scholarly journals Endosomal Targeting of the Phosphoinositide 3-Phosphatase MTMR2 Is Regulated by an N-terminal Phosphorylation Site

2011 ◽  
Vol 286 (18) ◽  
pp. 15841-15853 ◽  
Author(s):  
Norah E. Franklin ◽  
Gregory S. Taylor ◽  
Panayiotis O. Vacratsis
Keyword(s):  
Protein Tyrosine Phosphatase ◽  
Molecular Mechanisms ◽  
Tyrosine Phosphatase ◽  
Phosphorylation Site ◽  
Large Protein ◽  
Charcot Marie Tooth Disease ◽  
Lipid Phosphatases ◽  
Sensor Protein ◽  
Endosome Maturation ◽  
Tooth Disease

MTMR2 is a member of the myotubularin family of inositol lipid phosphatases, a large protein-tyrosine phosphatase subgroup that is conserved from yeast to humans. Furthermore, the peripheral neuromuscular disease Charcot-Marie Tooth disease type 4B has been attributed to mutations in the mtmr2 gene. Because the molecular mechanisms regulating MTMR2 have been poorly defined, we investigated whether reversible phosphorylation might regulate MTMR2 function. We used mass spectrometry-based methods to identify a high stoichiometry phosphorylation site on serine 58 of MTMR2. Phosphorylation at Ser58, or a phosphomimetic S58E mutation, markedly decreased MTMR2 localization to endocytic vesicular structures. In contrast, a phosphorylation-deficient MTMR2 mutant (S58A) displayed constitutive localization to early endocytic structures. This localization pattern was accompanied by displacement of a PI(3)P-specific sensor protein and an increase in signal transduction pathways. Thus, MTMR2 phosphorylation is likely to be a critical mechanism by which MTMR2 access to its lipid substrate(s) is temporally and spatially regulated, thereby contributing to the control of downstream endosome maturation events.

Protein tyrosine phosphatase-α complexes with the IGF-I receptor and undergoes IGF-I-stimulated tyrosine phosphorylation that mediates cell migration

2009 ◽  
Vol 297 (1) ◽  
pp. C133-C139 ◽  
Author(s):  
Shirley C. Chen ◽  
Ranvikram S. Khanna ◽  
Darrell C. Bessette ◽  
Lionel A. Samayawardhena ◽  
Catherine J. Pallen
Keyword(s):  
Cell Migration ◽  
Tyrosine Phosphorylation ◽  
Protein Tyrosine Phosphatase ◽  
Tyrosine Kinases ◽  
Tyrosine Phosphatase ◽  
Phosphorylation Site ◽  
Protein Tyrosine ◽  
Fibroblast Migration ◽  
Igf I ◽  
In Cells

Protein tyrosine phosphatase-α (PTPα) is a widely expressed receptor-type phosphatase that functions in multiple signaling systems. The actions of PTPα can be regulated by its phosphorylation on serine and tyrosine residues, although little is known about the conditions that promote PTPα phosphorylation. In this study, we tested the ability of several extracellular factors to stimulate PTPα tyrosine phosphorylation. The growth factors IGF-I and acidic FGF induced the highest increase in PTPα phosphorylation at tyrosine 789, followed by PMA and lysophosphatidic acid, while EGF had little effect. Further investigation of IGF-I-induced PTPα tyrosine phosphorylation demonstrated that this occurs through a novel Src family kinase-independent mechanism that does not require focal adhesion kinase, phosphatidylinositol 3-kinase, or MEK. We also show that PTPα physically interacts with the IGF-I receptor. In contrast to IGF-I-induced PTPα phosphorylation, this association does not require IGF-I. The interaction of PTPα and the IGF-I receptor is independent of PTPα catalytic activity, and expression of exogenous PTPα does not promote IGF-I receptor tyrosine dephosphorylation, indicating that PTPα does not act as an IGF-I receptor phosphatase. However, PTPα mediates IGF-I signaling, because IGF-I-stimulated fibroblast migration was reduced by ∼50% in cells lacking PTPα or in cells with mutant PTPα lacking the tyrosine 789 phosphorylation site. Our results suggest that PTPα tyrosine phosphorylation can occur in response to diverse stimuli and can be mediated by various tyrosine kinases. In the case of IGF-I, we propose that IGF-I-induced tyrosine 789 phosphorylation of PTPα, possibly catalyzed by the PTPα-associated IGF-I receptor tyrosine kinase, is required for efficient cell migration in response to this growth factor.

