scholarly journals Dynamic Interaction of PTPμ with Multiple Cadherins In Vivo

1998 ◽  
Vol 141 (1) ◽  
pp. 287-296 ◽  
Author(s):  
Susann M. Brady-Kalnay ◽  
Tracy Mourton ◽  
Joseph P. Nixon ◽  
Gregory E. Pietz ◽  
Michael Kinch ◽  
...  
Keyword(s):  
Tyrosine Phosphorylation ◽  
Tyrosine Phosphatase ◽  
Cross Reactivity ◽  
Receptor Protein ◽  
Temperature Sensitive ◽  
Mutant Form ◽  
Cell Biol ◽  
E Cadherin

There is a growing body of evidence to implicate reversible tyrosine phosphorylation as an important mechanism in the control of the adhesive function of cadherins. We previously demonstrated that the receptor protein tyrosine phosphatase PTPμ associates with the cadherin–catenin complex in various tissues and cells and, therefore, may be a component of such a regulatory mechanism (Brady-Kalnay, S.M., D.L. Rimm, and N.K. Tonks. 1995. J. Cell Biol. 130:977– 986). In this study, we present further characterization of this interaction using a variety of systems. We observed that PTPμ interacted with N-cadherin, E-cadherin, and cadherin-4 (also called R-cadherin) in extracts of rat lung. We observed a direct interaction between PTPμ and E-cadherin after coexpression in Sf9 cells. In WC5 cells, which express a temperature-sensitive mutant form of v-Src, the complex between PTPμ and E-cadherin was dynamic, and conditions that resulted in tyrosine phosphorylation of E-cadherin were associated with dissociation of PTPμ from the complex. Furthermore, we have demonstrated that the COOH-terminal 38 residues of the cytoplasmic segment of E-cadherin was required for association with PTPμ in WC5 cells. Zondag et al. (Zondag, G., W. Moolenaar, and M. Gebbink. 1996. J. Cell Biol. 134: 1513–1517) have asserted that the association we observed between PTPμ and the cadherin–catenin complex in immunoprecipitates of the phosphatase arises from nonspecific cross-reactivity between BK2, our antibody to PTPμ, and cadherins. In this study we have confirmed our initial observation and demonstrated the presence of cadherin in immunoprecipitates of PTPμ obtained with three antibodies that recognize distinct epitopes in the phosphatase. In addition, we have demonstrated directly that the anti-PTPμ antibody BK2 that we used initially did not cross-react with cadherin. Our data reinforce the observation of an interaction between PTPμ and E-cadherin in vitro and in vivo, further emphasizing the potential importance of reversible tyrosine phosphorylation in regulating cadherin function.

Abstract 12231: PECAM1 is Essential for Flow-mediated Gab1 Tyrosine Phosphorylation and Signaling in vitro and in vivo

Circulation ◽  
2015 ◽  
Vol 132 (suppl_3) ◽  
Author(s):  
Suowen Xu ◽  
Marina Koroleva ◽  
Keigi Fujiwara ◽  
Zheng Gen Jin
Keyword(s):  
Tyrosine Phosphorylation ◽  
Wheel Running ◽  
Tyrosine Phosphatase ◽  
Common Mechanism ◽  
Membrane Localization ◽  
No Production ◽  
Voluntary Wheel Running ◽  
Voluntary Wheel

Introduction: Impaired activation of endothelial nitric oxide (NO) synthase (eNOS) and ensued NO production is a common mechanism of various cardiovascular pathologies, including hypertension and atherosclerosis. Specific signaling cascades, generated by vascular endothelial cells (ECs) in response to laminar flow, modulate EC structure and functions, NO production in particular. We have previously shown that flow-stimulated Gab1 (Grb2-associated binder-1) tyrosine phosphorylation mediates eNOS activation. However, the upstream mechanism that regulates Gab1 tyrosine phosphorylation remains unclear. Hypothesis: We hypothesized that platelet endothelial cell adhesion molecule-1 (PECAM1), a key molecule in an endothelial mechanosensing complex, specifically mediates Gab1 tyrosine phosphorylation and its downstream Akt and eNOS activation in ECs upon flow rather than hepatocyte growth factor (HGF) stimulation. Methods: Western blot, en face staining and voluntary wheel running. Results: Small interfering RNA (siRNA) targeting PECAM1 abolished flow- but not HGF-induced Gab1 tyrosine phosphorylation and Akt, eNOS activation as well as Gab1 membrane translocation. Protein-tyrosine phosphatase SHP2, which has been shown to interact with Gab1, was involved in a flow signaling pathway as well as HGF-induced signaling, as SHP2 siRNA diminished the flow- and HGF-induced Gab1 tyrosine phosphorylation, membrane localization and downstream signaling. Pharmacological inhibition of PI3K by LY294002 decreased flow, but not HGF-mediated Gab1 phosphorylation and membrane localization as well as eNOS activation. Finally, we observed that flow-mediated Gab1 and eNOS phosphorylation in vivo induced by voluntary wheel running was reduced in PECAM1 knockout mice. Conclusions: These results demonstrate a specific role of PECAM1 in flow-mediated Gab1 tyrosine phosphorylation and eNOS signaling in ECs

