scholarly journals Podocyte Protein, Nephrin, Is a Substrate of Protein Tyrosine Phosphatase 1B

2011 ◽  
Vol 2011 ◽  
pp. 1-10 ◽  
Author(s):  
Lamine Aoudjit ◽  
Ruihua Jiang ◽  
Tae Hoon Lee ◽  
Laura A. New ◽  
Nina Jones ◽  
...  
Keyword(s):  
Actin Cytoskeleton ◽  
Tyrosine Phosphorylation ◽  
Tyrosine Phosphatase ◽  
Protein Tyrosine Phosphatases ◽  
Protein Tyrosine Phosphatase 1B ◽  
Tyrosine Phosphatases ◽  
Puromycin Aminonucleoside ◽  
Protein Tyrosine ◽  
Aminonucleoside Nephrosis ◽  
Puromycin Aminonucleoside Nephrosis

Glomerular podocytes are critical for the barrier function of the glomerulus in the kidney and their dysfunction causes protein leakage into the urine (proteinuria). Nephrin is a key podocyte protein, which regulates the actin cytoskeleton via tyrosine phosphorylation of its cytoplasmic domain. Here we report that two protein tyrosine phosphatases, PTP1B and PTP-PEST negatively regulate nephrin tyrosine phosphorylation. PTP1B directly binds to and dephosphorylates nephrin, while the action of PTP-PEST is indirect. The two phosphatases are also upregulated in the glomerulus in the rat model of puromycin aminonucleoside nephrosis. Both overexpression and inhibition of PTP1B deranged the actin cytoskeleton in cultured mouse podocytes. Thus, protein tyrosine phosphatases may affect podocyte function via regulating nephrin tyrosine phosphorylation.

scholarly journals Protein tyrosine phosphatase containing SH2 domains: characterization, preferential expression in hematopoietic cells, and localization to human chromosome 12p12-p13.

1992 ◽  
Vol 12 (2) ◽  
pp. 836-846 ◽  
Author(s):  
T L Yi ◽  
J L Cleveland ◽  
J N Ihle
Keyword(s):  
Tyrosine Phosphorylation ◽  
Protein Tyrosine Phosphatase ◽  
Human Gene ◽  
Tyrosine Phosphatase ◽  
Hematopoietic Cells ◽  
Protein Tyrosine Phosphatases ◽  
Hematopoietic Cell ◽  
Protein Tyrosine Phosphorylation ◽  
Tyrosine Phosphatases ◽  
Protein Tyrosine

Protein tyrosine phosphorylation has been implicated in the growth and functional responses of hematopoietic cells. Recently, approaches have been developed to characterize the protein tyrosine phosphatases that may contribute to regulation of protein tyrosine phosphorylation. One novel protein tyrosine phosphatase was expressed predominantly in hematopoietic cells. Hematopoietic cell phosphatase encodes a 68-kDa protein that contains a single phosphatase conserved domain. Unlike other known protein tyrosine phosphatases, hematopoietic cell phosphatase contains two src homology 2 domains. We also cloned the human homolog, which has 95% amino acid sequence identity. Both the murine and human gene products have tyrosine-specific phosphatase activity, and both are expressed predominantly in hematopoietic cells. Importantly, the human gene maps to chromosome 12 region p12-p13. This region is associated with rearrangements in approximately 10% of cases of acute lymphocytic leukemia in children.

p21-Activated kinases regulate actin remodeling in glomerular podocytes

2010 ◽  
Vol 298 (4) ◽  
pp. F951-F961 ◽  
Author(s):  
Jianxin Zhu ◽  
Ortal Attias ◽  
Lamine Aoudjit ◽  
Ruihua Jiang ◽  
Hiroshi Kawachi ◽  
...  
Keyword(s):  
Actin Cytoskeleton ◽  
Tyrosine Phosphorylation ◽  
Adaptor Proteins ◽  
Dominant Negative ◽  
Puromycin Aminonucleoside ◽  
Actin Remodeling ◽  
Cellular Processes ◽  
Aminonucleoside Nephrosis ◽  
Puromycin Aminonucleoside Nephrosis

