scholarly journals Multiple stimuli induce tyrosine phosphorylation of the Crk-binding sites of paxillin

2001 ◽  
Vol 360 (1) ◽  
pp. 57-66 ◽  
Author(s):  
Michael D. SCHALLER ◽  
Erik M. SCHAEFER
Keyword(s):  
Cell Adhesion ◽  
Tyrosine Phosphorylation ◽  
Binding Sites ◽  
Signalling Molecules ◽  
Src Homology 2 ◽  
Dependent Cell ◽  
Src Homology ◽  
Tyrosine Phosphorylated Protein ◽  
Src Homology 2 Domain

Paxillin is a focal-adhesion-associated, tyrosine-phosphorylated protein. In cells transformed by the src, crk or BCR-Abl oncogenes, the phosphotyrosine content of paxillin is elevated. In normal cells paxillin functions in signalling following integrin-dependent cell adhesion or exposure to a number of stimuli, including growth factors and neuropeptides. These stimuli induce tyrosine phosphorylation of paxillin, regulating the association of Src homology 2 domain-containing signalling molecules with paxillin. There are multiple sites of tyrosine phosphorylation on paxillin. To elucidate the role of paxillin in transducing signals in response to various stimuli, it is essential to identify all of the sites of phosphorylation on paxillin and to define which residues are phosphorylated in response to distinct stimuli. We describe two new sites of tyrosine phosphorylation on paxillin, residues at positions 40 and 88. Using paxillin variants with phenylalanine substitutions at phosphorylation sites and phospho-specific paxillin antibodies, tyrosine phosphorylation of paxillin in response to distinct stimuli was examined. The results demonstrate that Tyr31 and Tyr118, which are binding sites for Crk, are major sites of tyrosine phosphorylation following cell adhesion or stimulation with platelet-derived growth factor or angiotensin II. Thus multiple stimuli may elicit similar signalling events downstream of paxillin.

scholarly journals SRC Homology 2 Domain Binding Sites in Insulin, IGF-1 and FGF receptor mediated signaling networks reveal an extensive potential interactome

2012 ◽  
Vol 10 (1) ◽  
pp. 27 ◽  
Author(s):  
Bernard A Liu ◽  
Brett W Engelmann ◽  
Karl Jablonowski ◽  
Katherine Higginbotham ◽  
Andrew B Stergachis ◽  
...  
Keyword(s):  
Binding Sites ◽  
Signaling Networks ◽  
Fgf Receptor ◽  
Src Homology 2 ◽  
Src Homology ◽  
Src Homology 2 Domain

scholarly journals The control of phosphatidylinositol 3,4-bisphosphate concentrations by activation of the Src homology 2 domain containing inositol polyphosphate 5-phosphatase 2, SHIP2

2007 ◽  
Vol 407 (2) ◽  
pp. 255-266 ◽  
Author(s):  
Ian H. Batty ◽  
Jeroen van der Kaay ◽  
Alex Gray ◽  
Joan F. Telfer ◽  
Miles J. Dixon ◽  
...  
Keyword(s):  
Growth Factor ◽  
Tyrosine Phosphorylation ◽  
Specific Activity ◽  
Protein Tyrosine Phosphatases ◽  
Fold Increase ◽  
Inositol Polyphosphate ◽  
Src Homology 2 ◽  
Pi3k Activity ◽  
Src Homology ◽  
Src Homology 2 Domain

Activation of class Ia PI3K (phosphoinositide 3-kinase) produces PtdInsP3, a vital intracellular mediator whose degradation generates additional lipid signals. In the present study vanadate analogues that inhibit PTPs (protein tyrosine phosphatases) were used to probe the mechanisms which regulate the concentrations of these molecules allowing their independent or integrated function. In 1321N1 cells, which lack PtdInsP3 3-phosphatase activity, sodium vanadate or a cell permeable derivative, bpV(phen) [potassium bisperoxo(1,10-phenanthroline)oxovanadate (V)], increased the recruitment into anti-phosphotyrosine immunoprecipitates of PI3K activity and of the p85 and p110α subunits of class Ia PI3K and enhanced the recruitment of PI3K activity stimulated by PDGF (platelet-derived growth factor). However, neither inhibitor much increased cellular PtdInsP3 concentrations, but both diminished dramatically the accumulation of PtdInsP3 stimulated by PDGF or insulin and markedly increased the control and stimulated concentrations of PtdIns(3,4)P2. These actions were accounted for by the ability of PTP inhibitors to stimulate the activity of endogenous PtdInsP3 5-phosphatase(s), particularly SHIP2 (Src homology 2 domain containing inositol polyphosphate 5-phosphatase 2) and to inhibit types I and II PtdIns(3,4)P2 4-phosphatases. Thus bpV(phen) promoted the translocation of SHIP2 from the cytosol to a Triton X-100-insoluble fraction and induced a marked (5–10-fold) increase in SHIP2 specific activity mediated by enhanced tyrosine phosphorylation. The net effect of these inhibitors was, therefore, to switch the signal output of class I PI3K from PtdInsP3 to PtdIns(3,4)P2. A key component controlling this shift in the balance of lipid signals is the activation of SHIP2 by increased tyrosine phosphorylation, an effect observed in HeLa cells in response to both PTP inhibitors and epidermal growth factor.

