Regulation of PDGF‐stimulated SHIP2 tyrosine phosphorylation and association with Shc in 3T3‐L1 preadipocytes

Artemenko, Yulia; Gagnon, AnneMarie; Ibrahim, S. A.; Sorisky, Alexander

doi:10.1002/jcp.20965

Cited by 10 publications

(15 citation statements)

References 42 publications

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“…There is extensive research about the phosphorylation of SHIP by tyrosine kinases, such as Src family kinases or Syk (12), or by platelet-derived growth factor (35), but phosphorylation of SHIP1 on serine or threonine residues has not been reported. Here, we provide six lines of evidence that SHIP1 is phosphorylated by PKA and that this event stimulates the catalytic activity of SHIP1.…”

Section: Discussionmentioning

confidence: 99%

Regulation of the Src Homology 2 Domain-containing Inositol 5′-Phosphatase (SHIP1) by the Cyclic AMP-dependent Protein Kinase

Zhang

Walk

Ravichandran

et al. 2009

Journal of Biological Chemistry

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Many agents that activate hematopoietic cells use phosphatidylinositol 3,4,5-trisphosphate (PtdIns 3,4,5-P 3 ) to initiate signaling cascades. The SH2 domain-containing inositol 5 phosphatase, SHIP1, regulates hematopoietic cell function by opposing the action of phosphatidylinositol 3-kinase and reducing the levels of PtdIns 3,4,5-P 3 . Activation of the cyclic AMPdependent protein kinase (PKA) also opposes many of the proinflammatory responses of hematopoietic cells. We tested to see whether the activity of SHIP1 was regulated via phosphorylation with PKA. We prepared pure recombinant SHIP1 from HEK-293 cells and found it can be rapidly phosphorylated by PKA to a stoichiometry of 0.6 mol of PO 4 /mol of SHIP1. In Overall, activation of G protein-coupled receptors that raise cyclic AMP cause SHIP1 to be phosphorylated and stimulate its inositol phosphatase activity. These results outline a novel mechanism of SHIP1 regulation. Activation of phosphatidylinositol 3-kinase (PtdIns 3-kinase)2 is central to regulation of multiple cell functions including cell shape changes, cell migration, cell activation, and proliferation (1). PtdIns 3-kinase phosphorylates phosphatidylinositol 4,5-bisphosphate in the inner leaflet of the plasma membrane to generate phosphatidylinositol 3,4,5-trisphosphate (PtdIns 3,4,5-P 3 ) (2). PtdIns 3,4,5-P 3 then activates downstream signaling pathways by interacting with pleckstrin homology domain-containing proteins, such as phosphoinositide-dependent kinase 1 and the serine-threonine kinase Akt (3). The finding of abnormal activation of the PtdIns 3-kinase pathway in cancer cells has led to interest in the development of inhibitors for PtdIns 3-kinase (4).The level of PtdIns 3,4,5-P 3 is stimulated by multiple members of the PtdIns 3-kinase family (2) and is opposed by two phosphatidylinositol phosphatases: the Src homology 2 (SH2) domain-containing inositol 5Ј phosphatase (SHIP) and the 3Ј inositol phosphatase, phosphatase and tensin homolog (PTEN) (5). PTEN removes phosphate from the 3Ј position in the inositol ring of PtdIns 3,4,5-P 3 and converts it to phosphatidylinositol 4,5-bisphosphate (6). PTEN has a C2 domain, a PDZbinding motif, and a N-terminal phosphatidylinositol 4,5-bisphosphate binding motif essential for translocation to the membrane and interaction with other regulatory proteins (7). There are serine and threonine residues in PTEN that have been found to be phosphorylated, but their role in regulating the activity of the enzyme is not clear (8). Mutations in the PTEN protein have been observed in many tumors, suggesting a role for this enzyme in cancer (9).In contrast, SHIP dephosphorylates the 5Ј position on the inositol ring and produces phosphatidylinositol 3,4-bisphosphate (10). There are three isoforms of SHIP: the 145-kDa hematopoietic cell restricted SHIP (also known as SHIP1); the 104-kDa stem cell-restricted SHIP, sSHIP; and the more widely expressed 150-kDa SHIP2 (11). SHIP1 is the major inositol phosphatase regulating PtdIns 3,4,5-P 3 in monocytes, macrophages,...

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Section: Discussionmentioning

confidence: 99%

Regulation of the Src Homology 2 Domain-containing Inositol 5′-Phosphatase (SHIP1) by the Cyclic AMP-dependent Protein Kinase

Zhang

Walk

Ravichandran

et al. 2009

Journal of Biological Chemistry

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“…To determine if the truncation mutants could be phosphorylated in vitro, the four constructs were transiently expressed in HEK-293 cells, and the proteins were purified using anti-FLAG beads and incubated with 30 units of the catalytic subunit of PKA and [␥- 32 P]ATP at 30°C for 10 min. Fig.…”

Section: Identification Of the Serine/threonine Residues Phosphorylatmentioning

confidence: 99%

“…) in the C-terminal region of SHIP2 (32)(33)(34). These three residues are located near Tyr 986 , a well known tyrosine phosphorylation site in the NPXY motif of the molecule.…”

mentioning

confidence: 99%

“…These three residues are located near Tyr 986 , a well known tyrosine phosphorylation site in the NPXY motif of the molecule. Therefore, it has been suggested that the phosphorylation of Thr 958 , Ser 1003 , or Ser 982 could affect the affinity of Tyr 986 for its tyrosine kinase (32). Although there are a number of serine or threonine residues in the corresponding NPXY region of SHIP1 (see Fig.…”

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confidence: 99%

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A Key Role for the Phosphorylation of Ser440 by the Cyclic AMP-dependent Protein Kinase in Regulating the Activity of the Src Homology 2 Domain-containing Inositol 5′-Phosphatase (SHIP1)

