A new high affinity binding site for suppressor of cytokine signaling‐3 on the erythropoietin receptor

Hörtner, Michael; Nielsch, Ulrich; Mayr, Lorenz M.; Heinrich, Peter C.; Haan, Serge

doi:10.1046/j.1432-1033.2002.02916.x

Cited by 80 publications

(64 citation statements)

References 52 publications

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“…However, many reports have shown that SOCS3 inhibits cytokine signaling by binding cytokine receptors at a putative immunoreceptor tyrosine-based inhibitory motif (ITIM). 11,13 Mutation of the EPOR ITIM reduces the inhibitor effect of SOCS3, suggesting that it interacts with both JAK2, probably via its kinase inhibitory region (KIR), and the EPOR. This may explain why SOCS3 blunts the EPO response so strongly and why SOCS1 does not enhance the JAK2 V617F response.…”

Section: Discussionmentioning

confidence: 99%

“…Ba/F3-SOCS3 cells 11 were retrovirally infected with EPOR pMX-IRES-GFP, JAK2 V617F pMX-IRES-CD4, or JAK2 WT pMX-IRES-CD4. 2 293T cells were transfected with 2 g SOCS1 pME18S Flag, SOCS2 pME18S Flag, SOCS3 pME18S Flag, JAK2 WT pRK, and JAK2 V617F pRK as appropriate using FuGENE (Roche Diagnostics, West Sussex, United Kingdom).…”

Section: Cells and Transfectionsmentioning

confidence: 99%

“…9,10 Additionally, SOCS3 binds via its SH2 domain to tyrosine residues of the EPOR: Y401, where STAT5 and SHP-2 also bind, and Y429/Y431, where SHP-1 also binds. 11 The ability of SOCS3 to interact with both the EPOR and JAK2, may increase the inhibitory effect of SOCS3 on the EPO signaling pathway. Indeed, the inhibitory effect of SOCS3 is greatly enhanced in the presence of a cognate receptor, as has been reported for interleukin 2 receptor ␤ (IL-2R␤) 12 and GP130 signaling, 13 suggesting that receptor interaction may be essential for SOCS3-mediated inhibition.…”

Section: Introductionmentioning

confidence: 99%

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The myeloproliferative disorder–associated JAK2 V617F mutant escapes negative regulation by suppressor of cytokine signaling 3

Hookham

Elliott

Suessmuth

et al. 2007

Blood

111

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The somatic JAK2 valine-to-phenylalanine (V617F) mutation has been detected in up to 90% of patients with polycythemia and in a sizeable proportion of patients with other myeloproliferative disorders such as essential thrombocythemia and idiopathic myelofibrosis. Suppressor of cytokine signaling 3 (SOCS3) is known to be a strong negative regulator of erythropoietin (EPO) signaling through interaction with both the EPO receptor (EPOR) and JAK2. We report here that JAK2 V617F cannot be regulated and that its activation is actually potentiated in the presence of SOCS3. Instead of acting as a suppressor, SOCS3 enhanced the proliferation of cells expressing both JAK2 V617F and EPOR. Additionally, although SOCS1 and SOCS2 are degraded in the presence of JAK2 V617F, turnover of SOCS3 is inhibited by the JAK2 mutant kinase and this correlated with marked tyrosine phosphorylation of SOCS3 protein. We also observed constitutive tyrosine phosphorylation of SOCS3 in peripheral blood mononuclear cells (PBMCs) derived from patients homozygous for the JAK2 V617F mutant. These findings suggest that the JAK2 V617F has overcome normal SOCS regulation by hyperphosphorylating SOCS3, rendering it unable to inhibit the mutant kinase. Thus, JAK2 V617F may even exploit SOCS3 to potentiate its myeloproliferative capacity. IntroductionThe somatic valine-to-phenylalanine (V617F) mutation in JAK2 has been associated with a variety of myeloproliferative disorders (MPD), including polycythemia vera (PV), essential thrombocythemia (ET), and idiopathic myelofibrosis (IMF). [1][2][3][4][5] In wild-type JAKs the JH2 domain inhibits the JH1 kinase domain through interactions at 2 interfaces, with the region containing V617 being predicted to preserve the inactive conformation of the activation loop. 6 The V617F mutation might alter this conformation and perhaps stabilize the activation loop in an active state, or it may prevent access of other proteins to the catalytic domain. The V617 residue of JAK2 is conserved in the JH2 domain of JAK1 and TYK2, whereas in JAK3 it is replaced by methionine. Like JAK2 V617F, analogous mutations in JAK1 or TYK2 also results in their constitutive activation. 7 Janus kinases require the JH2 pseudokinase domain for normal physiologic activation of the JH1 catalytic domain. Therefore, it seems that the V617F mutation may disrupt the putative inhibition of the catalytic domain by the pseudokinase domain and create a constitutively activated kinase. However, the Janus kinases are also potently regulated by the suppressor of cytokine signaling (SOCS) proteins that are thought to bind to the JH1 catalytic loop and target the kinases for degradation. Whether SOCS can regulate the JAK2 V617F mutant has not been explored. 8 SOCS1 and SOCS3 bind to the catalytic groove of JAK2 via their kinase inhibitory region (KIR) to inhibit catalytic activity. 8 Both of these SOCS proteins can also target TEL-JAK2 and wild-type JAK2 for ubiquitination and degradation via their SOCS box ECS ubiquitin E3 ligase interaction motif. 9,10 A...

