scholarly journals Site-Selective Regulation of Platelet-Derived Growth Factor β Receptor Tyrosine Phosphorylation by T-Cell Protein Tyrosine Phosphatase

2004 ◽  
Vol 24 (5) ◽  
pp. 2190-2201 ◽  
Author(s):  
Camilla Persson ◽  
Catrine Sävenhed ◽  
Annie Bourdeau ◽  
Michel L. Tremblay ◽  
Boyka Markova ◽  
...  
Keyword(s):  
T Cell ◽  
Growth Factor ◽  
Tyrosine Kinase ◽  
Tyrosine Phosphorylation ◽  
Platelet Derived Growth Factor ◽  
Tyrosine Kinase Receptors ◽  
Protein Tyrosine ◽  
Phospholipase Cγ1 ◽  
Β Receptor ◽  
Ptp 1B

ABSTRACT The platelet-derived growth factor (PDGF) β receptor mediates mitogenic and chemotactic signals. Like other tyrosine kinase receptors, the PDGF β receptor is negatively regulated by protein tyrosine phosphatases (PTPs). To explore whether T-cell PTP (TC-PTP) negatively regulates the PDGF β receptor, we compared PDGF β receptor tyrosine phosphorylation in wild-type and TC-PTP knockout (ko) mouse embryos. PDGF β receptors were hyperphosphorylated in TC-PTP ko embryos. Fivefold-higher ligand-induced receptor phosphorylation was observed in TC-PTP ko mouse embryo fibroblasts (MEFs) as well. Reexpression of TC-PTP partly abolished this difference. As determined with site-specific phosphotyrosine antibodies, the extent of hyperphosphorylation varied among different autophosphorylation sites. The phospholipase Cγ1 binding site Y1021, previously implicated in chemotaxis, displayed the largest increase in phosphorylation. The increase in Y1021 phosphorylation was accompanied by increased phospholipase Cγ1 activity and migratory hyperresponsiveness to PDGF. PDGF β receptor tyrosine phosphorylation in PTP-1B ko MEFs but not in PTPε ko MEFs was also higher than that in control cells. This increase occurred with a site distribution different from that seen after TC-PTP depletion. PDGF-induced migration was not increased in PTP-1B ko cells. In summary, our findings identify TC-PTP as a previously unrecognized negative regulator of PDGF β receptor signaling and support the general notion that PTPs display site selectivity in their action on tyrosine kinase receptors.

scholarly journals Loss of T-Cell Protein Tyrosine Phosphatase Induces Recycling of the Platelet-derived Growth Factor (PDGF) β-Receptor but Not the PDGF α-Receptor

2006 ◽  
Vol 17 (11) ◽  
pp. 4846-4855 ◽  
Author(s):  
Susann Karlsson ◽  
Katarzyna Kowanetz ◽  
Åsa Sandin ◽  
Camilla Persson ◽  
Arne Östman ◽  
...  
Keyword(s):  
T Cell ◽  
Growth Factor ◽  
Cell Surface ◽  
Protein Tyrosine Phosphatase ◽  
Tyrosine Phosphatase ◽  
Dominant Negative ◽  
Platelet Derived Growth Factor ◽  
Cell Protein ◽  
Protein Tyrosine ◽  
Β Receptor

We have previously shown that the T-cell protein tyrosine phosphatase (TC-PTP) dephosphorylates the platelet-derived growth factor (PDGF) β-receptor. Here, we show that the increased PDGF β-receptor phosphorylation in TC-PTP knockout (ko) mouse embryonic fibroblasts (MEFs) occurs primarily on the cell surface. The increased phosphorylation is accompanied by a TC-PTP–dependent, monensin-sensitive delay in clearance of cell surface PDGF β-receptors and delayed receptor degradation, suggesting PDGF β-receptor recycling. Recycled receptors could also be directly detected on the cell surface of TC-PTP ko MEFs. The effect of TC-PTP depletion was specific for the PDGF β-receptor, because PDGF α-receptor homodimers were cleared from the cell surface at the same rate in TC-PTP ko MEFs as in wild-type MEFs. Interestingly, PDGF αβ-receptor heterodimers were recycling. Analysis by confocal microscopy revealed that, in TC-PTP ko MEFs, activated PDGF β-receptors colocalized with Rab4a, a marker for rapid recycling. In accordance with this, transient expression of a dominant-negative Rab4a construct increased the rate of clearance of cell surface receptors on TC-PTP ko MEFs. Thus, loss of TC-PTP specifically redirects the PDGF β-receptor toward rapid recycling, which is the first evidence of differential trafficking of PDGF receptor family members.