scholarly journals Tyrosine phosphorylation enhances activity of pneumococcal autolysin LytA

Microbiology ◽  
2014 ◽  
Vol 160 (12) ◽  
pp. 2745-2754 ◽  
Author(s):  
Alistair J. Standish ◽  
Jonathan J. Whittall ◽  
Renato Morona
Keyword(s):  
Tyrosine Phosphorylation ◽  
Protein Tyrosine Phosphatase ◽  
Capsular Polysaccharide ◽  
Regulatory Mechanism ◽  
Tyrosine Phosphatase ◽  
Phosphorylation Site ◽  
Regulatory Proteins ◽  
Amidase Activity ◽  
The Past

Tyrosine phosphorylation has long been recognized as a crucial post-translational regulatory mechanism in eukaryotes. However, only in the past decade has recognition been given to the crucial importance of bacterial tyrosine phosphorylation as an important regulatory feature of pathogenesis. This study describes the effect of tyrosine phosphorylation on the activity of a major virulence factor of the pneumococcus, the autolysin LytA, and a possible connection to the Streptococcus pneumoniae capsule synthesis regulatory proteins (CpsB, CpsC and CpsD). We show that in vitro pneumococcal tyrosine kinase, CpsD, and the protein tyrosine phosphatase, CpsB, act to phosphorylate and dephosphorylate LytA. Furthermore, this modulates LytA function in vitro with phosphorylated LytA binding more strongly to the choline analogue DEAE. A phospho-mimetic (Y264E) mutation of the LytA phosphorylation site displayed similar phenotypes as well as an enhanced dimerization capacity. Similarly, tyrosine phosphorylation increased LytA amidase activity, as evidenced by a turbidometric amidase activity assay. Similarly, when the phospho-mimetic mutation was introduced in the chromosomal lytA of S. pneumoniae, autolysis occurred earlier and at an enhanced rate. This study thus describes, to our knowledge, the first functional regulatory effect of tyrosine phosphorylation on a non-capsule-related protein in the pneumococcus, and suggests a link between the regulation of LytA-dependent autolysis of the cell and the biosynthesis of capsular polysaccharide.

scholarly journals Dual Specificity Phosphatases: From Molecular Mechanisms to Biological Function

2019 ◽  
Vol 20 (18) ◽  
pp. 4372 ◽  
Author(s):  
Rafael Pulido ◽  
Roland Lang
Keyword(s):  
Protein Tyrosine Phosphatase ◽  
Human Disease ◽  
Molecular Mechanisms ◽  
Biological Function ◽  
Tyrosine Phosphatase ◽  
Heterogeneous Group ◽  
Class I ◽  
Protein Tyrosine ◽  
Dual Specificity ◽  
Dual Specificity Phosphatases

Dual specificity phosphatases (DUSPs) constitute a heterogeneous group of enzymes, relevant in human disease, which belong to the class I Cys-based group of protein tyrosine phosphatase (PTP) gene superfamily [...]

scholarly journals Protein Tyrosine Phosphatase SHP-2 (PTPN11) in Hematopoiesis and Leukemogenesis

2011 ◽  
Vol 2011 ◽  
pp. 1-8 ◽  
Author(s):  
Xia Liu ◽  
Cheng-Kui Qu
Keyword(s):  
Protein Tyrosine Phosphatase ◽  
Molecular Mechanisms ◽  
Somatic Mutations ◽  
Tyrosine Phosphatase ◽  
Hematologic Malignancies ◽  
Cytokine Signaling ◽  
Interacting Proteins ◽  
Protein Tyrosine ◽  
And Function ◽  
Shed Light

SHP-2 (PTPN11), a ubiquitously expressed protein tyrosine phosphatase, is critical for hematopoietic cell development and function owing to its essential role in growth factor/cytokine signaling. More importantly, germline and somatic mutations in this phosphatase are associated with Noonan syndrome, Leopard syndrome, and childhood hematologic malignancies. The molecular mechanisms by which SHP-2 mutations induce these diseases are not fully understood, as the biochemical bases of SHP-2 functions still remain elusive. Further understanding SHP-2 signaling activities and identification of its interacting proteins/substrates will shed light on the pathogenesis of PTPN11-associated hematologic malignancies, which, in turn, may lead to novel therapeutics for these diseases.