scholarly journals Role of the Lck Src Homology 2 and 3 Domains in Protein Tyrosine Phosphorylation

1996 ◽  
Vol 271 (40) ◽  
pp. 25003-25010 ◽  
Author(s):  
Kay K. Lee-Fruman ◽  
Tassie L. Collins ◽  
Steven J. Burakoff
Keyword(s):  
Tyrosine Phosphorylation ◽  
Protein Tyrosine Phosphorylation ◽  
Protein Tyrosine ◽  
Src Homology 2 ◽  
Src Homology

scholarly journals B Cell Adaptor Containing Src Homology 2 Domain (Bash) Links B Cell Receptor Signaling to the Activation of Hematopoietic Progenitor Kinase 1

2001 ◽  
Vol 194 (4) ◽  
pp. 529-540 ◽  
Author(s):  
Sachiyo Tsuji ◽  
Mariko Okamoto ◽  
Koichi Yamada ◽  
Noriaki Okamoto ◽  
Ryo Goitsuka ◽  
...  
Keyword(s):  
B Cells ◽  
B Cell ◽  
Tyrosine Phosphorylation ◽  
Phosphorylation Site ◽  
Sh2 Domain ◽  
Hematopoietic Progenitor ◽  
Src Homology 2 ◽  
Bcr Signaling ◽  
Src Homology ◽  
Src Homology 2 Domain

The B cell adaptor containing src homology 2 domain (BASH; also termed BLNK or SLP-65), is crucial for B cell antigen receptor (BCR)-mediated activation, proliferation, and differentiation of B cells. BCR-mediated tyrosine-phosphorylation of BASH creates binding sites for signaling effectors such as phospholipase Cγ (PLCγ)2 and Vav, while the function of its COOH-terminal src homology 2 domain is unknown. We have now identified hematopoietic progenitor kinase (HPK)1, a STE20-related serine/threonine kinase, as a protein that inducibly interacts with the BASH SH2 domain. BCR ligation induced rapid tyrosine-phosphorylation of HPK1 mainly by Syk and Lyn, resulting in its association with BASH and catalytic activation. BCR-mediated activation of HPK1 was impaired in Syk- or BASH-deficient B cells. The functional SH2 domain of BASH and Tyr-379 within HPK1 which we identified as a Syk-phosphorylation site were both necessary for interaction of both proteins and efficient HPK1 activation after BCR stimulation. Furthermore, HPK1 augmented, whereas its kinase-dead mutant inhibited IκB kinase β (IKKβ) activation by BCR engagement. These results reveal a novel BCR signaling pathway leading to the activation of HPK1 and subsequently IKKβ, in which BASH recruits tyrosine-phosphorylated HPK1 into the BCR signaling complex.

scholarly journals A Regulatory Role for Src Homology 2 Domain–Containing Inositol 5′-Phosphatase (Ship) in Phagocytosis Mediated by Fcγ Receptors and Complement Receptor 3 (αMβ2; Cd11b/Cd18)

2000 ◽  
Vol 193 (1) ◽  
pp. 61-72 ◽  
Author(s):  
Dianne Cox ◽  
Benjamin M. Dale ◽  
Masaki Kashiwada ◽  
Cheryl D. Helgason ◽  
Steven Greenberg
Keyword(s):  
Cell Model ◽  
Complement Receptor ◽  
Phosphatidylinositol 3 Kinase ◽  
Src Homology 2 ◽  
Catalytically Active ◽  
Src Homology ◽  
Complement Receptor 3 ◽  
Phagocytic Cups ◽  
Src Homology 2 Domain

