An osteoclastic protein-tyrosine phosphatase may play a role in differentiation and activity of human monocytic U-937 cell-derived, osteoclast-like cells

2004 ◽  
Vol 287 (4) ◽  
pp. C874-C884 ◽  
Author(s):  
Mehran Amoui ◽  
Sung-Min Suhr ◽  
David J. Baylink ◽  
K.-H. William Lau
Keyword(s):  
Cell Proliferation ◽  
Bone Resorption ◽  
Enzymatic Activity ◽  
Phorbol Ester ◽  
Protein Tyrosine Phosphatase ◽  
Functional Activity ◽  
Tyrosine Phosphatase ◽  
Wild Type ◽  
Protein Tyrosine ◽  
Viable Cells

This study investigated if an osteoclastic protein-tyrosine phosphatase (PTP), PTP-oc, plays a role in the functional activity and differentiation of osteoclastic cells by determining the effects of overexpression of wild-type (WT)- or phosphatase-deficient (PD)-PTP-oc on bone resorption activity and differentiation of human promyelomonocytic U-937 cells, which could be induced to differentiate into “osteoclast-like” cells by phorbol ester/1,25(OH)2D3 treatment. U-937 cells overexpressing WT- or PD-PTP-oc were produced with a transposon-based vector. The size and depth of resorption pits created by WT-PTP-oc-overexpressing osteoclast-like cells were greater, while those by PD-PTP-oc-overexpressing osteoclast-like cells were less, than those created by control osteoclast-like cells. Overexpression of WT-PTP-oc also enhanced, while overexpression of PD-PTP-oc suppressed, their differentiation into osteoclast-like cells. Overexpression of WT-PTP-oc increased apoptosis and proliferation of U-937 cells, and overexpression of PD-PTP-oc reduced cell proliferation. Cells overexpressing WT-PTP-oc has also led to greater c-Src and NF-κβ activation, whereas cells overexpressing PD-PTP-oc resulted in less c-Src and NF-κβ activation. c-Src activation and NF-κβ activation each correlated with resorption activity and differentiation into osteoclast-like cells. In summary, these results show that 1) PTP-oc regulates both the activity and the differentiation of osteoclast-like cells derived from U-937 cells; 2) PTP-oc enzymatic activity is important to these processes; 3) high PTP-oc enzymatic activity caused an increase in U-937 cell apoptosis and proliferation, leading to no significant changes in the number of viable cells; and 4) some of the PTP-oc actions are mediated in part by the c-Src and/or NF-κβ pathways.

scholarly journals Protein tyrosine phosphatase receptor type E (PTPRE) regulates the activation of wild-type KIT and KIT mutants differently

2021 ◽  
Vol 26 ◽  
pp. 100974
Author(s):  
Shaoting Zhang ◽  
Liangying Zhang ◽  
Zongying Jiang ◽  
Yue Guo ◽  
Hui Zhao ◽  
...  
Keyword(s):  
Protein Tyrosine Phosphatase ◽  
Tyrosine Phosphatase ◽  
Receptor Type ◽  
Wild Type ◽  
Protein Tyrosine

scholarly journals AP-1 elements and TCL1 protein regulate expression of the gene encoding protein tyrosine phosphatase PTPROt in leukemia

Blood ◽  
2011 ◽  
Vol 118 (23) ◽  
pp. 6132-6140 ◽  
Author(s):  
Tasneem Motiwala ◽  
Nicola Zanesi ◽  
Jharna Datta ◽  
Satavisha Roy ◽  
Huban Kutay ◽  
...  
Keyword(s):  
Protein Tyrosine Phosphatase ◽  
Tyrosine Phosphatase ◽  
Lymphocytic Leukemia ◽  
Potential Mechanism ◽  
Wild Type ◽  
Truncated Form ◽  
Gene Encoding ◽  
Protein Tyrosine ◽  
Encoding Protein