scholarly journals Neural and Molecular Features on Charcot-Marie-Tooth Disease Plasticity and Therapy

2012 ◽  
Vol 2012 ◽  
pp. 1-11 ◽  
Author(s):  
Paula Juárez ◽  
Francesc Palau
Keyword(s):  
Schwann Cell ◽  
Cell Biology ◽  
Molecular Mechanisms ◽  
Mitochondrial Dynamics ◽  
Sensory Nerves ◽  
Peripheral Neuropathies ◽  
Charcot Marie Tooth ◽  
Charcot Marie Tooth Disease ◽  
Molecular Features ◽  
Tooth Disease

In the peripheral nervous system disorders plasticity is related to changes on the axon and Schwann cell biology, and the synaptic formations and connections, which could be also a focus for therapeutic research. Charcot-Marie-Tooth disease (CMT) represents a large group of inherited peripheral neuropathies that involve mainly both motor and sensory nerves and induce muscular atrophy and weakness. Genetic analysis has identified several pathways and molecular mechanisms involving myelin structure and proper nerve myelination, transcriptional regulation, protein turnover, vesicle trafficking, axonal transport and mitochondrial dynamics. These pathogenic mechanisms affect the continuous signaling and dialogue between the Schwann cell and the axon, having as final result the loss of myelin and nerve maintenance; however, some late onset axonal CMT neuropathies are a consequence of Schwann cell specific changes not affecting myelin. Comprehension of molecular pathways involved in Schwann cell-axonal interactions is likely not only to increase the understanding of nerve biology but also to identify the molecular targets and cell pathways to design novel therapeutic approaches for inherited neuropathies but also for most common peripheral neuropathies. These approaches should improve the plasticity of the synaptic connections at the neuromuscular junction and regenerate cell viability based on improving myelin and axon interaction.

scholarly journals Regulatory Functions of Protein Tyrosine Phosphatase Receptor Type O in Immune Cells

2021 ◽  
Vol 12 ◽  
Author(s):  
Feiling Xie ◽  
Hongmei Dong ◽  
Hao Zhang
Keyword(s):  
T Cells ◽  
B Cells ◽  
Immune Cells ◽  
Protein Tyrosine Phosphatase ◽  
Molecular Mechanisms ◽  
Tyrosine Phosphatase ◽  
Protein Tyrosine Phosphatases ◽  
Receptor Type ◽  
Protein Tyrosine ◽  
Cellular Processes

The members of the protein tyrosine phosphatase (PTP) family are key regulators in multiple signal transduction pathways and therefore they play important roles in many cellular processes, including immune response. As a member of PTP family, protein tyrosine phosphatase receptor type O (PTPRO) belongs to the R3 receptor-like protein tyrosine phosphatases. The expression of PTPRO isoforms is tissue-specific and the truncated PTPRO (PTPROt) is mainly observed in hematopoietic cells, including B cells, T cells, macrophages and other immune cells. Therefore, PTPROt may play an important role in immune cells by affecting their growth, differentiation, activation and immune responses. In this review, we will focus on the regulatory roles and underlying molecular mechanisms of PTPRO/PTPROt in immune cells, including B cells, T cells, and macrophages.

The Role of Protein Tyrosine Phosphatase, Shp2, in FLT3-ITD-Induced Leukemogenesis.

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 1804-1804
Author(s):  
Sarah C Nabinger ◽  
Seiji Fukuda ◽  
Reuben Kapur ◽  
Rebecca Chan
Keyword(s):  
Protein Tyrosine Phosphatase ◽  
Molecular Mechanisms ◽  
Tyrosine Phosphatase ◽  
Dependent Manner ◽  
Erk Activation ◽  
Protein Tyrosine ◽  
Knock Down ◽  
Mammalian Expression ◽  
Tandem Duplications