scholarly journals Tyrosine 425 within the activated erythropoietin receptor binds Syp, reduces the erythropoietin required for Syp tyrosine phosphorylation, and promotes mitogenesis

Blood ◽  
1996 ◽  
Vol 87 (11) ◽  
pp. 4495-4501 ◽  
Author(s):  
T Tauchi ◽  
JE Damen ◽  
K Toyama ◽  
GS Feng ◽  
HE Broxmeyer ◽  
...  
Keyword(s):  
Tyrosine Phosphorylation ◽  
Tyrosine Kinases ◽  
Intracellular Signaling ◽  
Tyrosine Phosphatase ◽  
Erythropoietin Receptor ◽  
Sh2 Domains ◽  
Proliferation And Differentiation ◽  
Stimulation Of

Erythropoietin (Epo), the primary in vivo stimulator of erythroid proliferation and differentiation, acts, in part, by altering the tyrosine phosphorylation levels of various intracellular signaling molecules. These phosphorylation levels are tightly regulated by both tyrosine kinases and tyrosine phosphatases. We have recently shown that the SH2 containing tyrosine phosphatase, Syp, binds directly to both the tyrosine phosphorylated form of the Epo receptor (EpoR) and to Grb2 after Epo stimulation of M07e cells engineered to express high levels of human EpoRs (T. Tauchi, et al: J Biol Chem 270:5631, 1995). To determine which tyrosine within the EpoR is responsible for binding Syp, we examined DA-3 cell lines expressing full-length mutant EpoRs bearing tyrosine to phenylalanine substitutions for each of the eight tyrosines within the intracellular domain of the EpoR. We found that: (1) all Epo-stimulated mutant EpoRs, except for the Y425F EpoR, coimmunoprecipitated with Syp; (2) all Epo-stimulated mutant EpoRs, except for the Y425F EpoR, bound to a GST-fusion protein containing both SH2 domains of Syp; (3) Jak2 could phosphorylate GST-Syp in vitro after Epo stimulation of wild-type (wt) EpoR expressing DA-3 cells; (4) Epo-stimulated tyrosine phosphorylation of Syp in vivo was markedly reduced in Y425F EpoR expressing DA-3 calls; and (5) DA-3 cells expressing the Y425F EpoR grow less well in response to Epo than wt EpoR expressing cells. These results suggest that Syp binds via its SH2 domains to phosphorylated Y425 within the EpoR and is then phosphorylated on tyrosine residues by Jak2. Moreover, Y425 in the EpoR reduces the Epo requirement for Syp tyrosine phosphorylation and promotes proliferation.

Identification and characterization of a high-affinity interaction between v-Crk and tyrosine-phosphorylated paxillin in CT10-transformed fibroblasts

1993 ◽  
Vol 13 (8) ◽  
pp. 4648-4656
Author(s):  
R B Birge ◽  
J E Fajardo ◽  
C Reichman ◽  
S E Shoelson ◽  
Z Songyang ◽  
...  
Keyword(s):  
Fusion Protein ◽  
Tyrosine Phosphorylation ◽  
Cell Transformation ◽  
Tyrosine Phosphatase ◽  
State Level ◽  
Sh2 Domain ◽  
Sequence Specificity ◽  
Src Homology