Abstract We previously demonstrated that the gene encoding PTPROt, the truncated form of protein tyrosine phosphatase receptor type O expressed predominantly in hematopoietic cells, is a candidate tumor suppressor and is down-regulated in chronic lymphocytic leukemia (CLL). Here, we show that PTPROt expression is significantly reduced in CD19+ spleen B cells from Eμ-T cell leukemia 1 (TCL1) transgenic mice relative to the wild-type mice. Strikingly, as much as a 60% decrease in PTPROt expression occurs at 7 weeks independently of promoter methylation. To elucidate the potential mechanism for this early suppression of PTPROt in these mice, we explored the role of activating protein-1 (AP-1) in its expression. We first demonstrate that AP-1 activation by 12-O-tetradecanoylphorbol-13-acetate induces PTPROt expression with concurrent recruitment of c-fos and c-jun to its promoter. The PTPROt promoter is also responsive to over- and underexpression of AP-1, confirming the role of AP-1 in PTPROt expression. Next, we demonstrate that TCL1 can repress the PTPROt promoter by altering c-fos expression and c-jun activation state. Finally, using primary CLL cells we have shown an inverse relationship between TCL1 and PTPROt expression. These findings further substantiate the role of TCL1 in PTPROt suppression and its importance in the pathogenesis of CLL.

Protein tyrosine phosphatase PTPεM negatively regulates PDGF β-receptor signaling induced by high glucose and PDGF in vascular smooth muscle cells

2010 ◽  
Vol 299 (5) ◽  
pp. C1144-C1152 ◽  
Author(s):  
Hidehisa Shimizu ◽  
Yoshimi Nakagawa ◽  
Chie Murakami ◽  
Naohito Aoki ◽  
Shokei Kim-Mitsuyama ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Vascular Smooth Muscle ◽  
Protein Tyrosine Phosphatase ◽  
High Glucose ◽  
Tyrosine Phosphatase ◽  
Wild Type ◽  
Accelerated Atherosclerosis ◽  
Protein Tyrosine ◽  
Β Receptor ◽  
And Migration

Vascular smooth muscle cell (VSMC) proliferation and migration and vascular endothelial cell (VEC) dysfunction are closely associated with the development of atherosclerosis. We previously demonstrated that protein tyrosine phosphatase ε M (PTPεM) promotes VEC survival and migration. The present study investigates the biological functions of PTPεM in VSMCs and determines whether PTPεM is implicated in diabetes-accelerated atherosclerosis. We overexpressed wild-type and inactive PTPεM and an small interfering RNA (siRNA) of PTPεM by using an adenovirus vector to investigate the effects of PTPεM upon platelet-derived growth factor (PDGF)- and high glucose (HG)-induced responses of rat VSMCs in vitro. We found that PTPεM decreased PDGF-induced DNA synthesis and migration by reducing the phosphorylation level of the PDGF β-receptor (PDGFRβ) with subsequently suppressed H2O2 generation. The HG content in the medium generated H2O2, upregulated PDGFRβ expression and its tyrosine-phosphorylation, and elevated NADPH oxidase 1 (Nox1) expression even without exogenous PDGF, all of which were downregulated by PTPεM. The PDGFR inhibitor AG1296 also blocked HG-induced Nox1 expression and H2O2 production. Moreover, HG suppressed PTPεM expression itself, which was blocked by the antioxidant N-acetyl-l-cysteine. The effects of PTPεM siRNA were the opposite of those of wild-type PTPεM. Therefore, PTPεM negatively regulates PDGFRβ-mediated signaling pathways that are crucial for the pathogenesis of atherosclerosis, and PTPεM may be involved in diabetes-accelerated atherosclerosis.

scholarly journals The Nonreceptor Protein Tyrosine Phosphatase PTP1B Binds to the Cytoplasmic Domain of N-Cadherin and Regulates the Cadherin–Actin Linkage

1998 ◽  
Vol 143 (2) ◽  
pp. 523-532 ◽  
Author(s):  
Janne Balsamo ◽  
Carlos Arregui ◽  
TinChung Leung ◽  
Jack Lilien
Keyword(s):  
Protein Tyrosine Phosphatase ◽  
Tyrosine Phosphatase ◽  
Cytoplasmic Domain ◽  
Dominant Negative ◽  
Wild Type ◽  
Protein Tyrosine ◽  
Tyrosine Residues ◽  
Cytoplasmic Proteins ◽  
Inactive Form