The Src homology 2 domain–containing inositol 5′-phosphatase (SHIP) is recruited to immunoreceptor tyrosine-based inhibition motif (ITIM)–containing proteins, thereby suppressing phosphatidylinositol 3-kinase (PI 3-kinase)–dependent pathways. The role of SHIP in phagocytosis, a PI 3-kinase–dependent pathway, is unknown. Overexpression of SHIP in macrophages led to an inhibition of phagocytosis mediated by receptors for the Fc portion of IgG (FcγRs). In contrast, macrophages expressing catalytically inactive SHIP or lacking SHIP expression demonstrated enhanced phagocytosis. To determine whether SHIP regulates phagocytosis mediated by receptors that are not known to recruit ITIMs, we determined the effect of SHIP expression on complement receptor 3 (CR3; CD11b/CD18; αMβ2)–dependent phagocytosis. Macrophages overexpressing SHIP demonstrated impaired CR3-mediated phagocytosis, whereas macrophages expressing catalytically inactive SHIP demonstrated enhanced phagocytosis. CR3-mediated phagocytosis in macrophages derived from SHIP−/− mice was up to 2.5 times as efficient as that observed in macrophages derived from littermate controls. SHIP was localized to FcγR- and CR3-containing phagocytic cups and was recruited to the cytoskeleton upon clustering of CR3. In a transfected COS cell model of activation-independent CR3-mediated phagocytosis, catalytically active but not inactive SHIP also inhibited phagocytosis. We conclude that PI 3-kinase(s) and SHIP regulate multiple forms of phagocytosis and that endogenous SHIP plays a role in modulating β2 integrin outside-in signaling.

scholarly journals Role of the protein tyrosine phosphatase SHP-1 (Src homology phosphatase-1) in the regulation of interleukin-3-induced survival, proliferation and signalling

2002 ◽  
Vol 368 (3) ◽  
pp. 885-894 ◽  
Author(s):  
Nicholas R.D. PALING ◽  
Melanie J. WELHAM
Keyword(s):  
Tyrosine Phosphorylation ◽  
Tyrosine Phosphatase ◽  
Ectopic Expression ◽  
Negative Regulator ◽  
Interleukin 3 ◽  
Extracellular Signal ◽  
Dependent Cell ◽  
Src Homology ◽  
Β Chain

The tyrosine phosphatase SHP-1 (Src homology phosphatase-1) has been widely implicated as a negative regulator of signalling in immune cells. We have investigated in detail the role of SHP-1 in interleukin-3 (IL-3) signal transduction by inducibly expressing wild-type (WT), C453S (substrate-trapping) and R459M (catalytically inactive) forms of SHP-1 in the IL-3-dependent cell line BaF/3. Expression of WT SHP-1 had little impact on IL-3-induced proliferation, but enhanced apoptosis following IL-3 withdrawal. Expression of R459M SHP-1 increased the proliferative response of BaF/3 cells to IL-3 and increased cell survival at low doses of IL-3 and following IL-3 withdrawal. Investigation into the biochemical consequences resulting from expression of these SHP-1 variants demonstrated that the β chain of the IL-3 receptor (Aic2A) was hypo-phosphorylated in cells expressing WT SHP-1 and hyper-phosphorylated in those expressing R459M SHP-1. Further, ectopic expression of the trapping mutant, C453S SHP-1, protected Aic2A from dephosphorylation, suggesting that Aic2A is a SHP-1 substrate in BaF/3 cells. Examination of overall levels of tyrosine phosphorylation demonstrated that they were not perturbed in these transfectants. Activation-specific phosphorylation of STAT (signal transducer and activator of transcription) 5a/b, protein kinase B and ERK (extracellular-signal-regulated kinase)-1 and −2 was also unaffected by expression of WT or R459M SHP-1. However, overall levels of IL-3-induced tyrosine phosphorylation of STAT5 were reduced upon expression of WT SHP-1 and increased when R459M SHP-1 was expressed, consistent with STAT5 being a potential SHP-1 substrate. These results demonstrate that SHP-1 acts to negatively regulate IL-3-driven survival and proliferation, potentially via regulation of tyrosine phosphorylation of Aic2A and STAT5.

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