Abstract Internal tandem duplications of the FMS-like receptor tyrosine kinase (FLT3-ITDs), an in-fame insertion of several amino acids within the juxtamembrane domain, are present in 25% of acute myeloid leukemia (AML) patients and confer a poor prognosis. FLT3-ITDs induce FLT3 ligand (FL)-independent hyperactivation of Erk and promiscuous activation of STAT5; however, the molecular mechanisms underlying aberrant activation of these signaling molecules is largely unknown. Tyrosine 599 (Y599) of WT FLT3 recruits the protein tyrosine phosphatase, Shp2, upon stimulation with FL, resulting Erk activation. In several FLT3-ITDs, including N51-FLT3 and N73-FLT3, Y599 is duplicated. These findings led us to hypothesize that increased recruitment of Shp2 to N51-FLT3 or N73- FLT3, via Y599, results in enhanced Shp2 activation and contributes to N51-FLT3- and N73-FLT3-induced cellular hyperproliferation, Erk hyperactivation, and promiscuous STAT5 activation. Using Baf3 cells stably expressing WT FLT3, N51-FLT3, or N73- FLT3, co-immunoprecipitation assays demonstrated that Shp2 is phosphorylated and associates with WT FLT3 in a FL-dependent manner. However, in contrast, Shp2 is constitutively hyperphosphorylated and associated with FLT3-N51 and FLT3-N73 independent of FL stimulation. To investigate the functional role of Shp2 in Flt3-ITD-induced leukemogenesis, Baf3 cells expressing WT FLT3, N51-FLT3, or N73-FLT3 were transfected with a mammalian expression vector encoding a U6 polymerase III– directed Shp2-specific short-hairpin RNA (shRNA) or a scrambled shRNA and selected in puromycin. Western blot analysis revealed significant reduction of Shp2 expression by the Shp2-specific shRNA and no change in Shp2 expression by the scrambled shRNA in all cell lines. Upon knock-down of Shp2 in Baf3/WT-FLT3 cells, proliferation was minimally reduced based on thymidine incorporation assays; however, knock-down of Shp2 in Baf3/N51-FLT3 and Baf3/N73-FLT3 cells significantly reduced proliferation, both at baseline and in response to FL stimulation. Collectively, these data suggest that constitutive recruitment of Shp2 to N51-FLT3 and N73-FLT3 contributes to the FLT3- ITD-induced hyperproliferative phenotype and imply that inhibition of Shp2 function may provide a novel therapeutic approach to FLT3-ITD-bearing leukemias.

scholarly journals The T-cell protein tyrosine phosphatase is phosphorylated on Ser-304 by cyclin-dependent protein kinases in mitosis

2004 ◽  
Vol 380 (3) ◽  
pp. 939-949 ◽  
Author(s):  
Patricia BUKCZYNSKA ◽  
Manuela KLINGLER-HOFFMANN ◽  
Kenneth I. MITCHELHILL ◽  
Mark H. C. LAM ◽  
Melissa CICCOMANCINI ◽  
...  
Keyword(s):  
T Cell ◽  
Protein Kinase ◽  
Protein Tyrosine Phosphatase ◽  
Tyrosine Phosphatase ◽  
Phosphorylation Site ◽  
Protein Kinase Inhibitors ◽  
Mitogen Activated Protein Kinase ◽  
Cell Protein ◽  
Protein Tyrosine ◽  
Dependent Protein

Two alternatively spliced forms of the human protein tyrosine phosphatase TCPTP (T-cell protein tyrosine phosphatase) exist: a 48 kDa form that is targeted to the endoplasmic reticulum (TC48) and a shorter 45 kDa form that is targeted to the nucleus (TC45). In this study we have identified Ser-304 (Phe301-Asp-His-Ser304-Pro-Asn-Lys307) as a major TCPTP phosphory-lation site and demonstrate that TC45, but not TC48, is phosphorylated on this site in vivo. Phosphorylation of TC45 on Ser-304 was cell cycle-dependent, and increased as cells progressed from G2 into mitosis, but subsided upon mitotic exit. Ser-304 phosphorylation was increased when cells were arrested in mitosis by microtubule poisons such as nocodazole, but remained unaltered when cells were arrested at the G2/M checkpoint by adriamycin. Phosphorylation of Ser-304 did not alter significantly the phosphatase activity or the protein stability of TC45, and had no apparent effect on TC45 localization. Ser-304 phosphorylation was ablated when cells were treated with the CDK (cyclin-dependent protein kinase) inhibitors roscovitine or SU9516, but remained unaltered when ERK1/2 activation was inhibited with the MEK (mitogen-activated protein kinase/extracellular-signal-regulated kinase kinase) inhibitor PD98059. In addition, recombinant CDKs, but not the Polo-like kinase Plk1, phosphorylated Ser-304 in vitro. Our studies identify Ser-304 as a major phosphorylation site in human TCPTP, and the TC45 variant as a novel mitotic CDK substrate.