The genome of avian sarcoma virus CT10 encodes a fusion protein in which viral Gag sequences are fused to cellular Crk sequences containing primarily Src homology 2 (SH2) and Src homology 3 (SH3) domains. Transformation of chicken embryo fibroblasts (CEF) with the Gag-Crk fusion protein results in the elevation of tyrosine phosphorylation on specific cellular proteins with molecular weights of 130,000, 110,000, and 70,000 (p130, p110, and p70, respectively), an event which has been correlated with cell transformation. In this study, we have identified the 70-kDa tyrosine-phosphorylated protein in CT10-transformed CEF (CT10-CEF) as paxillin, a cytoskeletal protein suggested to be important for organizing the focal adhesion. Tyrosine-phosphorylated paxillin was found to be complexed with v-Crk in vivo as evident from coimmunoprecipitation studies. Moreover, a bacterially expressed recombinant glutathione S-transferase (GST)-CrkSH2 fragment bound paxillin in vitro with a subnanomolar affinity, suggesting that the SH2 domain of v-Crk is sufficient for binding. Mapping of the sequence specificity of a GST-CrkSH2 fusion protein with a partially degenerate phosphopeptide library determined a motif consisting of pYDXP, and in competitive coprecipitation studies, an acetylated A(p)YDAPA hexapeptide was able to quantitatively inhibit the binding of GST-CrkSH2 to paxillin and p130, suggesting that it meets the minimal structural requirements necessary for the interaction of CrkSH2 with physiological targets. To investigate the mechanism by which v-Crk elevates the tyrosine phosphorylation of paxillin in vivo, we have treated normal CEF and CT10-CEF with sodium vanadate to inhibit protein tyrosine phosphatase activity. These data suggest that paxillin is involved in a highly dynamic kinase-phosphatase interplay in normal CEF and that v-Crk binding may interrupt this balance to increase the steady-state level of tyrosine phosphorylation. By contrast, the 130-kDa protein was not tyrosine phosphorylated upon vanadate treatment of normal CEF and only weakly affected in the CT10-CEF, suggesting that a different mechanism may be involved in its phosphorylation.

scholarly journals Functions of the Ectodomain and Cytoplasmic Tyrosine Phosphatase Domains of Receptor Protein Tyrosine Phosphatase Dlar In Vivo

2003 ◽  
Vol 23 (19) ◽  
pp. 6909-6921 ◽  
Author(s):  
Neil X. Krueger ◽  
R. Sreekantha Reddy ◽  
Karl Johnson ◽  
Jack Bateman ◽  
Nancy Kaufmann ◽  
...  
Keyword(s):  
Protein Tyrosine Phosphatase ◽  
Tyrosine Phosphatase ◽  
P Element ◽  
Receptor Protein ◽  
Loss Of Function ◽  
Protein Tyrosine ◽  
Receptor Protein Tyrosine Phosphatase ◽  
Catalytically Active

ABSTRACT The receptor protein tyrosine phosphatase (PTPase) Dlar has an ectodomain consisting of three immunoglobulin (Ig)-like domains and nine fibronectin type III (FnIII) repeats and a cytoplasmic domain consisting of two PTPase domains, membrane-proximal PTP-D1 and C-terminal PTP-D2. A series of mutant Dlar transgenes were introduced into the Drosophila genome via P-element transformation and were then assayed for their capacity to rescue phenotypes caused by homozygous loss-of-function genotypes. The Ig-like domains, but not the FnIII domains, are essential for survival. Conversely, the FnIII domains, but not the Ig-like domains, are required during oogenesis, suggesting that different domains of the Dlar ectodomain are involved in distinct functions during Drosophila development. All detectable PTPase activity maps to PTP-D1 in vitro. The catalytically inactive mutants of Dlar were able to rescue Dlar −/− lethality nearly as efficiently as wild-type Dlar transgenes, while this ability was impaired in the PTP-D2 deletion mutants DlarΔPTP-D2 and Dlarbypass . Dlar-C1929S, in which PTP-D2 has been inactivated, increases the frequency of bypass phenotype observed in Dlar −/− genotypes, but only if PTP-D1 is catalytically active in the transgene. These results indicate multiple roles for PTP-D2, perhaps by acting as a docking domain for downstream elements and as a regulator of PTP-D1.

scholarly journals Identification and characterization of a high-affinity interaction between v-Crk and tyrosine-phosphorylated paxillin in CT10-transformed fibroblasts.