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Section: Discussionmentioning

confidence: 99%

Section: Cells and Transfectionsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

The myeloproliferative disorder–associated JAK2 V617F mutant escapes negative regulation by suppressor of cytokine signaling 3

Hookham

Elliott

Suessmuth

et al. 2007

Blood

111

View full text Add to dashboard Cite

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“…Each of these modules contributes to attenuation of the duration and intensity of JAK-STAT signalling. The SH2 domain is responsible for SOCS3 binding to both the phosphotyrosine residues within cytoplasmic domain of the receptor and JAK kinase following cytokine-mediated activation (Dunn et al 2005;Hortner et al 2002a;Hortner et al 2002b;Nicholson et al 2000;Sasaki et al 1999). As a consequence, SOCS3 is thought to inhibit signal transduction by directly inhibiting JAK activity through the kinase inhibitory region (KIR) located in the SOCS3 N-terminus .…”

Section: Introductionmentioning

confidence: 99%

Regulation of multiple cytokine signalling pathways by SOCS3 is independent of SOCS2

Kiu¹,

Greenhalgh²,

Thaus³

et al. 2009

GGRF

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Suppressor of cytokine signalling (SOCS) 3 is an essential regulator of cytokine signalling, and in turn its expression is tightly regulated. Data from overexpression studies in cell lines suggest that SOCS2 regulates SOCS3 protein degradation, by forming a molecular bridge to an E3 ubiquitinligase complex. Whether this regulation is relevant in primary cells is unknown. In this study, we utilized Socs2 −/− mice to examine the role of SOCS2 in modulating SOCS3 expression and degradation, and its impact on IL-2 and IL-6 signalling in primary haemopoietic cells. Both biochemical and biological analyses demonstrated unperturbed SOCS3 expression and cytokine signalling in the absence of SOCS2. Our results suggest that SOCS2 is not a physiological regulator of SOCS3 expression and action in primary haemopoietic cells.