scholarly journals Protein tyrosine phosphatase SAP-1 protects against colitis through regulation of CEACAM20 in the intestinal epithelium

2015 ◽  
Vol 112 (31) ◽  
pp. E4264-E4271 ◽  
Author(s):  
Yoji Murata ◽  
Takenori Kotani ◽  
Yana Supriatna ◽  
Yasuaki Kitamura ◽  
Shinya Imada ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Tyrosine Kinase ◽  
Tyrosine Phosphorylation ◽  
Intestinal Epithelium ◽  
Protein Tyrosine Phosphatase ◽  
Molecular Mechanisms ◽  
Transmembrane Protein ◽  
Tyrosine Phosphatase ◽  
Intestinal Immunity ◽  
Protein Tyrosine

Intestinal epithelial cells contribute to regulation of intestinal immunity in mammals, but the detailed molecular mechanisms of such regulation have remained largely unknown. Stomach-cancer–associated protein tyrosine phosphatase 1 (SAP-1, also known as PTPRH) is a receptor-type protein tyrosine phosphatase that is localized specifically at microvilli of the brush border in gastrointestinal epithelial cells. Here we show that SAP-1 ablation in interleukin (IL)-10–deficient mice, a model of inflammatory bowel disease, resulted in a marked increase in the severity of colitis in association with up-regulation of mRNAs for various cytokines and chemokines in the colon. Tyrosine phosphorylation of carcinoembryonic antigen-related cell adhesion molecule (CEACAM) 20, an intestinal microvillus-specific transmembrane protein of the Ig superfamily, was greatly increased in the intestinal epithelium of the SAP-1–deficient animals, suggesting that this protein is a substrate for SAP-1. Tyrosine phosphorylation of CEACAM20 by the protein tyrosine kinase c-Src and the consequent association of CEACAM20 with spleen tyrosine kinase (Syk) promoted the production of IL-8 in cultured cells through the activation of nuclear factor-κB (NF-κB). In addition, SAP-1 and CEACAM20 were found to form a complex through interaction of their ectodomains. SAP-1 and CEACAM20 thus constitute a regulatory system through which the intestinal epithelium contributes to intestinal immunity.

scholarly journals The PTP1B mutant PTP1B2-4 is a positive regulator of the JAK/STAT signalling pathway in Hodgkin lymphoma

2020 ◽  
Author(s):  
Malena Zahn ◽  
Bianca Kaluszniak ◽  
Peter Möller ◽  
Ralf Marienfeld
Keyword(s):  
Hodgkin Lymphoma ◽  
Protein Tyrosine Phosphatase ◽  
Molecular Mechanisms ◽  
Tyrosine Phosphatase ◽  
Janus Kinase ◽  
Protein Tyrosine Phosphatase 1B ◽  
Oncogenic Potential ◽  
Protein Levels ◽  
Mrna Variants ◽  
Chronic Activation

Abstract The neoplastic Hodgkin/Reed-Sternberg (HRS) cells of classical Hodgkin lymphoma (cHL) depend on chronic activation of the Janus kinase (JAK)/signal transducer and activator of transcription (STAT) signalling pathways to maintain survival and proliferation. Accumulating reports highlight the importance of the inactivation or reduced expression of negative JAK/STAT regulators such as the protein-tyrosine phosphatase 1B (PTP1B/PTPN1) in this process. Various PTPN1 mRNA variants as well as truncated PTP1B proteins were identified in cHL cell lines and primary cHL tumour samples. These PTPN1 mRNA variants lack either one or several exon sequences and therefore render these PTP1B variants catalytically inactive. Here we show that one of these mutants, PTP1B▵2-4, is not only a catalytically inactive variant, but also augmented the IL-4-induced JAK/STAT activity similar to the recently reported PTP1B▵6 splice variant. Moreover, while PTP1B▵6 diminished the activity and protein levels of PTP1BWT, PTP1BWT remained unaffected by PTP1B▵2-4, arguing for different molecular mechanisms of JAK/STAT modulation by PTP1B▵6 and PTP1B▵2-4. Collectively, these data indicate that PTPN1 variants missing one or more exon sequences originated either from alternative splicing or from gene mutation, create PTP1B gain-of-function variants with oncogenic potential by augmenting JAK/STAT signalling in cHL.

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