1993 ◽  
Vol 13 (8) ◽  
pp. 4648-4656 ◽  
Author(s):  
R B Birge ◽  
J E Fajardo ◽  
C Reichman ◽  
S E Shoelson ◽  
Z Songyang ◽  
...  
Keyword(s):  
Fusion Protein ◽  
Tyrosine Phosphorylation ◽  
Cell Transformation ◽  
Tyrosine Phosphatase ◽  
State Level ◽  
Sh2 Domain ◽  
Sequence Specificity ◽  
Src Homology

The genome of avian sarcoma virus CT10 encodes a fusion protein in which viral Gag sequences are fused to cellular Crk sequences containing primarily Src homology 2 (SH2) and Src homology 3 (SH3) domains. Transformation of chicken embryo fibroblasts (CEF) with the Gag-Crk fusion protein results in the elevation of tyrosine phosphorylation on specific cellular proteins with molecular weights of 130,000, 110,000, and 70,000 (p130, p110, and p70, respectively), an event which has been correlated with cell transformation. In this study, we have identified the 70-kDa tyrosine-phosphorylated protein in CT10-transformed CEF (CT10-CEF) as paxillin, a cytoskeletal protein suggested to be important for organizing the focal adhesion. Tyrosine-phosphorylated paxillin was found to be complexed with v-Crk in vivo as evident from coimmunoprecipitation studies. Moreover, a bacterially expressed recombinant glutathione S-transferase (GST)-CrkSH2 fragment bound paxillin in vitro with a subnanomolar affinity, suggesting that the SH2 domain of v-Crk is sufficient for binding. Mapping of the sequence specificity of a GST-CrkSH2 fusion protein with a partially degenerate phosphopeptide library determined a motif consisting of pYDXP, and in competitive coprecipitation studies, an acetylated A(p)YDAPA hexapeptide was able to quantitatively inhibit the binding of GST-CrkSH2 to paxillin and p130, suggesting that it meets the minimal structural requirements necessary for the interaction of CrkSH2 with physiological targets. To investigate the mechanism by which v-Crk elevates the tyrosine phosphorylation of paxillin in vivo, we have treated normal CEF and CT10-CEF with sodium vanadate to inhibit protein tyrosine phosphatase activity. These data suggest that paxillin is involved in a highly dynamic kinase-phosphatase interplay in normal CEF and that v-Crk binding may interrupt this balance to increase the steady-state level of tyrosine phosphorylation. By contrast, the 130-kDa protein was not tyrosine phosphorylated upon vanadate treatment of normal CEF and only weakly affected in the CT10-CEF, suggesting that a different mechanism may be involved in its phosphorylation.

scholarly journals No Obvious Abnormality in Mice Deficient in Receptor Protein Tyrosine Phosphatase β

2000 ◽  
Vol 20 (20) ◽  
pp. 7706-7715 ◽  
Author(s):  
S. Harroch ◽  
M. Palmeri ◽  
J. Rosenbluth ◽  
A. Custer ◽  
M. Okigaki ◽  
...  
Keyword(s):  
Nervous System ◽  
Neurite Outgrowth ◽  
Tyrosine Phosphatase ◽  
Protein Tyrosine Phosphatases ◽  
Structural Features ◽  
Receptor Protein ◽  
Protein Tyrosine ◽  
Deficient Mice

ABSTRACT The development of neurons and glia is governed by a multitude of extracellular signals that control protein tyrosine phosphorylation, a process regulated by the action of protein tyrosine kinases and protein tyrosine phosphatases (PTPs). Receptor PTPβ (RPTPβ; also known as PTPζ) is expressed predominantly in the nervous system and exhibits structural features common to cell adhesion proteins, suggesting that this phosphatase participates in cell-cell communication. It has been proposed that the three isoforms of RPTPβ play a role in regulation of neuronal migration, neurite outgrowth, and gliogenesis. To investigate the biological functions of this PTP, we have generated mice deficient in RPTPβ. RPTPβ-deficient mice are viable, are fertile, and showed no gross anatomical alterations in the nervous system or other organs. In contrast to results of in vitro experiments, our study demonstrates that RPTPβ is not essential for neurite outgrowth and node formation in mice. The ultrastructure of nerves of the central nervous system in RPTPβ-deficient mice suggests a fragility of myelin. However, conduction velocity was not altered in RPTPβ-deficient mice. The normal development of neurons and glia in RPTPβ-deficient mice demonstrates that RPTPβ function is not necessary for these processes in vivo or that loss of RPTPβ can be compensated for by other PTPs expressed in the nervous system.