Zhang

Ravichandran

Garrison

2010

Journal of Biological Chemistry

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). Using a combination of approaches, we identified the serine residue regulating SHIP1 activity. After mass spectrometric identification of 17 serine and threonine residues on SHIP1 as being phosphorylated by PKA in vitro, studies with truncation mutants of SHIP1 narrowed the phosphorylation site to the catalytic region between residues 400 and 866. Of the two candidate phosphorylation sites located in this region (Ser 440 and Ser 2 is central to many intracellular signaling cascades (1). PtdIns-3,4,5-P 3 is produced in the inner leaflet of the plasma membrane by a family of phosphatidylinositol 3-kinases that are activated by receptor tyrosine kinases or G proteincoupled receptors (2). The PtdIns-3,4,5-P 3 localized at the plasma membrane forms a docking site to attract and regulate downstream signaling molecules containing pleckstrin homology domains, such as the serine kinase, Akt (PKB), that has an essential role in stimulating cell proliferation, growth, survival, and metabolism (2, 3). The level of PtdIns-3,4,5-P 3 in the membrane is opposed by two inositol lipid phosphatases, PTEN (phosphatase and tensin homologue) and SHIP (SH2 domaincontaining inositol 5Ј-phosphatase) (4). SHIP opposes the effects of phosphatidylinositol 3-kinases by dephosphorylating the 5Ј-position on the inositol ring of PtdIns-3,4,5-P 3 and producing phophatidylinositol 3,4-bisphosphate (5).There are two major members of the SHIP family, SHIP1 and SHIP2, that share a highly homologous catalytic region with less similarity in their C-terminal regions (6). SHIP2 is widely expressed, whereas SHIP1 is only expressed in hematopoietic cells (7). SHIP1 was originally identified based on its ability to bind to cytoplasmic adaptor proteins, such as Shc, Dab-1, and Dok-3 (8). SHIP1 contains an N-terminal SH2 domain that leads to interactions with immune receptors, such as Fc␥RIIB and Fc⑀RI (9), a central inositol 5Ј-phosphatase domain, and two tyrosines within NPXY motifs in the C-terminal prolinerich region (10). Genetic manipulations of SHIP1 in mice have shown that SHIP1 plays important roles in functions of myeloid cells and B lymphocytes; for example, in mature neutrophils and mast cells, PtdIns-3,4,5-P 3 levels and the phosphorylation of Akt activity are significantly elevated in the absence of SHIP1 (11). Similarly, B lymphocytes lacking SHIP1 are insensitive to inhibitory signaling via the Fc␥RIIB receptor (9). Moreover, SHIP1 Ϫ/Ϫ mice have a decreased viability due to an increased infiltration of myeloid cells into the lungs, perhaps due to activation of migration pathways because of the elevated levels of PtdIns-3,4,5-P 3 (12).Due to its importance in hematopoietic cells, the activity of SHIP1 is tightly regulated. One model for regulation of SHIP1 function envisions translocation of SHIP1 from the cytosol to the membrane (13). Upon stimulation by growth factors, cytokine receptors, or specific signaling receptors on lymphocytes, SHIP1 is recruited via its N-terminal SH2 domain to phosphorylated tyrosine residues in receptor kina...

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“…The first evidence of SHIP2 phosphorylation on Ser/Thr was provided in platelet-derived growth factor (PDGF)-stimulated 3T3-L1 preadipocytes overexpressing SHIP2 [41]. Phospho SHIP2 T958 was identified in response to PDGF and this phosphorylation event may decrease SHIP2 tyrosine phosphorylation and interaction with a major adaptor protein Shc.…”

Section: Ship2 Phosphorylation On T958 and S132 And Other Phosphositesmentioning

confidence: 99%

Reversible Ser/Thr SHIP phosphorylation: A new paradigm in phosphoinositide signalling?

et al. 2012

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Phosphoinositide (PI) phosphatases such as the SH2 domain-containing inositol 5-phosphatases 1/2 (SHIP1 and 2) are important signalling enzymes in human physiopathology. SHIP1/2 interact with a large number of immune and growth factor receptors. Tyrosine phosphorylation of SHIP1/2 has been considered to be the determining regulatory modification. However, here we present a hypothesis, based on recent key publications, highlighting the determining role of Ser/Thr phosphorylation in regulating several key properties of SHIP1/2. Since a subunit of the Ser/Thr phosphatase PP2A has been shown to interact with SHIP2, a putative mechanism for reversing SHIP2 Ser/Thr phosphorylation can be anticipated. PI phosphatases are potential target molecules in human diseases, particularly, but not exclusively, in cancer and diabetes. Therefore, this novel regulatory mechanism deserves further attention in the hunt for discovering novel or complementary therapeutic strategies. This mechanism may be more broadly involved in regulating PI signalling in the case of synaptojanin1 or the phosphatase, tensin homolog, deleted on chromosome TEN.

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Regulation of PDGF‐stimulated SHIP2 tyrosine phosphorylation and association with Shc in 3T3‐L1 preadipocytes

Cited by 10 publications

References 42 publications

Regulation of the Src Homology 2 Domain-containing Inositol 5′-Phosphatase (SHIP1) by the Cyclic AMP-dependent Protein Kinase

Regulation of the Src Homology 2 Domain-containing Inositol 5′-Phosphatase (SHIP1) by the Cyclic AMP-dependent Protein Kinase

A Key Role for the Phosphorylation of Ser440 by the Cyclic AMP-dependent Protein Kinase in Regulating the Activity of the Src Homology 2 Domain-containing Inositol 5′-Phosphatase (SHIP1)

Reversible Ser/Thr SHIP phosphorylation: A new paradigm in phosphoinositide signalling?

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