Molecular cloning and expression of a unique receptor-like protein-tyrosine-phosphatase in the leucocyte-common-antigen-related phosphatase family

Protein-tyrosine-phosphatases (PTPases) have been implicated in the regulation of certain tyrosine kinase growth factor receptors in that they dephosphorylate the activated (autophosphorylated) form of the receptors. In order to identify PTPases that potentially act on receptor targets in liver, we used the human leucocyte common antigen-related PTPase (LAR) cDNA [Streuli, Krueger, Hall, Schlossman and Saito (1988) J. Exp. Med. 168, 1523-1530] and isolated two closely related transmembrane PTPase homologues from a rat hepatic cDNA library. Both PTPases had large extracellular domains that contained three immunoglobulin-like repeats and eight type-III fibronectin repeats. Both enzymes had tandem homologous PTPase domains following a single hydrophobic transmembrane domain. One sequence encoded the rat homologue of LAR. The second PTPase, designated LAR-PTP2, had 79 and 90% identity with rat LAR in the respective cytoplasmic PTPase domains, with only 57% sequence similarity in the extracellular domain. The catalytic domains of LAR and LAR-PTP2 prepared by bacterial expression were active in dephosphorylating a variety of phosphotyrosyl substrates but did not hydrolyse phosphoserine or phosphothreonine residues of labelled casein. Both enzymes exhibited rapid turnover numbers of 4-7 s-1 for myelin basic protein and 78-150 s-1 for derivatized lysozyme. LAR and LAR-PTP2 displayed similar PTPase activity towards the simultaneous dephosphorylation of receptors of intact insulin and epidermal growth factor from liver membranes. These data indicate that there is a family of LAR-related PTPases that may regulate the phosphorylation state of receptor tyrosine kinases in liver and other tissues.

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Development of a Robust High-Throughput Screening Platform for Inhibitors of the Striatal-Enriched Tyrosine Phosphatase (STEP)

International Journal of Molecular Sciences ◽

10.3390/ijms22094417 ◽

2021 ◽

Vol 22 (9) ◽

pp. 4417

Author(s):

Lester J Lambert ◽

Stefan Grotegut ◽

Maria Celeridad ◽

Palak Gosalia ◽

Laurent JS De Backer ◽

...

Keyword(s):

Drug Discovery ◽

High Throughput ◽

Tyrosine Kinases ◽

High Throughput Screening ◽

Kinase Inhibitors ◽

Tyrosine Phosphatase ◽

Protein Tyrosine Phosphatases ◽

Synaptic Function ◽

Label Free ◽

Protein Tyrosine

Many human diseases are the result of abnormal expression or activation of protein tyrosine kinases (PTKs) and protein tyrosine phosphatases (PTPs). Not surprisingly, more than 30 tyrosine kinase inhibitors (TKIs) are currently in clinical use and provide unique treatment options for many patients. PTPs on the other hand have long been regarded as “undruggable” and only recently have gained increased attention in drug discovery. Striatal-enriched tyrosine phosphatase (STEP) is a neuron-specific PTP that is overactive in Alzheimer’s disease (AD) and other neurodegenerative and neuropsychiatric disorders, including Parkinson’s disease, schizophrenia, and fragile X syndrome. An emergent model suggests that the increase in STEP activity interferes with synaptic function and contributes to the characteristic cognitive and behavioral deficits present in these diseases. Prior efforts to generate STEP inhibitors with properties that warrant clinical development have largely failed. To identify novel STEP inhibitor scaffolds, we developed a biophysical, label-free high-throughput screening (HTS) platform based on the protein thermal shift (PTS) technology. In contrast to conventional HTS using STEP enzymatic assays, we found the PTS platform highly robust and capable of identifying true hits with confirmed STEP inhibitory activity and selectivity. This new platform promises to greatly advance STEP drug discovery and should be applicable to other PTP targets.

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RPTPμ tyrosine phosphatase promotes adipogenic differentiation via modulation of p120 catenin phosphorylation

Molecular Biology of the Cell ◽

10.1091/mbc.e11-03-0175 ◽

2011 ◽

Vol 22 (24) ◽

pp. 4883-4891 ◽

Cited By ~ 17

Author(s):

Won Kon Kim ◽

Hyeyun Jung ◽

Eun Young Kim ◽

Do Hyung Kim ◽

Yee Sook Cho ◽

...