scholarly journals Role of Escherichia coli DNA Polymerase I in Conferring Viability upon the dnaN159 Mutant Strain

2007 ◽  
Vol 189 (13) ◽  
pp. 4688-4695 ◽  
Author(s):  
Robert W. Maul ◽  
Laurie H. Sanders ◽  
James B. Lim ◽  
Rosemary Benitez ◽  
Mark D. Sutton
Keyword(s):  
Escherichia Coli ◽  
Dna Polymerase ◽  
Temperature Sensitive ◽  
Mutant Form ◽  
Sliding Clamp ◽  
Pol I ◽  
Pol Iii ◽  
Polymerase I

ABSTRACT The Escherichia coli dnaN159 allele encodes a mutant form of the β-sliding clamp (β159) that is impaired for interaction with the replicative DNA polymerase (Pol), Pol III. In addition, strains bearing the dnaN159 allele require functional Pol I for viability. We have utilized a combination of genetic and biochemical approaches to characterize the role(s) played by Pol I in the dnaN159 strain. Our findings indicate that elevated levels of Pol I partially suppress the temperature-sensitive growth phenotype of the dnaN159 strain. In addition, we demonstrate that the β clamp stimulates the processivity of Pol I in vitro and that β159 is impaired for this activity. The reduced ability of β159 to stimulate Pol I in vitro correlates with our finding that single-stranded DNA (ssDNA) gap repair is impaired in the dnaN159 strain. Taken together, these results suggest that (i) the β clamp-Pol I interaction may be important for proper Pol I function in vivo and (ii) in the absence of Pol I, ssDNA gaps may persist in the dnaN159 strain, leading to lethality of the dnaN159 ΔpolA strain.

scholarly journals Ras-induced activation of Raf-1 is dependent on tyrosine phosphorylation.

1996 ◽  
Vol 16 (3) ◽  
pp. 1027-1034 ◽  
Author(s):  
T Jelinek ◽  
P Dent ◽  
T W Sturgill ◽  
M J Weber
Keyword(s):  
Tyrosine Phosphorylation ◽  
Plasma Membranes ◽  
Tyrosine Phosphatase ◽  
3T3 Cells ◽  
Level Of Activity ◽  
Active Pool ◽  
Ptp 1B ◽  
Nih 3T3

Although Rafs play a central role in signal transduction, the mechanism(s) by which they become activated is poorly understood. Raf-1 activation is dependent on the protein's ability to bind Ras, but Ras binding is insufficient to activate Raf-1 tyrosine phosphorylation to this Ras-induced activation, in the absence of an over-expressed tyrosine kinase. We demonstrate that Raf-1 purified form Sf9 cells coinfected with baculovirus Ras but not Src could be inactivated by protein tyrosine phosphatase PTP-1B. 14-3-3 and Hsp90 proteins blocked both the tyrosine dephosphorylation and inactivation of Raf-1, suggesting that Raf-1 activity is phosphotyrosine dependent. In Ras-transformed NIH 3T3 cells, a minority of Raf-1 protein was membrane associated, but essentially all Raf-1 activity and Raf-1 phosphotyrosine fractionated with plasma membranes. Thus, the tyrosine-phosphorylated and active pool of Raf-1 constitute a membrane-localized subfraction which could also be inactivated with PTP-1B. By contrast, B-Raf has aspartic acid residues at positions homologous to those of the phosphorylated tyrosines (at 340 and 341) of Raf-1 and displays a high basal level of activity. B-Raf was not detectably tyrosine phosphorylated, membrane localized, or further activated upon Ras transformation, even though B-Raf has been shown to bind to Ras in vitro. We conclude that tyrosine phosphorylation is an essential component of the mechanism by which Ras activates Raf-1 kinase activity and that steady-state activated Ras is insufficient to activate B-Raf in vivo.

scholarly journals Transmembrane glycoprotein gp150 is a substrate for receptor tyrosine phosphatase DPTP10D in Drosophila cells.