Cadherin-mediated adhesion depends on the association of its cytoplasmic domain with the actin-containing cytoskeleton. This interaction is mediated by a group of cytoplasmic proteins: α-and β- or γ- catenin. Phosphorylation of β-catenin on tyrosine residues plays a role in controlling this association and, therefore, cadherin function. Previous work from our laboratory suggested that a nonreceptor protein tyrosine phosphatase, bound to the cytoplasmic domain of N-cadherin, is responsible for removing tyrosine-bound phosphate residues from β-catenin, thus maintaining the cadherin–actin connection (Balsamo et al., 1996). Here we report the molecular cloning of the cadherin-associated tyrosine phosphatase and identify it as PTP1B. To definitively establish a causal relationship between the function of cadherin-bound PTP1B and cadherin-mediated adhesion, we tested the effect of expressing a catalytically inactive form of PTP1B in L cells constitutively expressing N-cadherin. We find that expression of the catalytically inactive PTP1B results in reduced cadherin-mediated adhesion. Furthermore, cadherin is uncoupled from its association with actin, and β-catenin shows increased phosphorylation on tyrosine residues when compared with parental cells or cells transfected with the wild-type PTP1B. Both the transfected wild-type and the mutant PTP1B are found associated with N-cadherin, and recombinant mutant PTP1B binds to N-cadherin in vitro, indicating that the catalytically inactive form acts as a dominant negative, displacing endogenous PTP1B, and rendering cadherin nonfunctional. Our results demonstrate a role for PTP1B in regulating cadherin-mediated cell adhesion.

Double Knockouts Reveal That Protein Tyrosine Phosphatase 1B Is a Physiological Substrate of Calpain-1 in Platelets.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 396-396 ◽  
Author(s):  
Shafi M. Kuchay ◽  
William P. Fay ◽  
Athar H. Chishti
Keyword(s):  
Platelet Aggregation ◽  
Protein Tyrosine Phosphatase ◽  
Tyrosine Phosphatase ◽  
Wild Type Mouse ◽  
Cysteine Proteases ◽  
Protein Tyrosine Phosphatase 1B ◽  
Dependent Manner ◽  
Wild Type ◽  
Clot Retraction ◽  
Protein Tyrosine

Abstract Calpains are ubiquitous calcium-regulated cysteine proteases that have been implicated in cytoskeletal organization, cell proliferation, apoptosis, cell motility, and hemostasis. Previously we used gene-targeting to evaluate the physiological function of mouse calpain-1, and established that its inactivation results in reduced platelet aggregation and clot retraction, potentially by causing dephosphorylation of platelet proteins. Here, we present data showing that calpain-1 null platelets accumulate protein tyrosine phosphatase 1B (PTP1B) that correlates with enhanced tyrosine phosphatase activity and dephosphorylation of multiple substrates in platelets. Using antibodies specific for phosphotyrosines 747 and 759 of the b3 subunit of αIibβ3 integrin, we show that the tyrosine phosphorylation of both tyrosine residues at positions 747 and 759 in the cytoplasmic domain of b3 subunit is reduced by approximately 60–70% in the calpain-1 null platelets. Treatment of calpain-1 null platelets with DMHV, an inhibitor of tyrosine phosphatases, corrected the aggregation defect and recovered impaired clot retraction. Importantly, platelet aggregation, clot retraction, and tyrosine dephosphorylation defects were rescued in the double knockout mice lacking both calpain-1 and PTP1B. Consistent with this paradigm, treatment of wild type mouse platelets as well as human platelets with the tyrosine phosphatase inhibitor DMHV enhanced their aggregation at low doses of thrombin. Conversely, MDL, a cell permeable inhibitor of calpains, potently inhibited aggregation of wild type mouse platelets in a dose-dependent manner upon thrombin activation. Further evaluation of mutant mice by ferric chloride induced arterial injury model suggests that the calpain-1 null mice are relatively resistant to thrombosis in vivo. Finally, the calpain-1 mediated regulation of PTP1B appears to be a systemic event as evident by the enhanced tyrosine dephosphorylation of B lymphocytes and their resistance to apoptosis in calpain-1 null mice. Together, our results demonstrate that PTP1B is a physiological substrate of calpain-1 and suggest that a similar mechanism may regulate calpain-1 mediated tyrosine dephosphorylation in other cells.

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