Activity of STI571 in chronic myelomonocytic leukemia with a platelet-derived growth factor β receptor fusion oncogene

Blood ◽  
2002 ◽  
Vol 100 (3) ◽  
pp. 1088-1091 ◽  
Author(s):  
Magnus K. Magnusson ◽  
Kristin E. Meade ◽  
Ryotaro Nakamura ◽  
John Barrett ◽  
Cynthia E. Dunbar
Keyword(s):  
Growth Factor ◽  
Tyrosine Kinase ◽  
Kinase Inhibitor ◽  
Fusion Gene ◽  
Chronic Myelomonocytic Leukemia ◽  
Platelet Derived Growth Factor ◽  
Gene Transcript ◽  
Molecular Remission ◽  
Β Receptor ◽  
Myelomonocytic Leukemia

Abstract Platelet-derived growth factor β receptor (PDGFβR) fusion genes have been shown to be critical transforming oncogenes in a subset of patients with chronic myelomonocytic leukemia (CMML). The sensitivity of dysregulated tyrosine kinase oncogenes to the tyrosine kinase inhibitor STI571 (imatinib mesylate) makes it a potentially attractive treatment option in this subset of patients. We have recently cloned a novel member of the PDGFβR fusion oncogene family, rabaptin-5-PDGFβR. A patient with CMML carrying the rabaptin-5-PDGFβR fusion gene underwent allogeneic stem cell transplantation (SCT) and was monitored closely with a sensitive reverse transcriptase–polymerase chain assay to detect the novel fusion gene transcript. After achieving a molecular remission at 5 months after transplantation, 15 months after SCT the patient showed persistent and progressive evidence of molecular relapse. After demonstrating in vitro that cells transformed with this specific fusion oncogene are efficiently killed by STI571, the patient was started on STI571. The patient responded rapidly and entered molecular remission after 6 weeks of therapy, and he continues to be in remission 6 months later. These results suggest that STI571 may be an effective targeted therapy in patients with CMML related to PDGFβR fusion oncogenes.

Rabaptin-5 is a novel fusion partner to platelet-derived growth factor β receptor in chronic myelomonocytic leukemia

Blood ◽  
2001 ◽  
Vol 98 (8) ◽  
pp. 2518-2525 ◽  
Author(s):  
Magnus K. Magnusson ◽  
Kristin E. Meade ◽  
Kevin E. Brown ◽  
Diane C. Arthur ◽  
Lisa A. Krueger ◽  
...  
Keyword(s):  
Growth Factor ◽  
Fusion Protein ◽  
Tyrosine Kinase ◽  
Fusion Proteins ◽  
Growth Regulation ◽  
Chronic Myelomonocytic Leukemia ◽  
Platelet Derived Growth Factor ◽  
Fusion Partner ◽  
Β Receptor ◽  
Myelomonocytic Leukemia