The tyrosine phosphorylation of nephrin is reported to regulate podocyte morphology via the Nck adaptor proteins. The Pak family of kinases are regulators of the actin cytoskeleton and are recruited to the plasma membrane via Nck. Here, we investigated the role of Pak in podocyte morphology. Pak1/2 were expressed in cultured podocytes. In mouse podocytes, Pak2 was predominantly phosphorylated, concentrated at the tips of the cellular processes, and its expression and/or phosphorylation were further increased when differentiated. Overexpression of rat nephrin in podocytes increased Pak1/2 phosphorylation, which was abolished when the Nck binding sites were mutated. Furthermore, dominant-negative Nck constructs blocked the Pak1 phosphorylation induced by antibody-mediated cross linking of nephrin. Transient transfection of constitutively kinase-active Pak1 into differentiated mouse podocytes decreased stress fibers, increased cortical F-actin, and extended the cellular processes, whereas kinase-dead mutant, kinase inhibitory construct, and Pak2 knockdown by shRNA had the opposite effect. In a rat model of puromycin aminonucleoside nephrosis, Pak1/2 phosphorylation was decreased in glomeruli, concomitantly with a decrease of nephrin tyrosine phosphorylation. These results suggest that Pak contributes to remodeling of the actin cytoskeleton in podocytes. Disturbed nephrin-Nck-Pak interaction may contribute to abnormal morphology of podocytes and proteinuria.

Protein tyrosine phosphatase containing SH2 domains: characterization, preferential expression in hematopoietic cells, and localization to human chromosome 12p12-p13

1992 ◽  
Vol 12 (2) ◽  
pp. 836-846
Author(s):  
T L Yi ◽  
J L Cleveland ◽  
J N Ihle
Keyword(s):  
Tyrosine Phosphorylation ◽  
Protein Tyrosine Phosphatase ◽  
Human Gene ◽  
Tyrosine Phosphatase ◽  
Hematopoietic Cells ◽  
Protein Tyrosine Phosphatases ◽  
Hematopoietic Cell ◽  
Protein Tyrosine Phosphorylation ◽  
Tyrosine Phosphatases ◽  
Protein Tyrosine

Protein tyrosine phosphorylation has been implicated in the growth and functional responses of hematopoietic cells. Recently, approaches have been developed to characterize the protein tyrosine phosphatases that may contribute to regulation of protein tyrosine phosphorylation. One novel protein tyrosine phosphatase was expressed predominantly in hematopoietic cells. Hematopoietic cell phosphatase encodes a 68-kDa protein that contains a single phosphatase conserved domain. Unlike other known protein tyrosine phosphatases, hematopoietic cell phosphatase contains two src homology 2 domains. We also cloned the human homolog, which has 95% amino acid sequence identity. Both the murine and human gene products have tyrosine-specific phosphatase activity, and both are expressed predominantly in hematopoietic cells. Importantly, the human gene maps to chromosome 12 region p12-p13. This region is associated with rearrangements in approximately 10% of cases of acute lymphocytic leukemia in children.

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 Activation of Phosphotyrosine-Mediated Signaling Pathways in the Cortex and Spinal Cord of SOD1G93A, a Mouse Model of Familial Amyotrophic Lateral Sclerosis

2018 ◽  
Vol 2018 ◽  
pp. 1-10
Author(s):  
Cinzia Mallozzi ◽  
Alida Spalloni ◽  
Patrizia Longone ◽  
Maria Rosaria Domenici
Keyword(s):  
Spinal Cord ◽  
Amyotrophic Lateral Sclerosis ◽  
Tyrosine Phosphorylation ◽  
Tyrosine Kinases ◽  
Tyrosine Phosphatase ◽  
Protein Tyrosine Phosphatases ◽  
Tyrosine Phosphatases ◽  
Direct Stimulation ◽  
Tyrosine Kinase 2 ◽  
Lateral Sclerosis

Degeneration of cortical and spinal motor neurons is the typical feature of amyotrophic lateral sclerosis (ALS), a progressive neurodegenerative disease for which a pathogenetic role for the Cu/Zn superoxide dismutase (SOD1) has been demonstrated. Mice overexpressing a mutated form of the SOD1 gene (SOD1G93A) develop a syndrome that closely resembles the human disease. The SOD1 mutations confer to this enzyme a “gain-of-function,” leading to increased production of reactive oxygen species. Several oxidants induce tyrosine phosphorylation through direct stimulation of kinases and/or phosphatases. In this study, we analyzed the activities of src and fyn tyrosine kinases and of protein tyrosine phosphatases in synaptosomal fractions prepared from the motor cortex and spinal cord of transgenic mice expressing SOD1G93A. We found that (i) protein phosphotyrosine level is increased, (ii) src and fyn activities are upregulated, and (iii) the activity of tyrosine phosphatases, including the striatal-enriched tyrosine phosphatase (STEP), is significantly decreased. Moreover, the NMDA receptor (NMDAR) subunit GluN2B tyrosine phosphorylation was upregulated in SOD1G93A. Tyrosine phosphorylation of GluN2B subunits regulates the NMDAR function and the recruitment of downstream signaling molecules. Indeed, we found that proline-rich tyrosine kinase 2 (Pyk2) and ERK1/2 kinase are upregulated in SOD1G93A mice. These results point out an involvement of tyrosine kinases and phosphatases in the pathogenesis of ALS.