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“…Cytokine-inducible SH2-containing protein (CIS) interacts with phosphorylated Tyr-401 in EpoR and suppressor of cytokine signaling 3 (SOCS3) with phosphorylated Tyr-429 and Tyr-431 in addition to Tyr-401. CIS and SOCS3 both act as negative regulators of Epo signaling by inhibiting the activation of the STAT5 and ERK pathways (15)(16)(17). Furthermore, SH2 domain-containing tyrosine phosphatase 1 (SHP1) has been shown to associate with EpoR at Tyr-429 and Tyr-431.…”

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confidence: 99%

Three Tyrosine Residues in the Erythropoietin Receptor Are Essential for Janus Kinase 2 V617F Mutant-induced Tumorigenesis

Ueda

Tago

Tamura

et al. 2017

Journal of Biological Chemistry

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Edited by Alex TokerThe erythropoietin receptor (EpoR) regulates development of blood cells, and its full activation normally requires the cytokine erythropoietin (Epo). In the case of myeloproliferative neoplasms (MPN), Epo-independent signaling through EpoR can be caused by a point mutation, V617F, in the EpoR-interacting tyrosine kinase Janus kinase 2 (JAK2). In cells expressing the JAK2 V617F mutant, eight tyrosine residues in the intracellular domain of EpoR are phosphorylated, but the functional role of these phosphorylations in oncogenic signaling is incompletely understood. Here, to evaluate the functional consequences of the phosphorylation of these tyrosine residues, we constructed an EpoR-8YF mutant in which we substituted all eight tyrosine residues with phenylalanine. Co-expression of EpoR-8YF with the JAK2 V617F mutant failed to induce cytokine-independent cell proliferation and tumorigenesis, indicating that JAK2-mediated EpoR phosphorylation is the reason for JAK2 V617F mutant-induced oncogenic signaling. An exhaustive mutational analysis of the eight EpoR tyrosine residues indicated that three of these residues, Tyr-343, Tyr-460, and Tyr-464, are required for the JAK2 V617F mutant to exhibit its oncogenic activity. We also showed that phosphorylation at these three residues was necessary for full activation of the transcription factor STAT5, which is a critical downstream factor of JAK2 V617F-induced oncogenic signaling. In contrast, Epo stimulation could moderately stimulate the proliferation of cells expressing wild type JAK2 and EpoR-8YF, suggesting that the requirement of the phosphorylation of these three tyrosine residues seems to be specific for the oncogenic proliferation provoked by V617F mutation. Collectively, these results have revealed that phosphorylation of Tyr-343, Tyr-460, and Tyr-464 in EpoR underlies JAK2 V617F mutant-induced tumorigenesis. We propose that the targeted disruption of this pathway has therapeutic utility for managing MPN.The proliferation and differentiation of hematopoietic cells are regulated by various cytokines that act through their specific receptors (1, 2). Erythropoietin (Epo) 2 is a pleiotropic cytokine that exhibits hematopoietic functions such as the development of erythrocytes through the erythropoietin receptor (EpoR) (3). Once Epo binds to EpoR, the non-receptor tyrosine kinase, Janus kinase 2 (JAK2), which interacts with EpoR, is activated. Activated JAK2 then immediately phosphorylates multiple tyrosine residues in the cytoplasmic domain of EpoR (4).EpoR contains the following eight tyrosine residues in its intracellular domain that are phosphorylated by JAK2: Tyr-343, Tyr-401, Tyr-429, Tyr-431, Tyr-443, Tyr-460, Tyr-464, and Tyr-479. The JAK2-induced phosphorylation of these tyrosine residues in EpoR provides a platform for the recruitment and activation of signaling mediators and is critical for Epo-induced cellular proliferation (3, 5, 6). Previous studies clarified that the transcription factor, signal transducer and activator of transcript...

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A new high affinity binding site for suppressor of cytokine signaling‐3 on the erythropoietin receptor

Cited by 80 publications

References 52 publications

The myeloproliferative disorder–associated JAK2 V617F mutant escapes negative regulation by suppressor of cytokine signaling 3

The myeloproliferative disorder–associated JAK2 V617F mutant escapes negative regulation by suppressor of cytokine signaling 3

Regulation of multiple cytokine signalling pathways by SOCS3 is independent of SOCS2

Three Tyrosine Residues in the Erythropoietin Receptor Are Essential for Janus Kinase 2 V617F Mutant-induced Tumorigenesis

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