ◽  
Kenneth S. Kosik
Keyword(s):  
Tyrosine Phosphorylation ◽  
Dendritic Tree ◽  
Src Family Kinases ◽  
Dependent Manner ◽  
Neuronal Morphogenesis ◽  
Neuronal Protein ◽  
Neurite Elongation ◽  
Classical Cadherins

δ-Catenin is a neuronal protein that contains 10 Armadillo motifs and binds to the juxtamembrane segment of classical cadherins. We report that δ-catenin interacts with cortactin in a tyrosine phosphorylation–dependent manner. This interaction occurs within a region of the δ-catenin sequence that is also essential for the neurite elongation effects. Src family kinases can phosphorylate δ-catenin and bind to δ-catenin through its polyproline tract. Under conditions when tyrosine phosphorylation is reduced, δ-catenin binds to cortactin and cells extend unbranched primary processes. Conversely, increasing tyrosine phosphorylation disrupts the δ-catenin–cortactin complex. When RhoA is inhibited, δ-catenin enhances the effects of Rho inhibition on branching. We conclude that δ-catenin contributes to setting a balance between neurite elongation and branching in the elaboration of a complex dendritic tree.

Classical PKCs Regulate ADP-Induced Thromboxane Generation by Modulating Tyrosine Phosphorylation On Novel PKC Isoform Delta Through Shptp-1

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 1064-1064
Author(s):  
Dheeraj Bhavanasi ◽  
Carol T Dangelmaier ◽  
Jin Jianguo ◽  
Soochong Kim ◽  
Satya P. Kunapuli
Keyword(s):  
Tyrosine Phosphorylation ◽  
Conflicts Of Interest ◽  
Tyrosine Phosphatase ◽  
Src Family Kinases ◽  
Dependent Manner ◽  
Functional Responses ◽  
Pkc Isoforms ◽  
Adp Receptors ◽  
Gf 109203X

Abstract Abstract 1064 Introduction: Adenosine Di-phosphate (ADP) is stored in dense granules of platelets and is released upon platelet activation acting as a feedback activator by binding to G-protein coupled P2Y1 and P2Y12 receptors. ADP stimulation causes platelets to change shape, aggregate, release dense and a-granule contents and synthesize thromboxane A2 that can further act as a feedback activator potentiating platelet responses by binding to thromboxane receptor (TP). Protein kinase C is a serine threonine specific kinase that regulates multiple platelet functional responses. Specific PKC isoforms regulating platelet responses downstream of ADP receptors are not completely known. Aim: The aim of the current study is to elucidate the role of PKC isoforms in regulating ADP-induced platelet functional responses in platelets. Methods: We sought to delineate the mechanism of ADP-induced platelet responses by performing platelet aggregation (aggregometry), ATP secretion (luciferin-luciferase reaction) and thromboxane generation (ELISA kit measuring TxB2) in human or murine platelets by pre-incubating the platelets with control (DMSO) or inhibitors wherever mentioned. We also evaluated the role of PKCd to ADP-induced platelet responses by using murine platelets lacking PKCd. Background and Results: Murugappan et al have shown that PKCd was not activated downstream of ADP receptors based on the inability of ADP to cause threonine 507 phosphorylation on PKCd in platelets. However, studies from other labs have shown that PKCd can be activated when it is phosphorylated on its tyrosine residues. In the current study we show that, upon stimulation with 2MeSADP, PKCd is phosphorylated on tyrosine residue 311 in a time-dependent manner in platelets (Fig A). Also, ADP-induced thromboxane generation (Fig B) and ADP-induced thromboxane-mediated dense granule secretion were significantly inhibited in PKCd knockout murine platelets compared to those of wild type platelets. Similarly, thromboxane generation downstream of ADP receptors in human platelets pre-incubated with a PKCd inhibitor is significantly inhibited compared to control indicating a role for PKCd in mediating ADP-induced responses in platelets. Bynagari et al have shown that ADP-induced thromboxane generation is potentiated in the presence of the pan-PKC inhibitor, GF 109203X and the isoform regulating this effect is PKCe. We observed that pre-incubation of PKCe knockout murine platelets with GF 109203X further potentiated ADP-induced thromboxane generation suggesting that there are other PKC isoforms negatively regulating ADP-induced thromboxane generation. We show that this potentiating effect of thromboxane generation with GF 109203X in WT or PKCe KO murine platelets correlate with an increase in the phosphorylation of Y311 on PKCd (Fig C) suggesting that ADP-induced thromboxane generation is regulated through PKCd Y311 phosphorylation. Tyrosine phosphorylation on PKCd is mediated by Src family kinases (SFKs) as the phosphorylation is abolished with PP2, a SFK inhibitor and is only partially inhibited in Fyn knockout murine platelets suggesting that other SFKs also mediate this tyrosine phosphorylation. Surprisingly, pre-incubation of platelets with LY-333531, a classical PKC isoform (a/b) inhibitor potentiated PKCd Y311 phosphorylation (Fig D) as well as thromboxane generation (Fig E) downstream of ADP receptors suggesting a role for classical PKCs. Also, platelets pre-incubated with LY-333531 showed a decrease in the phosphorylation of SHPTP-1 (Fig F), a tyrosine phosphatase, rendering it active. The active SHPTP-1 phosphatase may dephosphorylate and activate SFKs, which can now phosphorylate PKCd on Y311 in platelets. Conclusions: In the current study, we report for the first time that the novel PKC isoform d is tyrosine phosphorylated downstream of ADP receptors through which it mediates ADP-induced thromboxane generation. We also show a novel role for classical PKC isoforms a/b in regulating tyrosine phosphorylation on novel isoform, PKCd possibly through the tyrosine phosphatase SHPTP-1 and Src family kinases in platelets. Disclosures: No relevant conflicts of interest to declare.