Keyword(s):

Tyrosine Kinases ◽

Adipocyte Differentiation ◽

Adipogenic Differentiation ◽

Tyrosine Phosphatase ◽

Ectopic Expression ◽

Protein Tyrosine Phosphatases ◽

P120 Catenin ◽

Protein Tyrosine ◽

Functional Roles ◽

Novel Target

Adipocyte differentiation can be regulated by the combined activity of protein tyrosine kinases (PTKs) and protein tyrosine phosphatases (PTPs). In particular, PTPs act as key regulators in differentiation-associated signaling pathways. We recently found that receptor-type PTPμ (RPTPμ) expression is markedly increased during the adipogenic differentiation of 3T3-L1 preadipocytes and mesenchymal stem cells. Here, we investigate the functional roles of RPTPμ and the mechanism of its involvement in the regulation of signal transduction during adipogenesis of 3T3-L1 cells. Depletion of endogenous RPTPμ by RNA interference significantly inhibited adipogenic differentiation, whereas RPTPμ overexpression led to an increase in adipogenic differentiation. Ectopic expression of p120 catenin suppressed adipocyte differentiation, and the decrease in adipogenesis by p120 catenin was recovered by introducing RPTPμ. Moreover, RPTPμ induced a decrease in the cytoplasmic p120 catenin expression by reducing its tyrosine phosphorylation level, consequently leading to enhanced translocation of Glut-4 to the plasma membrane. On the basis of these results, we propose that RPTPμ acts as a positive regulator of adipogenesis by modulating the cytoplasmic p120 catenin level. Our data conclusively demonstrate that differentiation into adipocytes is controlled by RPTPμ, supporting the utility of RPTPμ and p120 catenin as novel target proteins for the treatment of obesity.

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mSiglec-E, a novel mouse CD33-related siglec (sialic acid-binding immunoglobulin-like lectin) that recruits Src homology 2 (SH2)-domain-containing protein tyrosine phosphatases SHP-1 and SHP-2

Biochemical Journal ◽

10.1042/bj3530483 ◽

2001 ◽

Vol 353 (3) ◽

pp. 483-492 ◽

Cited By ~ 12

Author(s):

Zhenbao YU ◽

Meryem MAOUI ◽

Liangtang WU ◽

Denis BANVILLE ◽

Shi-Hsiang SHEN

Keyword(s):

Sialic Acid ◽

Sequence Similarity ◽

Tyrosine Phosphatase ◽

Protein Tyrosine Phosphatases ◽

Sh2 Domain ◽

Immunoglobulin Superfamily ◽

Protein Tyrosine ◽

Src Homology 2 ◽

Sialic Acid Binding ◽

Src Homology

The sialic acid-binding immunoglobulin-like lectins (siglecs) represent a recently defined distinct subset of the immunoglobulin superfamily. By using the Src homology 2 (SH2)-domain-containing protein tyrosine phosphatase SHP-1 as bait in a yeast two-hybrid screen, we have identified a new member of the mouse siglec family, mSiglec-E. The mSiglec-E cDNA encodes a protein of 467 amino acids that contains three extracellular immunoglobulin-like domains, a transmembrane region and a cytoplasmic tail bearing two immunoreceptor tyrosine-based inhibitory motifs (ITIMs). mSiglec-E is highly expressed in mouse spleen, a tissue rich in leucocytes. The ITIMs of mSiglec-E can recruit SHP-1 and SHP-2, two inhibitory regulators of immunoreceptor signal transduction. This suggests that the function of mSiglec-E is probably an involvement in haematopoietic cells and the immune system as an inhibitory receptor. When expressed in COS-7 cells, mSiglec-E was able to mediate sialic acid-dependent binding to human red blood cells, suggesting that mSiglec-E may function through cell–cell interactions. In comparison with the known members of the siglec family, mSiglec-E exhibits a high degree of sequence similarity to both human siglec-7 and siglec-9. The gene encoding mSiglec-E is localized in the same chromosome as that encoding mouse CD33. Phylogenetic analysis reveals that neither mouse mSiglec-E nor CD33 shows a clear relationship with any human siglecs so far identified.