scholarly journals Targeting Tyrosine Phosphatases by 3-Bromopyruvate Overcomes Hyperactivation of Platelets from Gastrointestinal Cancer Patients

2019 ◽  
Vol 8 (7) ◽  
pp. 936 ◽  
Author(s):  
Faria ◽  
Andrade ◽  
Reijm ◽  
Spaander ◽  
de Maat ◽  
...  
Keyword(s):  
Tumor Cell ◽  
Cancer Patients ◽  
Gastrointestinal Cancer ◽  
Molecular Mechanisms ◽  
Tyrosine Phosphatase ◽  
Protein Tyrosine Phosphatases ◽  
Cell Aggregation ◽  
Tyrosine Phosphatases ◽  
Indirect Contact ◽  
Protein Tyrosine

Venous thromboembolism (VTE) is one of the most common causes of cancer related mortality. It has been speculated that hypercoagulation in cancer patients is triggered by direct or indirect contact of platelets with tumor cells, however the underlying molecular mechanisms involved are currently unknown. Unraveling these mechanisms may provide potential avenues for preventing platelet-tumor cell aggregation. Here, we investigated the role of protein tyrosine phosphatases in the functionality of platelets in both healthy individuals and patients with gastrointestinal cancer, and determined their use as a target to inhibit platelet hyperactivity. This is the first study to demonstrate that platelet agonists selectively activate low molecular weight protein tyrosine phosphatase (LMWPTP) and PTP1B, resulting in activation of Src, a tyrosine kinase known to contribute to several platelet functions. Furthermore, we demonstrate that these phosphatases are a target for 3-bromopyruvate (3-BP), a lactic acid analog currently investigated for its use in the treatment of various metabolic tumors. Our data indicate that 3-BP reduces Src activity, platelet aggregation, expression of platelet activation makers and platelet-tumor cell interaction. Thus, in addition to its anti-carcinogenic effects, 3-BP may also be effective in preventing platelet-tumor cell aggregationin cancer patients and therefore may reduce cancer mortality by limiting VTE in patients.

scholarly journals SHP1 and SHP2 Protein-tyrosine Phosphatases Associate with βc after Interleukin-3-induced Receptor Tyrosine Phosphorylation

1997 ◽  
Vol 272 (22) ◽  
pp. 14470-14476 ◽  
Author(s):  
Heather Bone ◽  
Ute Dechert ◽  
Frank Jirik ◽  
John W. Schrader ◽  
Melanie J. Welham
Keyword(s):  
Tyrosine Phosphorylation ◽  
Protein Tyrosine Phosphatases ◽  
Tyrosine Phosphatases ◽  
Protein Tyrosine ◽  
Interleukin 3

scholarly journals Multiple Functions of the Eya Phosphotyrosine Phosphatase

2015 ◽  
Vol 36 (5) ◽  
pp. 668-677 ◽  
Author(s):  
Ilaria Rebay
Keyword(s):  
Developmental Regulation ◽  
Tyrosine Phosphatase ◽  
Protein Tyrosine Phosphatases ◽  
Transcriptional Coactivator ◽  
Tyrosine Phosphatases ◽  
Phosphotyrosine Phosphatase ◽  
Eyes Absent ◽  
Multiple Functions ◽  
Protein Tyrosine ◽  
Cellular Events

Eyes absent (Eya), a protein conserved from plants to humans and best characterized as a transcriptional coactivator, is also the prototype for a novel class of eukaryotic aspartyl protein tyrosine phosphatases. This minireview discusses recent breakthroughs in elucidating the substrates and cellular events regulated by Eya's tyrosine phosphatase function and highlights some of the complexities, new questions, and surprises that have emerged from efforts to understand how Eya's unusual multifunctionality influences developmental regulation and signaling.

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