scholarly journals CD45 regulation of tyrosine phosphorylation and enzyme activity of src family kinases.

1994 ◽  
Vol 269 (18) ◽  
pp. 13594-13600
Author(s):  
C.M. Burns ◽  
K. Sakaguchi ◽  
E. Appella ◽  
J.D. Ashwell
Keyword(s):  
Enzyme Activity ◽  
Tyrosine Phosphorylation ◽  
Src Family Kinases

scholarly journals Neurofascin as a novel target for autoantibody-mediated axonal injury

2007 ◽  
Vol 204 (10) ◽  
pp. 2363-2372 ◽  
Author(s):  
Emily K. Mathey ◽  
Tobias Derfuss ◽  
Maria K. Storch ◽  
Kieran R. Williams ◽  
Kimberly Hales ◽  
...  
Keyword(s):  
Axonal Injury ◽  
Dependent Manner ◽  
Nodes Of Ranvier ◽  
Native Form ◽  
Neuronal Protein ◽  
Axonal Pathology ◽  
Immune Mediated ◽  
Novel Target

Axonal injury is considered the major cause of disability in patients with multiple sclerosis (MS), but the underlying effector mechanisms are poorly understood. Starting with a proteomics-based approach, we identified neurofascin-specific autoantibodies in patients with MS. These autoantibodies recognize the native form of the extracellular domains of both neurofascin 186 (NF186), a neuronal protein concentrated in myelinated fibers at nodes of Ranvier, and NF155, the oligodendrocyte-specific isoform of neurofascin. Our in vitro studies with hippocampal slice cultures indicate that neurofascin antibodies inhibit axonal conduction in a complement-dependent manner. To evaluate whether circulating antineurofascin antibodies mediate a pathogenic effect in vivo, we cotransferred these antibodies with myelin oligodendrocyte glycoprotein–specific encephalitogenic T cells to mimic the inflammatory pathology of MS and breach the blood–brain barrier. In this animal model, antibodies to neurofascin selectively targeted nodes of Ranvier, resulting in deposition of complement, axonal injury, and disease exacerbation. Collectively, these results identify a novel mechanism of immune-mediated axonal injury that can contribute to axonal pathology in MS.

scholarly journals Nerve Growth Factor Stimulates Multisite Tyrosine Phosphorylation and Activation of the Atypical Protein Kinase C's via a src Kinase Pathway

2001 ◽  
Vol 21 (24) ◽  
pp. 8414-8427 ◽  
Author(s):  
Marie W. Wooten ◽  
Michel L. Vandenplas ◽  
M. Lamar Seibenhener ◽  
Thangiah Geetha ◽  
Maria T. Diaz-Meco
Keyword(s):  
Nerve Growth Factor ◽  
Growth Factor ◽  
Protein Kinase ◽  
Tyrosine Phosphorylation ◽  
Pc12 Cells ◽  
Catalytic Domain ◽  
Src Kinase ◽  
Dependent Manner ◽  
Nerve Growth ◽  
Atypical Protein Kinase