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Protein tyrosine phosphatase activity in human endometrium

Reproduction Fertility and Development ◽

10.1071/rd00106 ◽

2001 ◽

Vol 13 (3) ◽

pp. 175 ◽

Cited By ~ 1

Author(s):

Seppo Partanen

Keyword(s):

Growth Factors ◽

Growth Factor ◽

Phosphatase Activity ◽

Protein Tyrosine Phosphatase ◽

Tyrosine Kinases ◽

Tyrosine Phosphatase ◽

Intrauterine Device ◽

Human Endometrium ◽

Protein Tyrosine ◽

Glandular Cells

Protein tyrosine phosphatase (PTP) activity was demonstrated in human endometrium by a histochemical method using phosphotyrosine as substrate. For comparative purposes, non-specific acid phosphatase (AcP) activity was also examined. Protein tyrosine phosphatase activity was very low in proliferative and atrophic endometrium, but its activity was increased 9-fold in glandular epithelium during the secretory phase, and 48-fold in predecidual endometrium, induced by a progestagen-releasing intrauterine device, compared with the proliferative endometrium. Thus, PTP activity appeared to be progesterone-induced. Endometrial PTP appeared to be cellular rather than secretory in origin; its activity was inhibited by vanadate, and its histochemical properties were different from those of lysosomal AcP, but similar to those of prostatic-type AcP. Endometrial PTP may functionally counteract the effects of protein tyrosine kinases (PTKs) associated with growth factor receptors and cellular oncoproteins. Cyclic endometrial proliferation and differentiation are thought to be regulated by the autocrine and paracrine pathways by growth factors such as epidermal growth factor, insulin-like growth factor I and platelet-derived growth factors, and their receptors. However, cessation of proliferation could not be explained by the amounts of these growth factors present or their receptors, in that no constant changes at the interface of the late proliferative and early secretory phases were found. Down-regulation of stimulatory-signalling pathways of PTKs by endometrial PTP induced by progesterone may explain the decrease observed in proliferative activity of glandular cells in cyclic endometrium.

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Effects of Src Kinase Inhibition on Expression of Protein Tyrosine Phosphatase 1B after Brain Hypoxia in a Piglet Animal Model

Mediators of Inflammation ◽

10.1155/2017/2810295 ◽

2017 ◽

Vol 2017 ◽

pp. 1-7

Author(s):

Dimitrios Angelis ◽

Maria Delivoria-Papadopoulos

Keyword(s):

Posttranslational Modifications ◽

Tyrosine Kinases ◽

Kinase Inhibitor ◽

Tyrosine Phosphatase ◽

Src Kinase ◽

Protein Tyrosine Phosphatases ◽

Kinase Inhibition ◽

Protein Tyrosine ◽

Newborn Piglets ◽

Ptp 1B

Background. Protein tyrosine phosphatases (PTPs) in conjunction with protein tyrosine kinases (PTKs) regulate cellular processes by posttranslational modifications of signal transduction proteins. PTP nonreceptor type 1B (PTP-1B) is an enzyme of the PTP family. We have previously shown that hypoxia induces an increase in activation of a class of nonreceptor PTK, the Src kinases. In the present study, we investigated the changes that occur in the expression of PTP-1B in the cytosolic component of the brain of newborn piglets acutely after hypoxia as well as long term for up to 2 weeks.Methods. Newborn piglets were divided into groups: normoxia, hypoxia, hypoxia followed by 1 day and 15 days in FiO20.21, and hypoxia pretreated with Src kinase inhibitor PP2, prior to hypoxia followed by 1 day and 15 days. Hypoxia was achieved by providing 7% FiO2for 1 hour and PTP-1B expression was measured via immunoblotting.Results. PTP-1B increased posthypoxia by about 30% and persisted for 2 weeks while Src kinase inhibition attenuated the expected PTP-1B-increased expression.Conclusions. Our study suggests that Src kinase mediates a hypoxia-induced increased PTP-1B expression.