Abstract Chromosomal translocations involving the platelet-derived growth factor β receptor (PDGFβR) gene have been reported in some patients with chronic myelomonocytic leukemia (CMML). The resultant fusion proteins have constitutive PDGFβR tyrosine kinase activity, but the partner genes previously reported(tel, Huntingtin interacting protein 1[HIP-1], H4/D10S170) have poorly understood roles in the oncogenic activity of the fusion proteins. A novel PDGFβR fusion protein has been characterized in a patient with CMML and an acquired t(5;17)(q33;p13). Southern blot analysis on patient leukemia cells demonstrated involvement of the PDGFβR gene. Using 5′ rapid amplification of complementary DNA ends–polymerase chain reaction (RACE-PCR) on patient RNA, rabaptin-5 was identified as a novel partner fused in-frame to thePDGFβR gene. The new fusion protein includes more than 85% of the native Rabaptin-5 fused to the transmembrane and intracellular tyrosine kinase domains of the PDGFβR. Transduction with a retroviral vector expressing rabaptin-5/PDGFβRtransformed the hematopoietic cell line Ba/F3 to growth factor independence and caused a fatal myeloproliferative disease in mice. Rabaptin-5 is a well-studied protein shown to be an essential and rate-limiting component of early endosomal fusion through interaction with the Ras family GTPases Rab5 and Rab4. The fusion protein includes 3 of 4 coiled-coil domains (involved in homodimerization of native rabaptin-5), 2 caspase-3 cleavage sites, and a binding site for the tumor suppressor gene tuberin (tuberous sclerosis complex-2). Early endosomal transport is critical in regulation of various growth factor receptors, through ligand-induced clathrin-mediated endocytosis, and thus this new fusion protein links together 2 important pathways of growth regulation.

scholarly journals Activation of Src Family Members Is Not Required for the Platelet-Derived Growth Factor β Receptor To Initiate Mitogenesis

1998 ◽  
Vol 18 (4) ◽  
pp. 2014-2022 ◽  
Author(s):  
Kris A. DeMali ◽  
Andrius Kazlauskas
Keyword(s):  
Cell Cycle ◽  
Cell Proliferation ◽  
Growth Factor ◽  
Tyrosine Phosphorylation ◽  
Platelet Derived Growth Factor ◽  
Maximal Activation ◽  
Associated Proteins ◽  
Dependent Cell ◽  
Β Receptor ◽  
Stimulation Of

ABSTRACT The basal activity of Src family kinases is readily detectable throughout the cell cycle and increases by two- to fivefold upon acute stimulation of cells with growth factors such as platelet-derived growth factor. Previous reports have demonstrated a requirement for Src activity for the G1/S and G2/M transitions. With a chimeric α-β PDGF receptor (PDGFR) expressed in fibroblasts, we have investigated the importance of the PDGF-mediated increase in Src activity at the G0/G1 transition for subsequent cell cycle events. A mutant PDGFR chimera that was not able to detectably associate with or activate Src was compromised in its ability to mediate tyrosine phosphorylation of receptor-associated signaling molecules and initiated a submaximal activation of Erk. In contrast to these early cell cycle events, later responses such as entry of cells into S phase and cell proliferation proceeded normally when Src activity did not increase following acute stimulation with PDGF. We conclude that the initial burst of Src activity is required for efficient tyrosine phosphorylation of receptor-associated proteins such as PLCγ, RasGAP, Shc, and SHP-2 and for maximal activation of Erk. Surprisingly, these events are not required for PDGF-dependent cell proliferation. Finally, later cell cycle events do not require that Src be activated at the G0/G1 transition and leave open the possibility that events such as the G1/S transition require the basal Src activity and/or activation of Src at later times in G1.

Inhibition by 5′-methylthioadenosine of cell growth and tyrosine kinase activity stimulated by fibroblast growth factor receptor in human gliomas

1995 ◽  
Vol 83 (4) ◽  
pp. 690-697 ◽  
Author(s):  
Katsuya Miyaji ◽  
Eiichi Tani ◽  
Atsuhisa Nakano ◽  
Hideyasu Ikemoto ◽  
Keizo Kaba
Keyword(s):  
Growth Factor ◽  
Cell Growth ◽  
Tyrosine Kinase ◽  
Tyrosine Phosphorylation ◽  
Protein Tyrosine Kinase ◽  
Kinase Activity ◽  
Glioma Cells ◽  
Protein Tyrosine Phosphorylation ◽  
Tyrosine Kinase Activity ◽  
Protein Tyrosine