1997 ◽  
Vol 17 (12) ◽  
pp. 6859-6867 ◽  
Author(s):  
S J Fashena ◽  
K Zinn
Keyword(s):  
Tyrosine Phosphatase ◽  
Protein Tyrosine Phosphatases ◽  
Cytoplasmic Domain ◽  
Receptor Protein ◽  
S2 Cells ◽  
Wild Type ◽  
Downstream Signaling ◽  
Transmembrane Glycoprotein

We have begun to explore the downstream signaling pathways of receptor protein tyrosine phosphatases (RPTPs) that control axon guidance decisions in the Drosophila central nervous system. We have focused our studies on the adhesion molecule-like gp150 protein, which binds directly to and is an in vitro substrate for the RPTP DPTP10D. Here we show that gp150 and DPTP10D form stable complexes in Drosophila Schneider 2 (S2) cells and in wild-type larval tissue. We also demonstrate that the DPTP10D cytoplasmic domain is sufficient to confer binding to gp150. gp150 has a short cytoplasmic domain containing four tyrosines, all found within sequences similar to immunoreceptor family tyrosine-based activation motifs (ITAMs). We demonstrate that gp150 is tyrosine phosphorylated in wild-type larvae. In S2 cells, gp150 becomes tyrosine phosphorylated following incubation with PTP inhibitors or upon coexpression of the Dsrc tyrosine kinase. Phosphorylated Dsrc and an unknown 40-kDa phosphoprotein form stable complexes with gp150, thereby implicating them in a putative gp150 signaling pathway. When coexpressed with gp150, either full-length DPTP10D or its cytoplasmic domain mediates gp150 dephosphorylation whereas a catalytically inactive DPTP10D cytoplasmic domain does not. The neural RPTP DPTP99A can also induce gp150 dephosphorylation but does not coimmunoprecipitate with gp150. Taken together, the results suggest that gp150 transduces signals via phosphorylation of its ITAM-like elements. Phosphotyrosines on gp150 might function as binding sites for downstream signaling molecules, thereby initiating a signaling cascade that could be modulated in vivo by RPTPs such as DPTP10D.

scholarly journals Ultrasound-Based Molecular Imaging of Tumors with PTPmu Biomarker-Targeted Nanobubble Contrast Agents

2021 ◽  
Vol 22 (4) ◽  
pp. 1983
Author(s):  
Mette L. Johansen ◽  
Reshani Perera ◽  
Eric Abenojar ◽  
Xinning Wang ◽  
Jason Vincent ◽  
...  
Keyword(s):  
Contrast Agents ◽  
Ultrasound Imaging ◽  
Imaging Modality ◽  
Tyrosine Phosphatase ◽  
Receptor Protein ◽  
Contrast Enhanced Ultrasound ◽  
Core Lipid ◽  
Contrast Enhanced

Ultrasound imaging is a widely used, readily accessible and safe imaging modality. Molecularly-targeted microbubble- and nanobubble-based contrast agents used in conjunction with ultrasound imaging expand the utility of this modality by specifically targeting and detecting biomarkers associated with different pathologies including cancer. In this study, nanobubbles directed to a cancer biomarker derived from the Receptor Protein Tyrosine Phosphatase mu, PTPmu, were evaluated alongside non-targeted nanobubbles using contrast enhanced ultrasound both in vitro and in vivo in mice. In vitro resonant mass and clinical ultrasound measurements showed gas-core, lipid-shelled nanobubbles conjugated to either a PTPmu-directed peptide or a Scrambled control peptide were equivalent. Mice with heterotopic human tumors expressing the PTPmu-biomarker were injected with PTPmu-targeted or control nanobubbles and dynamic contrast-enhanced ultrasound was performed. Tumor enhancement was more rapid and greater with PTPmu-targeted nanobubbles compared to the non-targeted control nanobubbles. Peak tumor enhancement by the PTPmu-targeted nanobubbles occurred within five minutes of contrast injection and was more than 35% higher than the Scrambled nanobubble signal for the subsequent two minutes. At later time points, the signal in tumors remained higher with PTPmu-targeted nanobubbles demonstrating that PTPmu-targeted nanobubbles recognize tumors using molecular ultrasound imaging and may be useful for diagnostic and therapeutic purposes.

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