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EXPERIMENTAL AND THEORETICAL STUDY OF THE MOVEMENT OF THE WPD FLEXIBLE LOOP OF HUMAN PROTEIN TYROSINE PHOSPHATASE PTP1B IN COMPLEX WITH HALIDE IONS

Biophysical Reviews and Letters ◽

10.1142/s1793048012500087 ◽

2012 ◽

Vol 07 (03n04) ◽

pp. 197-217

Author(s):

ALINE KATZ ◽

PATRICIA SAENZ-MÉNDEZ ◽

ALEXANDRA COUSIDO-SIAH ◽

ALBERTO D. PODJARNY ◽

OSCAR N. VENTURA

Keyword(s):

Protein Tyrosine Phosphatase ◽

Tyrosine Kinases ◽

Tyrosine Phosphatase ◽

Enzymatic Catalysis ◽

Protein Tyrosine Phosphatases ◽

Md Simulations ◽

Crystallographic Structure ◽

Halide Ions ◽

Post Translational Modification ◽

Protein Tyrosine

Protein tyrosine phosphorylation is a post-translational modification mechanism, crucial for the regulation of nearly all aspects of cell life. This dynamic, reversible process is regulated by the balanced opposing activity of protein tyrosine kinases and protein tyrosine phosphatases. In particular, the protein tyrosine phosphatase 1B (PTP1B) is implicated in the regulation of the insulin-receptor activity, leptin-stimulated signal transduction pathways and other clinically relevant metabolic routes, and it has been found overexpressed or overregulated in human breasts, colon and ovary cancers. The WPD loop of the enzyme presents an inherent flexibility, and it plays a fundamental role in the enzymatic catalysis, turning it into a potential target in the design of new efficient PTP1B inhibitors. In order to determine the interactions that control the spatial conformation adopted by the WPD loop, complexes between the enzyme and halide ions ( Br- and I- in particular) were crystallized and their crystallographic structure determined, and the collective movements of the aforementioned complexes were studied through Molecular Dynamics (MD) simulations. Both studies yielded concordant results, indicating the existence of a relationship between the identity of the ion present in the complex and the strength of the interactions it establishes with the surrounding protein residues.

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A novel receptor-type protein tyrosine phosphatase with a single catalytic domain is specifically expressed in mouse brain

Biochemical Journal ◽

10.1042/bj3050499 ◽

1995 ◽

Vol 305 (2) ◽

pp. 499-504 ◽

Cited By ~ 39

Author(s):

W Hendriks ◽

J Schepens ◽

C Brugman ◽

P Zeeuwen ◽

B Wieringa

Keyword(s):

Mouse Brain ◽

Tyrosine Kinases ◽

Catalytic Domain ◽

Tyrosine Phosphatase ◽

Cell Signalling ◽

Protein Tyrosine Phosphatases ◽

Pcr Amplification ◽

Phosphatase Domain ◽

Protein Tyrosine ◽

The Brain

Protein tyrosine phosphatases (PTPases) are important regulatory proteins that, together with protein tyrosine kinases, determine the phosphotyrosine levels in cell signalling proteins. By PCR amplification of mouse brain cDNA fragments encoding the catalytic domains of these enzymes, we identified three novel members of the PTPase gene family. Northern-blot analysis showed that two of these novel clones represent brain-specific PTPases, whereas the third originates from a large-sized mRNA that is more ubiquitously expressed. A full-length cDNA encoding one of the brain-specific PTPases, PTP-SL, was isolated. Sequence analysis revealed a transmembrane PTPase containing a single catalytic phosphatase domain that has 45% homology to a rat cytoplasmic brain-specific PTPase named STEP. This suggests a role for PTP-SL in cell-cell signalling processes in the brain.

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Constitutive secretion of serum albumin requires reversible protein tyrosine phosphorylation events in trans-Golgi

AJP Cell Physiology ◽

10.1152/ajpcell.00019.2005 ◽

2005 ◽

Vol 289 (3) ◽

pp. C748-C756 ◽

Cited By ~ 13

Author(s):

Rachel J. Webb ◽

Jacob D. Judah ◽

Lee-Chiang Lo ◽

Geraint M. H. Thomas

Keyword(s):