ABSTRACT Atypical protein kinase C (PKC) isoforms are required for nerve growth factor (NGF)-initiated differentiation of PC12 cells. In the present study, we report that PKC-ι becomes tyrosine phosphorylated in the membrane coincident with activation posttreatment with nerve growth factor. Tyrosine phosphorylation and activation of PKC-ι were inhibited in a dose-dependent manner by both PP2 and K252a, src and TrkA kinase inhibitors. Purified src was observed to phosphorylate and activate PKC-ι in vitro. In PC12 cells deficient in src kinase activity, both NGF-induced tyrosine phosphorylation and activation of PKC-ι were also diminished. Furthermore, we demonstrate activation of src by NGF along with formation of a signal complex including the TrkA receptor, src, and PKC-ι. Recruitment of PKC-ι into the complex was dependent on the tyrosine phosphorylation state of PKC-ι. The association of src and PKC-ι was constitutive but was enhanced by NGF treatment, with the src homology 3 domain interacting with a PXXP sequence within the regulatory domain of PKC-ι (amino acids 98 to 114). Altogether, these findings support a role for src in regulation of PKC-ι. Tyrosine 256, 271, and 325 were identified as major sites phosphorylated by src in the catalytic domain. Y256F and Y271F mutations did not alter src-induced activation of PKC-ι, whereas the Y325F mutation significantly reduced src-induced activation of PKC-ι. The functional relevance of these mutations was tested by determining the ability of each mutant to support TRAF6 activation of NF-κB, with significant impairment by the Y325F PKC-ι mutant. Moreover, when the Y352F mutant was expressed in PC12 cells, NGF's ability to promote survival in serum-free media was reduced. In summary, we have identified a novel mechanism for NGF-induced activation of atypical PKC involving tyrosine phosphorylation by c-Src.

scholarly journals Tyrosine Phosphorylation of Tau by the Src Family Kinases Lck and Fyn

2011 ◽  
Vol 6 (1) ◽  
pp. 12 ◽  
Author(s):  
Timothy ME Scales ◽  
Pascal Derkinderen ◽  
Kit-Yi Leung ◽  
Helen L Byers ◽  
Malcolm A Ward ◽  
...  
Keyword(s):  
Tyrosine Phosphorylation ◽  
Src Family Kinases

Streptococcus sanguis-induced platelet activation involves two waves of tyrosine phosphorylation mediated by FcγRIIA and αIIbβ3

2005 ◽  
Vol 93 (05) ◽  
pp. 932-939 ◽  
Author(s):  
Caroline Pampolina ◽  
Archibald McNicol
Keyword(s):  
Signal Transduction ◽  
Platelet Aggregation ◽  
Tyrosine Phosphorylation ◽  
Platelet Activation ◽  
Tyrosine Phosphatase ◽  
Protein Tyrosine Phosphatases ◽  
Lag Phase ◽  
Dependent Manner ◽  
Protein Tyrosine ◽  
Streptococcus Sanguis

SummaryThe low-affinity IgG receptor, FcγRIIA, has been implicated in Streptococcus sanguis-induced platelet aggregation. Therefore, it is likely that signal transduction is at least partly mediated by FcγRIIA activation and a tyrosine kinase-dependent pathway. In this study the signal transduction mechanisms associated with platelet activation in response to the oral bacterium, S. sanguis were characterised. In the presence of IgG, S. sanguis strain 2017–78 caused the tyrosine phosphorylation of FcγRIIA 30s following stimulation, which led to the phosphorylation of Syk, LAT, and PLCγ2. These early events were dependent on Src family kinases but independent of either TxA2 or the engagement of the αIIbβ3 integrin. During the lag phase prior to platelet aggregation, FcγRIIA, Syk, LAT, and PLCγ2 were each dephosphorylated, but were re-phosphorylated as aggregation occurred. Platelet stimulation by 2017–78 also induced the tyrosine phosphorylation of PECAM-1, an ITIM-containing receptor that recruits protein tyrosine phosphatases. PECAM-1 co-precipitated with the protein tyrosine phosphatase SHP-1 in the lag phase. SHP-1 was also maximally tyrosine phosphorylated during this phase, suggesting a possible role for SHP-1 in the observed dephosphorylation events. As aggregation occurred, SHP-1 was dephosphorylated, while FcγRIIA, Syk, LAT, and PLCγ2 were rephosphorylated in an RGDS-sensitive, and therefore αIIbβ3-dependent, manner. Additionally, TxA2 release, 5-hydro-xytryptamine secretion and phosphatidic acid formation were all blocked by RGDS. Aspirin also abolished these events, but only partially inhibited αIIbβ3-mediated re-phosphorylation. Therefore, S.sanguis-bound IgG cross links FcγRIIA and initiates a signaling pathway that is down-regulated by PECAM-1-bound SHP-1. Subsequent engagement of αIIbβ3 leads to SHP-1 dephosphorylation permiting a second wave of signaling leading to TxA2 release and consequent platelet aggregation.

scholarly journals Eukaryotic initiation factor EIF-3.G augments mRNA translation efficiency to regulate neuronal activity

2021 ◽  
Author(s):  
Stephen M Blazie ◽  
Seika Takayanagi-Kiya ◽  
Katherine A McCulloch ◽  
Yishi Jin
Keyword(s):  
Rna Binding ◽  
Mrna Translation ◽  
Initiation Factor ◽  
Translation Efficiency ◽  
Dependent Manner ◽  
Control Activity ◽  
C Elegans ◽  
Protein Levels ◽  
Neuronal Protein