✓ Stimulation of three human glioma cell lines with basic fibroblast growth factor (bFGF) led to the enhancement of cell growth and the rapid tyrosine phosphorylation of cellular proteins, including major substrates of 90 kD. A methyltransferase inhibitor, 5′-methylthioadenosine (MTA), inhibited dose dependently the bFGF-stimulated cell growth and protein tyrosine phosphorylation in glioma cells by blocking both receptor autophosphorylation and substrate phosphorylation, as shown by immunoblotting with antiphosphotyrosine antibodies and cross-linking bFGF to receptors. The antiproliferative activity of MTA correlated quantitatively with its potency as an inhibitor of bFGF-stimulated protein tyrosine kinase activity. The methyltransferase inhibitor MTA had no effect on either epidermal growth factor— or platelet-derived growth factor—stimulated protein tyrosine phosphorylation in glioma cells, but inhibited specifically bFGF-stimulated protein tyrosine kinase activity. The concentration of MTA required for inhibition of protein methylation correlated well with the concentration required for inhibition of bFGF-stimulated cell growth and protein tyrosine phosphorylation. Because MTA had no effect on numbers and dissociation constants of high- and low-affinity bFGF receptors, the inhibition of bFGF-stimulated bFGF receptor tyrosine kinase activity is not likely to be the result of a reduction in bFGF receptor and bFGF binding capacity. In fact, MTA delayed and reduced the internalization and nuclear translocation of bFGF, and the internalized bFGF was submitted to a limited proteolysis that converted it to lower molecular peptides whose presence remained for at least 22 hours. The effect of MTA on bFGF-stimulated tyrosine phosphorylation was immediate and readily reversible.

scholarly journals Protein Tyrosine Phosphatase 1B Attenuates Growth Hormone-Mediated JAK2-STAT Signaling

2003 ◽  
Vol 23 (11) ◽  
pp. 3753-3762 ◽  
Author(s):  
Feng Gu ◽  
Nadia Dubé ◽  
Jin Wook Kim ◽  
Alan Cheng ◽  
Maria de Jesus Ibarra-Sanchez ◽  
...  
Keyword(s):  
Growth Hormone ◽  
Tyrosine Kinase ◽  
Tyrosine Phosphorylation ◽  
Protein Tyrosine Phosphatase ◽  
Tyrosine Phosphatase ◽  
Cytokine Signaling ◽  
Tyrosine Kinase Domain ◽  
Protein Tyrosine Phosphatase 1B ◽  
Protein Tyrosine ◽  
Ptp 1B

ABSTRACT Protein tyrosine phosphatase-1B (PTP-1B) attenuates insulin, PDGF, EGF, and IGF-I signaling by dephosphorylating tyrosine residues located in the tyrosine kinase domain of the corresponding receptors. More recently, PTP-1B was shown to modulate the action of cytokine signaling via the nonreceptor tyrosine kinase JAK2. Transmission of the growth hormone (GH) signal also depends on JAK2, raising the possibility that PTP-1B modulates GH action. Consistent with this hypothesis, GH increased the abundance of tyrosine-phosphorylated JAK2 associated with a catalytically inactive mutant of PTP-1B. GH-induced JAK2 phosphorylation was greater in knockout (KO) than in wild-type (WT) PTP-1B embryonic fibroblasts and resulted in increased tyrosine phosphorylation of STAT3 and STAT5, while overexpression of PTP-1B reduced the GH-mediated activation of the acid-labile subunit gene. To evaluate the in vivo relevance of these observations, mice were injected with GH under fed and fasted conditions. As expected, tyrosine phosphorylation of JAK2 and STAT5 occurred readily in the livers of fed WT mice and was almost completely abolished during fasting. In contrast, resistance to the action of GH was severely impaired in the livers of fasted KO mice. These results indicate that PTP-1B regulates GH signaling by reducing the extent of JAK2 phosphorylation and suggest that PTP-1B is essential for limiting the action of GH during metabolic stress such as fasting.

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