Serum Albumin ◽

Tyrosine Phosphorylation ◽

Tyrosine Kinases ◽

Kinase Inhibitor ◽

Tyrosine Phosphatase ◽

Protein Tyrosine Phosphatases ◽

Protein Tyrosine Phosphorylation ◽

Albumin Secretion ◽

Protein Tyrosine ◽

Constitutive Secretion

Serum albumin secretion from rat hepatocytes proceeds via the constitutive pathway. Although much is known about the role of protein tyrosine phosphorylation in regulated secretion, nothing is known about its function in the constitutive process. Here we show that albumin secretion is inhibited by the tyrosine kinase inhibitor genistein but relatively insensitive to subtype-selective inhibitors or treatments. Secretion is also blocked in a physiologically identical manner by the tyrosine phosphatase inhibitors pervanadate and bisperoxo(1,10-phenanthroline)-oxovanadate. Inhibition of either the kinase(s) or phosphatase(s) leads to the accumulation of albumin between the trans-Golgi and the plasma membrane, whereas the immediate precursor proalbumin builds up in a proximal compartment. The trans-Golgi marker TGN38 is rapidly dispersed under conditions that inhibit tyrosine phosphatase action, whereas the distribution of the cis-Golgi marker GM130 is insensitive to genistein or pervanadate. By using a specifically reactive biotinylation probe, we detected protein tyrosine phosphatases in highly purified rat liver Golgi membranes. These membranes also contain both endogenous tyrosine kinases and their substrates, indicating that enzymes and substrates for reversible tyrosine phosphorylation are normal membrane-resident components of this trafficking compartment. In the absence of perturbation of actin filaments and microtubules, we conclude that reversible protein tyrosine phosphorylation in the trans-Golgi network is essential for albumin secretion and propose that the constitutive secretion of albumin is in fact a regulated process.

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A protein-tyrosine phosphatase with sequence similarity to the SH2 domain of the protein-tyrosine kinases

Nature ◽

10.1038/352736a0 ◽

1991 ◽

Vol 352 (6337) ◽

pp. 736-739 ◽

Cited By ~ 262

Author(s):

Shi-Hsiang Shen ◽

Lison Bastien ◽

Barry I. Posner ◽

Pierre Chrétien

Keyword(s):

Protein Tyrosine Phosphatase ◽

Tyrosine Kinases ◽

Sequence Similarity ◽

Tyrosine Phosphatase ◽

Sh2 Domain ◽

Protein Tyrosine Kinases ◽

Protein Tyrosine

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Structure, mapping, and expression of erp, a growth factor-inducible gene encoding a nontransmembrane protein tyrosine phosphatase, and effect of ERP on cell growth.

Molecular and Cellular Biology ◽

10.1128/mcb.13.9.5195 ◽

1993 ◽

Vol 13 (9) ◽

pp. 5195-5205 ◽

Cited By ~ 120

Author(s):

T Noguchi ◽

R Metz ◽

L Chen ◽

M G Mattéi ◽

D Carrasco ◽

...

Keyword(s):

Growth Factor ◽

Phosphatase Activity ◽

Genomic Structure ◽

Tyrosine Phosphatase ◽

Protein Tyrosine Phosphatases ◽

Early Gene ◽

Structure Mapping ◽

Significant Similarity ◽

Protein Tyrosine ◽

Inducible Gene

We have characterized a growth factor-inducible gene, erp, and demonstrated that it encodes a 367-amino-acid nontransmembrane tyrosine phosphatase protein with significant similarity to the vaccinia virus H1 protein. Immunoprecipitation analyses show that the erp protein, ERP, is rapidly induced following serum stimulation of quiescent fibroblasts. ERP has been expressed as a fusion protein with glutathione S-transferase and shown to have tyrosine as well as serine protein phosphatase activity. The enzymatic activity of ERP depends on the presence of reducing agents such as dithiothreitol, and its tyrosine phosphatase activity is inhibited by sodium vanadate, a potent inhibitor of protein tyrosine phosphatases. The number of stable NIH 3T3 clones obtained after transfection with a vector expressing the complete ERP protein is reduced more than 90% compared with that after transfection with a vector expressing a mutated inactive ERP protein. The remaining ERP-expressing clones present a significant increase in the proportion of bi- and multinucleated cells and a decrease in proliferation rate. Studies on the genomic structure reveal that the erp transcription unit is 2.8 kbp long and split into four exons. The erp gene maps to the 17A2-17C region of the murine genome. Our results demonstrate that the protein product of the immediate-early gene erp has a negative effect on cell proliferation.

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