AbstractThe translation initiation complex eIF3 imparts specialized functions to regulate protein expression. However, understanding of eIF3 activities in neurons remains limited despite widespread dysregulation of eIF3 subunits in neurological disorders. Here, we report a selective role of theC. elegansRNA-binding subunit EIF-3.G in shaping the neuronal protein landscape. We identify a missense mutation in the conserved Zinc-Finger (ZF) of EIF-3.G that acts in a gain-of-function manner to dampen neuronal hyperexcitation. Using neuron type-specific seCLIP, we systematically mapped EIF-3.G-mRNA interactions and identified EIF-3.G occupancy on GC-rich 5′UTRs of a select set of mRNAs enriched in activity-dependent functions. We demonstrate that the ZF mutation in EIF-3.G alters translation in a 5′UTR dependent manner. Our study reveals anin vivomechanism for eIF3 in governing neuronal protein levels to control activity states and offers insights into how eIF3 dysregulation contributes to neuronal disorders.

scholarly journals GPR68 Contributes to Persistent Acidosis-Induced Activation of AGC Kinases and Tyrosine Phosphorylation in Organotypic Hippocampal Slices

2021 ◽  
Vol 15 ◽  
Author(s):  
Guokun Zhou ◽  
Xiang-ming Zha
Keyword(s):  
Tyrosine Phosphorylation ◽  
Tyrosine Kinases ◽  
Neurological Diseases ◽  
Hippocampal Slices ◽  
Signaling Cascades ◽  
Dependent Manner ◽  
Cyclin Dependent Kinase ◽  
Ataxia Telangiectasia Mutated ◽  
Agc Kinases ◽  
Profiling Analysis

Persistent acidosis occurs in ischemia and multiple neurological diseases. In previous studies, acidic stimulation leads to rapid increase in intracellular calcium in neurons. However, it remains largely unclear how a prolonged acidosis alters neuronal signaling. In our previous study, we found that GPR68-mediated PKC activities are protective against acidosis-induced injury in cortical slices. Here, we first asked whether the same principle holds true in organotypic hippocampal slices. Our data showed that 1-h pH 6 induced PKC phosphorylation in a GPR68-dependent manner. Go6983, a PKC inhibitor worsened acidosis-induced neuronal injury in wild type (WT) but had no effect in GPR68−/− slices. Next, to gain greater insights into acid signaling in brain tissue, we treated organotypic hippocampal slices with pH 6 for 1-h and performed a kinome profiling analysis by Western blot. Acidosis had little effect on cyclin-dependent kinase (CDK) or casein kinase 2 activity, two members of the CMGC family, or Ataxia telangiectasia mutated (ATM)/ATM and RAD3-related (ATR) activity, but reduced the phosphorylation of MAPK/CDK substrates. In contrast, acidosis induced the activation of CaMKIIα, PKA, and Akt. Besides these serine/threonine kinases, acidosis also induced tyrosine phosphorylation. Since GPR68 is widely expressed in brain neurons, we asked whether GPR68 contributes to acidosis-induced signaling. Deleting GPR68 had no effect on acidosis-induced CaMKII phosphorylation, attenuated that of phospho-Akt and phospho-PKA substrates, while abolishing acidosis-induced tyrosine phosphorylation. These data demonstrate that prolonged acidosis activates a network of signaling cascades, mediated by AGC kinases, CaMKII, and tyrosine kinases. GPR68 is the primary mediator for acidosis-induced activation of PKC and tyrosine phosphorylation, while both GPR68-dependent and -independent mechanisms contribute to the activation of PKA and Akt.

scholarly journals Tyrosine phosphorylation of guanosine triphosphatase activating protein by activation via surface IgG in human B cells

Blood ◽  
1993 ◽  
Vol 81 (6) ◽  
pp. 1535-1539
Author(s):  
H Yagura ◽  
N Oyaizu ◽  
S Pahwa
Keyword(s):  
B Cells ◽  
Tyrosine Phosphorylation ◽  
Signal Transduction Pathway ◽  
Dependent Manner ◽  
Transduction Pathway ◽  
Gtpase Activating Protein ◽  
Human B Cells ◽  
Associated Proteins ◽  
Guanosine Triphosphatase ◽  
Dose Dependent

In this study, we analyzed tyrosine phosphorylation of guanosine triphosphatase (GTPase) activating protein in human B cells stimulated through surface IgG, using Western blot and immunoprecipitation. Stimulation through surface IgG induced the tyrosine phosphorylation of GTPase-activating protein (GAP) and two associated proteins, a 190-Kd protein and a 62-Kd protein, within 1 minute and in a dose-dependent manner. This tyrosine phosphorylation was blocked by Genistein (Extrasynthese, Genay, France). These data suggest that GTPase- activating protein is involved in a signal transduction pathway initiated from surface IgG in human B cells.

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